Compared environmental impact of the life cycle of concrete with natural and recycled coarse aggregates. Extended Abstract

Transcription

1 Compared environmental impact of the life cycle of concrete with natural and recycled coarse aggregates Ana Margarida Gaspar de Oliveira Braga Extended Abstract Dissertation to obtain the Master Degree in Civil Engineering Supervisors Professor Dr. Jorge Manuel Caliço Lopes de Brito Professor Dr. José Dinis Silvestre Jury President: Professor Dr. João Pedro Ramôa Ribeiro Correia Supervisor: Professor Dr. Jorge Manuel Caliço Lopes de Brito Member: Professor Dr. Manuel Guilherme Caras Altas Duarte Pinheiro November 2015

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3 1. Introduction This study is intended to be a contribution to the research on the best concrete solutions from an environmental and economy point of view. This main goal was set due to the high Environmental Impacts (EI) generated by a representative activity in Europe - the construction sector: extraction of large quantities of raw materials, high energy consumption and significant production of pollutants and waste. According to the Associação dos Industriais da Construção Civil e Obras Públicas (AICCOPN) and to Banco de Portugal, the construction sector used to represent 11% of the Portuguese national employment (AICCOPN, 2007), about 7.3% of GDP (FEPICOP, 2012 ) and 48.8% of the total investment made in the country (Bportugal.pt, 2014). The sector is responsible for about 40% of the natural resources extracted (Amorim, 2008 citing Pinheiro, 2006), and about 30% of the waste generated in Europe (EDA-European Demolition Associations, 2014). CDW (construction and demolition wastes) result from: new construction, rehabilitation, reconstruction, natural disasters, and buildings demolition. In Western Europe, the highest percentage of waste comes from rehabilitation and demolitions (80%). In comparison, in Denmark, rehabilitation contributes with 20-25%, while 70-75% of waste comes from demolition (Mália, 2010). In Portugal, inert materials extraction accounts for about 80% of CDW, mainly composed of concrete, bricks and ceramics (Coelho, 2009). CDW can be reused on: road and pavement construction (Poon and Chan, 2004), the manufacture of concrete (Yang et al., 2010) and mortar (Assunção et al., 2007), or as secondary raw material for brick production (Klang et al., 2003), among others. About 80% of CDW can be recycled, as long as its proper management is assured (Fraga, 2012). Concerning more detailed scientific papers on this subject, the following authors were analysed: Marinkovic et al. (2010), Estanqueiro (2012), Knoeri et al. (2013), Simion (2013) and Tosic et al. (2014). All of these references were developed taking into account the conditions of a particular area: Serbia, Portugal, Switzerland, Italy and Serbia, respectively. Only Knoeri et al. (2013) analysed six stages of the life cycle of concrete: extraction, production, transportation, construction, use and demolition. The main reason is that Knoeri et al. (2013) are the only authors, along with Marinkovic et al. (2010) and Tosic et al. (2014), to perform a study on concrete and not just on the aggregates. Estanqueiro (2012) analysed three different scenarios: production of natural aggregates, and production of coarse aggregates recycled from concrete (CARC) with a stationary recycling plant and with a mobile recycling plant. This author concluded that, for reuse percentages below 50%, the production of natural aggregates leads to lower EI. Simion et al. (2013) reported that the most significant difference between the EI of these two materials is in the global warming potential category, since recycled aggregates have a value seven times lower than that of natural aggregates. According to Simion et al. (2013), the life cycle stages of C&DW recycling/reuse and natural aggregates with higher EI are: extraction, transportation and materials operation. Both Marinkovic et al. (2010) and Knoeri et al. (2013) reported that the production of cement is a major contributor to the high EI values of concrete production. 3

4 According to Marinkovic et al. (2010), the total EI of the use of recycled or natural aggregates concrete is highly dependent on the travel distance of the aggregates between construction sites and recycling plants. Knoeri et al. (2013) performed the most detailed study. They analysed 12 varieties of concrete by ranging the content of recycled aggregates, the amount of cement and the mechanical strength. The authors further indicated that the critical distance in the production of the two types of concrete (using natural or recycled aggregates) corresponds to 15 km, and the critical amount of cement ranges between 22 kg and 40 kg additional above, depending on the type of cement. Tosic et al. (2014) complement the study of Marinkovic et al. (2010) by applying the normative multi-criteria optimization method to determine the optimal solution (environmentally and economically). Tosic et al. (2014) concluded that the best solution features 50% of CRA. This study intends to find the best concrete composition, environmental and economic, from those which have been analysed in terms of strength by other authors. 2. Methodology 2.1 Goal and scope definition The aim of this study is the environmental and economy comparison between natural and recycled aggregates concrete, taking into account the strength of this structural material. For this purpose, the approach chosen for the life cycle of this material is from cradle-to-gate. The results of this study are intended to contribute to the analysis of the environmental and economic benefits of using recycled aggregates to replace natural aggregates. The life cycle assessment (LCA) methodology will be used for environmental assessment, based on ISO The functional unit of this study is 1 m 3 of ready-mixed NAC (natural aggregates concrete) and RAC (recycled aggregates concrete), considering its 28 days compressive strength. The life cycles stages considered were (Figure 1): Production/extraction of all raw materials needed for the production of each concrete (A1); Transportation of raw materials to the concrete plant (A2); Concrete production at the plant (A3). Figure 1 - Concrete life cycle In order to make this study feasible, it was necessary to make some assumptions: Since the use of normal hardening(n) or fast hardening (R) cement leads to the same strength of the 4

5 mixes at 28 days, this difference was not considered; Since it was not possible to obtain the EI of all families of cement type II analysed, only the cement type and its strength (disregarding its family) will; be taken into account The impacts associated with the transportation of waste of the CDW recycling plant will not be considered. From its beginning, this study presents some restrictions: Only eight EI categories will be accounted for (see section 2.3); Some emissions from different stages of production/extraction of raw materials (e.g. diffuse dust emissions in the processes developed at the quarry and at CDW recycling plant) cannot be accounted for, due to lack of information provided by the companies; No other life cycle stages of concrete will be included (application, maintenance and demolition), since this study is focused on the environmental impact with regard to its strength class; Some data collected were estimated by the technicians of the companies contacted, since not all expenses were being recorded separately for each task; It was not possible to estimate the emissions of some activities (e.g. greenhouse emissions in the transportation of materials), in which case the ones included in the databases of SimaPro software (Ecoinvent 3 and ELCD) were used as reference. 2.2 Life cycle inventory (LCI) At this stage of LCA, it is necessary to collect all inputs and outputs of the life cycle phases considered. All LCI data for coarse aggregates, CARC and concrete production were collected from Portuguese companies. Data for fine aggregate were collected from Marinkovic et al. (2010). Cement data were obtained from Blengini (2006), in a study based on the production of a Portuguese company. Superplasticizer (SP) data were collected by EFCA (European Federation of Concrete admixtures associations) by the year 2006, through an Environmental Product Declaration (EPD). With regard to the modelling it was necessary, in some cases, to use information from Ecoinvent 3 or ELCD databases. 2.3 Life cycle impact assessment (LCIA) Seven environmental categories were considered: abiotic depletion (ADP), global warming (GWP), ozone depletion (ODP), acidification (AP), eutrophication potential (EP), and photochemical ozone creation (POCP) potential, and consumption of primary energy, non-renewable (PE-NRe). To obtain these results, the CML baseline method were used for the six first categories, and Cumulative Energy Demand for the last one, in SimaPro programme. 3 Analysed mixes For this study, a total of 216 concrete mixes from 24 studies were analysed: Santos et al. (2002), Gonçalves et al. (2004), Ridzuan et al. (2005), Etxeberria et al. (2007), Malesev et al. (2010), Chen et al. (2010), Marinkovic et al. (2010), Fonseca et al. (2011), Rao et al. (2011), Safiuddin et al. (2011), Hao and Ren (2011), Corinaldesi (2011), Limbachiya et al. (2012), Kwan et al. (2012), Bearded et al. (2013), Matias et al. (2013), Thomas et al. (2013), Butler et al. (2013), Mefteh et al. (2013), Supper (2013), War et al. (2014), Pedro et al. (2014), Reis et al. (2015) and Tosic et al. (2014). These mixes have strengths between C8/10 and C55/67. The composition of each mix can be found in Braga s dissertation (2015). In this study, mixes with anomalous data were excluded: effective W/C ratio lower than 0.4 and cement quantities exceeding 450 kg/m 3 (except in class C50/60). 5

6 4 Environmental assessment results 4.1 Results Table 1 and Table 2 present the EI of each raw material and for production of concrete. The environmental impact of each mix can be found in Braga s dissertation (2015). Table 1 - Baseline CML method results for raw materials and production of concrete ADP GWP ODP POPC AP EP kg Sb eq kg CO 2 eq kg CFC-11 eq kg C 2 H 4 eq kg SO 2 eq kg PO -3 4 eq CEMI 32.5 (kg) 3.36E E E E E-4 CEMI 42.5 (kg) 3.83E E E E E-4 CEMI 52.5 (kg) 3.99E E E E E-4 CEMII 32.5 (kg) 3.09E E E E E-4 CEMII 42.5 (kg) 3.55E E E E E-4 River aggregate (kg) 3.37E E E E E E-5 Crushed aggregate (kg) 1.24E E E E E E-5 Granitic coarse aggregate (kg) 1.09E E E E E E-5 Limestone coarse aggregate (kg) 1.39E E E E E E-5 CARC (kg) 2.12E E E E E E-6 Water (kg) 1.57E E E E E E-8 SP (kg) 3.88E E E E E-3 Concrete production (m 3 ) 5.50E E E E-3 Table 2 - Cumulative Energy Demand results for raw materials and production of concrete Pe-NRe Pe-Re MJ MJ CEMI 32.5 (kg) CEMI 42.5 (kg) CEMI 52.5 (kg) CEMII 32.5 (kg) CEMII 42.5 (kg) River aggregate (kg) E-4 Crushed aggregate (kg) E-4 Granitic coarse aggregate (kg) E-4 Limestone coarse aggregate (kg) E-4 CARC (kg) E-5 Water (kg) 1.94E-3 0 SP (kg) E-5 Concrete production (m 3 ) E Discussion and interpretation The results of GWP by strength class are presented in Figure 2 (0% CARC) and Figure 3 (100% CARC). It was found that GWP is strongly related with the average amount of cement of each strength class - more cement corresponds to a larger EI. This conclusion is independent from the type of aggregates used (natural or recycled). On the other hand, Pe-NRe is significantly associated with the average amount of coarse aggregate of each strength class. Pe-NRe is lower in 100% CARC mixes, since this EI is significantly higher for natural coarse aggregates than for CARC. In order to assess how cement quantity influences the EI, four cement quantity ranges (kg/m 3 ) were pre-defined: CEM 300; 300 < CEM < 350; 350 CEM <400 and CEM 400. Through an evaluation of strength class influence (Figure 4, Figure 5 and Figure 6), it can be stated that higher amounts of cement lead to greater GWP. It was also found that, regardless of the amount of 6

7 kg CO 2 eq kg CO 2 eq kg CO 2 eq kg CO 2 eq cement, the introduction of CARC contributes to a GWP reduction. The same behaviour occurs for the other categories of EI, except for ADP. About this impact category is not possible to draw conclusions due to the limited representation and/or reduced R 2 values Production SP Water Coarse aggregates Fine aggregates Cement Figure 2 - Average GWP per m 3 of mixes without CARC by strength class Production SP Water CARC Fine aggregates Cement Figure 3 - Average GWP per m 3 of mixes with 100% of CARC by strength class 3,70E+02 3,50E+02 3,30E+02 3,10E+02 2,90E+02 2,70E+02 2,50E % CARC CEM<= <CEM<350 y = -0,5438x + 319,25 R² = 0,9295 y = -0,1343x + 314,84 R² = 0,2583 y = -0,4617x + 352,64 R² = 0,9647 Figure 4 - GWP per m 3 according to the amount of CEM for the class C20/25 350<=CEM<400 4,50E+02 4,00E+02 3,50E+02 3,00E+02 2,50E+02 2,00E % CARC CEM<= <CEM< <=CEM<400 CEM>=400 y = -0,3802x + 294,14 R² = 0,4105 y = -0,1293x + 325,22 R² = 0,3285 y = -0,3294x + 355,58 R² = 0,5913 y = -0,5749x + 420,37 R² = 0,5499 Figure 5 - GWP per m 3 according to the amount of CEM for the class C25/30 7

8 kg CO 2 eq 4,15E+02 3,65E+02 3,15E+02 2,65E % CARC Figure 6 - GWP per m 3 according to the amount of CEM for the class C30/37 In the SP parametric analysis, three intervals were defined: without SP, SP between 0 and 1% of the cement weight, and above 1%. The examination of the influence of SP incorporation in GWP does not provide enough evidence to draw conclusions. For some of the remaining environmental categories, the use of SP is beneficial from an environmental point of view (i.e. for POCP, EP and Pe-NRe). In the parametric study of the W/C ratio, the selected ranges were: less than 0.55; from 0.55 (included) to 0.6; and equal to or greater than 0.6. Regarding the strength class, it is possible to conclude that an increase of the W/C ratio results in a decrease of the associated GWP. This trend is confirmed in other environmental categories. It is also possible to claim that the use of CARC contributes to a decrease in the EI of concrete. 5 Comparative environmental and economic assessment 5.1 Economic analysis The cost of each raw material was collected from several Portuguese companies (Table 3). These costs were considered individually for each mix, taking into account the amount of raw materials needed. Concerning the strength class, the results were presented in Figure 7 (0% CARC) and Figure 8 (100% CARC). By comparing these graphs, it is possible to conclude that the concrete with CARC is cheaper than natural aggregates concrete, for any strength class. It is also possible to conclude that the highest portion of the cost comes from the cement content used. From a cement content point of view, concrete cost indicates that larger amounts of cement correspond to higher costs, regardless of the concrete strength class. Regarding SP, higher contents also correspond to higher costs. Concerning the W/C ratio, it is not possible to draw conclusions. Table 3 - Unitary cost of each raw material Raw material Unitary cost CEM I /ton CEM I /ton CEM I /ton CEM II /ton CEM II /ton River aggregate 4.15 /ton Crushed aggregate 4.41 /ton Granitic coarse aggregate 9.30 /ton Limestone coarse aggregate 4.59 /ton CARC 2 /ton Water 1.53 /m 3 SP 2.68 /kg CEM<= <CEM< <=CEM<400 CEM>=400 y = -0,1487x + 284,47 R² = 0,7968 y = -0,0922x + 327,03 R² = 0,3179 y = -0,1147x + 345,42 R² = 0,122 y = -0,3216x + 411,76 R² = 0,4556 8

9 Pe-NRe (MJ) 60,00 50,00 40,00 30,00 20,00 10,00 - SP Water Coarse aggregates Fine aggregates Cement Figure 7 - Average cost per m 3 of mixes without CARC, by strength class 50,00 40,00 30,00 20,00 10,00 - SP Water CARC Fine aggregates Cement Figure 8 - Average cost per m 3 of mixes with 100% CARC, by strength class 5.2 Results Generally, in order to conclude which mixes were the best and the worst in a comprehensive manner, three variables were analysed: GWP, Pe-NRe and cost. In mixes with 0% CARC in the C20/25 strength class (Figure 9), the mix presenting the worst results is # 116 of Santos et al. (2002). In the C25/30 strength class (Figure 10), mix 63 of Ridzuan et al. (2005) is the worst one. From the same author, mix # 67 is the one with the worst results in the strength class C30/37 (Figure 11). Moreover, in the same figures, it can be seen that the mixes with the best results are: #148 from Etxeberria et al. (2007) in the C20/25 class, #119 from Thomas et al. (2013) in the C25/30 class and #152 from Butler et al. (2013) in the C30/37 class. 2,00E+05 1,50E+05 36,64 (116) 1,00E+05 5,00E+04 52,66 (148) 38,49 (204) 0,00E+00 2,50E+05 2,70E+05 2,90E+05 3,10E+05 3,30E+05 GWP (kg CO 2 eq) Figure 9 - GWP by Pe-NRe considering the cost per m 3 for the C20/25 class and 0% CARC incorporated 9

10 Pe-NRe (MJ) Pe-NRe (MJ) Pe-NRe (MJ) 2,50E+05 2,00E+05 1,50E+05 1,00E+05 5,00E+04 0,00E+00 2,35E+05 2,85E+05 3,35E+05 GWP (kg CO 2 eq) 35,32 (119) 36,85 (30) 37,25 (39) 40,06 (75) 41,10 (183) 41,13 (203) 43,52 (91) 43,99 (201) 44,13 (171) 44,43 (175) 45,55 (55) 47,11 (172) 47,50 (59) 49,21 (144) 49,40 (63) 58,44 (160) Figure 10 - GWP by Pe-NRe considering the cost per m 3 for the C25/30 class and 0% CARC incorporated 2,50E+05 2,00E+05 1,50E+05 1,00E+05 5,00E+04 0,00E+00 2,30E+05 2,80E+05 3,30E+05 3,80E+05 GWP (kg CO 2 eq) 33,28 (152) 36,12 (115) 37,56 (94) 37,38 (98) 43,59 (213) 43,73 (17) 43,89 (102) 43,89 (202) 45,12 (83) 45,12 (87) 46,67 (71) 46,79 (200) 53,05 (67) Figure 11 - GWP by Pe-NRe considering the cost per m 3 for the C30/37 class and 0% CARC incorporated For 100% CARC, the mixes which show the worst results are: #164 from Safiuddin et al. (2011) in the C20/25 class (Figure 12), #58 from Ridzuan et al. (2005) and #74 from Rao et al. (2011) in the C25/30 class (Figure 13), and mix #106 from Matias et al. (2013) in the C30/37 class (Figure 14). From the same figures, it is possible to conclude that the mixes which have the best results are: #180 from Marinkovic et al. (2010) in the C20/25 class, #143 from Etxeberria et al. (2007) in the C25/30 class, and #154 of Butler et al. (2013) and #20 of Barbudo et al. (2013) in the C30 /37 class. Table 5 shows the detailed analysis of the composition of each mix referred. 2,50E+05 2,00E+05 1,50E+05 1,00E+05 5,00E+04 32,09 (33) 32,17 (36) 33,34 (180) 36,27 (54) 51,48 (164) 0,00E+00 2,40E+05 2,60E+05 2,80E+05 3,00E+05 3,20E+05 GWP (kg CO 2 eq) Figure 12 - GWP by Pe-NRe considering the cost per m 3 for the C20/25 class and 100% CARC incorporated 10

11 Pe-NRe (MJ) Pe-NRe (MJ) 2,50E+05 2,00E+05 1,50E+05 1,00E+05 5,00E+04 0,00E+00 2,00E+05 2,50E+05 3,00E+05 3,50E+05 GWP (kg CO 2 eq) 32,16 (45) 32,22 (42) 33,18 (76) 34,38 (101) 36,08 (184) 38,02 (181) 38,14 (216) 39,18 (174) 39,36 (58) 42,30 (143) 45,00 (74) 53,91 (151) Figure 13 - GWP by Pe-NRe considering the cost per m 3 for the C25/30 class and 100% CARC incorporated 2,50E+05 2,00E+05 1,50E+05 1,00E+05 5,00E+04 6 Conclusions 0,00E+00 2,40E+05 2,90E+05 3,40E+05 3,90E+05 GWP (kg CO 2 eq) Figure 14 - GWP by Pe-NRe considering the cost per m 3 for the C30/37 class and 100% CARC incorporated Based on the final results obtained, it is possible to define the more and less advantageous compositions from an environmental and economic point of view. The following conclusions stand out: It is preferable to use cement type II to using cement type I; 30,85 (153) 31,15 (154) 34,28 (93) 34,89 (97) 35,84 (155) 38,28 (20) 40,96 (103) 40,96 (104) 40,96 (105) 41,09 (62) 41,86 (86) 41,86 (90) 42,67 (182) 42,82 (66) 45,87 (78) 46,38 (70) 46,49 (106) 46,27 (107) 49,38 (147) 54,67 (139) 57,52 (140) Against the expectations, a higher concrete strength does not lead necessarily to a larger EI; When using natural coarse aggregates, it is advisable to use a limestone one and, in the case of fine aggregates, it is preferable that they are rolled, instead of crushed; The mixes with highest EI do not have SP in their composition (except for mix 148 from Etxeberria et al., 2007); Since cement is the main responsible for the EI, the use of SP in order to decrease the amount of cement is advisable. The amount of SP to be used should be low, in order to not increase significantly the concrete cost; A reduction in the W/C ratio does not seem to be an interesting solution according to this study; Greater environmental impacts are not necessarily associated with higher costs and vice versa; The use of cement type II, instead of type I, leads to a cost reduction of 12% and 7%, respectively for cement 32.5 and 42.5; By analysing the unitary costs, the use of limestone instead of granite aggregates corresponds to 50% savings, while using RAC corresponds to 80% savings; The cost of cement corresponds, on average, to 69% or 79% of the concrete cost, respectively for 11

12 concrete without CARC and concrete with 100% CARC; The mix with lower reductions of mechanical results, compared with the reference concrete, uses CARC with better characteristics (low water absorption and porosity, higher density and specific mass), usually it means better EI results; The advantage of using CARC is more significant in lower strength concrete; As expected, it is concluded that the incorporation of CARC in general contributes to a reduction of costs and EI. Table 4 briefly presents these conclusions. As expected, it is concluded that the incorporation of CARC in general contributes to a reduction of costs and EI. Table 4 - Influence of each raw material from an economic and environmental point of view EI &EI CEM I CEM II River aggregate Crushed aggregate Granitic coarse aggregate Limestone coarse aggregate CARC SP Note: + represents a reduction of impact; ++ represents a significant decrease of impact; - represents an increase of impact References Amorim, P. (2008). Influence of curing conditions in terms of durability on performance of concrete with recycled concrete aggregate (in Portuguese). Master s thesis in Civil Engineering, Instituto Superior Técnico, Lisbon. Assunção, L.; Carvalho, G.; Barata, M. (2007). Evaluation of properties of coating mortars produced with construction and demolition waste as aggregate. Directory of Open Access Journals (DOAJ). Barbudo, A.; Brito, J.; Evangelista, L.; Bravo, M.; Agrela, F. (2013). Influence of water-reducing admixtures on the mechanical performance of recycled concrete. Journal of Cleaner Production, Vol. 59, pp Blengini, G.A. (2006). Life cycle assessment tools for sustainable development: case studies for mining and construction industries in Italy and Portugal. PhD thesis in Mining Engineering, Universidade Técnica de Lisboa, Instituto Superior Técnico, Lisbon. Braga, M. (2015). Compared environmental impact of the life cycle of concrete with natural and recycled coarse aggregates (in Portuguese). Master s thesis in Civil Engineering, Instituto Superior Técnico, Lisbon. Butler, L.; West, J.S.; Tighe, S.L. (2013). Effect of recycled concrete coarse aggregate from multiple sources on the hardened properties of concrete with equivalent compressive strength. Construction and Building Materials, Vol. 47, pp Ceia, M.(2013). Shear strength of the interface between normal concrete and concrete with recycled aggregates (in Portuguese). Master s thesis in Civil Engineering, Instituto Superior Técnico, Lisbon. Chen, Z.; Huang, K.; Zhang, X.; Xue, J. (2010). Experimental research on the flexural strength of recycled coarse aggregate concrete. Mechanic Automation and Control Engineering (MACE), International Conference on Wuhan, China, pp Coelho, A. (2009). Analysis of the viability of construction and demolition waste recycling plants in Portugal - Part I Estimation of the generation of CDW (in Portuguese). Postdoctoral report, Instituto Superior Técnico, Lisbon. Corinaldesi, V. (2011). Structural concrete prepared with coarse recycled concrete aggregate: from investigation to design. Advances in Civil Engineering, Vol Estanqueiro, B. (2012). Life Cycle Assessment of the use of recycled aggregates in concrete production (in Portuguese). Master s thesis in Industrial Engineering and Management, Instituto Superior Técnico, Lisbon. Etxeberria, M; Vázquez, E.; Marí, A.; Barra, M. (2007) Influence of amount of recycled aggregates and production process on properties of recycled aggregate concrete. Cement and Concrete Research, Vol. 37, pp Fraga, C. (2012). Guide to construction and demolition waste in construction (in Portuguese). 79/2012 Report. Azores, LNEC. FEPICOP - Portuguese federation of the construction industry and public works (2012). Construction share of GDP reaches the minimum of last 18 years (in Portuguese). Information n.º 92, Lisbon. Fonseca, N.; Brito, J.; Evangelista, L. (2011). The influence of curing conditions on the mechanical performance of concrete made with recycled concrete waste. Cement & Concrete Composites, Vol. 33, pp

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14 # Authors Table 5 - Composition of mixes with best and worst overall characteristics in the C20/25, C25/30 and C30/37 strength classes Cement Fine aggregate Coarse aggregate CARC Water Type (kg/m 3 ) Type (kg/m 3 ) Type (kg/m 3 ) % (kg/m 3 ) (kg/m 3 ) 20 Barbudo et al. (2013) I 350 crushed C30/37 58 Ridzuan et al, 2005 I 355 river C25/30 63 Ridzuan et al, 2005 I 395 river 915 granitic C25/30 67 Ridzuan et al, 2005 I 435 river 860 granitic C30/37 74 Rao et al, 2011 I 401 river C25/ Matias et al, 2013 II river C30/ Santos et al, 2002 II river 697 limestone C20/ Thomas et al, 2013 I limestone C25/ Etxeberria et al, 2007 I crushed C25/ Etxeberria et al, 2007 I crushed 765,1-1206, C20/ Butler et al, limestone C30/ Butler et al, C30/ Safiuddin et al, 2011 I 342 river C20/ Marinkovic et al, 2010 I river C20/25 SP (%) w/c w/c effect. f ck (MPa) f cm (MPa) Strength class 14