Performance in durability terms of concrete incorporating waste. coarse aggregates from the marble industry

Transcription

1 Performance in durability terms of concrete incorporating waste coarse aggregates from the marble industry António Jorge Nunes Pedro André Extended Abstract Juri President: Prof. Dr. Augusto Martins Gomes Supervisor: Prof. Dr. Jorge Manuel Caliço Lopes de Brito Juri: Prof. Dr. António José da Silva Costa Lisbon, July 2012

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3 Performance in durability terms of concrete incorporating waste coarse aggregates from the marble industry 1. Introduction The stone industry is of major importance to the Portuguese economy as well as to that of world. However this industry frequently imposes significant environmental impacts, due to its inherent characteristics. The advances on the exploitation of quarries have led to the extraction of blocks with more impurities and worse quality, which consequently decreases the production of ornamental stone. The waste produced during the extraction process can be as high as 80% of all the extracted stone. Larger waste is disposed of at sites that are far from the excavation front, where they contribute to the degradation of the environment and of the natural landscape, and occupy the soil indiscriminately. Although there are currently various possibilities for this waste (e.g. using the larger blocks to recover inactive quarries; micronization) they are still clearly insufficient to reverse the growing backlog of materials. The construction industry comes naturally as an alternative due to the fact that, according to Saboya et al. (2006), such industry presents the highest potential for mineral consumption, thus generating a greater amount of waste. From the several alternatives, the marble dust is the most widely studied mainly due to its versatility. Binici et al. (2007) showed that using up to 15% of marble dust as an addition may lead to a more durable concrete. It is also possible to improve all of the properties of a self-compacting concrete by adding an amount of 200 kg/m 3 of marble dust, as shown by Topçu et al. (2009). Corinaldesi et al. (2010) observed that by replacing 10% of sand with marble dust, and using superplasticizers, the mortar s compressive strength is maximized while maintaining the same level of workability. Despite the successful use of marble dust, the potential of the larger residues remais untackled. Akbulut e Gürer (2007) explored that potential and concluded that the marble coarse aggregates (MCA) can be used in binder layers of light to medium traffic asphalt pavements. Moreover, Gencel et al. (2012) determined that the concrete pavement blocks made with MCA have an adequate quality. With regard to the concrete properties, in particular its durability, there are almost no studies that consider the use of marble coarse aggregates. However, Binici et al. (2008) showed that marble coarse aggregates significantly increases the resistance to chloride penetration and Pereira et al. (2009) found that the durability of a class C30/37 concrete is not affected by the aggregate mineralogy. 2. Objectives The main goal of this work is to evaluate the variation of the concrete s durability characteristics when replacing the primary aggregates (PA) with MCA. Another important aspect is the assessment of the feasibility of transforming a waste that has severe consequences for the environment into a byproduct with an alternative role. Such transformation restores some of the waste s economic value while simultaneously decreasing its dumped volume. To perform the assessment, three families of concrete were produced. Each of the families was made using conventional aggregates (basalt, granite and limestone) in which part of the PA were replaced by MCA at ratios of 20, 50 and 100% of the total volume of aggregates. António Jorge Nunes Pedro André 1

4 Extended Abstract The families were tested in the fresh state, for workability and specific gravity, and in the hardened state, for water absorption (by capillarity and immersion), carbonation and chloride penetration. The mechanical properties of the concretes made with MCA were assessed in the scope of a concurrent work performed by Pedro Jorge da Cruz Martins, also from Instituto Superior Técnico. 3. Experimental program 3.1. mix design The experiments considered 10 concrete mixes: Three of the mixes were used as reference concretes (RC) with 100% basalt (BRC), granite (GRC) and limestone (LRC) coarse aggregates. Six of the concrete mixes were obtained by replacing each of the PA used in the reference concrete by MCA at ratios of 20 and 50% of the total volume: concrete with 20 and 50% replaced basalt (BC20 and BC50), granite (GC20 and GC50) and limestone (LC20 and LC50). Finally, a concrete with 100% of MCA was also considered (MRC). In order to achieve a set of concrete families that are compatible with a significant number of current structural applications, it was guaranteed that the produced concrete complies with the requirements specified in the NP EN (2007) for a given class of environmental exposure. Therefore, the produced concrete complied with the following characteristics: Strength class: C30/37; Consistency class: S3 (100 a 150 mm); Exposure class: several; Maximum water/cement ratio: 0,55; Binder: CEM II A-L 42,5 R cement from Secil, Outão, Setúbal; Maximum aggregate size: 22,4 mm; Mixing water: tap water, from the public supply network; Manufacturing site: laboratory; Compression method: normal mechanical vibration (vibrating needle). All of the mixes were produced with a 115 ± 10 mm slump range, which is lower than the standard set. This allowed for a more reliable comparison between the different compositions. The three reference concretes were designed using the Faury reference curves. Table 1 shows the proportions of the materials used in the production of the reference concretes mixes Aggregate testing The characterization tests of the aggregates were conducted according to the standards and specifications provided in Table Fresh concrete testing The characterization tests of the fresh concrete were conducted according to the standards provided in Table 3. 2

5 Performance in durability terms of concrete incorporating waste coarse aggregates from the marble industry Table 1 Composition of the reference concretes Sieves (mm) Volume BRC LRC GRC (m 3 /m 3 ) Mass (kg/m 3 ) Mass (kg/m 3 ) Mass (kg/m 3 ) 16-22,4 0, ,4 324,9 337,5 11,2-16 0, ,4 321,3 333,8 Coarse aggregates 8-11,2 0, ,6 124,6 129,5 5,6-8 0, ,0 123,3 128,0 4-5,6 0, ,4 108,5 112,7 Fine aggregates Coarse sand 0, ,7 650,7 650,7 Fine sand 0, ,5 183,5 183,5 Total aggregates 0,679 Cement 0, ,0 350,0 350,0 Water 0, ,0 189,0 189,0 Voids volume 0, Total volume 1,000 Table 2 - Tests, standards and specifications used in the coarse aggregates characterization Tests Standards/Specifications Grading size analysis NP EN e NP EN Particle density and water absorption NP EN Loose bulk density and voids NP EN Los Angeles abrasion test LNEC E 237 Shape index NP EN Table 3 Tests and standards used in the fresh concrete characterization 3.4. Hardened concrete testing Tests Standards Slump test by Abrams cone NP EN Density NP EN The characterization tests of the hardened concrete were performed according to the specifications detailed in Table 4. Table 4 - Tests and specifications used in hardened concrete characterization Tests Specifications Absorption by immersion LNEC E 394 Absorption by capillary action LNEC E 393 Carbonation LNEC E 391 Chloride penetration LNEC E Experimental results and discussions 4.1. Aggregates properties Table 5 presents the experimental results of the several tests performed on the aggregates. It is concluded that there are no significant differences between the MCA and the PA. The MCA bulk density is similar to that of the limestone coarse aggregates () and that of the granite coarse aggregates () but slightly lower than that of the basalt coarse aggregates (BCA). The loose bulk density presents an identical behavior, although a slight difference is observed in the, due to the António Jorge Nunes Pedro André 3

6 Slump by Abrams cone (mm) Extended Abstract greater continuity of its grading curve. The MCA presents the lowest water absorption of all the tested aggregates. The Los Angeles coefficient of the MCA has large values but still below the recommended range for concrete. The shape index values of the MCA demonstrate that most of its particles are both elongated and angular. These two characteristics may lead to a concrete that presents a poorer performance when considering its mechanical and durability properties. Particle dry density (kg/m 3 ) Table 5 - Aggregate physical properties Particle saturated surface-dried density (kg/m 3 ) Water absorption Loose bulk density (kg/m 3 ) Los Angeles coefficient Shape index Fine sand 2575,7 2584,1 0, ,0 - - Coarse sand 2620,6 2625,1 0, ,0 - - gravel 0,5 2929,8 2956,7 0, ,5 14,8 29,4 Basalt gravel ,2 2991,3 0, ,3-25,4 gravel 1,5 2938,7 2959,4 0, ,9 9,2 17,0 gravel ,8 2995,4 0, ,1 11,3 21,8 gravel 0,5 2648,9 2680,5 1, ,3 34,2 17,6 Limestone gravel ,7 2676,2 1, ,9 30,8 18,2 gravel ,0 2655,8 0, ,2 31,9 12,7 gravel 0,5 2649,6 2694,6 1, ,6 27,4 24,9 Granite gravel ,8 2748,8 0, ,5-48,1 gravel ,3 2757,0 0, ,7 21,9 40,1 gravel 0,5 2665,3 2687,3 0, ,6 38,5 30,1 Marble gravel ,6 2704,8 0, ,1-31,5 gravel ,2 2722,2 0, ,3 39,1 28, Fresh concrete properties Workability Figure 1 shows the results of the slump test by Abrams s cone for all of the manufactured mixes. Note that, in order to ensure the reliability of the comparison between the various properties of the produced concretes mixes, it was guaranteed that all of the compositions presented a similar workability. Therefore, all of the results are contained in the range 115 ± 10 mm. 130,0 125,0 120,0 115,0 110,0 BCA 105,0 100,0 Replacement rate of PA by MCA Figure 1 - Slump by Abrams cone of the various concretes Figure 1 proves that workability shows no clear trend as PA is replaced by MCA. For the mixes made with, the replacement with MCA does not significantly affect the workability, possibly due 4

7 Fresh concrete density (kg/m 3 ) Performance in durability terms of concrete incorporating waste coarse aggregates from the marble industry to the high shape index of the. For the mixes made with the BCA and the, there is an increase in workability for the 20% replacement rate, most likely due to the MCA s plain surface and reduced absorption. On the contrary, the results show a decrease in the workability for the 50% replacement rate, most likely due to the shape index influence being higher than the flow increase observed for the 20% replacement ratio Density Figure 2 exhibits the density results of the produced mixes. The results show that the density of the concrete made with BCA decreases with the increase in the replacement ratio of the MCA. This is an expected behavior due to the differences between the density of both aggregates. When considering the and the mixes, the concrete density remains almost constant. The slight increase observed for the 20% replacement ratio in the and families may be due to the improved spatial disposition of the particles, given by the improved workability BCA Replacement rate of PA by MCA Figure 2 - Fresh concrete density 4.3. Hardened concrete properties Compressive strength The compressive strength test was performed as stipulated by the NP EN (2003) standard and the specimens were subjected to a uniform compression stress. Although the concrete durability cannot be directly characterized by the compressive strength, the latter is still repeatedly used to assess the concrete s quality, thus indirectly revealing its durability. As such, the results obtained by Pedro Martins in a concurrent research work were analyzed and the average compressive strength values at 28 days are presented in Table 6. In Figure 3 the comparison between the compressive strength of the concretes made with MCA and that of the reference concretes mixes is presented. From these results it is concluded that, in general, an increase of the replacement ratio is accompanied by a decrease of the average compressive strength at 28 days Water absorption by immersion The results of the water absorption by immersion test are presented in Table 7 and in Figure 4. António Jorge Nunes Pedro André 5

8 Water absorption by imersion in comparison with the reference concretes Compressive strength in comparison with the reference concretes Extended Abstract Table 6 - compressive strength at 28 days f cm 28 f cm 28 f cm 28 (MPa) (MPa) (MPa) BRC 45,9 0,0 LRC 43,4 0,0 GRC 46,6 0,0 BC20 44,0-4,2 LC20 43,2-0,5 GC20 43,7-6,2 BC50 44,1-3,9 LC50 44,2 1,8 GC50 41,3-11,4 MRC 41,8-9,0 MRC 41,8-3,7 MRC 41,8-10, BCA 85 Replacement rate of PA by MCA Absorption by immersion Figure 3 Compressive strength in comparison with the reference concretes Table 7 - Water absorption by immersion Absorption by immersion Absorption by immersion BRC 13,6 0,0 LRC 14,1 0,0 GRC 13,8 0,0 BC20 14,4 5,8 LC20 13,8-2,3 GC20 13,6-1,6 BC50 14,4 5,8 LC50 13,3-5,4 GC50 14,0 1,9 MRC 14,0 3,0 MRC 14,0-0,8 MRC 14,0 1,5 From these results it is seen that the mixes made with the MCA have a similar behavior to that of the reference concrete mixes. Such similar results were expected and are mainly due to the identical production and curing of all of the concrete families, the small aggregate absorption and the potential similarity of the concrete s microstructure BCA 90 Replacement rate of PA by MCA Figure 4 Water absorption in comparison with the reference concretes Water absorption by capillary action The results obtained for the water absorption and height at 72 hours are shown in Table 8. In Figure 5 the comparison between the water absorption by capillary action at 72 hours of the mixes made with the MCA and that of the reference concrete mixes is presented. 6

9 Absorption by capillary action in comparison with the reference concrete Performance in durability terms of concrete incorporating waste coarse aggregates from the marble industry Table 8 - Water absorption and water height by capillary action at 72 hours Water absorption by capillary Water height by capillarity action at 72 hours (g/mm 2 x 10-4 ) at 72 hours (mm) BRC 7,2 0,0 17,4 0,0 BC20 10,0 38,2 15,8-9,0 BC50 12,1 67,7 20,5 18,0 MRC 8,0 10,8 15,4-11,5 LRC 14,2 0,0 21,3 0,0 LC20 11,7-17,4 12,6-40,6 LC50 13,3-6,7 19,3-9,1 MRC 8,0-43,8 15,4-27,6 GRC 13,6 0,0 31,2 0,0 GC20 9,4-31,0 16,3-47,9 GC50 11,6-14,5 16,0-48,7 MRC 8,0-41,5 15,4-50,7 The results reveal that the water absorption by capillary action decreases with the addition of MCA for the mixes made with and. In the case of the concrete made with BCA such water absorption increases as a result of the worst adhesion between the MCA and the cement paste, when compared to the BCA, therefore increasing the interface zone pores, in which the absorption is more severe. From a global point of view, all of the concrete families made with the MCA have a good performance, especially when compared to other recycled aggregates Replacement rate of PA by MCA BCA Figure 5 - Water absorption by capillary action at 72 hours in comparison with the reference concrete Carbonation Table 9 and Figures 6-8 show the evolution of the carbonation depth, for all of the concrete mixes. From these results it is concluded that the carbonation depth is quite similar for the various mixes at any given age. The observed variations are extremely small; thus it is inferred that the incorporation of MCA contributes identically to the concrete matrix as the other PA do Chloride penetration The results for the chloride penetration at 28 and 91 days are presented in Table 10. Figures 9-10 show the comparison between the migration coefficient of the concrete produced with MCA and that of the reference concrete mixes. The results show that the chloride migration coefficient increases with the replacement ratio of PA by MCA. This increase may be due to the low percentage of alumina António Jorge Nunes Pedro André 7

10 Carbonation depth (mm) Carbonation depth (mm) Extended Abstract present in the used MCA, due to the fact that the alumina benefits the formation of tricalcium aluminate, which is responsible for fixing the chloride ions. With the low amount of alumina, the free chlorine percentage within the concrete matrix increases, therefore enhancing the chloride migration. Carbonation depth at 7 days (mm) Table 9 - Carbonation depth for the different concrete ages Carbonation depth at 28 days (mm) Carbonation depth at 56 days (mm) Carbonation depth at 91 days (mm) BRC 3,47 0,0 8,49 0,0 10,68 0,0 13,54 0,0 BC20 3,56 2,4 7,74-8,9 11,79 10,4 13,36-1,3 BC50 3,81 9,6 8,28-2,5 10,06-5,8 11,12-17,9 MRC 3,69 6,3 8,51 0,2 10,83 1,4 13,53 0,0 LRC 3,99 0,0 7,83 0,0 10,32 0,0 13,06 0,0 LC20 3,65-8,6 7,36-6,0 10,81 4,8 13,24 1,4 LC50 3,76-5,7 7,38-5,8 11,45 11,0 14,47 10,7 MRC 3,69-7,5 8,51 8,6 10,83 4,9 13,53 3,6 GRC 3,75 0,0 8,29 0,0 10,51 0,0 12,61 0,0 GC20 3,96 5,6 8,03-3,1 10,22-2,8 14,04 11,3 GC50 4,70 25,1 9,08 9,5 12,15 15,6 14,01 11,1 MRC 3,69-1,6 8,51 2,7 10,83 3,0 13,53 7,3 15,0 12,0 9,0 6,0 3,0 0,0 Replacement rate of BCA by MCA Figure 6 - Carbonation depth for the concrete made with BCA 7 days 28 days 56 days 91 days 15,0 12,0 9,0 6,0 3,0 7 days 28 days 56 days 91 days 0,0 Replacement rate of by MCA Figure 7 - Carbonation depth for the concrete made with 8

11 Chloride migration coefficient at 28 days in comparison with the reference concretes Carbonation depth (mm) Performance in durability terms of concrete incorporating waste coarse aggregates from the marble industry 15,0 12,0 9,0 6,0 3,0 0,0 Replacement rate of by MCA Figure 8 - Carbonation depth for the concrete made with Table 10 - Chloride migration coefficient 7 days 28 days 56 days 91 days Chloride migration coefficient at Chloride migration coefficient at days (x10-12 m 2 /s) days (x10-12 m 2 /s) MRC ,91 - BRC 13,51 0,0 - - BC BC50 15,24 12,8 - - LRC 17,92 0,0 14,34 0,0 LC20 21,49 19,9 14,86 3,6 LC ,27 13,5 GRC ,21 0,0 GC20 18,73 0,0 17,39 14,3 GC50 20,51 9,5 19,86 30, BCA Replacement rate of PA by MCA Figure 9 - Chloride migration coefficient at 28 days in comparison with the reference concretes 5. Conclusions The presented work allowed evaluating the durability of the concrete made with the addition of MCA. The experimental results allow drawing the following conclusions: 1. Workability is not significantly affected nor presents a defined trend when MCA is incorporated. Despite this, there is still an increase in the workability for the 20% replacement ratio and a decrease for the 50% replacement ratio, in the mixes made with BCA and. The mixes made with maintained a constant workability; António Jorge Nunes Pedro André 9

12 Chloride migration coefficient at 91 days in comparison with the reference concrete Extended Abstract Replacement rate of PA by MCA Figure 10 - Chloride migration coefficient at 91 days in comparison with the reference concretes 2. density reflects the density of each of its components and their imbrication. Therefore, the concrete density decreases with the addition of MCA to the mixes made with BCA and remains approximately constant for the concretes made with and ; 3. Overall, there is a decrease in the compressive strength, at 28 days, when there is an increase in the replacement rate of the PA by the MCA; 4. In terms of water absorption by immersion, the behavior of concrete made with the MCA is similar to that of the reference concrete. This may be due to the low absorption of the aggregates used and the potencial microstructural similarity between the mixes made; 5. The incorporation of MCA in the mixes made with and results in lower water absorption by capillary action. The opposite trend is observed in the mixes made with BCA. This can be explained by the worst adhesion of the MCA, with the consequent increase of the interface zone pores, which is where this phenomenon is more severe; 6. made with MCA has a similar carbonation depth to that of the reference concretes, thus supporting the microstructural similarity hypothesis between all of the families; 7. The incorporation of the MCA in the mixes resulted on a significant increase of the chloride migration coefficient. The low alumina percentage of these aggregates may be the main cause, due to the fact that this compound benefits the formation of tricalcium aluminate, which favors the fixation of the chloride ions. The results allow concluding that the incorporation of the MCA in concrete is perfectly feasible. In terms of durability, it was shown that the MCA confers similar characteristics the concrete as do BCA, and, typically used in the construction industry. However, major precautions must be adopted in chloride contaminated environments, where the MCA showed its worst performance. 6. References Akbulut, H., Gürer, C. (2005) - Use of aggregates produced from marble quarry waste in asphalt pavements. Building and Environment, 42 (5), pp ; Binici, H., Kaplan, H., Yilmaz, S., (2007) - Influence of marble and limestone dusts as additives on some mechanical properties of concrete. Scientific Research and Essay, 2 (9), pp ; 10

13 Performance in durability terms of concrete incorporating waste coarse aggregates from the marble industry Binici, H., Shah, T., Aksogan, O., Kaplan, H. (2008) - Durability of concrete made with granite and marble as recycle aggregates. Journal of Materials Processing Technology, 208 (1-3), pp ; Corinaldesi, V., Moriconi, G., Naik, T. R. (2009) - Characterization of marble powder for its use in mortar and concrete. Construction and Building Materials, 24 (1), pp ; EN (2005) - : Specification, performance, production and conformity (in Portuguese), IPQ, Lisboa; Gencel, O., Ozel, C., Koksal, F., Erdogmus, E., Martínez-Barrera, G., Brostow, W. (2012) - Properties of concrete paving blocks made with waste marble. Journal of Cleaner Production, 21 (1), pp ; LNEC E 237 (1971) - Aggregates: Los Angeles abrasion test (in Portuguese), LNEC, Lisboa; LNEC E 391 (1993) - : Calculation of carbonation resistance (in Portuguese), LNEC, Lisboa; LNEC E 393 (1993) - : Calculation of water absorption by capillary action (in Portuguese), LNEC Lisboa; LNEC E 394 (1993) - : Calculation of water absorption by immersion. Atmospheric pressure test (in Portuguese), LNEC, Lisboa; LNEC E 463 (2004) - : Calculation of the chloride coefficient by migration test under nonstationary conditions (in Portuguese), LNEC, Lisboa; Pereira, C. G., Castro-Gomes, J., Oliveira, L. (2009) - Influence of natural coarse aggregate size, mineralogy and water content on the permeability of structural concrete. Construction and Building Materials, 23 (2), pp ; NP EN (2000) - Geometric property test for aggregates: Granulometric analysis. Sieving method (in Poruguese), IPQ, Lisboa; NP EN (1999) - Geometric property test for aggregates: Calculation of granulometric distribution. Testing sieves, nominal hole size (in Portuguese), IPQ, Lisboa; NP EN (2002) - Geometric property tests for aggregates: Particle shape determination. Shape index (in Portuguese), IPQ, Lisboa; NP EN (2003) - Tests to find the mechanical and physical properties of aggregates: Method to determine density and voids (in Portuguese), IPQ, Lisboa; NP EN (2003) - Tests to find the mechanical and physical properties of aggregates: Determination of density and water absorption (in Portuguese), IPQ, Lisboa; NP EN (2002) - Tests on fresh concrete: Slump test (in Portuguese), IPQ, Lisboa; NP EN (2002) - Tests on fresh concrete: Density (in Portuguese), IPQ, Lisboa; NP EN (2003) - Tests on hardened concrete: Compressive strength of test specimens (in Portuguese), IPQ, Lisboa; Saboya Jr., F., Xavier, G. C., Alexandre, J. (2005) - The use of the powder marble by-product to enhance the properties of brick ceramic. Construction and Building Materials, 21 (10), pp ; Topçu, İ. B., Bilir, T., Uygunoğlu, T. (2009) - Effect of waste marble dust content as filler on properties of self-compacting concrete. Construction and Building Materials, 23 (5), pp António Jorge Nunes Pedro André 11