CONCRETE WITH RECYCLED AGGREGATES

Transcription

1 CONCRETE WITH RECYCLED AGGREGATES THE NATIONAL EXPERIMENTAL STATE-OF-THE-ART SUMMARY Fátima Alexandra Passarinho Alves Master Thesis in Civil Engineering Extended abstract Jury President: Doctor Joaquim Jorge da Costa Paulino Pereira Supervisor: Doctor Jorge Manuel Caliço Lopes de Brito Members: Eng. Manuel Vieira November of 2007

2 Introduction. Preliminary considerations As the world population increases, the use of natural resources and energy grows proportionally. Nowadays, one of the major environmental concerns is related to excessive consumption of natural resources. The search for a solution to this problem is already under way in several sectors. One of the sectors with major responsibility concerning this issue is the construction industry, due to its use of natural resources and originating waste related with concrete use. The handling of concrete has reached such a level of utilization of non-renewable natural materials that, in some countries, the shortage of these products is already being felt. The demolition of concrete structures originates waste difficult to store due to the lack of proper dumping places and high costs of transportation and storage. The concern with the need of raw materials and the production of enormous quantities of waste has been the cause of several studies with the intention of finding a solution to these problems. In this field, there are already several studies in the production of concrete with recycled aggregates. This dissertation is focused on several experimental campaigns on concrete with recycled aggregates, made by national researchers. The published information was handled in order to associate the many properties of the concrete with recycled aggregates that were tested..2 Objectives and methodology This research was initiated with the search for the experimental campaigns performed in Portugal that used recycled materials as aggregates in the production of structural concrete. Starting with these campaigns, a description of the results obtained for the properties of the recycled aggregates and for fresh and hardened concrete was made and then related with other properties of the aggregates (density and water absorption) and the concrete compressive strength at the age of 7 days. Summary forms were made for each campaign, indicating used materials, tested properties, and other relevant details. The weighed value for density and water absorption of all the aggregates in the mix was calculated using the density or water absorption of each individual aggregate and the proportion of each mix to produce concrete. The following equation was used in order to obtain such weighed values, in this case the weighed density of the aggregates in the concrete mix: D mix ( 00 subst ) FA subst FRA DFRA + FRA D = FNA + ( 00 FA) subst D + ( 00 subst ) 00 CRA CRA CRA D 00 CNA D mix - weighed density of the aggregates in the concrete mix; FA - percentage of fine aggregates used in the mix; subst FRA - substitution rate of fine recycled aggregates by fine natural aggregates; subst CRA - substitution rate of coarse recycled aggregates by coarse natural aggregates; D FRA - density of the fine recycled aggregates; D FNA - density of the fine natural aggregates; D CRA - density of the coarse recycled aggregates; D CNA - density of the coarse natural aggregates. For the calculation of the water absorption of the aggregates used in the mix, a similar equation was adopted where the density values were replaced by the water absorption values for each type of different aggregates used. With the conclusion of the data collection and respective organization and post-treatment, it was easier to proceed to-

3 wards its analysis and interpretation. In order to establish correlations between concrete properties and aggregates density and water absorption as well as the compressive strength of concrete at the age of 7 days, a graphic analysis methodology was created, according to the following steps: analysis and organization of the data available from each experimental campaign, including the information about the test results for the properties of the aggregates used in the production of the concrete; calculation of the exact value of the density and water absorption of the aggregates used in the mix, through the mix proportions of the concretes (with natural aggregates (NA) only and with recycled aggregates (RA)) and the individual density and water absorption of the aggregates (natural and recycled); graphical analysis of the relationship between the substitution rate of NA by RA and each property of concrete; graphical analysis of the variation of the ratio between the properties of concrete with RA and the one with NA only (reference conventional concrete) and the substitution rate of NA by RA; graphical analysis of the variation of the ratio between the properties of concrete with RA and the reference concrete and the ratio between the weighed value of density of aggregates in the concrete mix with RA and the reference concrete; graphical analysis of the variation of the ratio between the properties of concrete with RA and the reference concrete and the ratio between the weighed value of water absorption of aggregates in the concrete mix with RA and the reference concrete; graphical analysis of the variation of the ratio between the properties of concrete with RA and the reference concrete and the ratio between the compressive strength at the age of 7 days of concrete with RA and the reference concrete..3 Dissertation organization This study was divided in four chapters: the first is an introduction with the main goals definition and the methodology adopted; in the second, a description of the experimental state-of-the-art from the national campaigns considered in this investigation is presented; in the third, the experimental data collected were analysed, and presented ordered by concrete properties and then by campaign, in the end, this information was gathered so that the values from each campaign could be juxtaposed; the fourth chapter includes final results and conclusions.. In order to analyse this graphic summary for each property, qualitative criteria were established so that it would be possible to classify the correspondent correlation value. This classification is presented in Table. Table Qualitative classification of the correlation values Classification Values range Very good R 2 Good R 2 < Acceptable 0,65 R 2 < Not acceptable R 2 < 0,65 The summary forms for each campaign analysed were presented in an annex. 2 Main results of the dissertation 2. Final considerations In order to fight the increasingly use of natural resources, especially by the construction sector, and avoiding the severe environmental and economic consequences due to dumping and treatment of the waste produced, there is a need for solutions that emphasize the reuse and recycling of such waste products. The use of recycled aggregates in concrete production is already being implemented in some countries, but there is still some reluctance of this sector for the use of these resources to become current. The research works allow a growing knowledge of technical support in this area. In this dissertation a new approach was followed, concerning the relationship of some concrete properties with the den- 2

4 sity and water absorption of the aggregates mix and the compressive strength of concrete seven days old. This methodology was the object of a national patent (patent No. PT Methodology for the estimation of concrete with recycled aggregates properties ). The application of this concept can be exemplified by a structural designer willing to use demolition waste in the production of structural concrete who will be able to estimated the difference in this concrete s properties and, using this knowledge, adjust his project to these features. 2.2 General conclusions In each campaign analyzed, the w/c ratio was one of the properties kept constant between the reference concrete and the various concrete mixes made with recycled aggregates. In order for the comparison to be successful, the following properties should be kept unaltered: effective w/c ratio; slump; aggregates size distribution. The results presented by each experimental campaign individually exhibit a far better linearity and bigger correlation values when compared whit the juxtaposed campaigns values. Various hardened and fresh concrete properties were analyzed in this study. The primary property analyzed for fresh concrete was density. It showed a proportional decrease with the increase of the substitution rate, which can be linked to the lower density presented by recycled aggregates. The hardened concrete properties analyzed were mechanical and durability properties. Most of these properties had a performance decrease with the use of recycled aggregates. Each property is graphically analyzed, with the introduction of a regression line, corrected in order to go through the point corresponding to the reference concrete (concrete mix without recycled aggregates). The ratio between hardened concrete densities and the ratio between the densities of the aggregates in the mixes showed a linear trend with a good correlation coefficient. In Fig. 2. the relationship between the ratio between hardened concrete densities and the ratio between the densities of the aggregates in the mix is represented. density BAR /density BR y = -0,645x + 6 R 2 = ,02 0,04 0,06 -density BAR /density BR Rocha e Resende Fig Ratio between hardened concrete densities versus ratio between aggregates in the mix densities for the campaigns of Rocha and Resende and Fig. 2.2 represents the relationship between the ratio between hardened concrete densities and the ratio between the water absorptions of the aggregates in the mix. The correlation coefficient is acceptable. The relationship between the ratio between hardened concrete densities and the ratio between 7-day compressive strengths of concrete is represented in Fig The correlation coefficient is not acceptable. The relationship between the ratio between the compressive strengths of concrete and the ratio between the densities of the aggregates in the mix did not provide good correlation coefficients, although it presented a linear trend. It is possible to say that the closer the density value for recycled aggregate is to the natural ones, the lesser is the decrease of the compressive strength of concrete with recycled aggregates when compared to the reference concrete. The relationship between the 28-day compressive strengths of concrete and the ratio between the densities of the aggregates in the mix is represented in Fig

5 density BAR /density BR y = -0,028x + 6 R 2 = wa BAR /wa BR - Concrete with recycled aggregates Rocha e Resende Fig Ratio between hardened concrete densities versus ratio between aggregates in the mix water absorptions for the campaigns of Rocha and Resende and density BAR /density BR y = -0,528x + R 2 = 0, ,02 0,04 0,06 0,08 -f c7bar /f c7br Fig Ratio between hardened concrete densities versus ratio between concrete 7-day compressive strengths for the campaign of f cm_bar /f cm_br,40,30,20,0,00 y = 0,0845x + R 2 = -0,0005-0,05 0 0,05 0, -density BAR /density BR Rocha e Resende (mistos) Li (t d ) f cm_bar /f cm_br,05,00 y = -2,69x + R 2 = ,05 0, -density BAR /density BR Fig Ratio between concrete 28 day compressive strengths versus ratio between aggregates in the mix densities for the campaigns of,,,, Rocha and Resende, and (left) and without Rocha and Resende,, BAGRC (concrete with coarse ceramic recycled aggregates) of and the st stage of (right) The relationship between the 28-day compressive strengths of concrete and the ratio between the water absorptions of the aggregates in the mix is presented in Fig The value of the correlation coefficient is acceptable in the first case but not in the second. f cm_bar /f cm_br,40,30,20,0,00 y = 0,0088x + R 2 = 0, wa BAR /wa BR - Rocha e Resende (mistos) f cm_bar /f cm_br,05,00 y = -0,0587x + R 2 = 0, wa BAR /wa BR - Fig Ratio between concrete 28 day compressive strengths versus ratio between aggregates in the mix water absorptions for the campaigns of,,,, Rocha and Resende, and (left) and without Rocha and Resende,, BAGRC of and the st stage of (right) The relationship between the 28-day compressive strengths of concrete and the ratio between 7-day compressive 4

6 strengths of concrete obtained a correlation value not acceptable and is represented in Fig f cm_bar /f cm_br,05,00 y = -327x + R 2 = 0,5678-0,0 0,0 0,30 -f c7bar /f c7br (mistos) Li (t d ) Concrete with recycled aggregates f cm_bar /f cm_br,05,00 y = -908x + R 2 = 0,5409 0,00 0,0 0,20 0,30 0,40 -f c7bar /f c7br Fig Ratio between concrete 28-day compressive strengths and the ratio between concrete 7-day compressive strengths for the campaigns of,,, and (left) and without and (ceramic and mixed aggregates) (right) The relationship between the modules of elasticity of concrete and the ratio between the densities of the aggregates in the mix is found in the Fig The correlation coefficients are not acceptable. E BAR /E BR 0,65 y = -2,4562x + R 2 = 0, ,05 Rocha e Resende (mistos) E BAR /E BR 0,65 y = -3,84x + R 2 = 0, ,02 0,04 0,06 -density BAR /density BR -density BAR /density BR Fig Ratio between concrete modules of elasticity versus ratio between aggregates in the mix densities the for the campaigns of,,, Rocha and Resende and (left) and without Rocha and Resende (right) The relationship between the ratio between modules of elasticity of concrete and the ratio between water densities of the aggregates in the mix is represented in Fig The correlation coefficients are not acceptable and good. E BAR /E BR 0,65 y = -0,0384x + R 2 = 0, wa BAR /wa BR - Rocha e Resende (mistos) E BAR /E BR y = -0,0966x + R 2 = 76 0, wabar/wa BR - Fig Ratio between concrete modules of elasticity versus ratio between aggregates in the mix water densities for the campaigns of,,, Rocha and Resende and (left) and without Rocha and Resende and (right) The correlation coefficients of the ratio between modules of elasticity of concrete with the ratio between 7-day compressive strengths of concrete are represented in Fig. 2.9 with values not acceptable and good. For the relationship between the ratio between tensile strengths of concrete and the ratio between the densities of the aggregates in the mix, the correlation value is not acceptable (Fig. 2.0). The relationship between the ratio between tensile strengths of concrete and the ratio between the water absorptions of the aggregates in the mix is represented in Fig. 2.. The correlation values are similar to the one obtained for the density of the aggregates in the mix, both not acceptable. 5

7 E BAR /E BR y = -,335x + R 2 = -0,694 0,65-0,0 0,00 0,0 -f c7bar /f c7br (mistos) E BAR /E BR Concrete with recycled aggregates y = -,9852x + R 2 = 94 0,65 0,00 0,0 -f c7bar /f c7br Fig Ratio between concrete modules of elasticity versus ratio between concrete 7-day compressive strengths for the campaigns of,, and (left) and without (concrete and mixed aggregates) (left) f ctm_bar /f ctm_br y = -3,322x + R 2 = 0, ,05 -density BAR /density BR Rocha e Resende (mistos) Li (t d ) Fig Ratio between concrete tensile strengths versus ratio between aggregates in the mix densities for the campaigns of,,, and Rocha and Resende f ctm_bar /f ctm_br y = -0,0578x + R 2 = 0, wa BAR /wa BR - Rocha e Resende (mistos) f ctm_bar /f ctm_br y = -0,0573x + R 2 = 0, wabar/wa BR - Fig Ratio between concrete tensile strengths versus ratio between aggregates in the mix water absorptions for the campaigns of,,, and Rocha and Resende (left) and without (right) In Fig. 2.2 the relationship between the ratio between tensile strengths of concrete and the ratio between 7-day compressive strengths of concrete is represented with a good correlation coefficient. f ctm_bar /f ctm_br y = -72x + R 2 = -0, ,0 0,00 0,0 (mistos) f ctm_bar /f ctm_br y = -,4847x + R 2 = ,00 0,05 0,0 0,5 f c7bar /f c7br f c7bar /f c7br Fig Ratio between concrete tensile strengths versus ratio between concrete 7-day compressive strengths for the campaigns of,, and (left) and without (concrete and mixed aggregates) (right) The relationships between the ratio between flexural strengths of concrete and the ratio between the densities and water absorptions of the aggregates in the mix exhibit linear trends (Fig. 2.3) with very good correlation coefficients. 6

8 f ctbar /f ctbr,00 y = -,6606x + R 2 = 942 f ctbar /f ctbr,00 y = -0,0356x + R 2 = 942 0,00 0,05 0,0 0,5 0,00 2,00 4,00 6,00 -density BR /density BAR wa BR /wa BAR - Fig Ratio between concrete flexural strengths versus ratio between aggregates in the mix densities (left) and water absorptions (right) for the campaign of The relationship between the ratio between abrasions of concrete and the ratio between densities of the aggregates in the mix obtained correlation coefficients not acceptable, acceptable and good (Fig. 2.4). l BAR / l BR,0,00 y = -2,827x + R 2 = 0,5254 l BAR / l BR,0 y = -,7878x +,00 R 2 = 364 lbar/ lbr,0 y = -4,5726x +,00 R 2 = , -density BAR /density BR 0 0,05 0, 0,5 -density BAR /density BR 0 0,02 0,04 0,06 -density BAR /density BR Fig Ratio between concrete abrasions versus ratio between aggregates in the mix densities for the campaigns of, and (left), without (middle) and also without (left) The correlation values obtained for the correlation between the ratio between abrasions of concrete and the ratio between the water absorptions of the aggregates in the mix are similar to the ones obtained for the ratio between densities of the aggregates in the mix. The first are represented in Fig l BAR / l BR,0 y = -0,0463x +,00 R 2 = 0, wa BAR /wa BR - l BAR / l BR,0 y = -0,038x +,00 R 2 = l BAR / l BR,0 y = -0,083x +,00 R 2 = wa BAR /wa BR - wa BAR /wa BR - Fig Ratio between concrete abrasions versus ratio between aggregates in the mix water absorptions for the campaigns of, and (left), without (middle) and also without (right) In Fig. 2.6 the relationship between the ratio between abrasions of concrete and the ratio between 7-day compressive strengths of concrete is represented with a correlation coefficient not acceptable. l BAR / l BR,0,00 y = -2,375x + R 2 = 0,3473 0,00 0,05 0,0 -f c7bar /f c7br Fig Ratio between concrete abrasions versus ratio between concrete 7-day compressive strength for the campaigns of and The relationship between the ratio between concrete shrinkages and the ratio between densities of the aggregates in the mix is represented in Fig The correlation coefficients are not acceptable. 7

9 εcs_bar/εcs_br,7,5,3, 0,5 0,3 y = -,305x + R 2 = 0, ,05 0, ε cs_bar /ε cs_br,7,5,3, y = 8,74x + R 2 = 0, ,02 0,04 0,06 0,08 -density BAR /density BR -density BAR /density BR Fig Ratio between concrete shrinkages versus ratio between aggregates in the mix densities for the campaigns of,,, and (left) and without, (BAGRC) and (right) In Fig. 2.8 the relationship between the ratio between concrete shrinkages and the ratio between water absorptions of the aggregates in the mix is represented. The correlation values are not acceptable and acceptable. εcs_bar/εcs_br,7,5,3, 0,5 0,3 y = 0,0288x + R 2 = 0, wa BAR /wa BR - ε cs_bar /ε cs_br,7,5,3, y = 0,503x + R 2 = 0, wa BAR /wa BR - Fig Ratio between concrete shrinkages versus ratio between aggregates in the mix water absorptions for the campaigns of,,, and (left) and without, (BAGRC) and (right) The relationship between the ratio between concrete shrinkages and the ratio between 7-day compressive strengths of concrete (presented in Fig. 2.9) showed correlation coefficients not acceptable and very good. εcs_bar/εcs_br,7,5,3 y = -0,34x + R 2 = 0,02, 0,5 0,3-0,0 0,00 0,0 -f c7bar /f c7br (misto),7,6 y = 6,305x +,5,4 R 2 = 27,3,2, 0,00 0,05 0,0 -f c7bar /f c7br Fig Ratio between concrete shrinkages versus ratio between concrete 7-day compressive strengths for the campaigns of,,, and (left) and without, (concrete and mixed aggregates) and (right) The correlation coefficients obtained for the relationship between the ratio between capillary water absorptions of concrete and the ratio between water absorptions of the aggregates in the mix are not acceptable. They are represented in Fig The same relationship but with water absorptions of the aggregates in the mix obtained values for the correlation coefficient not acceptable. They are represented in Fig The same trends occurred with the 7-day compressive strengths of concrete, as shown in Fig The same trends and correlation coefficients presented by capillary water absorptions of concrete were observed in terms of concrete water absorptions by immersion except for the 7-day compressive strengths of concrete. In Fig. 2.23, Fig and Fig the three relationships mentioned are presented. εcs_bar/εcs_br 3 8

10 Concrete with recycled aggregates 2,5 2,5 y = 7,626x + R 2 = -0,0833 0,5-0,05 0,05 0,5 -density BAR /density BR (mistos) Li (t d ) 2,3,8,3 y = 8,4054x + R 2 = 0, , -density BAR /density BR,8,7,6,5,4 y = 6,578x +,3,2 R 2 = 0,5034, 0 0, -density BAR /density BR Fig Ratio between concrete capillary water absorptions versus ratio between aggregates in the mix densities for the campaigns of,,,, and (left), without (BAGRC) (middle) and also without (right) 2,5 2,5 0,5 y = 9x + R 2 = 0, (mistos) 2,3 y = 9x + R 2 = 76,8,3 0 5,8,7,6,5,4,3 y = 0,447x +,2 R 2 = 0,3689, 0 5 wa BAR /wa BR - wa BAR /wa BR - wa BAR /wa BR - Fig Ratio between concrete capillary water absorptions versus ratio between aggregates in the mix water absorptions for the campaigns of,,,, and (left), without (middle) and also without (right) 2, y = 2,6758x + R 2 = -0,625,6, 0,6-0,0 0,0 0,30 (mistos) 2,4 2,2 y = 2,9498x + 2 R 2 = -0,0853,8,6,4,2 0,00 0,20 -f c7bar /f c7br -f c7bar /f c7br Fig Ratio between concrete capillary water absorptions versus ratio between concrete 7-day compressive strengths for the campaigns i BAR / i BR 2,40 2,20 y = 4,649x + 2,00 R 2 = -0,3606,80,60,40,20,00-0,05 0,05 0,5 -density BAR /density BR of,,, and (left) and without (right) Figueredo (mistos) Li (t d ) ibar/ ibr,60,50,40,30,20,0 y = 5,9396x + R 2 = 0,5355,00 0 0,05 0, 0,5 -density BAR /density BR ibar/ ibr,50,40,30,20 y = 7,529x +,0 R 2 = 0,649,00 0 0,02 0,04 0,06 0,08 -density BAR /density BR Fig Ratio between concrete water absorptions by immersion versus ratio between aggregates in the mix densities for the campaigns of,,,, and (left), without (BAGRC) (middle) and also without and (right) Fig represents the relationship between the ratio between concrete carbonation depths and the ratio between densities of the aggregates in the mix. The correlation coefficients obtained were not acceptable and good. 9

11 Concrete with recycled aggregates i BAR / i BR 2,40 2,20 2,00,80,60,40,20 y = 0,24x + R 2 = -0,2, wa BAR /wa BR - (mistos Li (t d ) ibar/ ibr,60,50,40,30,20,0 y = 0,29x + R 2 = 0,4707, wa BAR /wa BR - ibar/ ibr,50,40,30,20 y = 0,69x +,0 R 2 = 0,5957, wa BAR /wa BR - Fig Ratio between concrete water absorptions by immersion versus ratio between aggregates in the mix water absorptions for the campaigns of,,,, and (left), without (BAGRC) (middle) and also without i BAR / i BR 2,40 2,20 2,00,80,60,40,20 y = 3,7259x + R 2 = 469,00-0,0 0,0 0,30 -f c7bar /f c7br (right) todos (mistos) Li (t d ) i BAR / i BR 2,50 2,00,50 y = 3,9972x + R 2 = 876,00 0,00 0,0 0,20 0,30 0,40 -f c7bar /f c7br Fig Ratio between concrete water absorptions by immersion versus ratio between concrete 7-day compressive strengths for the campaigns of,, and (left) and without (concrete and mixed aggregates) (right) Carb. depth BAR /Carb y = x + R 2 = (mistos) Carb. depth BAR /Carb y = 2.8x + R 2 = density BAR /density BR -density BAR /density BR Fig Ratio between concrete carbonation depths versus ratio between aggregates in the mix densities for the campaigns of,, and (left) and without (right) Carb. depth BAR /Carb y = 0.34x + R 2 = (mistos) Carb. depth BAR /Carb y = 0.038x + R 2 = Carb. depth BAR /Carb y = 0.206x + R 2 = wa BAR /wa BR - wa BAR /w a BR - wa BAR /wa BR - Fig Ratio between concrete carbonation depths versus ratio between aggregates in the mix water absorptions for the campaigns of,, and (left), without (middle) and without and (right) The relationship between the ratio between concrete carbonation depths and the ratio between water absorptions of the aggregates in the mix led to correlation coefficients not acceptable and good. These values are represented in Fig

12 The relationship between the ratio between carbonation depths of concrete and the ratio between 7-day compressive strengths of concrete showed a linear trend illustrated by a good correlation coefficient (Fig. 2.28). Carb. depth BAR /Carb y = x + R 2 = Go mes Go mes (mistos) Carb. depth BAR /Carb y = 4.488x + R 2 = f c7bar /f c7br -f c7bar /f c7br Fig Ratio between concrete carbonation depths versus ratio between concrete 7-day compressive strengths for the campaigns of,, and (left) and without (concrete and mixed aggregates)(right) For the relationship between the ratio between chloride penetration depths of concrete and the ratio between densities of the aggregates in the mix, the correlation coefficient was not acceptable and very good, as seen in Fig Cloret. depth BAR /Cloret y =.275x + R 2 = (mistos) Cloret. depth BAR /Cloret y = 3.329x + R 2 = Cloret. depth BAR /Cloret y = x + R 2 = density BAR /density BR -density BAR /density BR -density BAR /density BR Fig Ratio between concrete chloride penetration depths versus ratio between aggregates in the mix densities for the campaigns of,, and (left), without (middle) and also without (right) The same happens with the relationship between the ratio between chloride penetration depths of concrete and the ratio between water absorptions of the aggregates in the mix, but only a correlation coefficient good was achieved, as seen in Fig Cloret. depth BAR /Cloret y = x + R 2 = wa BAR /w a BR - (mistos) Cloret. depth BAR /Cloret y = 0.78x + R 2 = wa BAR /w a BR - Fig Ratio between concrete chloride penetration depths versus ratio between aggregates in the mix water absorptions for the campaigns of,, and (left) and without (right) The worst result for chloride depths of concrete is in Fig. 2.3, with correlation coefficients not acceptable, concerning the ratio between 7-day compressive strengths of concrete. It can be stated that the relationship between the ratio of various of the hardened concrete properties analyzed and the ratio between densities and water absorptions of the aggregates in the mix and the ratio between 7-day compressive strengths of concrete revealed some linear trends.

13 Cloret. depth BAR /Cloret y = x + R 2 = (mistos) Cloret. depth BAR /Cloret. Concrete with recycled aggregates,3,2, y =,275x + R 2 = 0, , -f c7bar /f c7br -f c7bar /f c7br Fig Ratio between concrete chloride penetration depths versus ratio between concrete 7-day compressive strengths for the campaigns of,, and (left) and without and (concrete and mixed aggregates) (right) This analysis will allow a methodology able to anticipate the behaviour of some fresh and hardened concrete properties. With the early knowledge of properties such as density and water absorption of the aggregates in the concrete mix, it will become possible to speculate on the results of some hardened concrete properties. The use of concrete with recycled aggregates should always take into consideration that they have, in most cases, a lower performance when compared to conventional concrete but that the variability of their properties are similar. This way, the anticipation of the decrease in the concrete with recycled aggregate performance in comparison to the conventional one can be determined with the knowledge of the substitution rate and of the aggregates properties. In Table 2 a summary of the correlation coefficients for the relationship of each hardened concrete property with the weighed densities and water absorptions of the aggregates in the mix and the 7-day compressive strengths of concrete is presented. The regression lines slopes are also presented in this table. The correlation coefficient classification was identified by different colours. 2.3 Future developments With this study it was possible to understand the development level of the experimental campaigns on this subject. It was also a valid contribution for future studies within this theme, which involve the correlation of concrete properties with aggregates properties and also the compressive strength of concrete at the age of 7 days. The many campaigns mostly developed in Instituto Superior Técnico follow very similar and strict scientific procedures that allowed the use of such results with increased safety and efficiency. This is only a small part of what can and should be done in order to make a deeper study and use of this methodology. This way it will be possible to achieve values that can be considered statistically valid. 2

14 Table 2 Summary of the correlation of each concrete property with de density and water absorption of the aggregates in the mix and the 7- day compressive strength of concrete Density Water absorption f c7d Property Campaigns R 2 Slope R 2 Slope R 2 Slope Rocha e Resende/ 22-0, , Density 0,5622-0,528 / / / / Rocha e Resende/ / -0,0005 0,0845 0,072 0, (without the st stage)/ (without BAGRC)/ / / 65-2,69 0,4605-0, f c / / / / , / / (without ceramic and mixed aggregates)/ , / / / Rocha e Resende/ 0,474-2,4562 0,048-0, / / / 0,6292-3, E c / / ,694 -,335 / / , / / ,9852 / / / / Rocha e Resende 0,6472-3,322 0,5222-0, / / / Rocha e Resende - - 0,6305-0, f ct / / / , / / (without concrete and mixed aggregates)/ ,4847 f ft 942 -, , / / 0,524-2,827 0,5965-0, Abrasion / 364 -, , / 05-4, ,083 0,3473-2,375 / / / / 0,0237 -,305 0,032 0,0288-0,02-0,34 / (without BAGRC)/ Shrinkage 0,648 8,74 0,6693 0, / (without concrete and mixed aggregates)/ ,305 / / / / / -0,0833 7,626 0, / / / / ,625 2,6758 / (without Water absorption by (without BAGRC)/ / BAGRC)/ / / / 0,098 8, / / 0,5034 6, capillarity / / / / / / / - - 0,3689 0, / / (without concrete and mixed aggregates)/ ,0853 2,9498 / / / / -0,3606 4,649-0,2 0, / / / / ,7259 Water absorption by concrete and mixed aggregates)/ / / / (without ,9972 immersion / (without 0,5355 BAGRC)/ / / 5,9396 0,4707 0, / (without 0,649 BAGRC)/ / 7,529 0,5957 0, / / / 0,3626 7,5568-0,39 0,34 5 3,0865 / / (without concrete and mixed aggregates)/ ,488 Carbonation // 347 2, / / - - 0,3065 0, / / / -0,0598,275 0,0356 0,0378-0,323 0,3686 / / 33 3, Chloride / 45 7, / / (without concrete and mixed aggregates) ,024,275 correlation coefficient acceptable (0,65 R 2 < ) correlation coefficient good ( R 2 < ) correlation coefficient very good (R 2 ) 3