properties as Portland Cement concrete, and sustainability benefits established. Keywords: ...... Lea's chemistry of cement and concrete. Oxford: Elservier ...
Submitted to School of Engineering and Physical sciences, University of Birmingham, as an MSc Individual Research Project 2016-17
Eurocode 2: Deformation properties of structural concrete made with BS EN 197 -1 Portland limestone cement
Mohammed Abdul Waheed Sadiq Sait MSc Candidate, Structural Engineering and Practice, School of Engineering, Civil Engineering Department The University of Birmingham, Edgbaston B15 2TT, Birmingham, United Kingdom
1
ABSTRACT A comprehensive analysis and evaluation of the data sourced from 69 studies undertaken by 175 researchers in 86 organisations in 30 countries since 1935, on the deformation of concrete made with Portland limestone cement (PLC), as defined in EN- 197-1, is presented. The addition of limestone to Portland cement to form PLC was found to adversely affect the elastic modulus and creep properties of concrete, as opposed to its drying shrinkage. Compliance with existing Eurocode 2 (EC2) in estimating the deformation properties of PLC concrete was evaluated and found that the existing EC2 can be used to determine the elastic modulus of PLC concrete, whereas amendments would be required for Creep and Drying shrinkage. Methods are proposed for PLC concrete to have similar deformation properties as Portland Cement concrete, and sustainability benefits established. Keywords: Portland Limestone Cement, Modulus of Elasticity, Creep, Drying Shrinkage, Eurocode 2, Practical implications, Sustainability.
INTRODUCTION The concrete construction industry is under pressure to design and build sustainable structures, and this has focused attention on minimising thermal energy consumption and CO2 emissions of cement used to produce concrete. In the past cement used was produced mainly from Portland clinker alone and this amounted to about 3730 MJ of thermal energy consumption and around one tonne of CO2 emission for each tonne of Portland cement produced (Cembureau.eu, 2015). In today’s term with the usage of cement increased to about 4.6 billion tonnes per annum globally (Cembureau.eu, 2015), a monumental adverse impact on the environment is created. To mitigate these environmental effects of the concrete construction industry, the use of blended Portland cement is being encouraged and accepted worldwide. For example, in Europe, standard EN 197-1 was introduced in the year 2000, accepting the use of eight materials in combination with Portland cement to create 27 series of basic grades of common cements, including the Portland limestone cements (PLC), with up to 35% limestone content. Although the use of a series of pozzolanic materials such as fly ash, granulated ground blast furnace slag is also included in the standard, the use of ground limestone to produce Portland Limestone Cements acts as a favourable option in terms of cost, as limestone is readily available at the plants making Portland clinker (Tennis et al., 2011; Kenai et al., 2004). To advocate the use of PLC, a significant amount of research has been undertaken globally regarding the properties of PLC concrete. However, lack of comprehensive understanding on the deformation of PLC concrete has been an immense challenge for the structural engineers in specifying the use of PLC for construction projects. Therefore, this study was devised to evaluate the effects of PLC on the deformation of concrete and to determine its conformity for structural engineering applications. To achieve the main aim of the study, a series of objectives were formulated, namely: 2
•
To carry out an in-depth analysis of the published test data on the effect of limestone replacement on the Modulus of Elasticity (MOE), creep and shrinkage of PLC concrete.
•
To evaluate the compliance of Eurocode 2 (EC2) in predicting the deformation of PLC concrete.
•
To provide methods to optimize the deformation properties of PLC concrete and to determine its suitability for structural applications.
•
To establish the sustainable aspects of using optimized PLC concrete in practical engineering applications.
METHODOLOGY As understood, every experimental research involves large data input and a significant amount of quality testing procedures to obtain definite results. However, the results obtained are confined to the specific research, and its viability is not evaluated with other published data. If this information is multiplied manifold by examining the global data, then a surmountable amount of information incorporating thousands of data inputs from across the world can be analysed, and extensive insight into the subject can be achieved. Therefore, global literature containing a total of 69 publications since 1935 analyzing the deformation of PLC concrete from 30 countries involving 175 researchers and 86 organizations were identified. Data from the literature was extracted and an excel matrix of 56,842 cells was created for analysis and evaluation. The data was evaluated in a way, that the results obtained can be directly used for specifying PLC in structural applications. As the data involved in the analysis comprised of a broad range of mix designs and testing procedures, results of the PLC concrete are majorly represented as relative values of the corresponding PC concrete used in the published literature. Therefore, all relative values of PLC concrete mentioned in this study are relative to the corresponding PC concrete unless specified otherwise.
DEFORMATION PROPERTIES OF PLC CONCRETE Modulus of Elasticity Replacement of PC with limestone can affect both static and dynamic MOE of the PLC concrete. However, due to limitation of data and the significance of static MOE in practical applications, this research is only focused on static MOE. Limestone Replacement effect Performance of the PLC depends on the amount of PC replaced by the GLS. According to Dhir et al. (2005) and Li and Kwan (2015), reduction in compressive strength of the PLC concrete due to the replacement of GLS, plays a vital role in determining its E values. Therefore, to understand the effect of limestone replacement on MOE, relative E values of PLC concrete were plotted against different 3
levels of limestone replacement for various strength groups in Fig. 1. For given strength group, the MOE of the PLC concrete decreased at an increasing rate with increase in limestone replacement levels, reflecting the dilution of PC and the insignificant contribution of GLS as a cementitious material (Das et al., 2015 and Lauch et al., 2016). Also, for a given limestone replacement level, increase in compressive strength of PLC concrete reduced the impact of limestone replacement on the E values, thereby, confirming the significance of strength reduction in determining the MOE. LIMESTONE REPLACEMENT, % 0
10
20
30
40
50
60
110
E VALUES RELATIVE TO PC, %
CEM II/A-L(or)LL
CEM II/B-L(or)LL
100 R² = 0.6341 90
80
70
R² = 0.7857 Low Strength (15 to 40 MPa) Medium Strength (40 to 60 MPa)
High Strength (60 to 80 MPa)
R² = 0.8391
60 Figure 1 Overall effect of Limestone replacement on E values of Concrete Influence of Water - Cement ratio on MOE Though W/C ratio is not associated with E values in general, over the year’s considerable amount of research has been undertaken to determine the effect of W/C ratio on the MOE of PLC concrete. To evaluate the same, E values of both PC and PLC concrete were normalised at a W/C ratio of 0.35 and the impact on MOE with increasing in W/C ratio were plotted in Fig. 2. Change in W/C ratio significantly affected the E values of PC concrete compared to PLC concrete, and the differences increased with increase in limestone replacement. This phenomenon might be attributed to the reduction in clinker content, as with an increase in W/C ratios for a given workability, the amount of clinker being reduced in PC is more compared to PLC. Thus, reducing the stiffness of concrete due to cement paste reduction and thereby having adverse effects on the E values. However, increased limestone replacement levels (>20 %) should be adopted to understand the complete phenomena. 4
110
NORMALIZED E VALUES , %
105
100
95
90 R² = 0.7325
85
R² = 0.7146
80
R² = 0.6592
PC
R² = 0.6759
6 to 10 % Limestone Content
75
11 to 15 % Limestone Content 16 to 20 % Limestone Content
70 0.3
0.4
0.5
0.6
0.7
W/C RATIO Figure 2 Effect of W/C ratio on E values of PLC Concrete Compliance with EC2 To evaluate the compatibility of the existing EC2 in determining the MOE of the PLC concrete, experimental E values and their corresponding EC2 results were plotted in Fig. 3. The experimental data on E values represented in the figure can be separated into two sets A and B, corresponding to the high and low MOE respectively. Only the values corresponding set B were found to comply with EC2 and to understand the nonconformity of data, further analysis was carried out. It was identified that all the values in set A correspond to data recorded at a testing age of 365 days, explaining the nonconformity, as the EC2 equations are only applicable for 28 day results. Additionally, the information on the type of aggregates provided by various authors was studied, and it was found that for a given type of aggregate more than 91% of the results complied with the EC2 equations, reflecting its suitability in determining the MOE of PLC concrete. 5
70
MODULUS OF ELASTICITY , GPa
60
50
Basalt
40
Quartzite
30
Limestone
Sandstone
20 PC 6 to 20 % Limestone content
10
20 to 35 % Limestone content >35 % Limestone content 0 0
20
40
60
COMPRESSIVE CYLINDER STRENGTH, MPa Figure 3 Compliance of EC2 equations for predicting MOE of PLC concrete Relationship between compressive strength and MOE Results established in the previous sections show that, apart from the influence of reduction in compressive strength due to limestone replacement, GLS also contributes to the change in MOE of the PLC concrete. To understand the precise effect of GLS, the effect of strength reduction on MOE due to limestone replacement should be removed from the overall decrease in elastic modulus due to GLS. To determine the same, initially, the amount of reduction in compressive strength due to limestone replacement was evaluated. Every 5% increase in limestone content decreased the compressive strength of the PLC concrete by about 4.7%.
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EFFECT OF GLS ON REDUCTION OF E VALUES , %
105 CEM II/A-L(or)LL CEM II/B-L(or)LL
100 100
99.5 98.5 97.5 96.5
R² = 0.9988
95.5 95
94.0 92.5 90.5
90
89.0
85
PC
10
15
20
25
30
35
40
45
50
LIMESTONE REPLACEMENT, % Figure 4 Effect of GLS on MOE# # Detailed Calculations provided in Appendix A With the compatibility of EC2 for determining the E values of PLC concrete already being established (Fig. 3), the decrease in MOE for a given strength reduction due to limestone replacement was evaluated using EC2 equations. The values obtained from the results were subtracted from the overall effect of limestone replacement (Fig. 1) and the effect of GLS on the MOE of a PLC concrete designed to the same strength as PC concrete were identified (Fig. 4). Apart from the reduction in compressive strength, increase in limestone content decreased the E values at an increasing rate with about 11% of reduction at a replacement level of 50%. Thus, concluding that PLC concrete designed to the same compressive strength as PC concrete, has lesser E values corresponding to its limestone content. Creep Limestone Replacement effect The data on the effect of limestone on the creep of PLC concrete was severely limited, and it was reported in varied forms such as, creep strain, creep coefficient and specific creep. To obtain a rational result, all the values were converted to a common factor (creep strain), and the data was evaluated (Fig. 5). However, as the stress applied to measure the creep of concrete had a significant impact on the creep strain values (He et al. 2016), the effect of applied stress was removed by calculating specific creep of the same data and the results were analysed (Fig. 5).
7
CREEP RELATIVE TO PC, %
240 CEM II/A-L(or)LL
CEM II/B-L(or)LL
220 200 R² = 0.8851
180 160
Creep Strain
140
Specific Creep
120
R² = 0.022
100 80 60 0
10
20
30
40
50
LIMESTONE REPLACEMENT, % Figure 5 Effect of Limestone replacement on the Creep of Concrete Increase in limestone content, enhanced the creep of PLC concrete, reflecting the effect of reduced clinker content leading to a decrease in cement gel available to resist the applied stress on concrete (Rossetti and Curcio, 1997). Values of specific creep were significantly higher compared to creep strain values and the differences enhanced with increase in limestone content, signifying the effect of applied stress and the impact of strength reduction due to limestone replacement on the creep of PLC concrete. Compressive Strength Vs Specific creep According to Taylor (2008), creep of concrete is closely related to its compressive strength, and as discussed in the previous section, the reduced compressive strength of PLC concrete plays a vital role in determining the creep values. To eliminate the effects of strength reduction and to understand the precise impact of GLS on the creep of PLC concrete, specific creep values were plotted against their corresponding compressive strengths (Fig 6). At similar compressive strength, specific creep of PLC concrete was higher compared to PC concrete, indicating a minimal negative effect of GLS on the creep values. Results obtained complied with the Fig. 4, which illustrated a minimal decrease in E values of PLC concrete designed to have equal strength relative to PC concrete. However, additional data on the creep of PLC concrete is required to identify the precise measure of creep development due to GLS.
8
130
R² = 0.6773
SPECIFIC CREEP, x 10^-6/ MPa
110
90
R² = 0.918
70
50 PC 6 to 20% Limestone content 21 to 35% Limestone content >35% Limestone content PC PLC
30
10 10
30
50
70
COMPRESSIVE STRENGTH , MPa Figure 6 Compressive Strength vs Specific Creep Compliance with EC2 As identified from EC2, there are no provisions for the usage of PLC in determining the creep values. To understand the viability of the existing EC2, experimental creep values were plotted along with their corresponding EC2 results, in Fig. 7. Though the correlation of the results calculated was average, creep coefficient predicted by the EC2 was considerably higher than the actual values, with results obtained for class R PC being the nearest. To evaluate the degree of nonconformity, the strength class of PC used in the mix design of PLC concrete was examined. It was identified that all the publications had used class R PC, except for Wang et al. (2015), in which the information regarding the cement class was not specified. Given the data, the results illustrate that suitable amendments incorporating the effects of GLS, corresponding to the strength class of PC used are required in EC2, for predicting the creep coefficient of PLC concrete. 9
3.5 EC 2 - Class S EC 2 - Class N EC 2 - Class R
3
Experimental Values
CREEP COEFFICIENT
2.5
2
R² = 0.4019 R² = 0.4555 R² = 0.4741
1.5
R² = 0.4945
1
0.5 10
20
30
40
50
60
COMPRESSIVE STRENGTH AT 28 DAYS, MPa Figure 7 Compliance of EC2 equations for predicting creep of PLC concrete Drying Shrinkage Shrinkage of concrete are of different types and can develop through various mechanisms at different ages of concrete. However, this study is only limited to the drying shrinkage of concrete, due to its dominance in determining the deformation of hardened concrete and its significance in practical engineering applications.
10
Limestone Replacement effect According to Meddah et al., (2014) and Tongaroonsri and Tangtermsirikul, (2008), GLS does not have any cementitious properties and only acts a filler in concrete. Therefore, when PC is replaced with GLS, there is a decrease in clinker content, increasing the water to binder ratio of the concrete and reducing the cement paste content. According to Lea and Hewlett (2008), for a PC concrete, an increase in W/C ratio increases the drying shrinkage. At the same time, reduction in cement paste content causes a significant decrease in the drying shrinkage of concrete (Neville, 1995). Therefore, replacement of PC with GLS can simultaneously have both positive and negative effects on the drying shrinkage of concrete. Thus, to determine the overall effect of GLS, mean of drying shrinkage values of PLC concrete relative to PC concrete are plotted in Fig. 8.
MEAN DRYING SHRINKAGE RELATIVE TO PC, %
105
CEM II/B-L(or)LL
CEM II/A-L(or)LL 100.0
100
98.6
96.8
96.6
95 R² = 0.9171 90
87.7
86.9
85.8
85
83.2
80 0
10
15
20
25
30
35
45
LIMESTONE REPLACEMENT, % Figure 8 Effect of Limestone replacement on the Drying Shrinkage of Concrete Despite the increase in water to binder ratio with limestone replacement, there is a considerable decrease in the drying shrinkage of PLC concrete, reflecting the combined effect of GLS to act as a filler material (Dhir et al., 2007; Mohammadi and South, 2016a) and the decrease in cement paste content (Courard and Michel, 2014; Meddah et al., 2014; Leeuwen et al. 2016). Moreover, the rate of decrease in drying shrinkage varies significantly between the different range of limestone content. Therefore, to identify the exact measure of shrinkage reduction and to comprehensively understand the phenomena of drying shrinkage with limestone replacement, research should be carried out on PLC concrete at different W/C ratios with varied cement paste content 11
Effect of Compressive Strength on Drying shrinkage Replacement of PC with GLS can have adverse effects on the drying shrinkage of concrete corresponding to its compressive strength, as concrete strength is detrimentally affected by GLS and this has significant effects on the drying shrinkage values (Itim et al. 2011 and Zhang et al., 2016). Therefore, to evaluate the influence of compressive strength on drying shrinkage values, relative shrinkage values of PLC concrete with different limestone content were plotted for various strength groups in Fig. 9. Despite the low co relation of the results obtained, a pattern was identified showing an increase in drying shrinkage with a reduction in compressive strength, for a given level of limestone replacement. However, even for a low strength PLC concrete, the values of drying shrinkage were similar or lesser compared to PC concrete, confirming the positive effect of GLS on drying shrinkage of concrete for any compressive strength.
DRYING SHRINKAGE RELATIVE TO PC, %
120
CEM II/A-L(or)LL
CEM II/B-L(or)LL
110
100
90 R² = 0.2414 R² = 0.3415
80
Low Strength (15 to 40 MPa) 70
R² = 0.4914
Medium Strength (40 to 60MPa) All
60 0
10
20
30
40
50
LIMESTONE REPLACEMENT, % Figure 9 Effect of compressive strength on the Drying Shrinkage of PLC Concrete Testing Age According to Neville, (2011), the age of the concrete plays a significant role in determining the drying shrinkage values. Therefore, to understand the effect of GLS on drying shrinkage at different ages of PLC concrete, mean values of the relative drying shrinkage for a given age, at various levels of limestone replacement were calculated. Average of the mean values were found, and the results 12
through a period of 7 to 720 days were plotted in Fig. 10. At all levels of limestone replacement, the rate of drying shrinkage of PLC concrete was almost similar compared to PC concrete, indicating minimal or no effect of GLS on the drying shrinkage rate. Thus, leading to a conclusion that regardless of the age, drying shrinkage of PLC concrete is lesser than that of PC concrete.
DRYING SHRINKAGE RELATIVE TO PC, %
105 100 95 90 85 80 6 to 15% Limestone Content 75
16 to 25% Limestone Content 26 to 35% Limestone Content
70 0
100
200
300
400
500
600
700
DAYS Figure 10 Drying Shrinkage of PLC Concrete Compliance with EC2 Suitability of EC2 equations to predict the drying shrinkage values of PLC concrete acts as a fundamental factor in standardizing the usage of PLC for practical applications. To determine the same, experimental values of drying shrinkage obtained from the literature, along with their corresponding EC2 results were evaluated in Table 1. For PLC concrete with class R PC, no relationship was identified between EC2 results and the experimental values, with EC2 results corresponding to the PC strength class used, predicting higher values of drying shrinkage. However, in case of PLC concrete with class N PC, though the values of EC 2 corresponding to PC strength class were lower than the actual values, the difference between them decreased with increase in limestone content, signifying the importance of PC class used. Thus it is concluded that to predict the drying shrinkage of PLC concrete, amendments are required in EC 2 equations, in correspondence with the limestone content and strength class of the PC used. 13
Table 1 Compliance of EC2 Drying Shrinkage Equations for PLC Concrete Limestone Replacement %
PC Class used
Mean Drying Shrinkage Strain x10^ -6
Experimental Values
EC2 , Cement Class - S
EC2 , Cement Class - N
Difference
EC2 , Cement Class - R
15
R
(a) 551
(b) 377
(c) 467
(d)
(a-b)
(a-c)
(a-d)
642
174
84
-91
25
R
605
399
490
670
206
115
-65
35
R
590
429
524
712
161
66
-122
45
R
575
459
558
754
116
17
-179
15
N
627
339
418
574
288
209
53
25
N
592
360
443
605
232
149
-13
35
N
581
388
474
644
193
107
-63
45
N
560
415
504
682
145
56
-122
SUITABILITY OF POZZOLANS WITH PLC IN CONCRETE Pozzolanic materials when replaced along with limestone can enhance or degrade the properties of the concrete, depending on their characteristics. Due to the limitation of data, only the effect of Fly ash (FA) on the MOE and the impact of FA and Ground Granulated Blast Furnace Slag (GGBS) on the drying shrinkage values are considered in this research. The data from the various authors were analysed, and the results for different levels of limestone replacement corresponding to their pozzolanic content were established below.
Modulus of Elasticity The Inclusion of FA to the PLC concrete had a considerable impact on its E values (Fig. 11). Though the correlation of the lines plotted in the graph were not high, a pattern was identified with the replacement of FA on the PLC concrete, indicating increased E values compared to PLC. Also, at low levels of limestone replacement, the E values of the PLC concrete with FA were higher or similar compared to PC concrete, reflecting the reduced porosity of concrete due to the filler effect of GLS and the formation of Calcium Silicate Hydrate (CSH) paste by the FA (Hesami et al., 2016). However, to determine the definite effect of FA on PLC concrete, consistent mix designs with fixed limestone replacement and varying FA content should be evaluated. 14
120 PLC
115
10 to 20 % of FA
E VALUES RELATIVE TO PC, %
110
20 to 30 % of FA
105 100 95 90 R² = 0.3841 85
R² = 0.4409
80 75
R² = 0.6662 70 0
10
20
30
40
50
LIMESTONE REPLACEMENT, % Figure 11 Influence of FA on E values of PLC Concrete Drying Shrinkage From Table 2, It is evident that at low levels of GGBS replacement the drying shrinkage of PLC concrete is reduced and as the GGBS content increases, development of drying shrinkage can be observed. According to Carrasco et al. (2003), this increase in drying shrinkage can be attributed to the enhanced hydration caused by the GGBS. Further, in case of FA, drying shrinkage of PLC concrete has minimal or no effect with an increase in FA content. Though drying shrinkage of PLC concrete is affected by pozzolanic materials, it should be noted that the values of drying shrinkage are similar or better than that of PC concrete; thereby, enhancing the viability of ternary cement in structural applications.
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Table 2 Effect of Pozzolanic Replacement on the Drying Shrinkage of PLC concrete
Pozzolanic Replacements
Mean Drying Shrinkage values relative to PC at different Limestone replacement level (%) 6 to 20
21 to 35
PLC
97%
86%
GGBS (10 to 30%)
88%
80%
GGBS (30 to 50%)
100%
84%
Fly Ash (10 to 20%)
101%
87%
Fly Ash (20 to 30%)
101%
86%
SPECIFYING PLC CONCRETE FOR ENGINEERING APPLICATIONS Deformation properties of PLC concrete, as established in the earlier sections, are significantly affected by the GLS depending upon its content. Therefore, for usage of PLC in practical applications, properties of PLC concrete should be optimized to achieve similar performance as that of PC concrete. It is understood that GLS enhances the drying shrinkage of PLC concrete, whereas degrades the MOE and creep. Thus, methods to optimize PLC concrete concerning the load dependent deformations are only discussed in this study. PLC concrete has reduced E values compared to PC concrete at equal compressive strength (Fig. 4), and an increase in compressive strength of PLC concrete enhances its MOE (Fig. 1). Therefore, PLC concrete should be designed to a higher strength compared to PC concrete to overcome the effect of GLS. To determine the additional strength required, the effect of GLS on MOE was considered from Fig. 4, and a corresponding increase in compressive strength was evaluated through the EC2 equations. The results of the additional strength required were plotted in Fig. 12; for example, at a limestone replacement level of 20%, PLC concrete should be designed to have an additional cylinder strength of about 7.6% to obtain E values similar to that of PC concrete. Moreover, even though the maximum limestone replacement is restricted to 35% by BS EN 197-1, the results of Fig. 12 are given up to 50%, to support any further changes in the standard.
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ADDITIONAL CYLINDER STRENGTH TO OPTIMIZE MOE OF PLC CONCRETE , %
40 R² = 1
CEM II/A-L(or)LL CEM II/B-L(or)LL
36.0
35 30.0 30 24.5
25 19.5
20 15.0
15 11.0 10
7.5 4.5
5
2.0 0.0
0 PC
10
15
20
25
30
35
40
45
50
LIMESTONE REPLACEMENT, % Figure 12 Compressive Strength of PLC concrete to achieve E values equivalent to PC concrete
Apart from E values, for a given compressive strength, creep of PLC concrete is also higher than that of PC concrete. It is understood from Fig. 6 that, increase in creep is minimal and similar to the reduced E value of PLC concrete compared to PC concrete of same compressive strength. According to BS EN 1992-1, creep coefficient of concrete is closely related to the tangent MOE E C, where EC can be taken as 1.05 ECM (secant/static MOE). Therefore, from the results obtained in Fig. 6 and the relationship between static MOE and creep coefficient established by EC2, it might be suggested optimum creep values of PLC concrete can be achieved by using similar optimization methods as used in MOE. However, due to the extreme limitation of data on the creep of concrete, the methods suggested for optimisation of creep are tentative, and further research needs to be carried out to confirm the same.
EFFECT OF PLC ON THE SUSTAINABLE ASPECT OF CONCRETE Sustainability imparted by PLC in concrete construction acts as the fundamental factor in advocating the use of PLC as an alternate to PC. Though the use of PLC adds a sustainable aspect, there is a significant reduction in the mechanical deformation properties of the structural concrete made with PLC. Therefore, the use of PLC can be defined as sustainable, only when the concrete made with PLC has similar or enhanced properties compared to the PC concrete (Ramezanianpour, 2014). As understood, PLC concrete can be optimized to have deformation properties similar to PC concrete by 17
designing it to a higher compressive strength. One of the fundamental methods of increasing the compressive strength of concrete is by reducing the W/C ratio. However, to decrease the W/C ratio for a given workability of concrete without the use of admixtures, the cement content needs to be increased. This increase in cement content increases CO 2 emission and the energy required for production, thereby decreasing the sustainability. Therefore, to understand the sustainability provided by the optimized PLC concrete, a life cycle analysis (LCA) for a standard mix design obtained from Teychenne (1997), is carried out based on the data provided by Palm et al., (2014) and Proske et al., (2014), and the results are compared with PC concrete (Fig. 13). 6 CEM II/A-L(or)LL
CEM II/B-L(or)LL
Effect of PLC , %
4
2
0 0 -2
-4
10
15
20
25
30
35
Limestone Replacement, %
Reduction in GWP Reduction in Total Energy
-6 Figure 13 Contribution of optimized PLC concrete towards sustainability The global warming potential (GWP) which considers the impact of a range of greenhouse gases and the total energy demand, being two dominant factors affecting the sustainability are used in calculating results of LCA. From Fig. 13, it can be seen that the maximum sustainable efficiency of about 5% can be obtained at limestone replacement level of 10%. Though the efficiency is only 5%, it has substantial impacts on the environment as the GWP is calculated in terms of Kg's of CO2 and Energy is calculated in Mega joules. Thus, proving the significant sustainable benefits of using GLS as a cement substitution material.
18
CONCLUSION The study has established a comprehensive understanding of the key deformation properties of PLC concrete, which can assist structural engineers in specifying PLC for use in concrete construction. The definitive conclusions derived from this study are: •
PLC has significant adverse effects on the elastic modulus and creep of concrete, as opposed to its drying shrinkage. However, when PLC concrete is designed to the same compressive strength as PC concrete, the negative effects of GLS becomes minimal. Moreover, by increasing the compressive strength of PLC concrete, depending on its limestone content, deformation properties similar to PC concrete can be achieved.
•
EC2 can be used to determine the modulus of elasticity of PLC concrete, whereas amendments are required to predict the creep coefficient and the drying shrinkage values.
•
The use of PLC in structural concrete applications provides sustainability benefits without compromising the integrity of concrete structures. To achieve maximum sustainability without compromising the deformation properties, PLC with 10% of GLS content is suggested
ACKNOWLEDGEMENT Firstly, I thank the Almighty for completing this work. I would like to express my gratitude to my family members for their support towards my studies at the University of Birmingham. I also like to extend my sincere thanks to Prof. Dhir, R.K. and Dr. G S Ghataora for their guidance throughout the course of project.
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REFERENCES Acharya, P. and Patro, S. (2015). Effect of lime and ferrochrome ash (FA) as partial replacement of cement on strength, ultrasonic pulse velocity and permeability of concrete. Construction and Building Materials, 94, pp.448-457. Alunno-Rosetti, V. and Curcio, F. (1997). A Contribution to the Knowledge of the Properties of Portland-Limestone Cement Concretes, with Respect to the Requirements of European and Italian Design Code. In: Proceedings of the 10th International Congress on the Chemistry of Cement. Ali Akbar Ramezanianpour. (2013). Cement Replacement Materials: Properties. Berlin: Springer Berlin Heidelberg. ASTM (American Society for Testing and Materials), (2017). C150/C150M – 17: Standard Specification for Portland Cement. Philadelphia: American Society for Testing and Materials, Barrett, T., Sun, H., Nantung, T. and Weiss, W. (2014). Performance of Portland Limestone Cements. Transportation Research Record: Journal of the Transportation Research Board, 2441, pp.112-120. Barrett, T., Sun, H., Villani, C., Barcelo, L. and Weiss, J. (2014) Early-Age Shrinkage Behavior of Portland Limestone Cement. Concrete International, 36(2), p.51. Bjegovic, D., Stirmer, N. and Serdar, M. (2012). Durability properties of concrete with blended cements. Materials and Corrosion, 63(12), pp.1087-1096. Bodnárová, L., Jarolím, T., Válek, J., Brozovsky, J. and Hela, R. (2014). Selected Properties of Cementitous Composites with Portland Cements and Blended Portland Cements in Extreme Conditions. Applied Mechanics and Materials, 507, pp.443-448. Bouasker, M., Khalifa, N., Mounanga, P. and Ben Kahla, N. (2014). Early-age deformation and autogenous cracking risk of slag–limestone filler-cement blended binders. Construction and Building Materials, 55, pp.158-167. BSI (British Standards Institution), (2004). BS EN 1992-1-1: Eurocode 2 – Design of concrete structures – Part 1-1: General rules and rules for buildings. London: British Standards Institution. BSI (British Standard Institution), (2011). BS EN 197-1: Cement Part 1 – Composition, specifications and conformity criteria for common cements. London: British Standard Institution.
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Cai, Y., Hou, P., Zhou, Z. and Cheng, X. (2016). Effects of Nano-CaCO3 on the Properties of Cement Paste: Hardening Process and Shrinkage at Different Humidity Levels. In: 5th International Conference on Durability of Concrete Structures. Shenzhen, Guangdong Province. Carette, J. and Staquet, S. (2016). Monitoring and modelling the early age and hardening behaviour of eco-concrete through continuous non-destructive measurements: Part II. Mechanical behaviour. Cement and Concrete Composites, 73, pp.1-9. Carette, J. and Staquet, S. (2016). Monitoring and modelling the early age and hardening behaviour of eco-concrete through continuous non-destructive measurements: Part I. Hydration and apparent activation energy. Cement and Concrete Composites, 73, pp.10-18. Carrasco, M., Bonavetti, V. and Irassar, E. (2003). Drying shrinkage of mortars with limestone filler and blast-furnace slag. Construction materials, 53(271-272), pp.5-16. Cembureau.eu. (2015). Key facts & figures. [online] Available at: https://cembureau.eu/cement101/key-facts-figures/ [Accessed 20 Aug. 2017]. Cost, V.T., G. Knight, W. Wilson, J. Shannon, and I.L. Howard. (2013) Performance of Typical Concrete Mixtures for Transportation Structures as Influenced by Portland-Limestone Cements from Five Sources. Proc. of 2013 International Concrete Sustainability Conference, San Francisco, CA, 11 pp. Courard, L. and Michel, F. (2014). Limestone fillers cement based composites: Effects of blast furnace slags on fresh and hardened properties. Construction and Building Materials, 51, pp.439-445. Davis, R.E., Kelly, J.W., Troxell, G.E., Davis, H.E. (1935). Properties of mortars and concretes containing portland - puzzolan cements, Proceedings. Journal of American Concrete Institute, 32, pp. 80-114. Davis, R.E., C. Hanna, W. and H. Brown, E., (1950)., Strength, Volume changes, and Sulfate resistance of mortars containing Portland-Pozzolan cements. In: Symposium on Pozzolanic materials in Mortars and Concretes. Philadelphia: American Society of Testing Materials, pp.131 - 153. Das, S., Aguayo, M., Sant, G., Mobasher, B. and Neithalath, N. (2015). Fracture process zone and tensile behavior of blended binders containing limestone powder. Cement and Concrete Research, 73, pp.51-62. Dhir, R., Limbachiya, M., McCarthy, M. and Chaipanich, A. (2007). Evaluation of Portland limestone cements for use in concrete construction. Materials and Structures, 40(5), pp.459-473.
21
Dhir, R., McCarthy, M. and Paine, K. (2005). Engineering property and structural design relationships for new and developing concretes. Materials and Structures, 38(1), pp.1-9. Diab, A., Abd Elmoaty, A. and Aly, A. (2016). Long term study of mechanical properties, durability and environmental impact of limestone cement concrete. Alexandria Engineering Journal, 55(2), pp.1465-1482. Hartshorn, S., Swamy, R. and Sharp, J. (2001). Engineering properties and structural implications of Portland limestone cement mortar exposed to magnesium sulphate attack. Advances in Cement Research, 13(1), pp.31-46. Hawkins, P., Tennis, P. and Detwiler, R. (2003). The use of limestone in Portland cement. Skokie, Ill.: Portland Cement Association. He, Z. and Qian, C. (2011). Internal relative humidity and creep of concrete with modified admixtures. Progress in Natural Science: Materials International, 21(5), pp.426-432. He, Z., Qian, C., Li, L. and Du, S. (2016). Creep analysis of concrete with different mineral admixtures. Materials Express, 6(4), pp.328-336. Helmuth, R. A., Whiting, D. A., Dubovoy, V. S., Tang, F. J., and Love, H. (1986) Performance of Blended Cements Made with Controlled Particle Size Distributions. Blended Cements, ASTM STP 897, G. Frohnsdorff, Ed., American Society for Testing and Materials, Philadelphia, 1986, pp. 106-127. Hesami, S., Modarres, A., Soltaninejad, M. and Madani, H. (2016). Mechanical properties of roller compacted concrete pavement containing coal waste and limestone powder as partial replacements of cement. Construction and Building Materials, 111, pp.625-636. Higgins, D., Sear, L., King, D., Price, B., Barnes, R. and Clear, C. (2011). Cementitious materials. Camberley, Surrey: The Concrete Society. Hooton, R. D., Nokken, M. A., and Thomas, M. D. A. (2007). Portland-Limestone Cement: State-ofthe-Art Report and Gap Analysis for CSA A3000, SN3053, Cement Association of Canada, Ottawa, Ontario, Canada. Hooton, D., Ramezanianpour, A., and Schutz, U. (2010) Decreasing the Clinker Component in Cementing Materials: Performance of Portland-Limestone Cements in Concrete in Combination with SCM’s. 2010 Concrete Sustainability Conference, NRMCA. Irassar, E.F., Bonavetti, V.L., Menendez, G., Cabrera O. and Donza, H. (2001) Mechanical Properties and Durability of Concrete Made with Portland Limestone Cement, Proc. International Syposium on
22
the Sustainable Development and Concrete Technology, V.M. Malhotra Ed, ACI Special Publication 202-27, Farminton Hill, MI, USA, pp. 431-450. Itim, A., Ezziane, K. and Kadri, E. (2011). Compressive strength and shrinkage of mortar containing various amounts of mineral additions. Construction and Building Materials, 25(8), pp.3603-3609. Jones, M., Newlands, M., Halliday, J., Csetenyi, L., Zheng, L., McCarthy, M. and Dyer, T. (2012) Concrete in the low carbon era. In: Proceedings of the International Conference held at the University of Dundee, Scotland, UK. Dundee: University of Dundee., pp.330 – 341. Jones, M., Newlands, M., Halliday, J., Csetenyi, L., Zheng, L., McCarthy, M. and Dyer, T. (2012) Concrete in the low carbon era. In: Proceedings of the International Conference held at the University of Dundee, Scotland, UK. Dundee: University of Dundee., pp.479 – 489. Kenai, S., Soboyejo, W. and Soboyejo, A. (2004). Some Engineering Properties of Limestone Concrete. Materials and Manufacturing Processes, 19(5), pp.949-961. Kucharczyk, S., Zajac, M. and Deja, J. (2015). The Influence of Limestone and Al2O3 Content in the Slag on the Performance of the Composite Cements. Procedia Engineering, 108, pp.402-409. Lauch, K., Dieryck, V. and Parmentier, B. (2016). Predictions of the mechanical performance of concrete made with ternary cements. In: International RILEM Conference on Materials, Systems and Structures in Civil Engineering Conference segment on Concrete with Supplementary Cementitious Materials. Lyngby: Technical University of Denmark, pp.153 - 164. Lauch, K., Dieryck, V. and Pollet, V. (2016). The use of ternary cements to reduce the environmental impact of concrete. RILEM Technical Letters, 1, pp.88-93. Lea, F. and Hewlett, P. (2008). Lea's chemistry of cement and concrete. Oxford: Elservier ButterworthHeinemann. Leeuwen, R., Kim, Y. and Sriraman, V. (2016). The Effects of Limestone Powder Particle Size on the Mechanical Properties and the Life Cycle Assessment of Concrete. Journal of Civil Engineering Research, 6(4), pp.104-113. Li, L. and Kwan, A. (2015). Adding limestone fines as cementitious paste replacement to improve tensile strength, stiffness and durability of concrete. Cement and Concrete Composites, 60, pp.17-24. Li, B., Liang, W. and He, Z. (2002). Study on high-strength composite portland cement with a larger amount of industrial wastes. Cement and Concrete Research, 32(8), pp.1341-1344.
23
Li, J., Tu, L., Liu, K., Jiao, Y. and Qin, M. (2013). Test and Study on Green High-Performance Marine Concrete Containing Ultra-Fine Limestone Powder. Applied Mechanics and Materials, 368-370, pp.1112-1117. Maia, L., Azenha, M., Geiker, M. and Figueiras, J. (2012). E-modulus evolution and its relation to solids formation of pastes from commercial cements. Cement and Concrete Research, 42(7), pp.928936. Marzouki, A., Lecomte, A., Beddey, A., Diliberto, C. and Ben Ouezdou, M. (2013). The effects of grinding on the properties of Portland-limestone cement. Construction and Building Materials, 48, pp.1145-1155. Meddah, M., Limbachiya, M. and Dhir, R. (2014). Potential use of binary and composite limestone cements in concrete production. Construction and Building Materials, 58, pp.193-205. Mohammadi, I. and South, W. (2015). Decision-making on Increasing Limestone Content of General Purpose Cement. Journal of Advanced Concrete Technology, 13(11), pp.528-537. Mohammadi, J. and South, W. (2016). Effects of Intergrinding 12% Limestone with Cement on Properties of Cement and Mortar. Journal of Advanced Concrete Technology, 14(5), pp.215-228. Mohammadi, J. and South, W. (2016). Effect of up to 12% substitution of clinker with limestone on commercial grade concrete containing supplementary cementitious materials. Construction and Building Materials, 115, pp.555-564. Mohammadi, I. and South, W. (2016). General Purpose Cement with Increased Limestone Content in Australia. ACI Materials Journal, 113(3). Mohammadi, I. and South, W. (2016). The influence of the higher limestone content of General Purpose cement according to high-strength concrete test results and construction field data. Materials and Structures, 49(11), pp.4621-4636. Mounanga, P., Khelidj, A., Loukili, A. and Baroghel-Bouny, V. (2004). Predicting Ca(OH)2 content and chemical shrinkage of hydrating cement pastes using analytical approach. Cement and Concrete Research, 34(2), pp.255-265. Mounanga, P., Khokhar, M., El Hachem, R. and Loukili, A. (2010). Improvement of the early-age reactivity of fly ash and blast furnace slag cementitious systems using limestone filler. Materials and Structures, 44(2), pp.437-453.
24
Mun, K., So, S. and Soh, Y. (2007). The effect of slaked lime, anhydrous gypsum and limestone powder on properties of blast furnace slag cement mortar and concrete. Construction and Building Materials, 21(7), pp.1576-1582. Neville, A. (2011). Properties of concrete, 5th ed. Harlow, Sussex: Pearson. Palm, S., Proske, T., Rezvani, M., Hainer, S., Müller, C. and Graubner, C. (2016). Cements with a high limestone content – Mechanical properties, durability and ecological characteristics of the concrete. Construction and Building Materials, 119, pp.308-318. Piasta, W. and Sikora, H. (2015). Effect of air entrainment on shrinkage of blended cements concretes. Construction and Building Materials, 99, pp.298-307. Proske, T., Hainer, S., Rezvani, M. and Graubner, C. (2014). Eco-friendly concretes with reduced water and cement content – Mix design principles and application in practice. Construction and Building Materials, 67, pp.413-421. Shao,B., and Gauvreau, P. (2015). Mix design and basic properties of a new uhpfrc featuring portlandlimestone cement. In: HPFRCC-7 Proceedings of the 7th RILEM Workshop on High Performance Fiber Reinforced Cement Composites. Stuttgart: RILEM Proceedings, pp.37 - 44. Taylor, P. (2008). Specifications and protocols for acceptance tests on processing additions in cement manufacturing. Washington, D.C.: Transportation Research Board. Tennis, P., Thomas, M. and Weiss, W. (2011). State-of-the-Art Report on Use of Limestone in Cements at Levels of up to 15%. Illinois: Portland Cement Association. Teychenne, D. (1997). Design of normal concrete mixes. Garston, Watford: BRE Bookshop. Tongaroonsri, S. and Tangtermsirikul, S. (2009). Effect of mineral admixtures and curing periods on shrinkage and cracking age under restrained condition. Construction and Building Materials, 23(2), pp.1050-1056. Tsivilis, S., Chaniotakis, E., Badogiannis, E., Pahoulas, G. and Ilias, A. (1999). A study on the parameters affecting the properties of Portland limestone cements. Cement and Concrete Composites, 21(2), pp.107-116. Voglis, N., Kakali, G., Chaniotakis, E. and Tsivilis, S. (2005). Portland-limestone cements. Their properties and hydration compared to those of other composite cements. Cement and Concrete Composites, 27(2), pp.191-196.
25
Wang, Y., Xu, Y. and He, Z. (2015). Effect of limestone powder on creep of high-strength concrete. Materials Research Innovations, 19(sup9), pp.S9-220-S9-223. Wang, Q., Yang, J. and Chen, H. (2017). Long-term properties of concrete containing limestone powder. Materials and Structures, 50(3). Wenyu, L. and Zhihui, Z. (2015). Partially Replacing Fly Ash with Limestone Powder in the Paste Influence and Characterization. The Open Construction and Building Technology Journal, 9(1), pp.2126. Zhang, Z., Wang, Q. and Chen, H. (2016). Properties of high-volume limestone powder concrete under standard curing and steam-curing conditions. Powder Technology, 301, pp.16-25.
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APPENDIX A Table 3 Effect of GLS on MOE
(a)
Reduction in 28 day Cylinder strength relative to PC, % (b)
Overall Reduction of relative E values, % (c)
PC
0
10
Limestone Replacement level
Effect of strength reduction on relative E values *, %
Effect of GLS on Reduction of relative E values, %
(d)
(c - d)
0
0
0
4.7
2.1
1.4
0.5
15
9.4
4.31
2.9
1.5
20
14.1
6.7
4.3
2.5
25
18.8
9.27
5.8
3.5
30
23.5
11.97
7.2
4.5
35
28.2
14.8
8.7
6.0
40
32.9
17.8
10.1
7.5
45
37.6
21
11.6
9.5
50
42.3
24.2
13.0
11.0
* Obtained using EC2 equations for reduction in strength corresponding to (b)
APPENDIX B Table 4.1 References for Data Used in Figures and Tables Tables and Figures
Indication
Figure 1 & 3 Figure 2 Figure 4 & 12 Figure 5 Figure 6
a b c d e
Figure 7 Figure 8 & 9 Figure 10 Figure 11 Figure 13 Table 1 Table 2
f g h i j k l
27
Table 4.2 References for Data Used in Figures and Tables Papers
Indication
Papers
Indication
Alunno-Rosetti and Curcio, 1997
d,e
Lauch et al., 2016a
i
Barrett et al., 2014a
a,b,c,i,g
Lauch et al., 2016b
i
Barrett et al., 2014b
a,b,c
Leeuwen et al., 2016
g,h
Carrasco et al., 2003
g,l
Li and Kwan, 2015
a,b,k
Carette and Staquet , 2016 a
a,c
Li et al., 2013
l
Carette and Staquet , 2016 b
a,c
Marzouki et al., 2013
g,h
Cost et al., 2013
g,h,l
Meddah et al., 2014
a,c,i,g,k,l
Courard and Michel, 2014
g,l
Mohammadi and South, 2015
g,h,l
Das et al., 2015
a,c,i
Mohammadi and South, 2016 a
g,l
Davis et al., 1935
a,g
Mohammadi and South, 2016 b
g
Davis et al., 1950
g
Mohammadi and South, 2016 c
g,h
Dhir et al., 2005
a,c
Mohammadi and South, 2016 d
a,i,g,h,l
Dhir et al., 2007
a,c,d,e, f,g,h,k
Mounanga et al., 2004
l
Diab et al., 2016
a,c
Mounanga et al., 2010
l
Hartshorn et al., 2001
g
Mun So and Soh, 2007
l
He and Qian, 2011
d,e,f
Palm et al., 2016
a,b,c,e,f, g,h,j,k
He et al., 2016
i
Piasta and Sikora, 2015
g,h,k
Helmuth et al., 1986
i,l
Proske et al., 2014
i,j,l
Hesami et al., 2016
i
Ramezanianpour, 2013
g,h
Higgins et al., 2011
d,g
Shao and Gauvreau, 2015
l
Hooton et al., 2007
d
Tennis et al., 2011
d
Hooton et al., 2010
g,h,k,l
Tongaroonsri and Tangtermsirikul, 2009
g,h
Irassar et al., 2001
a,b,c
Tsivillis et al., 1999
g
Itim et al., 2011
g
Voglis et al., 2005
g
Jones et al., 2012a
g,h,l
Wang et al., 2015
d,e,f
Jones et al., 2012b
l
Wang et al., 2017
g,h,k
Kenai et al., 2004
g
Wenyu and Zhihui, 2015
a,i,g,h,k,l
Kwan et al., 2013
g,h
Zhang et al., 2016
g,h,l
28
