applied sciences Article
Research on the Hygroscopicity of a Composite Hygroscopic Material and its Influence on Indoor Thermal and Humidity Environment Huahui Xie 1 , Guangcai Gong 1, *, Yi Wu 2 , Yongchao Liu 1 and Yingjuan Wang 1 1 2
*
College of Civil Engineering, Hunan University, Changsha 410006, China;
[email protected] (H.X.);
[email protected] (Y.L.);
[email protected] (Y.W.) College of Engineering, Hunan Agriculture University, Changsha 410128, China;
[email protected] Correspondence:
[email protected]; Tel.: +86-139-7312-3865; Fax: +86-731-8882-3082
Received: 12 February 2018; Accepted: 10 March 2018; Published: 13 March 2018
Abstract: Indoor air humidity is closely related to daily life and productivity. It is necessary to develop new materials which can maintain the indoor humidity environment steady within an acceptable range of 40–70%. In this paper a new composite hygroscopic material composed of wood fibre and sepiolite with expanded perlite (CHM-WSE) is used in a building envelope to evaluate its moisture buffering performance. A series of experiments assessing the microstructure, hygroscopicity, mechanical and thermodynamic properties of the new composite hygroscropic material have been executed. Furthermore, a numerical model for predicting the influence of humidity environment and energy consumption on composite hygroscopic mortar in different climatic regions has been established. The experiments show that the indoor moisture buffering performance in late spring is better than that in winter, when the practical moisture buffering performance can reach at 0.89 g/(m2 %RH)@8/16h; and the non-uniformity coefficient of indoor relative humidity is about 0.006. The simulation results show that a room with CHM-WSE is more comfortable than a common mortar (CM) room, and it has better energy-saving performance in the hot summer and cold winter (HSCW) region in China. The experiments and simulations show that the developed hygroscopic material could be feasible for application in buildings. Keywords: composite hygroscopic material; building envelope; microstructure; hygroscopicity; multi-climatic region; thermal and humidity environment
1. Introduction Relative air humidity is one of the important environmental parameters closely related to daily life and productivity [1]. Many evidences have indicated that high or low indoor humidity environments are closely related to many health problems [2–4], energy consumption [5] and the durability of the building envelope [6,7]. Therefore, it is essential to maintain the indoor humidity environment steady within an acceptable range of 40–70% [8]. It is well known that porous materials have excellent adsorption properties. For example, hygroscopic building materials can absorb moisture in a high humidity environment and desorb it in a low humidity environment, and thus they can adjust the indoor relative humidity without energy consumption. These materials have drawn increasing interest of researchers. The humidity level in a building depends on a combination of factors, such as moisture sources, ventilation and air movement, sources and sinks, heating, insulation, external conditions, as well as building materials and occupant behaviour. Among these, the moisture buffering performance of the materials used in a building is an important factor. Researchers have carried out extensive studie
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on the microstructure, the adsorption/desorption isotherm, and moisture absorption performance of composite hygroscopic materials. Kaufhold et al. [9] investigated specific surface area of different bentonites considering them strictly relating to microporosity. Several studies have investigated the hygrothermal properties of unfired clays and shown their potential for passive buffering of relative humidity fluctuations in building physics applications [10–14]. Standard evaluation methods for the assessment of the moisture buffering performance of building materials have been issued in Japan, America and China. The moisture buffering characteristics of hygroscopic materials used for interior finishing or furnishing materials in buildings can improve thermal comfort and save energy by reducing the operating hours and/or the size of HVAC systems [15–19]. Mitchell et al. [20] investigated the hygroscopic adsorption/desorption and thermal properties of expanded vitrified small hollow ball (EVSB) and normal expanded perlite particle (NEPP) mortars. Osanyintola et al. [21,22] used the moisture buffer value (MBV) testing method to investigate the factors influencing the buffering capacity of plywood in two different facilities. Wu et al. [23] moulded a series of wood fibre, sepiolite and expanded perlite (WSE)-based mortars, and tested the hygroscopic performance, thermal and mechanical properties of these mortars. They pointed out that WSE-based mortars have good moisture adsorption and desorption properties. Moisture buffering is the dynamic process of the interaction between the hygroscopic materials and the indoor humid air, and it is related to the building structure characteristics. In previous research, priority was given to analysis and evaluation the moisture absorption ability of the specimen of hygroscopic building materials. The NORDTEST Project [24], Japanese Industrial Standard (JIS) A1470-1 [25], and ISO/DIS 24353 [26] have proposed experimental methods to evaluate the moisture buffering performance. However, all these methods assume a well-mixed room air and only tested a material sample in a small climatic oven without ventilation. These evaluation methods are limited to the material level. The moisture buffering performance is often disregarded by building designers and engineers. The moisture buffer capacity of the wall covering materials, as well as furniture and textiles inside the buildings, define the hygroscopic inertia level of a room, which can play an important role in the reduction of RH peaks. There are few studies about the application of hygroscopic materials for building envelopes and its impact on the indoor environment. At the same time few large-scale experimental investigations have been carried out on the hygroscopic material buffering performance at the room level. In this paper, a variety of energy-saving and environment-friendly hygroscopic materials are studied. A composite hygroscopic mortar is made using different mixing proportions, and those with better performance are selected and applied to a building envelope. Comparative temperature and humidity distribution experiments on the indoor air of a room with CHM-WSE and CM are performed. Based on these results the effect of hygroscopic materials on the distribution of the relative humidity in the large scale space in different seasons, temperatures and humidity conditions of central China are tested. Central China has some typical climate characteristics such as wet and cold weather in winter and wet and hot weather in late spring. The heating and cooling energy consumption and humidity distribution of the test room in different climatic regions are simulated to study the hygroscopictiy and energy-saving performance of the materials. 2. Materials and Method 2.1. Testing the Composite Hygroscopic Material 2.1.1. Specimens The hygroscopic aggregate is composed of wood fibre, sepiolite, expanded perlite, and abbreviated as WSE. The pore structure and bulk density parameters are shown in Table 1. Xie [27] and Wu [28] concluded that the WSE-based mortar has good adsorption properties.
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Table 1. Properties of insulated aggregates [16]. Raw Materials
Specific Surface Area (m2 /g)
Total Pore Volume (mL/g)
Desorption of Pore Volume (mL/g)
Average Pore Diameter (nm)
Bulk Density (kg/m3 )
Wood fibre Expanded perlite Sepiolite
3.000 2.851 125.83
0.0103 0.0091 0.319
0.01122 0.00989 0.31969
13.733 12.77 10.14
86 76 277.5
Polypropylene fibres of 6 mm average fibre length, were obtained from company (Tian Xie Chemical Co., Ltd., Nanjing, China). Redispersible powder (RP) can improve the workability of the cement paste and increase the adhesive strength and enhance the application performance of the mortar. The main component of diatom ooze is diatomite. It has large specific surface area and good adsorbability. Taking WSE as a reference, and adding in different ratios of diatom ooze, polypropylene fiber, redispersible powder, Portland cement (P.O 42.5) we prepared composite hygroscopic mortar specimens with different mixing proportions. The ratios are shown in Table 2. In group A, cement is replaced by diatom ooze (by mass ratio), and the polypropylene fiber mortar incorporated in group A is 10%, 30%, 70% of that in group C, respectively. In Group B, 50% sepiolite is replaced by diatom ooze (by mass ratio), and wood fiber, sepiolite, and expanded perlite are mixed in volume proportions of 1:1:4. Group C-1 composed of wood fiber, sepiolite and expanded perlite in a volume proportion of 1:2:4 functions as the reference material. Group C-2 does not contain added polypropylene fiber. Table 2. Mix ratios of the experimental mortars. Mortar Samples
Wood Fibre (mL)
Sepiolite (mL)
Expanded Perlite (mL)
Polypropylene Fibre (g)
Redispersible Powder (g)
Portland Cement (g)
Diatom Ooze (g)
A-1 A-2 A-3 B-1 C-1 C-2
17 17
34 34 34 17 34 34
68 68 68 68 68 68
0.3 0.9 2.1 3 3 0
4 4 4 4 4 4
50 70 50 100 100 100
50 25 50 45 -
17 17 17
In order to ensure the aggregate, reinforcing fiber, modified component and gelling components are well mixed and at the same time that the aggregate is not damaged, a multi-stage mixing method is adopted in mixing the raw materials. Before mechanical stirring, an artificial premix is adopted to ensure the raw materials are well mixed, and then the cement is added with a blender, mixing for 1 min, then a moderate amount of water is added with stirring for 3 min. The composite hygroscopic mortars are cured in an environment of 23◦ C and 98% RH for 7 days and then the RH is adjusted to 45%~75% for 21 days. The surface is covered with polyethylene film. 2.1.2. Microstructure Characterization The porous structure, pore size distribution, pore volume and specific surface area of the material determine the rate of moisture absorption and desorption and the rate of moisture absorption and desorption. In this study, an environmental scanning electron microscope (SEM) (QUANTA 200, FEI, Hillsboro, TX, USA) is used to observe and study the micromorphology of the composite hygroscopic materials. According to ISO15901 [29], a Brunauer-Emmett-Teller (BET) surface area analyzer and the Barret-Joyner-Halenda (BJH) (Tri-star 3020, Micromeritics, Norcross, GA, USA) method are used to describe the pore features of the specimens. 2.1.3. Mechanical Strength Composite hygroscopic materials used as the coating mortar in a building envelope, should meet the mechanical requirements of building materials. Compressive strength and flexural strength
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are tested to meet the plastering requirement of mortar. According to the Chinese standard GB/T 5486.2 [30], 40 mm × 40 mm × 160 mm cube specimens are moulded for test, taking the average of 10 groups of measurement. 2.1.4. Adsorption/Desorption Isotherm The adsorption/desorption isotherm is the basis of any dynamic analysis of moisture transfer and represents an important means of assessing the hygroscopic properties of materials. The isothermal adsorption curve is based on the moisture content of the test material according to ISO 12571 [31]. The experimental climate chamber is equipped with an oven. The temperature of the oven is controlled by an electric heater wire and the relative humidity is controlled by different saturated salt solutions. The specimen size is 100 mm × 100 mm × 20 mm. The specimens were dried at 105 ◦ C to constant weight after being cured under standard conditions. Before each test, the cured specimens are placed in the climatic chamber for a test interval of not less than 24 h until the mass change of two consecutive measurements is less than 0.1%. After drying, the specimens are wrapped in plastic, cooled to room temperature and weighed. The specimens are then placed in the air above saturated salt solutions in 1-L glass jars until equilibrium is reached. The mass is weighed, and the specimens are placed in a jar with a different salt and the process is repeated with increments of about 10% RH up to 97% RH for the adsorption process. In the experiments, the temperature of isothermal adsorption is set as 20 ◦ C, 25 ◦ C and 40 ◦ C, respectively. The hygroscopic properties of specimens are tested respectively in six kinds of humidity conditions. The equilibrium moisture content (u) at a given relative humidity is calculated as: u=
m − m0 m0
(1)
where m is the final mass of a specimen after equilibrium is attained between the specimen and the air in the jar at a particular relative humidity, in g; m0 is the mass of the dry specimen, in g. 2.1.5. Density and Effective Thermal Conductivity After the application of the mortar, the wall components usually contain moisture, and this moisture content changes with the surrounding environment, as does the thermal performance of the material. The thermal conductivities of specimens for different equilibrium moisture contents are tested in this paper according to the ASTM standard C518-04 [32]. Composite hygroscopic mortar was poured into 300 mm × 300 mm × 30 mm steel moulds with glass bottom plates, and the specimens were covered with polyethylene mulch after being moulded. The specimens were dried at 105 ◦ C to constant weight after being cured under standard conditions for testing their dry density and thermal conductivity, taking the average of three measurements. After testing the thermal conductivity of the dried state, each specimen is moved into the climatic chamber, where the temperature is set to 23 ◦ C, and the relative humidity is set to 5%, 15%, 30%, 50%, respectively. After reaching a constant weight (a weight change of less than 0.1% within three days), the specimen was moved into the thermal conductivity apparatus for testing. A thermal conduction coefficient measurement apparatus DRCD-3030 (Hexing, Shenyang, Liaoning, China) was applied in the tests. 2.1.6. Water Vapor Permeability Materials which are able to take in or let out moisture either need to be porous or selectively permeable. The water vapor permeability is one of the parameters of the simulation. The transport properties of cement-based materials significantly affect their durability and hygroscopicity. The research of Zhang [33] shows that the water vapor permeability coefficient of expanded perlite under different relative humidity conditions is different (Table 3).
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Table 3. Water vapor diffusion coefficient of expanded perlite. Relative Humidity δs (kg/(m·Pa·s))
35.28–58.67%
58.67–64.46%
58.67–71.40%
10−11
10−11
10−11
2.953 ×
3.133 ×
2.980 ×
60.06–100% 3.251 × 10−11
The fitting formula of water vapor permeability coefficient of expanded perlite is as follows [33]: δs = 3.001 × 10−11 + 9.289 × 10−12 × ϕ8.08
(2)
where ϕ is relative humidity, in %. Referring to the multi-component physical parameter and weighted average molecular weight method, the water vapor permeability of a composite hygroscopic material is determined by the density of the water-absorbing material mixture: n
1/2 ∑ (ρi ) δi
δ=
i =1 n
1/2 ∑ ( ρi )
(3)
i =1
where δ is the water vapor permeability, in kg/(m·Pa·s); ρ is the density of material, in kg/m3 ; and i is the material category. 2.2. Moisture Buffer Performance of Room The moisture buffer performance of a room is the ability of the materials within the room to moderate variations in the relative humidity. These variations can be seasonal or diurnal. The determination of a practical moisture buffer value (MBVpractical ) should involve a run time which corresponds to that of typical exposure in practice—typically a daily variation. 2.2.1. Building Descriptions The test room is located in Changsha City, Ningxiang County, Hunan Province. Hunan is located in central China, with a highly humid climate. This test was conducted in January and April. In January, the outdoor temperature is low and relative humidity is high (for most of the time it is more than 95%), but the temperature and humidity changes between day and night are not obvious. April belongs to the late spring season, with typical climate characteristics of high temperature and high humidity, and the changes between day and night are large. Two identical rooms in a building are selected as the test rooms, which are the basic chamber (room I) and hygroscopic chamber (room II), with the same room area and layout. The two rooms are both located on the fifth floor and facing north (Figure 1). The envelope of the test rooms was a typical China residential RC frame structure. The size of each room is 3.0 m × 3.8 m × 3.2 m (length × width × height, Figure 2). There is a washroom in the test room. The washroom door is closed during the testing time, so the influence of the washroom on the tests is ignored. The structure of the building envelope is shown in Table 4. Room I has common cement mortar (CM) plastered on its inner surface. Room II has composite hygroscopic mortar (CHM-WSE) plastered on the inner surface with an area of 39.76 m2 . When CHM-WSE is used as interior wall insulation mortar, should be handled gently so as to protect its pore structure.
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Table 4. Structural form of the building envelope. Position
Structure (From Inside to Outside)
Roof
CM layer 20 mm + Steel Reinforced Concrete 100 mm + CM layer 20 mm + Waterproof layer + Plywood 25 mm + CM layer 20 mm
Room I
Exterior wall Interior wall
CM layer 20 mm + Porous brick 240 mm + CM layer 20 mm CM layer20 mm + Porous brick 190 mm + CM layer 20 mm
Room II
Exterior wall Interior wall
CHM-WSE 20 mm + Porous brick 240 mm + CM layer 20 mm CHM-WSE 20 mm + Porous brick 190 mm + CM layer 20 mm
Window
Double Low-E glass window + Aluminum alloy frame
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Figure 1. The tested building. Figure 1. The tested building. Figure 1. The tested building. 1.2 m
Window Window 0.8 m
washroom
0.8 m 2.0 m2.0 m
3.2 m3.2 m
washroom
1.8 m1.8 m
1.2 m
1.1 m 1.1 m
Door Door
3.0 m 3.0 m
Figure 2. Drawing of the test room. Figure 2. Drawing of the test room. Figure 2. Drawing of the test room.
2.2.2. Experimental Setting 2.2.2. Experimental Setting the performance test of specimens, a small blender is used for preparing the test materials. 2.2.2.InExperimental Setting In the performance test specimens, a small blender hygroscopic is used for preparing materials. However, there is a need for of a large amount of composite mortar forthe thetest room test, so In the performance test of specimens, a small blender is used for preparing the test materials. However, thereequipment is a need for a large amount medium-sized is used (Figure 3). of composite hygroscopic mortar for the room test, so However, there is a need for a large amount of composite hygroscopic mortar for the room test, so medium-sized equipment is used (Figure 3). medium-sized equipment is used (Figure 3).
Figure 2. Drawing of the test room.
2.2.2. Experimental Setting In the performance test of specimens, a small blender is used for preparing the test materials. 7 of so 28 a need for a large amount of composite hygroscopic mortar for the room test, medium-sized equipment is used (Figure 3).
Appl. Sci. 2018, 8, 430is However, there
(a)
(b)
Figure 3. The experimental set-up of text. (a) Cement paste mixer (b) Electronic balance (≤5 kg). Figure 3. The experimental set-up of text. (a) Cement paste mixer (b) Electronic balance (≤5 kg).
In order to ensure the performance of the porous material was not damaged, a multi-stage In order to ensure performance of thethe porous material was mixing mixing method is alsothe adopted in mixing raw materials for not thedamaged, room test.a multi-stage Before mechanical method ismanual also adopted in mixing the raw materials room test. Before stirring, Appl. Sci. 2018, 8, x 7 of 27 stirring, pre-mixing is conducted to ensurefor thethe good mixing of the mechanical raw materials. The manual pre-mixing is conducted to ensure the good mixing of the raw materials. The CHM-WSE was evenly plastered the inner surface theinner wall, surface except for and floor. 15 days of good CHM-WSE was on evenly plastered onofthe of the theceiling wall, except for After the ceiling and floor. ventilation, the of primer finish were in sequence. After the construction was After finished, After 15 days goodand ventilation, theplastered primer and finish were plastered in sequence. the test room was cross ventilated to dry the initial moisture to the mortar application. Tests are carried out construction was finished, test room was cross ventilated to dry the initial moisture to the mortar independently in each room. Temperature sensorsinare fixed on the wall, ceiling and floor. The layout application. Tests are carried out independently each room. Temperature sensors are fixed on the of the ceiling test room shown in layout Figuresof4the andtest 5. Temperature sensors are protected by silver paper from wall, andisfloor. The room is shown in Figures 4 and 5. Temperature sensors direct radiation. Data is recorded and stored by a 48-channel paperless recorder and a temperature and are protected by silver paper from direct radiation. Data is recorded and stored by a 48-channel humidity recorder. The outdoor and humidity meter arrangedtemperature in an open paperless automatic recorder and a temperature and temperature humidity automatic recorder. Theis outdoor space. The sealing performance of doors and windows which are closed during the test to the and humidity meter is arranged in an open space. The sealing performance of doors andreduce windows influence of outdoor parameters on indoor humidity is good. Temperature and humidity are recorded which are closed during the test to reduce the influence of outdoor parameters on indoor humidity is every h. good. 0.5 Temperature and humidity are recorded every 0.5 h.
9
Exterior window
3.8
Washroom
1 2
3
4 (Room center)
6
5
Door
8 3.0
Figure 4. Horizontal test point (h = 1.5 m). Figure 4. Horizontal test point (h = 1.5 m).
Ceiling
2m
10 11
7
Door
8 3.0
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Figure 4. Horizontal test point (h = 1.5 m).
10 11
Ceiling
H=3.2m
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4
12 13
Floor
Figure Figure5.5.Vertical Verticaltest testpoint. point.
The features of the measuring instruments used in this test are listed in Table 5. The features of the measuring instruments used in this test are listed in Table 5. The test compares the indoor temperature and humidity change between the room with The test compares the indoor temperature and humidity change between the room with CHM-WSE and CM, and takes 24 h as the test duration. In the January test of air conditioning mode, CHM-WSE and CM, and takes 24 h as the test duration. In the January test of air conditioning during a 24 h air conditioned heating, humidification is divided into two time periods, daytime mode, during a 24 h air conditioned heating, humidification is divided into two time periods, daytime 8:30~16:30, with a total of 8 h humidification, and 16:30~8:30 the next day, for a total of 16 h without 8:30~16:30, with a total of 8 h humidification, and 16:30~8:30 the next day, for a total of 16 h without humidification. In April, tests of no air conditioning and humidifying mode is conducted. humidification. In April, tests of no air conditioning and humidifying mode is conducted. Table 5. Equipment and technical indices. Equipment
Technical Index
Pt100 temperature sensor
±0.15 ◦ C
48-Channel paperless recorder
±(0.2% FS + 1), Supply voltage 85–240 VAC Ambient temperature: 0–50, Ambient humidity: 0–85%
ZDR-20 temperature and humidity automatic recorder
Temperature: −40 ◦ C–100 ◦ C, ±0.2 ◦ C Relative humidity: 0–100%, ±3%RH
In the practical moisture buffering performance experiment, the moisture load consists of three parts: G (t) = Gb (t) + ∆Go (t) + ∆Gw (t) (4) where Gb (t) is the moisture load in the room, in kg/m2 ; ∆G0 (t) is the hourly humidity load caused by the difference of indoor and outdoor relative humidity, in kg/m2 ; ∆Gw (t) is the moisture transfer of the internal wall, in kg/m2 . The practical moisture buffering can be expressed as: MBVpractical =
G (t) × t p As × ϕ
(5)
where As is the used area of hygroscopic material, in m2 ; tp is the period; ϕ is the relative humidity, in %. 2.3. Hygroscopicity and Energy-Saving Performance of the Composite Hygroscopic Material In order to further investigate the influence of composite hygroscopic material on the indoor thermal environment and energy consumption of buildings in different climatic region, the simulation model of Combined Heat and Moisture Finite Element (CHMFE) of EnergyPlus is applied.
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Table 6. Comparison of appearance properties. Appl. Sci. 2018, 8, 430
8, 8, x
1
1
2
3
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To fully evaluate the performance of the composite hygroscopic materials, the EnergyPlus software (8.4, GARD Analytics, Inc., Arlington Heights, IL, USA) is used for further analysis and calculation. Taking the measured room as the research object, typical cities in each climatic zone are selected as the representative to analyze the indoor temperature, humidity and energy consumption characteristics of the composite hygroscopic mortar and common mortar room. Weather data, which includes solar radiation, ambient air dry temperature, ambient air 9 of bulb 27 A-2 Smooth but with a and so on were provided by relative humidity, atmospheric pressure, wind speed, wind direction, A-1 * Smooth surface A-3 Has a few micro cracks few concave points Table 6. Comparison of appearance properties. the Chinese Standard Weather Data (CSWD). The indoor temperature is set as 18 ◦ C and 26 ◦ C in winter and summer, respectively [34], winter interior design temperature is 18 ◦ C, summer interior 2 3 ◦ design temperature is 26 C. Outdoor air temperature, relative humidity and solar radiation and other outdoor weather parameters are the typical annual meteorological parameters. The room schedule is shown in Table 5. Taking into account the sealing performance and orientation of on-site doors and windows, the room ventilation is set to an air exchange rate of 0.5 times/h. 3. Results and Discussion B-1 Smooth surface but with uneven color
C-1 Delicate and uniform color
C-2 Rough surface
3.1. Specimen Experiment * The numbers of the specimen are their temporary numbers. A-2 Smooth but with a 3.1.1. Appearance PropertyProperty A-1 * Smooth surface 3.1.2. Micromorphology few concave points
A-3 Has a few micro cracks
Based theexperiment Chinese standard 20473 [35]surface and GB/T 9779 [36], massive optimizing of of The on SEM requires GB/T that the sample not be broken, andselection with a size theless appearance quality and initial cracking resistance are made. Six test sample groups with better than 1 cm2. As it is seen in Figure 6, after being magnified 1000 times, the plush wood fiber, appearance propertyand are selected for furtherexpanded analysis. The results shown in Table in 6. In molding fibrous sepiolite honeycomb-like perlite are are clearly observed thethetest sample. test, the water consumption of A-3 and B-3 is about 10% more than that of the other samples. According to the SEM pictures, there is few macropore in samples A-1 and B-1. The micropore is
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dominant in these samples. There are many macropores in specimens A-2 and C-2, while in A-3 and Table 6. Comparison of appearance properties. Appl.there Sci. 2018, x 9 of 27 C-1 are 8,mainly micropore and mesopore.
Table Table 6. 6. Comparison Comparison of of appearance appearance properties. properties. 1 2 Table color 6. Comparison appearance th surface but with uneven color C-1 Delicate and uniform C-2of Rough 11 22 surfaceproperties. * The numbers of the specimen are 1 their temporary numbers. 2
3 33
3
omorphology Property
EM experiment requires that the sample surface not be broken, massive and with a size of cm2. As it is seen in Figure 6, after being magnified 1000 times, the plush wood fiber, piolite and honeycomb-like expanded perlite are clearly observed in the test sample. of samples 27 to the SEM pictures, there is few macropore9 in A-1 and B-1. The micropore is n these samples. There are many macropores in specimens A-2A-2 andSmooth C-2, while in A-3 and A-2 Smooth but but with with aa of appearance properties. A-1 A-1 ** Smooth Smooth surface surface A-3 A-3 Has Has aa few few micro micro cracks cracks A-2 Smooth but with re mainly micropore and mesopore. A-1 surface A-2 points (c)micro A-3 cracks few few(b) concave concave points A-1 * (a) Smooth A-3 Has a few A-13* Smooth surface
2
B-1 B-1 Smooth Smooth surface surface but but with with uneven uneven color color
Smooth but with a a fewA-2 concave points few concave points
C-1 C-1 Delicate Delicate and and uniform uniform color color
A-3 Has a few micro cracks
C-2 C-2 Rough Rough surface surface
** The The numbers of of the the specimen specimen are their their temporary temporary numbers. numbers. B-1 Smooth surface butnumbers with uneven color C-1 are Delicate and uniform color C-2 Rough surface 2 Smooth but with a B-1 Smooth surface withcracks uneven color C-1 Delicate and uniform color C-2 Rough surface A-3 Has a fewbut micro * The numbers of the specimen are their temporary numbers. ew concave points (d) B-1 (f) C-2 * The numbers of the specimen(e) areC-1 their temporary numbers. 3.1.2. 3.1.2. Micromorphology Micromorphology Property Property (a) A-1 (b) A-2 (c) A-3 Figure 6. SEM pictures. 3.1.2. Micromorphology Property
The The SEM SEM experiment experiment requires requires that that the the sample sample surface surface not not be be broken, broken, massive massive and and with with aa size size of of 22.. As less less than than The 11 cm cmSEM Asexperiment itit is is seen seen in in Figure Figure that 6, 6, after after being magnified magnified 1000 1000 times, times, the the plush plushand wood wood fiber, fiber, requires the being sample surface not be broken, massive with a size of 2. As fibrous fibrous sepiolite and and honeycomb-like honeycomb-like expanded expanded perlite perlite are clearly clearly observed observed in inthe the theplush test test sample. sample. lesssepiolite than 1 cm it is seen in Figure 6, after beingare magnified 1000 times, wood fiber, According According tosepiolite the the SEM SEMand pictures, pictures, there there is is few fewexpanded macropore macropore in in samples samples A-1 A-1 and and B-1. B-1. The The micropore is is fibrousto honeycomb-like perlite are clearly observed inmicropore the test sample. dominant dominant in in these these samples. samples. There There are are many many macropores macropores in in specimens specimens A-2 A-2 and and C-2, C-2, while while in in A-3 A-3 and and According to the SEM pictures, there is few macropore in samples A-1 and B-1. The micropore is C-1 C-1 there there are are mainly mainly micropore micropore and mesopore. mesopore. dominant in these samples.and There are many macropores in specimens A-2 and C-2, while in A-3 and
licate and uniform colorC-1 there C-2are Rough surface mainly micropore and mesopore.
en are their temporary numbers.
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B-1 Smooth surface but with uneven color
C-1 Delicate and uniform color
C-2 Rough surface
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* The numbers of the specimen are their temporary numbers.
3.1.2. Micromorphology Property 3.1.2. Micromorphology Property The SEM experiment requires that the sample surface not be broken, massive and with a size of The SEM experiment requires that the sample surface not be broken, massive and with a size of less than 1 cm2 . As it is seen in Figure 6, after being magnified 1000 times, the plush wood fiber, fibrous less than 1 cm2. As it is seen in Figure 6, after being magnified 1000 times, the plush wood fiber, sepiolite and honeycomb-like expanded perlite are clearly observed in the test sample. According to fibrous sepiolite and honeycomb-like expanded perlite are clearly observed in the test sample. theAccording SEM pictures, there is few macropore in samples A-1 and B-1. The micropore is dominant in these to the SEM pictures, there is few macropore in samples A-1 and B-1. The micropore is samples. There are macropores specimens A-2 and C-2, while A-2 in A-3 there dominant in thesemany samples. There areinmany macropores in specimens andand C-2,C-1 while in are A-3mainly and micropore and mesopore. C-1 there are mainly micropore and mesopore.
(a) A-1
(b) A-2
(c) A-3
(d) B-1
(e) C-1
(f) C-2
Figure 6. SEM pictures. Figure 6. SEM pictures.
Polypropylene fibers are interlaced in the mortar to form a network structure, and the sepiolite, wood fiber and diatom ooze are enclosed therein to increase the mechanical properties of the composite materials. 3.1.3. Microstructure Properties Samples A-3, B-1 and C-1 were selected for the specific pore structure tests based on the SEM analysis. The pore structure results are shown in Table 7. The specific surface area of sample C-1 is the largest, which is three times larger than that of sample A-3 and twice as large as that of sample B-1. The pore structure characteristics of CHM-WSE specimens are shown in Table 8. In the pore size distribution of sample C-1, the number of pores in the 10–50 nm range is the largest, the specific surface area and the average pore size are the largest, showing a good pore structure distribution. Most pores of sample A-3 are micropores. Most pores are less than 10 nm, giving the smallest specific surface area and pore volume. Sample B-1 has mostly micropores and macropores, and larger specific surface area. According to the Kelvin capillary condensation theory, relative pressure of adsorbate during capillary condensation is related to pore diameter. The larger pore size, the greater the relative pressure required for the occurrence of capillary condensation. At the same time, the pore volume decreases along with the pore size. Above all, the sample C-1 sample has more adsorption sites and space to accommodate the adsorbent.
surface area and the average pore size are the largest, showing a good pore structure distribution. Most pores of sample A-3 are micropores. Most pores are less than 10 nm, giving the smallest specific surface area and pore volume. Sample B-1 has mostly micropores and macropores, and larger specific surface area. According to the Kelvin capillary condensation theory, relative pressure of adsorbate during capillary condensation is related to pore diameter. The larger pore size, the greater the relative Appl. Sci. 2018, 8, 430 11 of 28 pressure required for the occurrence of capillary condensation. At the same time, the pore volume decreases along with the pore size. Above all, the sample C-1 sample has more adsorption sites and space to accommodate the adsorbent. Table 7. Pore structure analyses. Mortar Samples Mortar A-3 Samples B-1 A-3 C-1 B-1 C-1
TableArea 7. Pore structure analyses. Specific Surface Total Pore Volume Average Pore Diameter (m2 /g) (mL/g) (nm) Total Pore Volume Average Pore Diameter Specific Surface Area 0.02187 2/g) (mL/g) (nm) 11.43 (m7.656 11.434 0.0269 9.41 7.656 0.02187 11.43 33.331 0.1016 12.2 11.434 0.0269 9.41 33.331 0.1016 12.2 Table 8. Distribution of the pore diameter.
Mortar Samples 50 15.18 34.60 17.61
results of of nitrogen nitrogen adsorption/desorption adsorption/desorptiontests tests(Figure (Figure indicate that three kinds The results 7)7) indicate that allall thethe three kinds of of sample show hysteresisloop loopduring duringthe the adsorption adsorption and and desorption The nitrogen sample show a ahysteresis desorption processes. The adsorption isotherms isotherms are are all all Type Type IV. IV. Sample A-3 and sample B-1 B-1 have have aa smaller smaller adsorption adsorptioncapacity. capacity. adsorption Sample A-3 has aa maximum Sample maximum hysteresis hysteresis loop loop and and aa poor poorregulation regulation performance. performance. The adsorption adsorption is five times larger than than that ofthat the of previous two, which a smaller capacity of ofsample sampleC-1 C-1 is five times larger the previous two,has which has hysteresis a smaller loop, and aloop, better regulation performance. hysteresis and a better regulation performance.
16
Volume Adsorbed (ml/g)
Volume Adsorbed (ml/g)
18
A-3
14 12 10 8 6 4 2 0
B-1
16 14 12 10 8 6 4 2
0.0
Appl. Sci. 2018, 8, x
0.2 0.4 0.6 0.8 Relative Pressure (Ps/P0)
Volume Adsorbed (ml/g)
70
1.0
0.0
0.2
0.4
0.6
0.8
Relative Pressure (Ps/P0)
1.0 11 of 27
C-1
60 50 40 30 20 10 0
0.0
0.2
0.4
0.6
0.8
1.0
Relative Pressure (Ps/P0)
Figure Figure7.7.The Theadsorption-desorption adsorption-desorptionisotherms isothermsof ofspecimens. specimens.
3.1.4. Mechanical Property Mechanical properties test results are shown in Table 9. The flexural strength and compressive strength of sample C-1 are the best, and the ratio of compressive strength to flexural strength is 3.73. Table 9. Testing of mechanical property. Mortar Samples
A-3
B-1
C-1
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3.1.4. Mechanical Property Mechanical properties test results are shown in Table 9. The flexural strength and compressive strength of sample C-1 are the best, and the ratio of compressive strength to flexural strength is 3.73. Table 9. Testing of mechanical property. Mortar Samples
A-3
B-1
C-1
Flexural strength (MPa) Compressive strength (MPa)
4.31 16.35
4.37 15.21
5.23 19.49
3.1.5. Equilibrium Moisture Content As it can be seen from the isothermal equilibrium moisture content test results in Figure 8, as the temperature increases, the adsorption capacity of the CHM-WSE increases; as the relative humidity increases, the adsorption capacity of the CHM-WSE also increases. The adsorption increases significantly when the relative humidity is around 80%. The experimental results show that the fitted curve of adsorption content is related to temperature, relative humidity and the specific surface area of the composite hygroscopic mortar. The isothermal adsorption curve of composite hygroscopic mortar is written as follows [31]: φ ≤ 60% : u = 6.93T 0.48 φ1.01 s0.3 (6) φ > 60% : u = 2.52T 0.34 φ5.31 s1.39
(7)
where u is equilibrium moisture content per unit area (in kg/m2 ); T is environment temperature (in K); φ is the relative humidity (in %); s is specific surface area (in m2 /g). According to the equilibrium moisture content equation, the adsorption/desorption moisture content of hygroscopic material is related to the distribution of material aperture. When the specific surface area rises, the pore volume increases and the adsorption/desorption capacity grows accordingly. 3.1.6. Thermodynamic Performance After testing, the thermal conductivity of sample A-3, B-1 and sample C-1 under dry conditions are about 0.114 W/(m·K), 0.117 W/(m·K) and 0.115 W/(m·K), respectively. The results show that the thermal conductivity of the two groups all meet the requirements of a thermal insulation material [37]. After completing the thermal conductivity test under dry condition, the thermal conductivity of the test specimens after reaching the moisture absorption equilibrium is tested under the relative humidity of 5%, 15%, 30% and 50%. The results are shown in Figure 9. It can be seen from the test results that the thermal conductivity increases with the increase of the relative humidity of the environment. The relative humidity of the environment has a great influence on the thermal conductivity of the mortar. The maximum effective thermal conductivity over the tested range is 0.2533 W/(m·K), which is two times higher than the dry value of 0.1173 W/(m·K). The experimental data are curved fitted with a continuous relationship that is represented by a polynomial given below: k e f f = a + bφ + cφ2 + dφ3 (8) where a = 0.1167, b = 0.0076, c = −3 × 10−4 , d = 3 × 10−6 , R2 = 0.9823.
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Equilibrium Moisture Content (g/g⋅%)
20
A-3 20℃ 25℃ 40℃
16 12 8 4 0 0
20
Equilibrium Moisture Content (g/g⋅%)
20
100
B-1
16
20℃ 25℃ 40℃
12 8 4 0 0
20
Equilibrium Moisture Content (g/g⋅%)
40 60 80 Relative Humidity (%)
20
40 60 80 Relative Humidity (%)
100
C-1 20℃ 25℃ 40℃
16 12 8 4 0 0
20
40 60 80 Relative Humidity (%)
100
Figure ◦ C, 25 ◦ C, 40 ◦ C). Figure 8. 8. Equilibrium Equilibrium moisture moisture content content of of specimens specimens (20 (20 °C, 25 °C, 40 °C).
It can be seen from the test results that the thermal conductivity increases with the increase of the relative humidity of the environment. The relative humidity of the environment has a great influence on the thermal conductivity of the mortar. The maximum effective thermal conductivity over the tested range is 0.2533 W/(m∙K), which is two times higher than the dry value of 0.1173 W/(m∙K). The experimental data are curved fitted with a continuous relationship that is represented by a polynomial given below:
keff = a + bφ + cφ 2 + dφ 3 where a = 0.1167, b = 0.0076, c = −3 × 10−4, d = 3 × 10−6, R2 = 0.9823.
(8)
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Thermal conductivity Thermal conductivity (W/m(W/m ⋅K) ⋅K)
0.28
B-1 A-3 C-1 B-1
0.24 0.24
C-1
0.20 0.20
0.16 0.16
0.12 0.12
0
10
20 30 40 50 Relative humidity (%) 0 10 20 30 40 50 humidity (%) humidity for specimens. Figure 9. Thermal conductivity as aRelative function of relative Figure 9. Thermal conductivity as a function of relative humidity for specimens. Figure 9. Thermal conductivity as a function of relative humidity for specimens.
3.2. Test and Evaluation of Hygroscopicity and Practical Moisture Buffering Performance 3.2. Test and Evaluation of Hygroscopicity and Practical Moisture Buffering Performance 3.2. Test and Evaluation of Hygroscopicitycomparison and PracticalofMoisture Performance According to the comprehensive the testBuffering results by microscopic performance, According to the comprehensive comparison of the test results by microscopic performance, adsorption performance, mechanical properties and thermodynamic performance, new type of According to the comprehensive comparison of the test results by microscopica performance, adsorption performance, mechanical properties and thermodynamic performance, a new type of composite hygroscopic mortar is prepared using the ratio of the C-1 group and applied to large adsorption performance, mechanical properties and thermodynamic performance, a new atype of composite hygroscopic is prepared using theand ratio of the C-1 group and applied to a large scale scale space test. Threemortar days after construction maintenance, mortars photographed composite hygroscopic mortar is the prepared using the ratio of the C-1the group and are applied to a large space Three days after theafter and the maintenance, thecomposite mortars are photographed and are and are shown Figure 10. Itconstruction canthe be construction seen that surface of the mortar tiny pores, scaletest. space test.in Three days and maintenance, the mortars arehas photographed shown in surface Figure 10. It can 10. be seen theobvious surface of the composite mortarmortar has tiny pores, and the and mortar has no and the are shown of in ordinary Figure It canthat be seen that thepores. surface of the composite has tiny pores, surface of ordinary mortar has no obvious pores. and the surface of ordinary mortar has no obvious pores.
(a) Composite Hygroscopic mortar wall
(b) Common mortar wall
(a) Composite Hygroscopic mortar wall (b) Common mortar wall Figure 10. Two types of mortar wall (without primer and finish). Figure 10. Two types of mortar wall (without primer and finish).
10.Winter Two types of mortar wall (without primer and finish). 3.2.1. HygroscopicityFigure Test in
3.2.1.The Hygroscopicity Test in Winter measured indoor temperature and humidity of the two tested rooms for January is shown 3.2.1. Hygroscopicity Test in Winter in Figure 11. Both rooms have been heated humidified air conditioner and humidifier, The measured indoor temperature and and humidity of the by twothe tested rooms for January is shown respectively. The indoor temperature is set as 24 °C. The outdoor temperature was measured the The measured indoor temperature and humidity of the two tested rooms for January isatshown in Figure 11. Both rooms have been heated and humidified by the air conditioner and humidifier, 4 °C–6 relative humidity between 95% 99%, which is a typical wet inrange Figureof11. Both rooms have been heated and humidified by the air conditioner and and humidifier, respectively. The°C, indoor temperature isisset as 24 °C. Theand outdoor temperature was measured atcold the ◦ C. The outdoor temperature was measured at climate condition. respectively. The indoor temperature is set as 24 range of 4 °C–6 °C, relative humidity is between 95% and 99%, which is a typical wet and cold It can seen◦ C, in relative Figure 12 that the isindoor temperature basically at 14:00, theclimate range of 4be◦ C–6 humidity between 95% and is 99%, whichstable is a typical wetand andthe cold condition. temperature continues to be around 24 °C, with little difference between the two rooms. The indoor climateItcondition. can be seen in Figure 12 that the indoor temperature is basically stable at 14:00, and the relative moisture ofindoor the two tested roomsbetween compared and the14:00, results arethe temperature to be around °C, with little difference the two rooms. The indoor It canhumidity be continues seen and in Figure 12 content that24the temperature isare basically stable at and shown Figures 13 and 14, around where it24 is ◦indicated thattested the indoor moisture increases relativeinhumidity and content ofwith the two roomsair are compared and the results are temperature continues tomoisture be C, little difference between thecontent two rooms. Theafter indoor humidification. After the humidification finishes, the relative humidity and moisture content of the shownhumidity in Figuresand 13 and 14, where it is indicated thattested the indoor airare moisture content afterare relative moisture content of the two rooms compared andincreases the results room with CM do not change, but the finishes, fluctuation obvious, while and the moisture relative humidity humidification. the the is relative humidity ofand the shown in Figures After 13 and 14,humidification where it is indicated that the indoor air moisture contentcontent increases after room with CM do not change, but the fluctuation is obvious, while the relative humidity and humidification. After the humidification finishes, the relative humidity and moisture content of the
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18 20 20 16 18 18 14 16 16 12 14 14 10 12 12 8 10 10 68 8 46 6 24 4 1/7 2 2 1/7
90 100 100 80 90 90 Relative Humidity 70 80 Temperature 80 Relative Humidity 60 70 Relative Humidity 70 Temperature 50 60 Temperature 60 40 50 50 30 40 40 20 30 30 10 1/8 1/9 1/10 1/11 1/12 20 20 Time (d) 10 1/8 1/9 1/10 1/11 1/12 10 1/7Outdoor 1/8 temperature 1/9 (d) and 1/10 1/11 test 1/12 Time 11. humidity in January.
Relative Humidity Relative Humidity (% Relative Humidity (% ) ) (%)
Temperature Temperature (℃)(℃) Temperature (℃)
room with CM do not change, but the fluctuation is obvious, while the relative humidity and moisture Appl. Sci. 8,room x 14 of than 27 content of2018, the CHM-WSE decreases gradually, the relative is 14.3% lower Appl. Sci. 2018, 8, x ofwith of 27 moisture content the room with CHM-WSE decreases gradually, thehumidity relative humidity is 14 14.3% that of the room and theCM, air moisture content is reduced byreduced 3.1 g/kg air. lower than thatwith ofof theCM, room with and the air moisture content is by·dry 3.1 g/kg∙dry moisture content the room with CHM-WSE decreases gradually, the relative humidity is air. 14.3% moisture content of the room with CHM-WSE decreases gradually, the relative humidity is 14.3% lower than that of the room with CM, and the air moisture content is reduced by 3.1 g/kg∙dry air. 100 lower than that of the room20with CM, and the air moisture content is reduced by 3.1 g/kg∙dry air.
Figure Figure 11. Outdoor temperature Time (d) and humidity test in January. Figure 11. Outdoor temperature and humidity test in January. Figure 11.relative Outdoorhumidity temperature humidity points test in January. Figure 15 shows that the of and monitoring in room with CM fluctuates
Figure 15 shows that thetorelative humidity of monitoring pointsofinthe room with CM fluctuates more frequently. According relative humidity distributionpoints curve room with Figure 15 shows that the the relative humidity of monitoring in room with CMCHM-WSE fluctuates more frequently. According to the relative humidity distribution curve of the room with CHM-WSE Figure 15 shows the relative humidity points in room with CM fluctuates (Room II) (Figure 16), that the relative humidity curveofismonitoring relatively smooth and a downward trend more frequently. According to the relative humidity distribution curve of thehas room with CHM-WSE more frequently. According to the relative humidity distribution curve of the room with CHM-WSE (Room II) (Figure 16), the relative humidity curve is relatively smooth and has a downward trend except ceilings,16), which an obvious fluctuation, and this is because thehas ceiling is not covered (Room for II) (Figure the has relative humidity curve is relatively smooth and a downward trend (Room II) (Figure 16), the relative humidity curve is relatively smooth and has a downward trend 3 2 except for ceilings, which has an obvious fluctuation, and this is because the ceiling is not covered with CHM-WSE. The test room volume is 36.48 m , theand usable of CHM-WSE is 40.8 m , covered and the except for ceilings, which has an obvious fluctuation, thisarea is because the ceiling is not 3 , theand 2 , and the except forabsorption ceilings, hasper an obvious fluctuation, this is because is not2mcovered 2. the ceiling with CHM-WSE. Thewhich test room volume is 36.48 mCHM-WSE usable area of CHM-WSE is 40.8 moisture capacity unit area of the is 2.77 g/m 3 with CHM-WSE. The test room volume is 36.48 m 3, the usable area of CHM-WSE is 40.8 m 2, and the 2 with CHM-WSE. The test room volume is 36.48 m , the usable area of CHM-WSE is 40.8 m , and the moisture absorption 2.77g/m g/m 2. . moisture absorptioncapacity capacityper perunit unitarea area of of the the CHM-WSE CHM-WSE isis2.77 2 moisture absorption capacity26per unit area of the CHM-WSE is 2.77 g/m . CM Room
Temperature Temperature (℃)(℃) Temperature (℃)
24 26 26 22 24 24 20 22 22 18 20 20 16 18 18 14 16 16 12 14 14 10 12 12 8 10 108:00 12:00 8 8 8:00 12:00 12:00 Figure8:00 12. Indoor
CHM-WSE Room
CM Room CM RoomRoom CHM-WSE CHM-WSE Room
16:00
20:00 00:00 4:00 Time (h) 16:00 20:00 00:00 4:00 16:00 Time 20:00(h) 00:00 4:00 temperature in the center of Time (h)
8:00 8:00
the 8:00 room.
Relative humidity Relative humidity (% Relative humidity (% ) ) (%)
Figure 12. Indoor temperature in the center of the room. 75 12. Figure Indoor in the thecenter centerofofthe theroom. room. Figure 12. Indoor temperature temperature in Humidification 70 75 CM Room 75 Humidification CHM-WSE Room Humidification 65 70 CM Room 70 CM Room Room CHM-WSE 60 65 CHM-WSE Room 65 55 60 60 50 55 55 45 50 50 40 45 45 35 408:00 12:00 16:00 20:00 00:00 4:00 8:00 40 Time (h) 35 00:00 4:00 8:00 358:00 12:00 16:00 20:00 8:00 12:00 16:00 Time 20:00 8:00 (h) 00:00 4:00
Figure 13. Indoor relative humidity in the center of the room. Time (h)
Figure 13. Indoor relative humidity in the center of the room. Figure 13. Indoor relative humidity in the center of the room. Figure 13. Indoor relative humidity in the center of the room.
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Humiditication
Moisture content(g/kg dry air)
10 CM Room CHM-WSE Room
9 8 7 6 5 4 8:00
12:00
16:00 20:00 Time (h)
00:00
4:00
8:00
Figure room. Figure 14. 14. Indoor Indoor air air moisture moisture content content in in the the center center of of the the room.
In the testing area, n points are selected and the temperature and relative humidity of each In the testing area, n points are selected and the temperature and relative humidity of each point point are measured respectively. The arithmetic mean value is as follows: are measured respectively. The arithmetic mean value is as follows:
t tt = = ∑ ti i nn
(9) (9)
∑ φφi φφ = = n i
(10) (10)
n
The root-mean-square deviation is calculated as: The root-mean-square deviation is calculated as: s 2 t) 2 ∑ ((tti − i −t ) σt = σt = n n s 2 φ) 2 ∑ ((φφi − σφ = i −φ ) σφ = n
(11) (11)
(12) (12)
n
The non-uniformity coefficient is calculated as: The non-uniformity coefficient is calculated as: σt kt = σt t
kt =
kφ =
(13) (13)
σtφ u
(14)
σφ
(14) kφ humidity, = where t is the temperature, in ◦ C; φ is the relative in %; σ is the root-mean-square deviation; u κ is the non-uniformity coefficient. According to the room temperature humidity and temperature and is the relativedistribution humidity, (Figure in %; σ17)is thethe root-mean-square where t is the temperature, in °C; φ and humidity non-uniformity coefficient coefficient. (Table 10), the uniformity of temperature and relative humidity κ is the non-uniformity deviation; within the room with CHM-WSE is better than in the room with CM at 1.517) mand above floor. According to the room temperature and humidity distribution (Figure thethe temperature and humidity non-uniformity coefficient (Table 10),air-conditioning the uniformitycondition. of temperature andtherelative humidity Table 10. Non-uniformity coefficient under (Time: 8:30 next day). within the room with CHM-WSE is better than in the room with CM at 1.5 m above the floor. Position
Non-Uniformity
Room10. Non-uniformity Parameter Table coefficient under air-conditioning condition. (Time: 8:30 the next day). Coefficient P2
Temperature (◦ C) Room Parameter Room I (CM) Relative humidity (%)
26.4 48P2
Room I
Temperature (°C)
26.4
Room II (CHM-WSE)
Temperature (°C) Relative humidity (%)
25.1 38.9
Room II Temperature (◦ C) 25.1 Relative humidity (%) 48 (CM) (CHM-WSE) Relative humidity (%) 38.9
P3
P4
Position25.1 24.8 P3 P5 46.8 P4 51.1 24.8 24.1 46.8 40.7 24.1 40.7
25.1 25.3 24.2 51.1 50.4 38.7 24.2 25.2 38.7 39.4
P5
P6
25.3Non-Uniformity 26.1 0.0238 Coefficient P650.4 49.6 0.0320 26.1 25.2 49.6 39.4 24.8 38.1
0.0238
24.8 0.0320 38.1 0.0184 0.0224
0.0184 0.0224
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Relative Humidity(%) Relative Humidity(%) Relative Humidity(%)
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85 85 80 85 80 75 80 75 70 75 70 65 70 65 60 65 60 55 60 55 50 55 50 45 50 45 40 45 408:00 8:00 40 8:00
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Ceiling Ceiling Ceiling Room center (h=1.5m) Room center (h=1.5m) South wall Room center South(h=1.5m wall ) South wall North wall North wall North wall 16:00 20:00
12:00 12:00 12:00
0:00 16:00 Time 20:00(h) 0:00 16:00 Time 20:00 (h) 0:00
4:00 4:00 4:00
8:00 8:00 8:00
Relative Humidity (%) Relative Humidity Relative Humidity (%)(%)
Timehumidity (h) Figure 15. Indoor relative of room І. Figure humidityof ofroom roomІ.I. Figure15. 15. Indoor Indoor relative relative humidity Figure 15. Indoor relative humidity of room І. 85 85 80 85 80 75 80 75 70 75 70 65 70 65 60 65 60 55 60 55 50 55 50 45 50 45 40 45 40 35 408:00 35 8:00 35 8:00
Ceiling Ceiling Room center ) Ceiling((h=1.5m Room center h=1.5m) South wall Room center (h=1.5m South wall ) South wall
North wall North wall 12:00 North 16:00 wall 20:00 0:00 4:00 8:00 12:00 16:00 20:00 4:00 8:00 Time (h) 0:00 12:00 16:00 20:00 4:00 8:00 Time (h) 0:00 Time (h) Figure 16. Indoor relative humidity of room ІІ. (Ceiling: P10; South wall: P8; North wall: P9; Room Figure 16. Indoorrelative relativehumidity humidityof ofroom room II. ІІ. (Ceiling: (Ceiling: P10; P9;P9; Room Figure 16.P4). Indoor P10; South Southwall: wall:P8; P8;North Northwall: wall: Room center: Figure 16. Indoor relative humidity of room ІІ. (Ceiling: P10; South wall: P8; North wall: P9; Room center: P4). 38 38 36 38 36 34 36 34 32 34 32 30 32 30 28 30 28 26 28 26 24 26 24 22 24 22 20 22 20 20
Relative Humidity of CM Room Relative Humidity of CHM-WSE CM Room Room Relative Humidity of CHM-WSE Room Relative Humidity of CM Room Relative Humidity of CHM-WSE Room
Temperature of Temperature Temperature of of Temperature of Temperature of Temperature of
CM Room CHM-WSE CM Room Room 55 CHM-WSE Room CM Room 55 CHM-WSE Room
50 55 50 45 50 45 40 45 40 35 40 35 30 35 30 25 30 25 20 25 20 15 20 15 10 15 10 10
Relative Humidity(%) Relative Humidity(%) Relative Humidity(%)
Temperature (℃) Temperature (℃) Temperature (℃)
center: P4). center: P4).
P2 P2 P2
P3 P3 P3
P4
P5
P6
P4 P5 P6 Position Position P4 P5 P6 Position Figure 17. Indoor temperature and humidity distribution under air-conditioning condition. (Time: Figure 17. Indoor temperature and humidity distribution under air-conditioning condition. (Time: 8:30 the next day). Figure 17. Indoor temperature and humidity distribution under air-conditioning condition. (Time: 8:30 the day). Figure 17. next Indoor temperature and humidity distribution under air-conditioning condition. (Time: 8:30 8:30 the next day). the Hygroscopicity next day). 3.2.2. Test in Late Spring
3.2.2. Hygroscopicity Test in Late Spring 3.2.2.The Hygroscopicity Test in temperature Late Spring and humidity in April is shown in Figure 18. It is shows measured outdoor The measured outdoor temperature 3.2.2. Hygroscopicity Test in Late Spring and humidity in April is shown in Figure 18. It is shows that the outdoor temperature is in the range of 10 °C–22 °C and relative humidity is between 60% Theoutdoor measured outdoor temperature andof humidity April shownhumidity in Figureis18. It is shows that the temperature is in the range 10 °C–22in°C and is relative between 60% and 99%. The measured outdoor temperature and humidity in April is shown in Figure 18. It is shows that that the outdoor temperature is in the range of 10 °C–22 °C and relative humidity is between 60% and 99%. ◦ C–22 ◦ C and relative humidity is between 60% and 99%. theand outdoor temperature is in the range of 10 99%.
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60 55 60 60 50 55 55 45 50
100
17 of 27 17 of 27
100 90 100 90 80
Relative Humidity Relative Humidity (%)(%)(%) Relative Humidity
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Temperature (℃) Temperature (℃) Temperature (℃)
90 80 70 50 40 45 80 70 60 45 35 40 70 Relative Humidity 50 60 40 30 35 Temperature Relative Humidity 40 60 50 35 25 30 Temperature Relative Humidity 50 40 30 30 20 Temperature 25 40 30 20 25 15 20 30 20 10 20 10 15 20 15 5 010 10 8:00 16:00 00:00 8:00 16:00 00:00 8:00 10 105 0 Time (h) 8:00 16:00 00:00 8:00 16:00 00:00 8:00 5 0 Time (h) 16:00 temperature 00:00 8:00 and 16:00 00:00 test 8:00in April. Figure 18.8:00 Outdoor humidity Figure 18. Outdoor temperature Time (h)and humidity test in April. Figure 18. Outdoor temperature and humidity test in April. Figures 19–21 show the indoor temperature andand humidity theinroom Figure 18. Outdoor temperature humidityintest April.with CM and the room
Figures 19–21 show and humidity inthe theroom room withCM CM and the room with CHM-WSE without airindoor conditioning condition. is indicated that the relative humidity of the Figures 19–21 showthe the indoortemperature temperature andIthumidity in with and the room with CHM-WSE without air conditioning condition. It is indicated that the relative humidity of 19–21 show the temperature andIthumidity with androom the of room room with CHM-WSE is controlled at a range of 55–70%, which in is the lower than thatCM ofhumidity the with with Figures CHM-WSE without air indoor conditioning condition. is indicated thatroom the relative thethe room with CHM-WSE is at aarange of 55–70%, which lower than thatof ofthe theroom room with with CHM-WSE without air condition. It is is also indicated that the relative humidity ofwith the CM by 6–10% (Figure 20), andconditioning the air content lower by 0.3 g/kg∙dry air −0.5 g/kg∙dry room with CHM-WSE iscontrolled controlled atmoisture range of 55–70%, which isislower than that CM by 6–10% (Figure 20), and the air moisture content is also lower by 0.3 g/kg · dry air − 0.5 g/kg ·dry room with CHM-WSE is controlled at a range of 55–70%, which is lower than that of the room with air (Figure 21). CM by 6–10% (Figure 20), and the air moisture content is also lower by 0.3 g/kg∙dry air −0.5 g/kg∙dry airCM (Figure 21). by 6–10% (Figure 20), and the air moisture content is also lower by 0.3 g/kg∙dry air −0.5 g/kg∙dry air (Figure 21). 20 air (Figure 21).
Relative Humidity Relative Humidity ( %()% )( % ) Relative Humidity
Temperature (℃) Temperature (℃) Temperature (℃)
CM Room 20 19 CHM-WSE CM Room Room 20 19 CHM-WSE CM Room Room 18 19 CHM-WSE Room 18 17 18 17 16 17 16 15 16 15 14 15 14 13 14 13 12 13 8:00 16:00 00:00 8:00 16:00 00:00 8:00 12 Time (h) 8:00 16:00 00:00 8:00 16:00 00:00 8:00 12 (h) 16:00 00:00 8:00 8:0019. 16:00 00:00 Time Figure Temperature in8:00 the center of the room. Time (h) Figure 19. Temperature in the center of the room. Figure Temperature in the center of the room. 78 19. Figure 19. Temperature in the center of the room. CM Room 76 78 CHM-WSE Room CM Room 78 74 76 CHM-WSE CM Room Room 76 72 CHM-WSE Room 74 74 70 72 72 68 70 70 66 68 68 64 66 66 62 64 64 60 62 62 58 60 60 56 58 8:00 16:00 00:00 8:00 16:00 00:00 8:00 58 56 (h) 16:00 00:00 8:00 8:00 16:00 00:00Time8:00 56 Time (h) 16:00 00:00 8:00 8:00 16:00 00:00 8:00 Figure 20. Relative humidity in the center of the room.
Time (h)
Figure 20. Relative humidity in the center of the room. Figure 20. Relative humidity in the center of the room. Figure 20. Relative humidity in the center of the room.
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Moisture content (g/kg ⋅dry Moisture content (g/kg ⋅dry airair ) )
10.5 10.5 10.0 10.0 9.5 9.5 9.0 9.0 8.5 8.5 8.0 8.0 7.5 7.5 7.0 7.0 6.5 6.5 8:00 8:00
CM Room CM Room Room CHM-WSE CHM-WSE Room
16:00 00:00 8:00 16:00 00:00 8:00 16:00 00:00Time 8:00 (h) 16:00 00:00 8:00 Time (h) Figure 21. Air moisture content in the center of the room. Figure Figure 21. 21. Air Air moisture moisture content content in in the the center center of of the the room. room.
Compared with the room with CM, Figure 22 shows that the temperature and humidity Compared with the room with with CM, CM, Figure Figure 22 22 shows shows that the the temperature and and humidity humidity Compared distribution in the room with CHM-WSE is relatively uniform. that From thetemperature temperature and humidity distribution in the room with CHM-WSE is relatively uniform. From the temperature and humidity distribution in the room (Table 11), the temperature and humidity uniformity in the room with non-uniformity coefficient 11), the the temperature and humidity humidity uniformity in the room with with non-uniformity coefficient (Table 11), CHM-WSE are better than that in the roomtemperature with CM at 1.5 m from the floor. CHM-WSE are are better better than than that that in in the the room room with with CM CM at at 1.5 1.5 m mfrom fromthe thefloor. floor. CHM-WSE Temperature of CM Room Temperature Temperatureof of CHM-WSE CM Room Room 90 Temperature of CHM-WSE Room
90 85 85 80 80 75 75 70 70 65 65 60 60 55 55 50 50
Relative Humidity Relative Humidity (%()%)
Relative Humidity of CM Room Relative RelativeHumidity Humidityof ofCHM-WSE CM Room Room Relative Humidity of CHM-WSE Room
Temperature (℃ Temperature (℃ ) )
28 28 26 26 24 24 22 22 20 20 18 18 16 16 14 14 12 12
P2 P2
P3 P3
P4 P4 Position Position
P5 P5
P6 P6
Figure 22. Indoor temperature and humidity distribution. (Time: 8:30 the next day). and humidity humidity distribution. distribution. (Time: (Time: 8:30 the the next next day). day). Figure 22. Indoor temperature and Table 11. Non-uniformity coefficient. (Time: 8:30 the next day) Table 11. 11. Non-uniformity Non-uniformity coefficient. coefficient. (Time: (Time: 8:30 8:30 the the next next day) day) Table Position Room Parameter Non-Uniformity Coefficient Position P2 P3 P4Position P5 P6 Room Parameter Non-Uniformity Coefficient Non-Uniformity P2 14.1 P3 16.5 P4 14.2 P5 14.1 P6 Room Parameter (°C) 13.8 0.0681Coefficient Room I Temperature P213.8 14.1 P3 16.5 P4 P6 14.2 14.1P5 0.0681 Room Temperature (°C) 0.0189 Relative humidity (%) 81.8 78.8 77.6 78.1 78.3 (CM) I ◦ 81.8 78.8 77.6 16.5 78.1 78.3 0.0189 Temperature ( C) (%) 13.8 14.1 14.2 14.1 Relative humidity (CM) 16.2 16.3 17.5 16.4 16.1 0.0309 0.0681 Room II Temperature (°C) Room I (CM) Relative humidity (%) 81.8 78.8 17.5 77.6 78.1 78.3 0.0309 0.0189 16.2 16.3 16.4 16.1 Room II Temperature (°C) 0.0154 (CHM-WSE) Relative humidity (%) 73.3 72.3 70.2 72.3 73.2 73.3 72.3 72.3 73.2 Relative humidity (CHM-WSE) Room II Temperature (◦ C) (%) 16.2 16.3 70.2 17.5 16.4 16.1 0.0154 0.0309 (CHM-WSE)
Relative humidity (%)
73.3
72.3
70.2
72.3
73.2
0.0154
3.2.3. Practical Moisture Buffering of Room 3.2.3. Practical Moisture Buffering of Room testing the changeBuffering of air temperature 3.2.3.By Practical Moisture of Room and relative humidity in the room, the moisture buffering By testing the change of air temperature and relative humidity in the room, the moisture buffering value of the building envelope material is further analyzed. As the test is conducted three months after valueBy oftesting the building envelope is further analyzed. As the test is conducted three months after the change of airmaterial temperature and relative humidity in the room, the moisture buffering the test room construction was completed, it is assumed that the impact of the moisture balance between the testofroom construction was completed, it is assumed that theAs impact of the balance value the building envelope material is further analyzed. the test is moisture conducted three between months different wall materials on the humidity distribution within the room can be ignored. different wallroom materials on the humidity distribution the room canimpact be ignored. after the test construction was completed, it iswithin assumed that the of the moisture balance According to NORDTEST Project, the practical Moisture Buffer Value is presented using According NORDTEST Project, the practical Moisture Buffer Valuecanis bepresented between different2towall materials on the humidity distribution within the room ignored. using dimensions g/(m % RH)@8/16h which indicates the change of the mass of moisture in the material 2 dimensions g/(m % RH)@8/16h which indicates the change of the mass of moisture in the material per free surface area and the step change of relative humidity during 8/16 h wetting/drying cycle. per free surface area and the step change of relative humidity during 8/16 h wetting/drying cycle. But it does not take into account other parameters that might influence the buffer performance, like But it does not take into account other parameters that might influence the buffer performance, like
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According to NORDTEST Project, the practical Moisture Buffer Value is presented using dimensions g/(m2 % RH)@8/16h which indicates the change of the mass of moisture in the material per free surface area and the step change of relative humidity during 8/16 h wetting/drying cycle. But it does not take into account other parameters that might influence the buffer performance, like moisture production and ventilation rates. According to the calculation results of moisture buffering performance (Table 12), it can be found that the CHM-WSE has good hygroscopic performance, while the CM has a relatively poor one. Meanwhile, the effect of moisture buffering in late spring is slightly better than that in winter. Table 12. Results of the MBVpractical .
Room
Interior Wall Material
Dry Density (kg/m3 )
Room I Room II
CM CHM-WSE
20332 654
MBVpractical (g/(m2 %RH)@8/16h) Winter
Late Spring
0.2 0.85
0.55 0.89
3.3. Application of the Composite Hygroscopic Material in Different Climate Regions The computational modeling of hygroscopic material is validated by combining the benchmark test with the benchmarks of the CHMFE model which was initiated to develop a platform to assess the heat, moisture and air transport mechanism in building physics. The basic properties of the composite hygroscopic mortar are based on the above experiments. The properties of composite hygroscopic material are obtained from experiments. The properties of the wall components are shown in Table 13. Table 13. Properties of the wall components.
Material
Thermal Conductivity (W/(m·k))
Thermal Storage Coefficient (W/(m2 ·k))
Density (kg/m3 )
Specific Heat (kJ/(kg·k))
Thermal Inertia Index (D)
Water Vapor Permeability (kg/(m·Pa·s))
CM Porous brick CHM-WSE
0.930 0.580 0.115
11.30 7.87 2.45
1800 1400 654
1.05 1.05 1.05
0.24 3.28 0.80
5.467 × 10− 11 2.6 × 10− 11 5.08 × 10− 11
Taking typical cities as examples, the indoor relative humidity distribution and thermal performance of residential buildings with CHM-WSE and CM as the surface material are analyzed. In order to compare the impact on indoor thermal environment of hygroscopic material and common mortar, the building size and envelop structure of different climatic region keep the same, which may be different from practical situation. The room schedule of residential building air conditioning is shown in Table 14. The sealing performance and orientation of on-site doors and windows are taken into account, and the air exchange rate of 0.5 times/h. Table 14. Schedule of residential building air conditioning in summer and winter. Season
Typical City
Operating Date
Time (Weekend)
Time (Weekday)
Winter
Guangzhou Changsha, Wuhan, Nanjing Xi’an
1.1–2.28 12.1–2.28 11.15–3.15
0:00–24:00 0:00–24:00 0:00–24:00
18:00–8:00 18:00–8:00 00:00–24:00
Summer
Guangzhou Changsha, Wuhan, Nanjing Xi’an
6.1–9.30 7.1–9.30 7.1–8.31
0:00–24:00 0:00–24:00 0:00–24:00
18:00–8:00 18:00–8:00 18:00–8:00
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Hot summer and cold winter region
This paper mainly focuses on the hot summer and cold winter region with high humidity in both summer and winter. Therefore, three typical cities in this region, including Changsha, Wuhan, and Nanjing are selected to study the performance of CHM-WSE. In the hot summer and cold winter region where the relative humidity fluctuates greatly during day and night, the indoor relative humidity in the room with CHM-WSE is controlled at 35–65% in winter (Figure 23) and 50–70% in summer (Figure 24). The results show that the indoor relative humidity fluctuation of the room with CHM-WSE is about 10% lower than that of the room with CM. The results of building heating load show that the Appl. Sci. 2018, 8, x 20 of 27 Appl. Sci. 2018, 20 of25). 27 heating load8,ofx the room with CHM-WSE is obviously lower than that of the room with CM (Figure The results of building cooling load that cooling the sensible andthe latent cooling load ofand thelatent room with CM (Figure 25). The results ofshow building loadcooling show that sensible cooling with CM (Figure are 25).lower The results of building cooling load show that the sensible cooling and latent with CHM-WSE than that of the room with CM (Figure 26). cooling load of the room with CHM-WSE are lower than that of the room with CM (Figure 26). cooling load of the room with CHM-WSE are lower than that of the room with CM (Figure 26). (2) (2) Cold Cold region region (2) Cold region This This study study chooses chooses Xi’an Xi’an as as aa typical typical city city in in the the cold cold region. region. This This region region has has dry dry and and cold cold winters winters This study chooses Xi’an as a typical city in the cold region. This region has dry and cold winters and and humid humid and and hot hot summers. summers. and humid and hot summers. 100 100 90 90
CM Room CM Room Room CHM-WSE CHM-WSE Room
Relative Humidity (%) Relative Humidity (%)
80 80 70 70 60 60 50 50 40 40 30 3012/1 12/10 12/20 12/30 01/10 01/20 01/30 02/09 02/19 2/28 01/10 01/20 01/30 02/09 02/19 2/28 12/1 12/10 12/20 12/30 Time (Daily) Time (Daily)
Figure 23. Indoor relative humidity in heating season (Changsha). Figure 23. 23. Indoor Indoorrelative relative humidity humidity in in heating heating season season (Changsha). (Changsha). Figure 110 110
Relative Humidity (%) Relative Humidity (%)
100 100
CM Room CM Room Room CHM-WSE CHM-WSE Room
90 90 80 80 70 70 60 60 50 50 40 40 7/1 7/1
07/15 07/15
07/30 08/14 08/29 07/30Time 08/14 (Daily)08/29
Time (Daily)
09/13 09/13
09/28 09/28
Figure 24. Indoor relative humidity in cooling season (Changsha). Figure 24. Indoor relative humidity in cooling season (Changsha). Figure 24. Indoor relative humidity in cooling season (Changsha). Sensible Heating Load of CM Room
2 2
Building Heating Load (W/m Building Heating Load (W/m) )
Sensible Room Room 140 Sensible Heating Heating Load Load of of CM CHM-WSE 140 Sensible Heating Load of CHM-WSE Room 120 120 100 100 80 80 60 60 40 40 20 20 012/1 12/10 12/20 12/30 01/10 01/20 01/30 02/09 02/19 2/28 012/1 12/10 12/20 12/30 Time 01/10(Daily) 01/20 01/30 02/09 02/19 2/28
Time (Daily)
Figure 25. Heating Load (Changsha). Figure 25. Heating Load (Changsha).
Rel
50 40 7/1
07/15
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Figure 24. Indoor relative humidity in cooling season (Changsha). Sensible Heating Load of CM Room Sensible Heating Load of CHM-WSE Room
2
Building Heating Load(W/m )
140 120 100 80 60 40 20 012/1
12/10 12/20 12/30 01/10 01/20 01/30 02/09 02/19 2/28
Time (Daily)
Figure (Changsha). Figure25. 25.Heating Heating Load Load (Changsha).
Appl. Sci. 2018, 8, x Appl. Sci. 2018, 8, x
Sensible Cooling Load of CM Room Latent Cooling Sensible CoolingLoad LoadofofCM CMRoom Room Total Cooling Load of CM Room Room Latent Sensible Cooling of CHM-WSE Room Total Cooling LoadLoad of CM Room Latent Cooling Sensible CoolingLoad LoadofofCHM-WSE CHM-WSERoom Room Total Cooling Load of CHM-WSE Room Latent Total Cooling Load of CHM-WSE Room
2 2 Building Cooling Load (W/m ) ) Building Cooling Load (W/m
105 105 90 90 75 75 60 60 45 45 30 30 15 15 0 0 07/1 07/1
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07/15 07/15
07/30 08/14 08/29 07/30Time08/14 (Daily) 08/29
Time (Daily)
09/13 09/13
09/28 09/28
Figure 26. Cooling load (Changsha). Figure 26. 26. Cooling Cooling load load (Changsha). (Changsha). Figure
In the cold region where the relative humidity of day and night do not change obviously, the In region where the relative humidity of of dayday andand night do not change obviously, the In the the cold cold regioneffect where night do not change obviously, CHM-WSE has small onthe therelative indoor humidity humidity environment in winter (Figure 27), but the CHM-WSE has has small effect on on thethe indoor humidity environment ininwinter (Figure 27), but the the CHM-WSE small effect indoor humidity winter (Figure the indoor relative humidity is about 55% in summer (Figureenvironment 28), which is 10% higher than 27), that but of CM. indoor relative humidity is about 55% in summer (Figure 28), which isis 10% higher than that of CM. indoor relative humidity is about 55% in summer (Figure 28), which 10% higher than that of CM. The results (Figures 29 and 30) of building load indicated that both the heating load and cooling load The results (Figures 29 building load indicated that both the The results 29 and and 30) 30)isof of building that both the heating heating load load and and cooling cooling load load of the room(Figures with CHM-WSE lower thanload that indicated of the room with CM. of that of of the the room room with with CM. CM. of the the room room with with CHM-WSE CHM-WSE is is lower lower than than that 70 70
Relative Humidity (%()%) Relative Humidity
60 60
CM Room CM Room CHM -W SE Room CHM -W SE Room
50 50 40 40 30 30 20 2011/15 11/29 12/14 12/29 01/13 01/28 02/12 02/27 03/14 11/15 11/29 12/14 12/29 01/13 01/28 02/12 02/27 03/14 Time (Daily)
Time (Daily)
Figure 27. Indoor relative humidity in heating season (Xi’an). Figure 27. Indoor relative humidity in heating season (Xi’an). Figure 27. Indoor relative humidity in heating season (Xi’an). 100 100
elative Humidity (%()%) Relative Humidity
90 90 80 80 70 70 60 60 50
CM Room CM Room CHM -W SE Room CHM -W SE Room
Relati
30
20 11/15 11/29 12/14 12/29 01/13 01/28 02/12 02/27 03/14
Time (Daily)
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Figure 27. Indoor relative humidity in heating season (Xi’an). 100 CM Room CHM -W SE Room
Relative Humidity(%)
90 80 70 60 50 40 7/1
07/15
07/30
Time (Daily)
08/14
08/29
Figure 28. Indoor relative humidity in cooling season (Xi’an). Figure 28. Indoor relative humidity in cooling season (Xi’an).
(3) Hot summer and warm winter region (HSWW) (3) Hot summer and warm winter region (HSWW) Guangzhou is chosen as the typical city in the hot summer and warm winter region. This region Guangzhou is chosen as the typical city in the hot summer and warm winter region. This region has high humidity throughout the year. In the unheated hot summer and warm winter region, in the has high humidity throughout the year. In the unheated hot summer and warm winter region, in the room where the CHM-WSE is used, the indoor relative humidity is reduced in winter by about 10% room where the CHM-WSE is used, the indoor relative humidity is reduced in winter by about 10% (Figure 31) and the relative humidity in summer is controlled at 55–70% with a small fluctuation (Figure 31) and32). the relative humidity in summer is controlled at 55–70% with a small fluctuation The range range (Figure Appl. Sci. 2018, 8, x It can be seen in Figure 33 that the heating load of Guangzhou is very small. 22 of 27 (Figure 32). It can be seen in Figure 33 that the heating load of Guangzhou is very small. The results Appl. Sci. 2018, 8, x 22 of 27 also show that the building cooling load of the room with CHM-WSE is lower than that of the room results also show that the building cooling load of the room with CHM-WSE is lower than that of the results also show that the building cooling load of the room with CHM-WSE is lower than that of the with CM (Figure 34). room with CM (Figure 34). room with CM (Figure 34).
2 2 Building Heating Load (W/m Building Heating Load (W/m ) )
140 140
Sensible Sensible Sensible Sensible
Heating Load of CM Room Heating Load Load of of CHM-WSE CM Room Room Heating Heating Load of CHM-WSE Room
120 120 100 100 80 80 60 60 40 40 20 2012/1 11/29 12/14 12/29 01/13 01/28 02/12 02/27 03/14 12/1
11/29 12/14 12/29 01/13 01/28 02/12 02/27 03/14 Time (Daily)
Time (Daily) Figure 29. Heating load (Xi’an). Figure load (Xi’an). (Xi’an). Figure29. 29. Heating Heating load
105 105
Sensible Cooling Load of CM Room Latent Cooling Load of of CM Room Sensible Cooling Load CM Room Total LatentCooling CoolingLoad LoadofofCM CMRoom Room Sensible Cooling Load of CHM-WSE Room Total Cooling Load of CM Room Latent Cooling Load of of CHM-WSE Room Sensible Cooling Load CHM-WSE Room Total LatentCooling CoolingLoad LoadofofCHM-WSE CHM-WSERoom Room Total Cooling Load of CHM-WSE Room
2 2 Building Cooling Load (W/m Building Cooling Load (W/m ) )
90 90 75 75 60 60 45 45 30 30 15 15 0 007/1 07/1
110 110 100 100
umidity idity(%()%)
90 90 80 80
07/15 07/15
07/30
Time (Daily) 07/30 Time (Daily)
08/14 08/14
Figure 30. Cooling load (Xi’an). Figure 30. Cooling load (Xi’an). Figure 30. Cooling load (Xi’an). CM Room CMMRoom CH -W SE Room CH M -W SE Room
08/29 08/29
Building
30 15 0 07/1
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08/14
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Figure 30. Cooling load (Xi’an). 110
CM Room CH M -W SE Room
Relative Humidity(%)
100 90 80 70 60 50 40
1 2 /1
Appl. Sci. 2018, 8, x Appl. Sci. 2018, 8, x
1 2 /1 0 12 /2 0 1 2 /3 0 0 1 /1 0 0 1 /2 0 01 /3 0 0 2 /0 9 0 2 /1 9 2/2 8
Time (D aily)
Figure 31. Indoor relative humidity in heating season (Guangzhou). Figure 31. Indoor relative humidity in heating season (Guangzhou).
23 of 27 23 of 27
100 100
Relative Humidity (%()%) Relative Humidity
90
90
CM Room CHM-WSE CM Room Room CHM-WSE Room
80
80 70
70 60
60 50
50 40 6/1 06/15 06/30 07/15 07/30 08/14 08/29 09/13 09/28 40 Time (Daily) 6/1 06/15 06/30 07/15 07/30 08/14 08/29 09/13 09/28
Time (Daily)
Figure32. 32.Indoor Indoorrelative relative humidity humidity in Figure in cooling cooling season season(Guangzhou). (Guangzhou). Figure 32. Indoor relative humidity in cooling season (Guangzhou). 50 2 Building Heating Load (W/m ) 2) Building Heating Load (W/m
50 40
Sensible Heating Load of CM Room Sensible Heating HeatingLoad Loadof ofCM CHM-WSE Sensible Room Room Sensible Heating Load of CHM-WSE Room
40 30
30 20
20 10
10 0 0 12/1 12/10 12/20 12/30 01/10 01/20 01/30 02/09 02/19 2/28
(Daily) 12/1 12/10 12/20 12/30 Time 01/10 01/20 01/30 02/09 02/19 2/28 Time (Daily)
105
2 Building Cooling Load (W/m ) 2) Building Cooling Load (W/m
105 90
Figure 33. Heating load (Guangzhou). Figure 33. Heating load (Guangzhou). Figure 33. Heating load (Guangzhou). Sensible Cooling Load of CM Room Latent Cooling Load of CM Room Sensible Cooling Load of CM Room Total Cooling Load of CM Room Latent Cooling Load of CM Room Sensible Cooling Load of CHM-WSE Room Total Cooling Load of CM Room Latent Cooling Load of CHM-WSE Room Sensible Cooling Load of CHM-WSE Room Total Cooling Load of CHM-WSE Room Latent Cooling Load of CHM-WSE Room Total Cooling Load of CHM-WSE Room
The relative humidity and 90 energy saving rate of the two rooms are compared and analyzed based 75 on the simulation results of different cities. The results in Table 15 shows that in the heating season, 75 the room with CHM-WSE in60the HSCW region has better energy-saving performance, and the energy 60 consumption rate is 20% lower 45 than that in the room with CM. The energy consumption rate of the latent cooling load in HSWW 45 region is the lowest, which is 12.4% lower than that in the room with 30 CM. In the cooling season, there is little difference in the energy-saving rate of the total cooling load, 30 15 and the energy-saving performance of latent cooling load in the cold region is better. 15 0 07/1 06/15 06/30 07/15 07/30 08/14 08/29 09/13 09/28 0 Time (Daily) 07/1 06/15 06/30 07/15 07/30 08/14 08/29 09/13 09/28
Time (Daily)
Figure 34. Cooling load (Guangzhou). Figure 34. Cooling load (Guangzhou).
The relative humidity and energy saving rate of the two rooms are compared and analyzed
Building
10 0 12/1 12/10 12/20 12/30 01/10 01/20 01/30 02/09 02/19 2/28
Time (Daily)
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Figure 33. Heating load (Guangzhou).
Building Cooling Load(W/m2)
105
Sensible Cooling Load of CM Room Latent Cooling Load of CM Room Total Cooling Load of CM Room Sensible Cooling Load of CHM-WSE Room Latent Cooling Load of CHM-WSE Room Total Cooling Load of CHM-WSE Room
90 75 60 45 30 15 0 07/1 06/15
06/30
07/15
07/30
Time (Daily)
08/14
08/29
09/13
09/28
Figure 34. Cooling load (Guangzhou). Figure 34. Cooling load (Guangzhou). Appl. Sci. The 2018, relative 8, x 24 of 27 humidity and energy saving rate of the two rooms are compared and analyzed
15. Hygroscopicity performance and energy saving rate of CM and CHM-WSE. based on Table the simulation results of different cities. The results in Table 15 shows that in the heating Table 15. Hygroscopicity performance andregion energyhas saving rateenergy-saving of CM and CHM-WSE. season, the room with CHM-WSE in the HSCW better performance, and Heating Season Cooling Season the energy consumption rate is 20% lower than that in the room with CM. The energy consumption Heating Season Cooling Season Sensible Latent Total rate of the latent Relative cooling load inSensible HSWW region Relative is the lowest, which is 12.4% lower than in the Relative Sensible Cooling Latent that Total Cooling Cooling Relative Humidity Sensible Humidity (%) Heating Load Humidity (%) Humidity Cooling Cooling Cooling room with the cooling season, there is little difference inLoad the energy-saving the total Load rate of Load Typical CityCM. In (%) Heating Load Typical Cityload, and the energy-saving performance of latent (%) cooling load Load Load Load cooling in the cold region is better. Energ Energy Energy
CHMEnerg Energy Energy Saving Rate Saving Rate Saving Rate CHM-W WSE Saving Rate Saving Rate Saving (%) (%) (%) SE (%) (%) Rate (%) Changsha 50–70 50–70 45–65 20.6 40–90 24.0 24.0 12.3 12.3 20.520.5 Changsha 45–65 20.6 40–90 50–70 50–70 Wuhan 40–72 40–65 18.4 40–97 50–60 24.8 12.4 20.9 Wuhan 40–72 40–65 18.4 40–97 50–60 24.8 12.4 20.9 Nanjing 35–72 35–60 19.4 45–95 55–60 24.4 11.1 20.5 Nanjing 35–72 35–60 19.4 45–95 55–60 24.4 11.1 20.5 Xi’an 25–68 30–55 17.2 40–90 50–70 21.8 15.7 20.1 Xi’an 30–55 17.2 40–90 55–85 50–70 Guangzhou 25–68 60–95 50–85 12.4 45–98 24.2 21.8 10.5 15.7 19.820.1 Guangzhou 60–95 50–85 12.4 45–98 55–85 24.2 10.5 19.8 * Energy saving rate in % is calculated using the value of CM as the reference. CM CM
CHM- Energy Saving CHM-W Energy Saving WSE Rate * (%) SE Rate * (%)
CM CM
* Energy saving rate in % is calculated using the value of CM as the reference.
Energy Per Total Building Area (MJ/m2)
According to to the the simulation simulation results, results, the the compound compound humidity humidity control control mortar mortar not not only only maintains maintains According the stable stable relative relative humidity humidity in in the the room, room, but but also also has has the the function function of of heat heat preservation preservation and and humidity humidity the adjustment. Figure 35 indicates that annual energy-saving rate per unit area of Changsha, Wuhan, adjustment. Figure 35 indicates that annual energy-saving rate per unit area of Changsha, Wuhan, Nanjing, Guangzhou, Guangzhou, Xi’an Xi’an are are about about 24.8%, 24.8%, 23.2%, 23.2%, 22.3%, 22.3%, 21.3%, 21.3%, 20.6%, respectively. Compared Compared Nanjing, 20.6%, respectively. with the room with CM, the energy saving rate of the room with CHM-WSE in the cold region is with the room with CM, the energy saving rate of the room with CHM-WSE in the cold region is the the smallest, followed by the hot summer and warm summer region. It can be concluded that the smallest, followed by the hot summer and warm summer region. It can be concluded that the compound humidity relative humidity indoor. At At the the same timetime it also compound humidity control controlmortar mortarcan cankeep keepstable stable relative humidity indoor. same it can play as an insulation material for the building envelope. also can play as an insulation material for the building envelope. 1000
CM Room CHM-WSE Room
800 600 400 200 0
Changsha
Wuhan
Nanjing
Xi'an
Guangzhou
Figure 35. Energy building area area (MJ/m (MJ/m22).). Figure 35. Energy per per conditioned conditioned building
4. Conclusions The purpose of this study was to obtain a new type of composite hygroscopic building material and put forward methods for its application research. Through the preparation of hygroscopic materials, sample tests, large-scale space experiment and different climate region analysis, conclusions
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4. Conclusions The purpose of this study was to obtain a new type of composite hygroscopic building material and put forward methods for its application research. Through the preparation of hygroscopic materials, sample tests, large-scale space experiment and different climate region analysis, conclusions can be drawn as follows: (1) A series of experiments assessing the properties of the new composite hygroscropic material are conducted. The microstructure and adsorption properties of multiple sets of CHM-WSE are studied. The mechanical properties and thermodynamic properties experiment is conducted of specimen has excellent hygroscopic property and a specific surface area of 33.331 m2 /g, aiming to meet the engineering requirements. Importantly, the structural characteristics of the hygroscopic material are firstly considered for quantifying its performance of engineering requirements. (2) A large-scale space comparison experiment is established. The test results show that the temperature and humidity uniformity in the room with CHM-WSE are better than that in the room with CM at 1.5 m from the floor. The relative humidity of the room with CHM-WSE is 14.3% lower than that of the room with CM in winter. The relative humidity of the room with CHM-WSE is lower than that of the room with CM by 6–10% in spring. Furthermore, the room with CHM-WSE has better moisture buffering performance than the room with CM, and the practical moisture buffering performance is better in spring and summer alternating season than in winter. (3) The influence of CHM-WSE on the indoor humidity environment and energy consumption in the multi-climate zone is studied. The simulation results show that the relative humidity fluctuation of the room with CHM-WSE is about 10% lower than that of the room without CHM-WSE, which has better hygroscopic ability and energy saving potential, and is more suitable for hot summer and cold winter region. The raw materials of the CHM-WSE presented in this paper are common environmental materials, which are cheap and easy to handle. The CHM-WSE not only meets the requirements of mechanics and thermodynamics, but also regulates indoor humidity environment, improves indoor comfort and reduces building energy consumption. It is a new type of composite hygroscopic building material which could replace the traditional mortar. Acknowledgments: The authors are grateful for the financial support of the Major Science and Technology Projects of Hunan Province, China (No. 2010FJ1013), the International Science and Technology Cooperative in Project of China (No. 2010DFB63830), National Natural Science Foundation of China (Grant No. 51378186) and National Key Technology Support Program (No. 2015BAJ03B00). Author Contributions: Huahui Xie and Guangcai Gong conceived and designed the experiments; Huahui Xie and Yi Wu performed the experiments; Huahui Xie and Guangcai Gong analyzed the data; Huahui Xie, Yi Wu, Yongchao Liu and Yingjuan Wang contributed materials/test/analysis tools; Huahui Xie wrote the paper. Conflicts of Interest: The authors declare no conflict of interest.
References 1. 2. 3. 4. 5.
Bomberg, M.T.; Brown, W.C. Building envelope design through environmental control—Part 1: Heat, air and moisture interactions. Constr. Can. 1993, 2, 116–119. [CrossRef] Sato, M.; Fukayo, S.; Yano, E. Adverse environmental health effects of ultra-low relative humidity indoor air. J. Occup. Health 2003, 45, 133–136. [CrossRef] [PubMed] Fisk, W.J.; Lei-Gomez, Q.; Mendell, M.J. Meta-analyses of the associations of respiratory health effects with dampness and mold in homes. Indoor Air 2007, 17, 284–296. [CrossRef] [PubMed] Yang, W.; Wong, N.H.; Jusuf, S.K. Thermal comfort in outdoor urban spaces in Singapore. Build. Environ. 2013, 59, 426–435. [CrossRef] Mendes, N.; Winkelmann, F.C.; Lamberts, R.; Philippi, P.C. Moisture effects on conduction loads. Energy Build. 2003, 35, 631–644. [CrossRef]
Appl. Sci. 2018, 8, 430
6.
7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.
18. 19.
20. 21. 22. 23.
24. 25. 26.
27.
28.
27 of 28
Chung, S.Y.; Lehmann, C.; Abd Elrahman, M.; Stephan, D. Pore characteristics and their effects on the material properties of foamed concrete evaluated using micro-CT images and numerical approaches. Appl. Sci. 2017, 7, 550. [CrossRef] Li, C.Q. Life Cycle Modeling of Corrosion Affected Concrete Structures: Propagation. J. Struct. Eng. 2003, 15, 753–761. [CrossRef] GB 50736::2012. Design Code for Heating Ventilation and Air Conditioning of Civil Buildings; Ministry of Housing and Urban-Rural Construction of the People’s Republic of China: Beijing, China, 2012. Kaufhold, S.; Dohrmann, R.; Klinkenberg, M.; Siegesmund, S.; Ufer, K. N2-BET specific surface area of bentonites. J. Colloid Interface Sci. 2010, 349, 275–282. [CrossRef] [PubMed] Allinson, D.; Hall, M. Hygrothermal analysis of a stabilised rammed earth test building in the UK. Energy Build. 2010, 42, 845–852. [CrossRef] Ashour, T.; Georg, H.; Wu, W. An experimental investigation on equilibrium moisture content of earth plaster with natural reinforcement fibres for straw bale buildings. Appl. Therm. Eng. 2011, 31, 293–303. [CrossRef] Hall, M.; Allinson, D. Analysis of the hygrothermal functional properties of stabilised rammed earth materials. Build. Environ. 2009, 44, 1935–1942. [CrossRef] Padfield, T. The Role of Absorbent Building Materials in Moderating Changes of Relative Humidity. Ph.D. Thesis, The Technical University of Denmark, Kongens Lyngby, Denmark, 1999. Murata, K.; Watanabe, Y.; Nakano, T. Effect of thermal treatment on fracture properties and adsorption properties of spruce wood. Materials 2013, 6, 4186–4197. [CrossRef] [PubMed] Fang, L.; Clausen, G.; Fanger, P.O. Impact of temperature and humidity on the perception of indoor air quality during immediate and longer whole-body exposures. Indoor Air 1998, 8, 276–284. [CrossRef] Simonson, C.J.; Salonvaara, M.; Ojanen, T. The effect of structures on indoor humidity-possibility to improve comfort and perceived air quality. Indoor Air 2002, 12, 243–251. [CrossRef] [PubMed] Kurnitski, J.; Kalamees, T.; Palonen, J.; Eskola, L.; Seppanen, O. Potential effects of permeable and hygroscopic lightweight structures on thermal comfort and perceived IAS in a cold climate. Indoor Air 2007, 17, 37–49. [CrossRef] [PubMed] Li, Z.; Chen, W.; Deng, S.; Lin, Z. The characteristics of space cooling load and indoor humidity control for residences in the subtropics. Build. Environ. 2006, 41, 1137–1147. [CrossRef] Woloszyn, M.; Kalamees, T.; Abadie, M.O.; Steeman, M.; Kalagasidis, A.S. The effect of combining a relative-humidity-sensitive ventilation system with the moisture-buffering capacity of materials on indoor climate and energy efficiency of buildings. Build. Environ. 2009, 44, 515–524. [CrossRef] Mitchell, M.R.; Link, R.E.; Fang, P.; Mukhopadhyaya, P.; Kumaran, K.; Shi, C. Sorption and thermal properties of insulating mortars with expanded and vitrified small ball (EVSB). J. Test. Eval. 2011, 39, 102378. [CrossRef] Osanyintola, O.F.; Talukdar, P.; Simonson, C.J. Effect of initial conditions, boundary conditions and thickness on the moisture buffering capacity of spruce plywood. Energy Build. 2006, 38, 1283–1292. [CrossRef] Osanyintola, O.F.; Simonson, C.J. Moisture buffering capacity of hygroscopic building materials, experimental facilities and energy impact. Energy Build. 2006, 38, 1270–1282. [CrossRef] Wu, Y.; Gong, G.; Yu, C.W.; Fang, P. The hygroscopic properties of wood fibre, sepiolite and expanded perlite-based breathable wall for moderating the humidity environment. Indoor Built Environ. 2014, 23, 299–312. [CrossRef] Rode, C.; Grau, K. Moisture Buffering of Building Materials; Department of Civil Engineering, Technical University of Denmark: Kongens Lyngby, Denmark, 2005; pp. 11–78. ISBN 87-7877-195-1. Test Method of Adsorption/Desorption Efficiency for Building Material to Regulate Indoor Humidity; JIS A 1470-1:2002; Japanese Industrial Standards, Japanese Standards Association: Tokyo, Japan, 2002. Hygrothermal Performance of Building Materials and Products-Determination of Moisture Adsorption/Desorption Properties in Response to Humidity Variation; ISO 24353:2008; International Organization for Standardization: Geneva, Switzerland, 2008. Xie, H.; Gong, G.; Wu, Y. Investigations of equilibrium moisture content with Kelvin modification and dimensional analysis method for composite hygroscopic material. Constr. Build. Mater. 2017, 139, 101–113. [CrossRef] Wu, Y.; Gong, G.; Yu, C.W.; Huang, Z. Proposing ultimate moisture buffering value (UMBV) for characterization of composite porous mortars. Constr. Build. Mater. 2015, 82, 81–88. [CrossRef]
Appl. Sci. 2018, 8, 430
29. 30. 31. 32. 33.
34. 35. 36. 37.
28 of 28
Pore Size Distribution and Porosity of Solid Materials by Mercury Porosimetry and Gas Adsorption-Part 1: Mercury Porosimetry; ISO 15901-1:2016; The British Standards Institution: London, UK, 2016; ISBN 9780580815584. Test Methods of Inorganic Rigid Thermal Insulation; GB/T5486.2:2001; Standardization Administration of China: Beijing, China, 2001. Hygrothermal Performance of Building Materials and Products—Determination of Hygroscopic Sorption Properties; ISO 12571:2013; British Standard: Geneva, Switzerland, 2013. Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus; ASTM Standard C518-04; ASTM International: West Conshohocken, PA, USA, 2010. Zhang, W.S. Study on the Performances of Heat Moisture and Air Permeation for the Wall Materials of Composite Insulation Block. Master’s Thesis, China University of Mining and Technology, Beijing, China, 2016. Design Code for Heating Ventilation and Air Conditioning of Civil Building; GB50736:2016; Standardization Administration of China: Beijing, China, 2016. Building Thermal Insulation Mortar; GB/T 20473:2006; Standardization Administration of China: Beijing, China, 2006. Multi-Layer Coating for Architecture; GB/T 9779:2015; Standardization Administration of China: Beijing, China, 2015. Hunan Universtiy; Tianjin University; Tongjing University; Southeast University. Civil Engineering Materials; China Architecture and Building Press: Beijing, China, 2003; pp. 253–254. ISBN 7-112-04784-6. © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
