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Technical note on sorption and permeability of concrete containing rubber and quartz sandstone aggregates
Construction and Building Materials 145 (2017) 311–317
Contents lists available at ScienceDirect
Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat
Technical note
Technical note on sorption and permeability of concrete containing rubber and quartz sandstone aggregates Sanjeev Kumar ⇑, Ajay Kumar Sharma, Deepak Sherawat, Mohit Dutt , Ramesh Chandra Gupta Department of Civil Engineering, Malaviya National Institute of Technology, Jaipur, India
a r t i c l e
i n f o
Article history: Received 17 October 2016 Received in revised form 22 March 2017 Accepted 5 April 2017
Keywords: Quartz sandstone Rubber Water permeability Microstructure
a b s t r a c t The presence of waste is a warning of overconsumption of materials and are not being used to its full potential. There has been a consistent decrease in environmental potential to absorb these wastes and a useful resource of matter and energy are lost due to the disposal of such wastes. The main problem associated is the excess production of wastes such as rubber and stones which could be utilised efficiently in many other ways. One of the sustainable utilisation of these wastes is by using them in the production of cement concrete. M30 concrete grade (water-cement ratio of 0.4) is designed as per Indian specifications with discarded tyre rubber as a partial replacement of fine aggregate and quartz sandstone as a partial replacement for coarse aggregates. The water absorption properties of concrete containing crumb rubber, quartz sandstone and a mixture of both were studied. Three sandstone replacement levels (0%, 50% and 100%) are taken and five rubber replacement levels (0%, 2.5%, 5%, 7.5% and 10%) were considered for the study. Concrete having quartz sandstones as coarse aggregates and crumb rubber as fine aggregates are recommended to be used at 50% substitution level of quartz sandstone. The maximum rubber replacement in the same mix can be limited to 7.5% to maintain the increase in sorption rate below 15%. Ó 2017 Elsevier Ltd. All rights reserved.
1. Introduction The overall production of rubber tyres has increased to a greater extent and the automotive industry uses tyres which are highly durable and not easily recycled. The improper disposal of waste tyres is dangerous to the environment and human health [1]. Due to these environmental and health issues attributed from rubber waste, a broad area of research is focussed on the utilisation of them as a partial substitute for mineral aggregates. This considerable recycling of rubber wastes reduces the disposal problems and also lessens the use of natural mineral aggregates [2]. Rubber is a good absorber of shock and also possess moderate sound insulating properties. Although having its advantages, rubber, when utilised in concrete, shows a considerable decrease in mechanical strength with an increase in permeability [3,4]. The composition of cement paste being hydrophilic material and the rubber aggregates being a hydrophobic material makes it even more difficult for the resulting concrete to have an adhesive interlocking mecha-
Abbreviations: QS, quartz sandstone; QSC, quartz sandstone concrete; QSRC, quartz sandstone and rubber concrete; SEM, scanning electron microscope. ⇑ Corresponding author. E-mail address: [email protected] (S. Kumar). http://dx.doi.org/10.1016/j.conbuildmat.2017.04.022 0950-0618/Ó 2017 Elsevier Ltd. All rights reserved.
nism. Irrespective of reduced adhesion property, many researchers have found concrete with rubber aggregates showing better toughness and impact strength than concrete made with standard mineral aggregates [5–8]. On the other hand, sandstone being a consolidated sand is a well-known sedimentary type of rock. It is composed of rock fragments and silt-sized mineral grains which are held together by the cementing material. Kumar et al. (2016) observed an increase in water absorption of concrete as the quartz sandstone coarse aggregate was increased [9]. This phenomenon was observed due to the increase in microvoids between the interface of cement paste and foreign aggregate. The act of achieving consistent workability in concrete with sandstone aggregates is usually by increasing the dosage of super plasticisers [10]. The measurement of water absorption in concrete with different aggregates remains important for quantifying the interconnected pores. Also, the initial water absorption of an aggregate allows the casting person to determine the amount of excess water to be mixed before casting [11]. The rate of deterioration of concrete structures is directly related to moisture ingress. Also, the water permeability of concrete is a property that can alter the durability and serviceability of massive concrete structures [12,13]. The replacement and substitution of natural aggregates
312
S. Kumar et al. / Construction and Building Materials 145 (2017) 311–317
by alternate source has become a widespread research in the area of construction sustainability. Thence it becomes necessary to reduce the excessive use of depleting construction materials and find new ones which are less aggressive towards the environment [14]. In the event of mixing one or more aggregates to produce concrete, gradation plays a vital role in attaining a good packing density. Fineness modulus and gradation of an aggregate play a vital role in determining the overall performance of fresh and hardened concrete [15]. This paper compares the water absorption characteristics of concrete with rubber, quartz sandstones and a mixture of both. The substitution of quartz sandstone as coarse aggregates was done at three levels (0%, 50% and 100%) and crumb rubber for fine aggregates at five levels (0%, 2.5%, 5%, 7.5% and 10%).
2. Materials and properties Ordinary Portland cement (OPC) of grade 43 was used for the casting. River sand conforming to zone II obtained from local sources were used as fine aggregates. Coarse aggregates of sizes 20 mm and 10 mm were procured and tested for specific gravity, water absorption, impact value test, Los Angeles abrasion test and gradation using sieve analysis. By sieve analysis, the ratio of mixing coarse aggregates (20 mm: 10 mm) was fixed to 55:45 for natural coarse and 60:40 for quartz sandstone coarse aggregates [10]. Discarded tyre rubber of sizes 0.8–2 mm, 2–4 mm and rubber powder was used based on the results of gradation for zone II fine aggregate confirmed with IS: 383-1970 [16,17]. To maintain a consistent workability, superplasticisers were added as a percentage by weight of cement in the range 0.8% - 1.6%. The properties of aggregates used are given in Table 1.The details of mix proportions for concrete containing solely rubber and quartz sandstone aggregates are same as given in Thomas et al. [17] and Kumar et al. [10]. The mix proportions of concrete containing both rubber and quartz sandstones together are given in Tables 2–4.
Table 1 Properties of aggregates. Material
Results
Specific gravity (g/cc)
Fine aggregate Rubber Natural coarse aggregate Quartz sandstone Fine aggregate Rubber Natural coarse aggregate Quartz sandstone Natural coarse aggregate Quartz sandstone Natural coarse aggregate Quartz sandstone
2.74 1.09 2.74 2.63 0.11 2.45 0.14 1.64 29.92 36.74 37.92 47.24
Aggregate impact value test (%) Los Angeles abrasion test (%)
The concrete samples having rubber and quartz sandstones were tested for sorptivity and permeability tests. The details of tests are as follows: 3.1. Water absorption test by sorptivity The Sorptivity test was done as per ASTM C 1585-04 [18]. The test method is used to determine the rate of absorption (Sorptivity) of water in hydraulic cement concrete by measuring the increase in the mass of a specimen resulting from absorption of water as a function of time when only one of the sample surfaces is exposed to water. The exposed surface of the specimen is immersed in water and water ingress of unsaturated concrete dominated by capillary suction during initial contact with water. The test was done on 28 days cured concrete cubes (which are oven dried at 65 ± 5 °C for 7 days) of 100 mm x100 mm x 100 mm. The side surface of each specimen is sealed with a suitable sealing material and the mass of the sealed specimen is noted. A support device is placed at the bottom of the pan and water is filled 1–3 mm above the top of the support apparatus (Fig. 1). The timing device is started immediately after the test surface of the specimen is placed on the top of the support device. The mass of specimen is noted at 1 min, 5 min, 10 min, 20 min, 30 min and 60 min and then every hour up to 6 h. The sorptivity values of concrete samples having various replacements of rubber and quartz sandstones are shown in Fig. 2. The water sorption of concrete samples with quartz sandstones and rubber increased as the replacement level increased. This increase in the rate of water absorption can be related to the use of rubber and sedimentary sandstone aggregate. A maximum sorptivity of 0.55 mm was observed for concrete samples having 100% quartz sandstone and 10% rubber aggregates. Thomas et al., (2014) [17] observed a maximum sorptivity of 0.7 mm at 20% replacement on utilising crumb rubber as fine aggregates in concrete. 3.2. Water permeability by DIN 1048
Technical Information
Water absorption (%)
3. Laboratory testing and results
To check the water permeability of concrete, water permeability test was performed. Three cubes of sizes 150 mm were oven dried. Before placing the cubes in the apparatus, weighing of the cube was done. The cubes were placed in such a manner that the direction of water pressure (0.5 N/mm2) was normal to the direction of concrete filled in the mould for three days (Fig. 4). After three days, the pressure was released and cubes were taken out from apparatus. The cubes were weighed again. After weighing, split down the centre of the cube, with the facing which was exposed to water pressure facing down. Measure the maximum
Table 2 Mix proportions of concrete with 0% quartz sandstone. Ingredients
Cement (kg/m3) Fine Aggregate(kg/m3) Water (kg/m3) Natural aggregate 10 mm (kg/m3) Natural aggregate 20 mm (kg/m3) Quartz Sandstone 10 mm (kg/m3) Quartz Sandstone 20 mm (kg/m3) Rubber (0.8–2 mm) (kg/m3) Rubber (2–4 mm) (kg/m3) Rubber powder (kg/m3)
Rubber replacement percentage 0%
2.5%
5%
7.5%
10%
340.13 732.89 136.05 287.27 351.11 255.35 383.03 0 0 0
340.13 703.86 136.05 287.27 351.11 255.35 383.03 6.31 4.51 7.21
340.13 675.38 136.05 287.27 351.11 255.35 383.03 12.44 8.88 14.21
340.13 647.45 136.05 287.27 351.11 255.35 383.03 18.37 13.12 20.99
340.13 620.07 136.05 287.27 351.11 255.35 383.03 24.11 17.25 27.55
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S. Kumar et al. / Construction and Building Materials 145 (2017) 311–317 Table 3 Mix proportions of concrete with 50% quartz sandstone. Ingredients
Rubber replacement percentage
Cement (kg/m3) Fine Aggregate(kg/m3) Water (kg/m3) Natural aggregate 10 mm (kg/m3) Natural aggregate 20 mm (kg/m3) Quartz Sandstone 10 mm (kg/m3) Quartz Sandstone 20 mm (kg/m3) Rubber (0.8–2 mm) (kg/m3) Rubber (2–4 mm) (kg/m3) Rubber powder (kg/m3)
0%
2.5%
5%
7.5%
10%
340.13 732.89 136.05 287.27 351.11 255.35 383.03 0 0 0
340.13 703.86 136.05 287.27 351.11 255.35 383.03 6.31 4.51 7.21
340.13 675.38 136.05 287.27 351.11 255.35 383.03 12.44 8.88 14.21
340.13 647.45 136.05 287.27 351.11 255.35 383.03 18.37 13.12 20.99
340.13 620.07 136.05 287.27 351.11 255.35 383.03 24.11 17.22 27.55
Table 4 Mix proportions of concrete with 100% quartz sandstone. Ingredients
Cement (kg/m3) Fine Aggregate(kg/m3) Water (kg/m3) Natural aggregate 10 mm (kg/m3) Natural aggregate 20 mm (kg/m3) Quartz Sandstone 10 mm (kg/m3) Quartz Sandstone 20 mm (kg/m3) Rubber (0.8–2 mm) (kg/m3) Rubber (2–4 mm) (kg/m3) Rubber powder (kg/m3)
Rubber replacement percentage 0%
2.5%
5%
7.5%
10%
340.13 732.89 136.05 0 0 500.24 750.37 0 0 0
340.13 703.86 136.05 0 0 500.24 750.37 6.3167 4.511 7.21
340.13 675.38 136.05 0 0 500.24 750.37 12.44 8.88 14.21
340.13 647.45 136.05 0 0 500.24 750.37 18.37 13.12 20.99
340.13 620.07 136.05 0 0 500.24 750.37 24.11 17.22 27.55
Fig. 1. Test setup for measuring sorptivity of concrete samples.
thickness of water penetration. The average of all the three maximum penetration depth was taken as the test result. The water permeability values increased as the substitution of rubber and quartz sandstones increased in cement concrete (Fig. 3). A maximum permeability of 73 mm was observed at 100% quartz sandstone replacement as coarse aggregate and 10% of rubber as fine aggregate in the same concrete mix. The increase in water permeability can be related to change is average water absorption of concrete samples having different aggregates mixed together. This could have led to a formation of interconnected
pores making characteristics.
the
concrete
less
durable
to
permeation
3.3. Comparative analysis of penetration characteristics The sorptivity results were further compared with the concrete samples made solely from quartz sandstone aggregates. The results showed a considerable increase in sorption rate among all the excess percentage of rubber addition in the concrete mix. A maximum increase of 36% sorption rate in was observed compared to
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S. Kumar et al. / Construction and Building Materials 145 (2017) 311–317
Fig. 2. Sorptivity values of concrete specimens quartz sandstone and rubber.
Fig. 3. Water permeability values of concrete specimens with 100% quartz sandstone.
concrete having 50% substitution level. However, the rate of sorption was found to be only 25% at 100% replacement level (Figs. 5 and 6). The increase in sorption rate at 50% replacement level may be due to using of two different coarse aggregates with different gradation. The interfacial zone showed some microvoids at the 50% replacement level than the 100% replacement level of quartz sandstones (Fig. 7). These microvoids might have increased the porosity in the aggregate-paste interface leading to increasing in
sorptivity of the concrete samples. This reason is also attributed to the increase in permeability of concrete samples containing rubber and quartz sandstones. 4. Discussions The following results were observed on utilising quartz sandstones and rubber in cement concrete;
S. Kumar et al. / Construction and Building Materials 145 (2017) 311–317
315
Fig. 4. Apparatus used for checking water permeability of concrete specimens.
Fig. 5. Graph showing percentage increase in sorption rate at 50% QS (QSC vs. QSRC).
By trial mixing, the dosage of quartz sandstone as the coarse aggregate was done at 0%, 50%, 100% and the crumb rubber as fine aggregates at 0%, 2.5%, 5%, 7.5% and 10%. In order to achieve a consistent workability, superplasticisers dosage were altered to produce a standard compaction factor. A maximum sorptivity of 0.55 mm was observed for concrete samples having 100% quartz sandstone and 10% rubber aggregates. A maximum permeability of 73 mm was found at 100% quartz sandstone replacement as coarse aggregate and 10% of rubber as fine aggregate in the same concrete mix. The SEM image showed some microvoids at the 50% replacement level than the 100% replacement level of quartz sandstones which lead to the increase in permeability of concrete specimens.
5. Conclusion Experiments were conducted to study the suitability of quartz sandstone and rubber in cement concrete as the replacement for conventional coarse aggregates. M30 grade of concrete is designed as per IS: 10262–2010, with water/cement ratio 0.40. The following conclusions may be drawn from this study. A maximum rate of increase in sorptivity and permeability was observed at 50% replacement levels of quartz sandstones as coarse aggregates in concrete. This may be due to the usage of two different coarse aggregates with different gradation or can be due to a rearrangement of the particles in time or to inhomogeneity.
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S. Kumar et al. / Construction and Building Materials 145 (2017) 311–317
Fig. 6. Graph showing percentage increase in sorption rate at 100% QS (QSC vs. QSRC).
Fig. 7. SEM image of the concrete sample with rubber and QS.
The substitution of fine aggregate (rubber) was found to have a lower impact on permeation rate than the substitution for coarse aggregate (quartz sandstone). The study on the use of quartz sandstones and crumb rubber in the same concrete mix establishes the importance of combined gradation to achieve a concrete output with good packing density. The penetration characteristics of 100% quartz sandstone substitution along with rubber showed a less index of micro voids than the 50% replacement level. Concrete having quartz sandstones as coarse aggregates and crumb rubber as fine aggregates are recommended to be used at 50% substitution level of quartz sandstone. The maximum rubber replacement in the same mix can be limited to 7.5% to maintain the increase in sorption rate below 15%.
References [1] Samar Raffoul, Reyes Garcia, Kypros Pilakoutas, Maurizio Guadagnini, Nelson flores medina, optimisation of rubberised concrete with high rubber content: an experimental investigation, Constr. Build. Mater. 124 (2016) 391–404. [2] Osama Youssf, Julie E. Mills, Reza Hassanli, Assessment of the mechanical performance of crumb rubber concrete, Constr. Build. Mater. 125 (2016) 175– 183. [3] R. Siddique, T.R. Naik, Properties of concrete containing scrap-tire rubber - an overview, Waste Manage. 24 (6) (2004) 563–569. [4] Zeno Ghizdaveț, Bianca-Maria Ștefan, Daniela Nastac, Ovidiu Vasile, Mihai Bratu, Sound absorbing materials made by embedding crumb rubber waste in a concrete matrix, Constr. Build. Mater. 124 (2016) 755–763. [5] Jing Lv, Tianhua Zhou, Du Qiang, et al., Effects of rubber particles on mechanical properties of lightweight aggregate concrete, Constr. Build. Mater. 91 (2015) 145–149. [6] A. Ali Aliabdo, Abd Elmoaty M. Abd Elmoaty, Utilization of waste rubber in non-structural applications, Constr. Build. Mater. 91 (2015) 195–207.
S. Kumar et al. / Construction and Building Materials 145 (2017) 311–317 [7] Trilok Gupta, Ravi K. Sharma, Sandeep Chaudhary, Impact strength of concrete containing waste rubber fiber and silica fume, Int. J. Impact Eng 83 (2015) 76– 87. [8] Liang He, Yu Ma, Quantao Liu, Yuanhua Mu, Surface modification of crumb rubber and its influence on the mechanical properties of rubber-cement concrete, Constr. Build. Mater. 120 (2016) 403–407. [9] Sanjeev Kumar, Ramesh Chandra Gupta, Sandeep Shrivastava, Strength, abrasion and permeability studies on cement concrete containing quartz sandstone coarse aggregates, Constr. Build. Mater. 125 (2016) 884–891. [10] Sanjeev Kumar, Ramesh Chandra Gupta, Sandeep Shrivastava, Lazlo Csetenyi, Blessen Skariah Thomas, Preliminary study on the use of quartz sandstone as a partial replacement of coarse aggregate in concrete based on clay content, morphology and compressive strength of combined gradation, Constr. Build. Mater. 107 (2016) 103–108. [11] M. Quattrone, B. Cazacliu, S.C. Angulo, E. Hamard, A. Cothenet, Measuring the water absorption of recycled aggregates, what is the best practice for concrete production?, Constr Build. Mater. 123 (2016) 690–703. [12] Danny Smyl, Farnam Ghasemzadeh, Mohammad Pour-Ghaz, Modeling water absorption in concrete and mortar with distributed damage, Constr. Build. Mater. 125 (2016) 438–449.
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[13] Xinxin Li, Xu Qing, Shenghong Chen, An experimental and numerical study on water permeability of concrete, Constr. Build. Mater. 105 (2016) 503–510. [14] F. López-Gayarre, R. Blanco Viñuela, M.A. Serrano-López, C. López-Colina, Influence of the water variation on the mechanical properties of concrete manufactured with recycled mixed aggregates for pre-stressed components, Constr. Build. Mater. 94 (2015) 844–850. [15] Gauhar Sabiha, Rafiqul A. Tarefderb, Syed M. Jamil, Optimization of gradation and fineness modulus of naturally fine sands for improved performance as fine aggregate in concrete, Procedia Eng. 145 (2016) 66–73. [16] IS: 383, Indian Standard Specification for Coarse and Fine Aggregates From Natural Sources for Concrete, Bureau of Indian Standards, New Delhi, India, 1970. [17] Blessen Skariah Thomas, Ramesh Chandra Gupta, Pawan Kalla, Laszlo Cseteneyi, Strength, abrasion and permeation characteristics of cement concrete containing discarded rubber fine aggregates, Constr. Build. Mater. 59 (2014) 204–212. [18] ASTM C 1585–04, Standard test method for measurement of rate of absorption of water by hydraulic cement concretes.
Contents lists available at ScienceDirect
Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat
Technical note
Technical note on sorption and permeability of concrete containing rubber and quartz sandstone aggregates Sanjeev Kumar ⇑, Ajay Kumar Sharma, Deepak Sherawat, Mohit Dutt , Ramesh Chandra Gupta Department of Civil Engineering, Malaviya National Institute of Technology, Jaipur, India
a r t i c l e
i n f o
Article history: Received 17 October 2016 Received in revised form 22 March 2017 Accepted 5 April 2017
Keywords: Quartz sandstone Rubber Water permeability Microstructure
a b s t r a c t The presence of waste is a warning of overconsumption of materials and are not being used to its full potential. There has been a consistent decrease in environmental potential to absorb these wastes and a useful resource of matter and energy are lost due to the disposal of such wastes. The main problem associated is the excess production of wastes such as rubber and stones which could be utilised efficiently in many other ways. One of the sustainable utilisation of these wastes is by using them in the production of cement concrete. M30 concrete grade (water-cement ratio of 0.4) is designed as per Indian specifications with discarded tyre rubber as a partial replacement of fine aggregate and quartz sandstone as a partial replacement for coarse aggregates. The water absorption properties of concrete containing crumb rubber, quartz sandstone and a mixture of both were studied. Three sandstone replacement levels (0%, 50% and 100%) are taken and five rubber replacement levels (0%, 2.5%, 5%, 7.5% and 10%) were considered for the study. Concrete having quartz sandstones as coarse aggregates and crumb rubber as fine aggregates are recommended to be used at 50% substitution level of quartz sandstone. The maximum rubber replacement in the same mix can be limited to 7.5% to maintain the increase in sorption rate below 15%. Ó 2017 Elsevier Ltd. All rights reserved.
1. Introduction The overall production of rubber tyres has increased to a greater extent and the automotive industry uses tyres which are highly durable and not easily recycled. The improper disposal of waste tyres is dangerous to the environment and human health [1]. Due to these environmental and health issues attributed from rubber waste, a broad area of research is focussed on the utilisation of them as a partial substitute for mineral aggregates. This considerable recycling of rubber wastes reduces the disposal problems and also lessens the use of natural mineral aggregates [2]. Rubber is a good absorber of shock and also possess moderate sound insulating properties. Although having its advantages, rubber, when utilised in concrete, shows a considerable decrease in mechanical strength with an increase in permeability [3,4]. The composition of cement paste being hydrophilic material and the rubber aggregates being a hydrophobic material makes it even more difficult for the resulting concrete to have an adhesive interlocking mecha-
Abbreviations: QS, quartz sandstone; QSC, quartz sandstone concrete; QSRC, quartz sandstone and rubber concrete; SEM, scanning electron microscope. ⇑ Corresponding author. E-mail address: [email protected] (S. Kumar). http://dx.doi.org/10.1016/j.conbuildmat.2017.04.022 0950-0618/Ó 2017 Elsevier Ltd. All rights reserved.
nism. Irrespective of reduced adhesion property, many researchers have found concrete with rubber aggregates showing better toughness and impact strength than concrete made with standard mineral aggregates [5–8]. On the other hand, sandstone being a consolidated sand is a well-known sedimentary type of rock. It is composed of rock fragments and silt-sized mineral grains which are held together by the cementing material. Kumar et al. (2016) observed an increase in water absorption of concrete as the quartz sandstone coarse aggregate was increased [9]. This phenomenon was observed due to the increase in microvoids between the interface of cement paste and foreign aggregate. The act of achieving consistent workability in concrete with sandstone aggregates is usually by increasing the dosage of super plasticisers [10]. The measurement of water absorption in concrete with different aggregates remains important for quantifying the interconnected pores. Also, the initial water absorption of an aggregate allows the casting person to determine the amount of excess water to be mixed before casting [11]. The rate of deterioration of concrete structures is directly related to moisture ingress. Also, the water permeability of concrete is a property that can alter the durability and serviceability of massive concrete structures [12,13]. The replacement and substitution of natural aggregates
312
S. Kumar et al. / Construction and Building Materials 145 (2017) 311–317
by alternate source has become a widespread research in the area of construction sustainability. Thence it becomes necessary to reduce the excessive use of depleting construction materials and find new ones which are less aggressive towards the environment [14]. In the event of mixing one or more aggregates to produce concrete, gradation plays a vital role in attaining a good packing density. Fineness modulus and gradation of an aggregate play a vital role in determining the overall performance of fresh and hardened concrete [15]. This paper compares the water absorption characteristics of concrete with rubber, quartz sandstones and a mixture of both. The substitution of quartz sandstone as coarse aggregates was done at three levels (0%, 50% and 100%) and crumb rubber for fine aggregates at five levels (0%, 2.5%, 5%, 7.5% and 10%).
2. Materials and properties Ordinary Portland cement (OPC) of grade 43 was used for the casting. River sand conforming to zone II obtained from local sources were used as fine aggregates. Coarse aggregates of sizes 20 mm and 10 mm were procured and tested for specific gravity, water absorption, impact value test, Los Angeles abrasion test and gradation using sieve analysis. By sieve analysis, the ratio of mixing coarse aggregates (20 mm: 10 mm) was fixed to 55:45 for natural coarse and 60:40 for quartz sandstone coarse aggregates [10]. Discarded tyre rubber of sizes 0.8–2 mm, 2–4 mm and rubber powder was used based on the results of gradation for zone II fine aggregate confirmed with IS: 383-1970 [16,17]. To maintain a consistent workability, superplasticisers were added as a percentage by weight of cement in the range 0.8% - 1.6%. The properties of aggregates used are given in Table 1.The details of mix proportions for concrete containing solely rubber and quartz sandstone aggregates are same as given in Thomas et al. [17] and Kumar et al. [10]. The mix proportions of concrete containing both rubber and quartz sandstones together are given in Tables 2–4.
Table 1 Properties of aggregates. Material
Results
Specific gravity (g/cc)
Fine aggregate Rubber Natural coarse aggregate Quartz sandstone Fine aggregate Rubber Natural coarse aggregate Quartz sandstone Natural coarse aggregate Quartz sandstone Natural coarse aggregate Quartz sandstone
2.74 1.09 2.74 2.63 0.11 2.45 0.14 1.64 29.92 36.74 37.92 47.24
Aggregate impact value test (%) Los Angeles abrasion test (%)
The concrete samples having rubber and quartz sandstones were tested for sorptivity and permeability tests. The details of tests are as follows: 3.1. Water absorption test by sorptivity The Sorptivity test was done as per ASTM C 1585-04 [18]. The test method is used to determine the rate of absorption (Sorptivity) of water in hydraulic cement concrete by measuring the increase in the mass of a specimen resulting from absorption of water as a function of time when only one of the sample surfaces is exposed to water. The exposed surface of the specimen is immersed in water and water ingress of unsaturated concrete dominated by capillary suction during initial contact with water. The test was done on 28 days cured concrete cubes (which are oven dried at 65 ± 5 °C for 7 days) of 100 mm x100 mm x 100 mm. The side surface of each specimen is sealed with a suitable sealing material and the mass of the sealed specimen is noted. A support device is placed at the bottom of the pan and water is filled 1–3 mm above the top of the support apparatus (Fig. 1). The timing device is started immediately after the test surface of the specimen is placed on the top of the support device. The mass of specimen is noted at 1 min, 5 min, 10 min, 20 min, 30 min and 60 min and then every hour up to 6 h. The sorptivity values of concrete samples having various replacements of rubber and quartz sandstones are shown in Fig. 2. The water sorption of concrete samples with quartz sandstones and rubber increased as the replacement level increased. This increase in the rate of water absorption can be related to the use of rubber and sedimentary sandstone aggregate. A maximum sorptivity of 0.55 mm was observed for concrete samples having 100% quartz sandstone and 10% rubber aggregates. Thomas et al., (2014) [17] observed a maximum sorptivity of 0.7 mm at 20% replacement on utilising crumb rubber as fine aggregates in concrete. 3.2. Water permeability by DIN 1048
Technical Information
Water absorption (%)
3. Laboratory testing and results
To check the water permeability of concrete, water permeability test was performed. Three cubes of sizes 150 mm were oven dried. Before placing the cubes in the apparatus, weighing of the cube was done. The cubes were placed in such a manner that the direction of water pressure (0.5 N/mm2) was normal to the direction of concrete filled in the mould for three days (Fig. 4). After three days, the pressure was released and cubes were taken out from apparatus. The cubes were weighed again. After weighing, split down the centre of the cube, with the facing which was exposed to water pressure facing down. Measure the maximum
Table 2 Mix proportions of concrete with 0% quartz sandstone. Ingredients
Cement (kg/m3) Fine Aggregate(kg/m3) Water (kg/m3) Natural aggregate 10 mm (kg/m3) Natural aggregate 20 mm (kg/m3) Quartz Sandstone 10 mm (kg/m3) Quartz Sandstone 20 mm (kg/m3) Rubber (0.8–2 mm) (kg/m3) Rubber (2–4 mm) (kg/m3) Rubber powder (kg/m3)
Rubber replacement percentage 0%
2.5%
5%
7.5%
10%
340.13 732.89 136.05 287.27 351.11 255.35 383.03 0 0 0
340.13 703.86 136.05 287.27 351.11 255.35 383.03 6.31 4.51 7.21
340.13 675.38 136.05 287.27 351.11 255.35 383.03 12.44 8.88 14.21
340.13 647.45 136.05 287.27 351.11 255.35 383.03 18.37 13.12 20.99
340.13 620.07 136.05 287.27 351.11 255.35 383.03 24.11 17.25 27.55
313
S. Kumar et al. / Construction and Building Materials 145 (2017) 311–317 Table 3 Mix proportions of concrete with 50% quartz sandstone. Ingredients
Rubber replacement percentage
Cement (kg/m3) Fine Aggregate(kg/m3) Water (kg/m3) Natural aggregate 10 mm (kg/m3) Natural aggregate 20 mm (kg/m3) Quartz Sandstone 10 mm (kg/m3) Quartz Sandstone 20 mm (kg/m3) Rubber (0.8–2 mm) (kg/m3) Rubber (2–4 mm) (kg/m3) Rubber powder (kg/m3)
0%
2.5%
5%
7.5%
10%
340.13 732.89 136.05 287.27 351.11 255.35 383.03 0 0 0
340.13 703.86 136.05 287.27 351.11 255.35 383.03 6.31 4.51 7.21
340.13 675.38 136.05 287.27 351.11 255.35 383.03 12.44 8.88 14.21
340.13 647.45 136.05 287.27 351.11 255.35 383.03 18.37 13.12 20.99
340.13 620.07 136.05 287.27 351.11 255.35 383.03 24.11 17.22 27.55
Table 4 Mix proportions of concrete with 100% quartz sandstone. Ingredients
Cement (kg/m3) Fine Aggregate(kg/m3) Water (kg/m3) Natural aggregate 10 mm (kg/m3) Natural aggregate 20 mm (kg/m3) Quartz Sandstone 10 mm (kg/m3) Quartz Sandstone 20 mm (kg/m3) Rubber (0.8–2 mm) (kg/m3) Rubber (2–4 mm) (kg/m3) Rubber powder (kg/m3)
Rubber replacement percentage 0%
2.5%
5%
7.5%
10%
340.13 732.89 136.05 0 0 500.24 750.37 0 0 0
340.13 703.86 136.05 0 0 500.24 750.37 6.3167 4.511 7.21
340.13 675.38 136.05 0 0 500.24 750.37 12.44 8.88 14.21
340.13 647.45 136.05 0 0 500.24 750.37 18.37 13.12 20.99
340.13 620.07 136.05 0 0 500.24 750.37 24.11 17.22 27.55
Fig. 1. Test setup for measuring sorptivity of concrete samples.
thickness of water penetration. The average of all the three maximum penetration depth was taken as the test result. The water permeability values increased as the substitution of rubber and quartz sandstones increased in cement concrete (Fig. 3). A maximum permeability of 73 mm was observed at 100% quartz sandstone replacement as coarse aggregate and 10% of rubber as fine aggregate in the same concrete mix. The increase in water permeability can be related to change is average water absorption of concrete samples having different aggregates mixed together. This could have led to a formation of interconnected
pores making characteristics.
the
concrete
less
durable
to
permeation
3.3. Comparative analysis of penetration characteristics The sorptivity results were further compared with the concrete samples made solely from quartz sandstone aggregates. The results showed a considerable increase in sorption rate among all the excess percentage of rubber addition in the concrete mix. A maximum increase of 36% sorption rate in was observed compared to
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Fig. 2. Sorptivity values of concrete specimens quartz sandstone and rubber.
Fig. 3. Water permeability values of concrete specimens with 100% quartz sandstone.
concrete having 50% substitution level. However, the rate of sorption was found to be only 25% at 100% replacement level (Figs. 5 and 6). The increase in sorption rate at 50% replacement level may be due to using of two different coarse aggregates with different gradation. The interfacial zone showed some microvoids at the 50% replacement level than the 100% replacement level of quartz sandstones (Fig. 7). These microvoids might have increased the porosity in the aggregate-paste interface leading to increasing in
sorptivity of the concrete samples. This reason is also attributed to the increase in permeability of concrete samples containing rubber and quartz sandstones. 4. Discussions The following results were observed on utilising quartz sandstones and rubber in cement concrete;
S. Kumar et al. / Construction and Building Materials 145 (2017) 311–317
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Fig. 4. Apparatus used for checking water permeability of concrete specimens.
Fig. 5. Graph showing percentage increase in sorption rate at 50% QS (QSC vs. QSRC).
By trial mixing, the dosage of quartz sandstone as the coarse aggregate was done at 0%, 50%, 100% and the crumb rubber as fine aggregates at 0%, 2.5%, 5%, 7.5% and 10%. In order to achieve a consistent workability, superplasticisers dosage were altered to produce a standard compaction factor. A maximum sorptivity of 0.55 mm was observed for concrete samples having 100% quartz sandstone and 10% rubber aggregates. A maximum permeability of 73 mm was found at 100% quartz sandstone replacement as coarse aggregate and 10% of rubber as fine aggregate in the same concrete mix. The SEM image showed some microvoids at the 50% replacement level than the 100% replacement level of quartz sandstones which lead to the increase in permeability of concrete specimens.
5. Conclusion Experiments were conducted to study the suitability of quartz sandstone and rubber in cement concrete as the replacement for conventional coarse aggregates. M30 grade of concrete is designed as per IS: 10262–2010, with water/cement ratio 0.40. The following conclusions may be drawn from this study. A maximum rate of increase in sorptivity and permeability was observed at 50% replacement levels of quartz sandstones as coarse aggregates in concrete. This may be due to the usage of two different coarse aggregates with different gradation or can be due to a rearrangement of the particles in time or to inhomogeneity.
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Fig. 6. Graph showing percentage increase in sorption rate at 100% QS (QSC vs. QSRC).
Fig. 7. SEM image of the concrete sample with rubber and QS.
The substitution of fine aggregate (rubber) was found to have a lower impact on permeation rate than the substitution for coarse aggregate (quartz sandstone). The study on the use of quartz sandstones and crumb rubber in the same concrete mix establishes the importance of combined gradation to achieve a concrete output with good packing density. The penetration characteristics of 100% quartz sandstone substitution along with rubber showed a less index of micro voids than the 50% replacement level. Concrete having quartz sandstones as coarse aggregates and crumb rubber as fine aggregates are recommended to be used at 50% substitution level of quartz sandstone. The maximum rubber replacement in the same mix can be limited to 7.5% to maintain the increase in sorption rate below 15%.
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