Design of a Brick With Sound Absorption Properties ...

Received May 29, 2015, accepted July 9, 2015, date of publication August 6, 2015, date of current version August 11, 2015. Digital Object Identifier 10.1109/ACCESS.2015.2461536

Design of a Brick With Sound Absorption Properties Based on Plastic Waste & Sawdust ANGEL DANIEL MUÑOZ GUZMAN AND MARÍA GIOVANNA TROTTA MUNNO Instituto Tecnológico y de Estudios Superiores de Monterrey, Zapopan 45201, Mexico

Corresponding author: A. D. Muñoz Guzman ([email protected])

ABSTRACT This paper applies to the redesign of a brick in which the selection of the material and the internal geometry are designed to increase sound absorption together with an improvement in structural strength. The definition of the material opportunity is given by the sawmill industry in Mexico, which produces about 2 million tons of sawdust per year, almost all wasted, and another important waste material: plastic. Each year, Mexico produces 992 000 tons of low density polyethylene. These two waste products can be used as raw materials to create wood plastic composite. INDEX TERMS Acoustic absorption, sawdust, WPC, design, brick, structure, wood, plastic, LDPE. I. INTRODUCTION

Mexico occupies the 10th place in the world in waste generation. It is estimated that the country generates 30 million tons of waste per year with about 25% entering the composting, incinerating, and landfill waste streams [32]. Five point eight percent of the total amount consists of plastic, which approximates to roughly 1.7 million tons of plastic per year. Plastic waste can cause water, air and soil contamination. Shuffling and mixing the trash increases the difficulty and cost of recovering and recycling it. Most plastics take at least 240 years to degrade and consequently are a source of pollution, which this research wants to help reduce. Another contribution is avoiding incineration and the subsequent generation and release of toxic gases into the atmosphere [7]. Additionally, the sawmill industry alone generates more than a million tons of sawdust-waste each year, which could be reduced together with air and soil pollution. This research is focused on sustainability and aims to be applicable to the revaluation of forest resources. In Mexico, only 25% of forest communities have ethically exploited forest resources. The other 75% of communities exploit the forest in an inappropriate or illegal manner (FAO, 2010). In 2003, SEMARNAT registered 3497 companies using forest resources, with 88.6% (3 098) belonging to the sawmill industry. According to INEGI, Mexico produces 0.35 m3 of sawdust for each 1m3 of wood. In the year 2011, national production of wood rolls was 5’897,357 m3 . Seventy-four point seven percent of this sawdust comes from pine [12], which means about 2 million m3 of sawdust. This research analyzes wood plastic composites (WPC) in order to understand physical and mechanical properties and 1260

apply them to a new brick. This new design will solve the problem of absorbing acoustic waves in order to increase the perceived quality inside a building. The new design will create advantages for suppliers, manufactures and the construction industry and simultaneously help to reduce environmental impact. A. PLASTIC WASTE

The polymer that will be considered in terms of chemical composition, is LDPE, one of the simplest compounds. This plastic has different applications, and can be used in toys, cups, plates, plastic cutlery, bottles for powdered pharmaceuticals, industrial packaging, lamination, flexible films, wires and cables, conduit pipe, greenhouse film, irrigation piping and irrigation systems [26]. According to the U.S. Environmental Protection Agency, approximately 500 billion plastic bags are consumed per year worldwide, with only 1% being recycled. In Mexico, 992 thousand pounds of low-density polyethylene is produced [14] every year. B. SAWDUST

Sawdust is the most abundant waste obtained from the sawmill production process in Mexico; it represents approximately 35% of the total wood obtained from the processing of pine trees. The mean density of pinesawdust is 367 kg per cubic meter. The size of the particles generated in the sawmill process varies from 0.25mm [21] to 1.72mm [33]. Once the materials that will be used to create the composite WPC have been identified, the next step is the development of the new design proposals. These proposals

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VOLUME 3, 2015

A. D. Muñoz Guzman, M. G. Trotta Munno: Design of a Brick With Sound Absorption Properties

were based on an acoustic analysis, with the purpose of creating a sound-absorbent brick.

internal structure of the hollow brick, to increase performance as a sound buffer. 2) MEASUREMENT OF SOUND

FIGURE 1. Sound waves are described by their wavelength, amplitude and frequency and intensity (in decibels).

In order to define the best design solution for sound absorption, a basis for sound measurement will be defined in this paragraph. Sound manifests in the atmosphere as a waveform with a speed of approximately 340 m/s depending on temperature, relative environmental humidity and atmospheric pressure. Sound propagation is fastest within solid and less elastic materials such as metals [15]. Table 1 below shows the value of the speed of sound related to different materials. TABLE 1. Sound speed on different materials.

1) ACOUSTIC ANALYSIS

Sound, conventionally, is represented by curved waves like those shown in figure 1. Sound waves expand through the air, and if they touch a flat or reflective surface, they will be reflected with the same intensity at which they were emitted. If the sound wave hits a porous surface, part of the energy will be absorbed by the object [8]. For this reason, porosity has been considered as fundamental characteristic of the new brick. The new design is based on the property of acoustic absorption and not acoustic insulation; this is because the new design is made to create a comfortable environment within the walls of a house, blocking all echoes in the interior and diminishing exterior sounds.

In the table, it can be seen that the more porous the material is, the slower the sound wave will travel. It is important to note this because the WPC brick is a porous material which is able to cushion a small quantity of sound on its own. Sound levels and noise can be measured through decibels (dB) within the logarithmic scale. In order to better understand different levels of sound the following examples are given: a) whispers in a library: 40 dB; b) the sound of a fan: up to 60 dB; c) a truck engine: 80 dB; d) a night club: 110 dB [6]. Table 2 presents the noise measured in dB from highest to the lowest. For further details on noise levels see ‘‘The Science of Sound’’ [15]. TABLE 2. Subjective valuation of sound levels.

FIGURE 2. Differences between acoustic isolation and acoustic absorption.

Figure 2 shows the behavior of the acoustic insulation and acoustic absorption in a wall. It can be assumed that the materials destined to absorb sound must be porous due to the fact that the sound wave loses energy while traveling across the material [8]. When a sound wave hits an object, three effects take place: a) a part of the wave reflects on the same wall; b) part is eliminated through the interior wall; c) the rest is transmitted to the other side of the wall. These three particular points were considered for the selection of the geometrical shape of the VOLUME 3, 2015

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II. MATERIALS AND METHODS

TABLE 3. Mechanical properties of the WPC.

As previously stated, pine sawdust is an abundant waste product in Mexico, one which is used in plastic bags made of LDPE. The materials used for the WPC compound are: pine sawdust, low-density polyethylene and the bonding R agent Fusabond . Data related to the mechanical properties of WPC has been used along with the SolidWorks software to assist in designing the digital model of the WPC brick and the simulation of the load performances. For the acoustic test, 2 commercial bricks were used and two bricks prototyped and manufactured with a CNC machine (CNC signifies Computer Numerical Control: a computer which converts into numbers the design produced by Computer Aided Design software). One of these designs features triangles and the other has hexagonal holes.

1) VECTOR MEASUREMENT

A. PREPARING THE MIX

The mechanical properties of WPC vary according to the amount of sawdust and plastic mixed to obtain it. The proportion considered for this investigation is 49% sawdust, 49% LDPE plastic and 2% Fusabond. The presence of moisture in the mix of these two materials represents a decrease in the mechanical properties of the WPC. For this reason, the first step is heat-treating the sawdust and plastic so that they are completely dry. This process takes 1 hour at a temperature of 70 ◦ C for the sawdust and 100 ◦ C for the LDPE [16]. Proper temperature adjustment for both sawdust and LDPE is critical; improper mixing can cause dispersion of the plastic molecules and fibers. This can cause a reduction in the mechanical properties of the WPC [34]. Thermoplastic extrusion techniques give effective results with solid or hollowed volumes. For this composite the main stage in the mixing process is extrusion, where the combination of sawdust and LDPE means the pine sawdust retains its properties at high temperatures, for example in the injection process. Combining sawdust and thermoplastic PE generally requires a considerable amount of thermic and physical energy for the mixing of the polymer [20]. The elements are combined in rotating machines, a process which produces enough heat to melt the plastic and create a homogeneous mixture [24]. The mechanical properties of the WPC are shown below in Table 3: The following table is the same as table 3 but the units are in the International System for ease of reference. The samples for obtaining these values were taken by the Trex Company [31]. They were subsequently entered into the SolidWorks software to carry out a simulation of a mechanical test on the digital brick. B. DESIGNING THE INTERNAL STRUCTURE OF THE BRICK

Having defined the compound, the next step was to proceed to the analysis and the development of three tests to determine the best design for the brick structure. These tests are presented below. 1262

Geometrical acoustics is the study of sound reflections. To do this, the sound is treated like a light beam which must travel over an area with the following characteristics: • Solid surface (a porous surface would absorb a part of the energy); • Flat surface (a convex surface would diffuse a part of the energy); • A dimension larger that the longitude of the wave (a smaller surface would diffract part of the energy); • The sound beam should be reflected at an angle equal to that of its incidence (specularity law) [15]. Considering the points above, it can be deduced that this WPC brick will absorb part of the sound by itself due to its porous structure. The arrangement of the hollows must distribute the sound waves to all the internal walls of the brick in order to reduce their energy. The analysis of the acoustic data of certain geometries, like the honeycomb and the Mayan Atecocolli, was the inspiration for the two designs developed for this research, as will be explained later. The geometric method of the optic law will be also be applied to the acoustics. This method has been used to obtain the length of the vector representing the sound path across the walls of the brick from one side to the other. 2) ACOUSTIC TEST

The tests were done on 4 different bricks, two of which were made of compressed sawdust and with the hollows designed and proposed for this research. The other two hollow bricks were made of clay using a design already commercially available. The acoustic tests were run on each design to discover which one amortizes sound waves better. For these tests, an enclosed cabin with insulated walls was built as shown in figure 3. This cabin was divided in three parts. The first side contained the sound source which emitted a constant sound of 50 dB; the brick was placed in the middle and on the left side the sound meter was positioned. The information recorded by the soundmeter was transferred via wireless to a monitor to analyze the results. VOLUME 3, 2015


FIGURE 3. Cabin built for the acoustic test.

The sound pressure level was taken at about 100 dB and 6 measurements were taken over a minute for each brick. 3) MECHANICAL TEST

Mechanical testing was performed on the 4 designs to calculate their structural behavior. SolidWorks Simulation 2004 software was used, where the weight of a 2m high wall was considered over one single brick.

FIGURE 5. Law of sound reflection.

C. PROPOSED DESIGN OF THE BRICKS

The internal residential environment varies depending on the types of walls and their width. Many buildings are made with double walls, where the materials in the center are the insulating covering providing a thermal and acoustic insulation barrier. Thus the temperature inside is retained independently of the external temperature, and the sound is absorbed to reduce the noise level. The hypothesis is that the brick proposed achieves the acoustic absorption without the necessity for an extra insulation wall.

FIGURE 6. Painting of the Mayan Atecocolli.

FIGURE 4. Sound path across the hollow brick.

Sound is transmitted along walls through vibration. It crosses the solid brick and the vibrations travel directly to the other side being weakened only by the pores of the material. If vertical and perpendicular channels were added, the sound waves would lose energy when passing through each of the inner faces as shown in figure 4. The law of specularity or sound reflection says that the angle of the reflected vector is equal to the angle when the vector hits the wall. This law is presented in figure 5. Given this rule, 4 geometric arrangements of possible internal structures were designed. Each one was analyzed considering the path of the reflection when the vector hits VOLUME 3, 2015

each part of the internal wall and then calculating the length of the vector across the brick. For a quantitative analysis, a value of 100 was taken as a source/amount of energy; and for each reflection on the internal walls, a value of 1 was subtracted. Whilst closing each structure, the arrangements with the lesser value will be considered for subsequent acoustic tests. III. DESIGN OF THE BRICKS

This section describes the method used to create the 4 design proposals for the internal structure of the brick. A. DESIGN 1: ACOUSTIC TRIANGULATION

To understand how a geometric figure can reduce or bounce sound, it must be understood how a geometrical and acoustical object can increase it. One of the oldest wind instruments is the Mayan Atecocolli (see figure 6), which in Nahuatl means ‘‘water snail’’. 1263


FIGURE 9. Sound reflection inside the spiral.

FIGURE 7. The spiral of Theodorus up to the triangle with a hypotenuse √ of 17.

FIGURE 10. Design of the triangles for the brick’s holes.

FIGURE 8. Theodore Cyrene’s Pythagorean spiral digital model.

This shell was cut in such a way as to enable a sound to be produced when the shell was blown. The atecocolli was used by indigenous Americans to make calls for different kinds of events. The shell has a geometry that amplifies sound waves and has the ability to generate sounds at high-pitched frequencies. Mathematically, this phenomenon is expressed with Theodore Cyrene’s Pythagorean spiral, which is presented below in figure 7. In geometry, the spiral of Theodorus (also called square root spiral, Einstein spiral or Pythagorean spiral) is a spiral composed of contiguous right-slanting triangles. It was first constructed by Cyrene. The digital design was created in order to apply the geometric method of equality between the incidence angle and the reflection as illustrated in the figure 8. This spiral is obtained by the arrangement of triangles; the sound source is located at the center. On the computer, two vectors were drawn with different initial angles, the result is shown in figure 9: As shown in Figure 9, regardless of the initial direction of the sound, always there’s an outward reflection. This means that the vector of the sound is never reflected back. 1264

These triangles were the inspiration for the creation of the first proposal, which consists of triangular holes throughout the internal part of the brick. However, instead of setting all the triangles together, the triangles were positioned alternately face down and face up, as shown in figure 10. The hypothesis was that the sound wave will hit the walls of each hollow and hence will lose energy. Based on the above premise, proposal 1 uses the following arrangement: In this design it can be seen that the triangles are arranged alternately face up and down, instead of the Pythagorean spiral arrangement which features triangles with a common vertex. In the Pythagorean spiral, the sound wave hits the walls and goes straight to the outside, but in this new design, the sound wave will bounce many times in the triangles within the brick and lose energy before the wave goes completely through it. This design will provide superior acoustic damping to that currently available in commercially-made bricks. B. DESIGN 2: REFLECTION ON HEXAGONS

Tiling is the division of a plane into different geometrical sections each of which do not overlap and no not have spaces between them. Geometric shapes used for repeat-pattern tiling are frequently squares, equilateral triangles or hexagons. This is because the value of the angles of the three figures is divisible by 360. For example, pentagons cannot be used for tiling as VOLUME 3, 2015


FIGURE 13. Design of the rectangles for the brick’s holes.

FIGURE 11. Structure of a Honeycomb (Showing the hexagonal structure).

they have an interior angle of 108 degrees, whereas that of a square is 90◦ , an equilateral triangle 60◦ and a hexagon 120◦ : In all of these aforementioned shapes 360◦ can be divided into whole numbers. A natural example of tiling design can be seen in honeycomb. Honeycomb panels are rigid structures composed of hexagonal cells that are used to store honey and incubate larvae. Charles Darwin describes in his book ‘‘The Origin of Species’’ the honeycomb as a work of both engineering and art because its structure enables bees to minimize labor and materials and optimize space, as shown in figure 11. Applying this geometry to the brick will hypothetically maximize acoustic damping by distributing the sound across all the walls [10]. By using this geometry, a lighter brick will be obtained which will also offer the necessary structural strength.

two commercially-available geometric designs (rectangular and octagonal holes). In order to know which of the four designs has the longer path, the four designs (using SolidWorks) were drawn on the computer. After that, 3 paths were drawn on each design, starting with a different angle to calculate the shortest distance on each design. The following figures (figures 13, 14, 15, 16) present the shortest path calculated on each design.

FIGURE 14. Design of the octagons for the brick’s holes.

FIGURE 12. Design of the hexagons for the brick’s holes.

Based on the above, the second proposal, which comprises the following array of hexagons, is shown in figure 12. FIGURE 15. Design of the triangular-shaped holes in the brick.

IV. RESULTS OF ACOUSTIC AND MECHANICAL TESTS A. VECTOR MEASUREMENT

The path of sound through the two previouslyintroduced design proposals was calculated (triangular and hexagonal holes). It was also calculated for the VOLUME 3, 2015

1) DESIGN WITH RECTANGLES

For this configuration (currently on the market), it can be seen that the vector of the sound can pass directly through the 1265


a: CONCLUSION

In the vector analysis it can be observed that the two new designs proposed (triangular and hexagonal holes) cause the sound wave to take longer to pass through the brick. Although the number of reflections in the hexagonal configuration was higher than the in the triangular configuration, the sound path is greater in the latter. In conclusion, the design that makes the sound take longer to cross the brick is the one with the triangles. B. ACOUSTIC TESTING FIGURE 16. Design of the hexagons for the brick’s holes.

brick without any bouncing on the walls, giving us a length of 140 mm. For quantitative questions, allocating a value of 100 incoming sound energy and a loss of 1 point of energy with each bounce, a final value of 100 is obtained, because no reflections are assumed.

The second test performed was an acoustic test, which was performed separately for each one of the four designs. The sound source was calibrated to emit a constant sound of 50 dB per minute, and during this time 4 measurements were taken every 10 seconds for each brick. Subsequently the average was calculated to obtain the result of the sound absorption of each brick. Table 5 shows the results of these tests:

2) DESIGN WITH OCTAGONS

In the configuration of octagons, the distance traveled by the vector has a value of 202.67 mm. assuming an incoming energy of 100 points and a loss of 1 point for each reflection; the resulting total energy is 88 points.

TABLE 5. Vector length of each design.

3) DESIGN WITH TRIANGLES

The arrangement of triangles inspired by the Pythagorean spiral of Theodor of Cyrene won, as it had the longest distance analyzed at 281.41 mm. The score of the energy lost due to reflection was 84 points. 4) DESIGN WITH HEXAGONS

The second proposed design is based on the structure of a honeycomb. The trajectory of the vector reached was 239.4 mm and the sound score dropped from 100 to 80 points. Finally, the following values obtained are shown in table 4: TABLE 4. Mechanical properties of the WPC.

The results showed that a solid clay brick has the least ability to absorb sound dampening, at only 15.8%. The two proposed designs had the best sound absorption performance, and of these two designs, that featuring triangles yielded the best results, with noise reduction of 40.2%. 1) EVALUATION OF THE TWO PROPOSED DESIGNS

After performing acoustic testing with the 4 bricks, a specific test to compare the hexagons and triangle designs was performed. The procedure was the same but this time the sound source was calibrated to 62.4 dB. The results were the following: The design with the hexagonal holes obtained a score of 46.4 dB (as shown in figure 17) with a sound source of 62.4dB. Figure 18 shows the results for the design with the triangular holes. In figure 18 it can be seen that the brick gave a measurement of 43.9 dB with a sound source of 62.4dB. It can be seen that the design with the hexagons had the highest number of reflections but the design with the triangles had the largest travel distance and therefore the greatest loss of acoustic energy. 1266

2) CONCLUSIONS

The 2 design proposals in this investigation had better sound absorption than the commercial bricks. These two designs were compared, and the design featuring VOLUME 3, 2015


The results of this test are shown next: 1. Rectangular holes design.

FIGURE 17. Sound measurement l.

FIGURE 18. Sound measurement ll.

Maximum Stress: 123,121 N/m2 Minimum Stress: 22,653 N/m2 Yield strength: 23, 399,978 N/m2 Maximum displacement: 0.0048mm 2. Octagonal holes design.

Maximum Stress: 150,659 N/m2 Minimum Stress: 27,906.7 N/m2 Yield strength: 23, 399,978 N/m2 Maximum displacement: 0.0059mm 3. Triangular holes design.

triangular holes had the best sound absorption. This design gave the best results in both tests. A mechanical test was subsequently carried out on the four designs. C. MECHANICAL TEST

A mechanical test was carried out on the 4 previous designs to analyze their structural behavior. For this test a wall 2.5m high and 5m long was assumed. The weight of this wall was considered as a force over one single brick. The bricks have the dimensions of 9cm × 14cm × 29cm, hence the wall has 27.7 rows of bricks and each row has 17.2 bricks, this means that the wall has a total of 477 bricks. If it is assumed that the weight of each brick is 2.3Kg each, it can be calculated that the total weight of the wall is 1,099kg. The force used in the simulation for the mechanical test is calculated as follows: the first row has 17.2 bricks, giving a weight of 39.56Kg (17.2kg × 2.3kg). This weight is subtracted from the weight of the wall (1,099kg – 39.56kg) giving a result of 1059.44kg. This means that the first row of bricks is supporting 1059.44kg, and if this weight is divided between the 17.2 bricks in the row, it can be implied that that each brick is supporting 61.59kg. To analyze the 4 designs, a safety factor of 4 has been considered, showing that the force over the analyzed brick is 246kg (61.59kg × 4). VOLUME 3, 2015

Maximum Stress: 123,152 N/m2 Minimum Stress: 21,842.3 N/m2 Yield strength: 23, 399,978 N/m2 Maximum displacement: 0.0042mm 4. Hexagonal holes design

Maximum Stress: 162,036 N/m2 Minimum Stress: 33,630 N/m2 Yield strength: 23, 399,978 N/m2 Maximum displacement: 0.0058mm The results are shown in table 6: It is clear that the design with the triangular holes had the lowest displacement when compressed and 20% less stress than the hexagonal design. 1267


TABLE 6. Acoustic test results.

FIGURE 20. WPC Brick design - Lateral Profiles. TABLE 7. Mechanical test results.

This satisfies the requirements of the Mexican code N-CMT-2-01-001/02. Figure 21 shows the general dimensions of this new WPC brick.

Conclusions: Taking into account a force of 180 Kg over each design, the design with the structure of triangular holes had the best performance. In the previous acoustic test, this design (triangle holes) also yielded the best results, and is therefore considered as the final design. D. THE FINAL DESIGN

The new WPC brick design, based on the previouslydescribed test, has triangular vertical holes, which give better sound absorption.

FIGURE 21. WPC Brick Drawings.

FIGURE 22. Assembled wall. FIGURE 19. WPC Brick design.

The new design is shown here in figure 19: The two lateral small faces have a geometric profile that helps to assemble the wall faster as shown in figure 20. With these two profiles, the wall can be built faster and a complete vertical direction can be assured. This brick has a dimension of 29cm long, 14cm width and 9cm height and an approximate weight of 2.5 Kg. 1268

This brick can be assembled faster than ordinary bricks because of its shape. An example of a wall constructed with these bricks is shown in figure 22. In figure 22 it can be seen that the end of one brick fits with the beginning of the following brick because of its shape. Walls built of WPC brick will be held together with mortar in order to create a secure structure. Previous investigations show that building with plastic compounds is also possible, VOLUME 3, 2015


FIGURE 23. House made of plastic bricks.

FIGURE 27. Special brick for supports on walls.

FIGURE 24. Hose made of composite brick.

FIGURE 25. Cement-Plastic Brick.

FIGURE 28. Second special design of the WPC Brick.

FIGURE 26. Cover for supports on walls.

like the project in Swansea, United Kingdom, where Andrew (2009) created a block made with recycled plastic to build houses as shown in figure 23. Another example of the feasibility of constructing with WPC brick is a project carried out in Colombia. In this case VOLUME 3, 2015

FIGURE 29. Third special design of the WPC Brick.

the brick was made with a composite of recycled plastic and concrete as shown in the following Figure [19]. Other investigations took place in Cordoba, Argentina; where a brick was developed by the CEVEC [13]. CEVEC 1269


The results are that the force needed to separate two WPC bricks joined with mortar is 2611.61 Newtons. V. CONCLUSIONS

By using the WPC brick forest communities add value to sawdust by converting it into a raw material and reducing the waste produced in sawmills. A. REDUCTION OF WASTE

Mexico produces approximately 2 million m3 of sawdust per year, which means that 570 million WPC bricks could be produced annually. B. INCREASE IN REVENUES

Forest communities currently derive no economic benefit from selling sawdust. Through the development of this WPC brick, these communities will become suppliers of raw material. C. ENVIROMENTAL BENEFITS

The manufacture of the WPC brick has a positive impact on the natural environment because it replaces the current clay brick production process. In Mexico, a typical kiln has a 10,000 brick capacity. Each kiln generates about 280 Kg of CO2. The WPC Brick does not generate that pollution because it is produced using extrusion rather than kiln firing. D. LESS PLASTIC WASTE

FIGURE 30. Compression Test to a assembled WPC.

developed a brick which was a composite of PET, PE and PVC and cement. These bricks are shown in figure 25: It is also designed to be an ‘‘apparent brick’’ that needs no cover as it has an aesthetic appearance that resembles wood. There are three other designs to complete the whole system. These designs are created to be used in conjunction with the wall supports and to disguise them. This will avoid covering the walls as in figure 26: The first of these three designs is intended to be used as a support holder in the middle of a wall as shown in figure 27. The second design of this WPC-Brick is intended to be used at the end of a wall where it is necessary to have a straight edge in order to position doors, windows or elements involved in construction. This design can be seen below. The third design is intended to be used as a superior support; the profile shown in figure 29 is a solution designed for hiding horizontal supports. This design is presented here: This brick can be used for the construction of walls with the addition of mortar between each individual brick. A test was made to prove the adhesion properties of mortar when used with WPC and this is shown in figure 30. 1270

Mexico produces about 992 thousand tons of low-density polyethylene per year and only 1.2% is recycled [29]. If all this waste was recycled, more than 755 million tons of WPC bricks could be produced per annum. E. IMPROVEMENTS ON CONSTRUCTION

The rate of building construction will depend on the workers but, by using this new design, a building can be constructed 55% faster because of the shape and size of the WPC brick. F. ECONOMIC SAVINGS

This WPC brick has integral acoustic absorption properties eliminating the requirement for additional special coverings. In addition, the production cost is very low because the raw materials are waste materials: sawdust and plastic. The WPC brick also absorbs only 0.7% moisture, less than clay bricks or wood. VI. FUTURE RESEARCH

An immediate continuation of this investigation, is to find suppliers with the infrastructure and requisite technology to manufacture the WPC brick. Further research that could follow this investigation is investigating the possibility of using these bricks for support walls. It would be necessary to carry out tests on walls constructed entirely of WPC bricks. There is still a lot of work to do in the WPC field. The only current application for the material apart from the brick developed in this investigation is in the production of VOLUME 3, 2015


decking. However, the mechanical properties and the variables in the mixture for this composite have wide potential for application. Another investigation which needs to be carried out is testing the adherence of these bricks with mortar. It would also be interesting to investigate how the extrusion process could be improved to require less energy and make the process more productive, by using alternative sources of energy for example. To conclude, WPC lends itself to the creation of a wide range of products. It could be modified to use other organic waste like corn or peanut shells for example, helping to reduce waste from other industries and create new materials with different applications. REFERENCES [1] G. O. Young, ‘‘Synthetic structure of industrial plastics (book style with paper title and editor),’’ in Plastics, vol. 3, J. Peters, Ed., 2nd ed. New York, NY, USA: McGraw-Hill, 1964, pp. 15–64. [2] A. E. Grimm, P. R. Bonelli, and A. L. Cukierman, ‘‘Degradación térmica de mezclas de residuos plásticos y lignocelulósicos: Caracterización cinética,’’ Avances Energías Renovables Medio Ambiente, vol. 5, pp. 17–20, 2001. [3] E. Andrews. (Sep. 14, 2009). New Homes to be Built From 18 Tonnes of Recycled Plastic. Daily Mail. [Online]. Available: http://www.dailymail. co.uk/sciencetech/article-1253514/New-homes-built-18-tonnes-recycledplastic.html [4] M. A. Antal, Jr., ‘‘Biomass pyrolysis: A review of the literature part 2—Lignocellulose pyrolysis,’’ in Advances in Solar Energy, K. W. Böer and J. A. Duffie, Eds. New York, NY, USA: Springer-Verlag, 1985. [5] K. Attenborough, ‘‘Acoustical characteristics of rigid fibrous absorbents and granular materials,’’ J. Acoust. Soc. Amer., vol. 73, no. 3, p. 785, 1983. [6] C. E. Boschi, S. G. Acosta, and A. F. González, ‘‘Determinación del coeficiente de aislación acústica de un muro construido con bloques de cemento rellenos con arena,’’ in Proc. Memorias EnIDI, 2005, pp. 1–7. [7] T. Canal. (Sep. 29, 2014). Obtenido de Los Residuos Plásticos y Su Reciclado. Colegio San Lorenzo. [Online]. Available: http://www.arpet. org/docs/Los-residuos-plasticos-y-su-reciclado.pdf [8] X. E. Castells, Reciclaje de Residuos Industriales. Madrid, Spain: Diaz de Santos, 2000. [9] M. R. Stinson and Y. Champoux, ‘‘Propagation of sound and the assignment of shape factors in model porous materials having simple pore geometries,’’ J. Acoust. Soc. Amer., vol. 91, no. 2, pp. 685–695, 1992. [10] Carbon Core. (Sep. 25, 2014). Plastic Structural Honeycombs. Honeycomb Engineering. [Online]. Available: http://www.carboncore.com/honeycomb-plastic.htm, accessed Sep. 25, 2014. [11] R. Echenique, Ciencia y Tecnología de la Madera I. Veracruz, Mexico: Univ. Veracruzana, 1993. [12] I.-E. Forestal. (Oct. 1, 2014). Estadísticas Sector Forestal. Obtenido de Inegi. [Online]. Available: http://www.inegi.org.mx/inegi/contenidos/ espanol/prensa/contenidos/estadisticas/2011/forestal0.doc [13] R. A. Gaggino, Aplicación de Material Plástico Reciclado en Elementos Constructivos a Base de Cemento. Córdoba, Spain: Centro Experimental de la Vivienda Económica, 2007. [14] J. I. Hernández. (Nov. 28, 2008). Obtenido de México No Recicla Bolsas de Plástico. El Universal. [Online]. Available: http://www. eluniversal.com.mx/ciudad/92930.html [15] A. M. Jaramillo, Acústica: La Ciencia del Sonido. Medellín, Colombia: Fondo Editorial ITM, 2007. [16] L. W. Gallagher and A. G. McDonald, ‘‘The effect of micron sized wood fibers in wood plastic composites,’’ Maderas, Ciencia Tecnol., vol. 15, no. 3, pp. 357–374, 2013. [Online]. Available: http://dx.doi.org/10.4067/ S0718-221X2013005000028 [17] M. R. López, Acondicionamiento Acústico. Madrid, Spain: Thomson Editores Spain, 2001. [18] J. López-Miranda, N. O. Soto-Cruz, O. M. Rutiaga-Quiñones, H. Medrano-Roldán, and K. Arévalo-Niño, ‘‘Optimización del proceso de obtención enzimática de azúcares fermentables a partir de aserrín de pino,’’ Revista Int. Contaminación Ambiental, vol. 25, no. 2, pp. 95–102, 2009. VOLUME 3, 2015

[19] E. S. Marín, W. P. Castro, and J. F. Arroyave, ‘‘Energías alternativas, experiencias desde el semillero de investigación en tecnología mecánica,’’ Sci. Tech., vol. 3, no. 49, pp. 260–265, 2011. [20] D. H. Morton-Jones, Polymer Processing. London, U.K.: Chapman & Hall, 1989. [21] H. R. C. Muñoz, Caracterización de Astillas y Aserrín Para Una Planta de Tableros de Partículas en Valdivia. Valdivia, Chile: Universidad Austral de Chile, 2003. [22] C. G. Orozco, El Ejido El Balcón. Chimalistac, Mexico: Consejo Civil Mexicano Para la Silvicultura Sostenible A.C. [23] P. I. Gramann and T. A. Osswald, Simulation of the Melt Mixing Process of Natural Fiber-Filled Polyolefin Composites. Madison, WI, USA: Forest Products Society, 1993. [24] B.-D. Park and J. J. Balatinecz, ‘‘A comparison of compounding processes for wood-fiber/thermoplastic composites,’’ Polym. Compos., vol. 18, no. 3, pp. 425–431, 1997. [25] S. Programa, Resumen Público de Certificación del Ejido Salto de Camellones. Mexico City, Mexico: Consejo Civil Mexicano Para la Silvicultura Sostenible, 2001. [26] ProMéxico. (Sep. 11, 2014). Los Usos del Polietileno de Baja Densidad. [Online]. Available: http://www.promexico.gob.mx/proveedores/los -usos-del-polietileno-de-baja-densidad-sabias-que-entre-otros-sirve-parafabricar-bolsas-de-supermercado-frascos-de-champu-o-juguetes.html [27] J. W. S. Rayleigh, The Theory of Sound. New York, NY, USA: Dover, 1945. [28] C. Rougeron, Aislamiento Acústico y Térmico en la Construcción. Barcelona, Spain: Editores Técnicos Asociados, 1977. [29] SEMARNAT. (Oct. 1, 2014). Secretaría del Medio Ambiente. [Online]. Available: http://app1.semarnat.gob.mx/dgeia/informe_12/pdf/Cap7 _residuos.pdf [30] E. Sjöström, Wood Chemistry: Fundamentals and Applications. New York, NY, USA: Academic, 1981, p. 223. [31] Trex. (Oct. 14, 2014). Trex. [Online]. Available: http://www.trex.com/trexowners/customer-support/downloads/, accessed Oct. 17, 2014. [32] A. M. Viveros. (Jun. 4, 2012). Obtenido de Los Mexicanos Producimos 30 Millones de Toneladas de Basura al Año. Desde la Red. [Online]. Available: http://www.desdelared.com.mx/noticias/2012/2-opinion/ 0604-albino-0706141224.html [33] H. P. Wilson, ‘‘Inclusión de aserrín en tableros de partículas,’’ Bosque, vol. 3, no. 1, pp. 39–46, 1979. [34] K. Yam, ‘‘Composites form compounding wood fibers with recycled HDPE,’’ Polym. Eng. Sci., vol. 30, no. 11, pp. 696–699, 1990.

ANGEL DANIEL MUÑOZ GUZMAN received the master’s degree in industrial design and product innovation from the Instituto Tecnológico y de Estudios Superiores de Monterrey, Campus Guadalajara. He was a Professor of Industrial Design and a Mechatronic Engineer with the Universidad del Valle de Mexico, in 2009. He has a specialty in industrial design with the Universidad Europea de Madrid, Spain.

MARÍA GIOVANNA TROTTA MUNNO received the Ph.D. degree in production systems and industrial design from the Italian Inter-Polytechnic Doctorate School as a Professor of Industrial Design.

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