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1
Tenório, J. J. L., P. C. C. Gomes, C. C. Rodrigues, and T. F. F. de Alencar. "Concrete produced with recycled aggregates." Revista IBRACON de Estruturas e Materiais 5, no. 5 (October 2012): 692–701. http://dx.doi.org/10.1590/s1983-41952012000500006.
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This paper presents the analysis of the mechanical and durable properties of recycled aggregate concrete (RAC) for using in concrete. The porosity of recycled coarse aggregates is known to influence the fresh and hardened concrete properties and these properties are related to the specific mass of the recycled coarse aggregates, which directly influences the mechanical properties of the concrete. The recycled aggregates were obtained from construction and demolition wastes (CDW), which were divided into recycled sand (fine) and coarse aggregates. Besides this, a recycled coarse aggregate of a specific mass with a greater density was obtained by mixing the recycled aggregates of the CDW with the recycled aggregates of concrete wastes (CW). The concrete was produced in laboratory by combining three water-cement ratios, the ratios were used in agreement with NBR 6118 for structural concretes, with each recycled coarse aggregates and recycled sand or river sand, and the reference concrete was produced with natural aggregates. It was observed that recycled aggregates can be used in concrete with properties for structural concrete. In general, the use of recycled coarse aggregate in combination with recycled sand did not provide good results; but when the less porous was used, or the recycled coarse aggregate of a specific mass with a greater density, the properties of the concrete showed better results. Some RAC reached bigger strengths than the reference concrete.
2
Boudina, Tounsia, Dalila Benamara, and Rebih Zaitri. "Optimization of High-Performance-Concrete properties containing fine recycled aggregates using mixture design modeling." Frattura ed Integrità Strutturale 15, no. 57 (June 22, 2021): 50–62. http://dx.doi.org/10.3221/igf-esis.57.05.
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This investigation means to predict and modeling the fresh and hardened concrete behavior containing fine aggregates from concrete and brick wastes, for different recycled aggregates substitution rates. To succeed this, the design of experiments DOE method was used. It is observed that slump of recycled concrete is significantly influenced by the content in recycled concrete aggregates (RCA), natural sand (NS) and recycled brick aggregates (RBA), respectively.The compressive strength (CS) reaches a maximum value of 83.48 MPa with factors values of 25% RBA, and 75% RCA. And HPC’s based on RBA sand presented greater values of flexural strength at 7 days than HPC’s based on RCA sand, it was revealed that this is due to the RBA fines pozzolanic reaction and the production of new CSHs, which leads to better cement matrix densification.Under optimal conditions, themaximum desirability is 0.65, who has given HPC no added natural sand, by mixing recycled sands RBA (9.5%) with RCA (90.5%).The statistical terms result show that the expected models are very well correlated with the experimental data and have shown good accuracy.
3
Soultana, Athanasia, Michael Galetakis, Anthoula Vasiliou, Konstantinos Komnitsas, and Despina Vamvuka. "Utilization of Upgraded Recycled Concrete Aggregates and Recycled Concrete Fines in Cement Mortars." Recent Progress in Materials 03, no. 03 (February 11, 2021): 1. http://dx.doi.org/10.21926/rpm.2103035.
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Waste concrete is the most predominant constituent material among construction and demolition waste. Current waste concrete recycling is limited to the use of recycled concrete aggregates as a road-base material and less as aggregates in new concrete mixes. Further, the production of recycled concrete aggregates results in the generation of a high amount of fines, consisting mainly of cement paste particles. Hence, this study aims to produce the cement mortars using the upgraded recycled concrete aggregates (sand granulometry) for the total replacement of natural aggregates and recycled concrete fines activated through a thermal treatment method as a partial cement substitution material. Cement mortar specimens were tested for their compressive and flexural strength, density and water absorption performance. The results showed that the combined usage of upgraded recycled concrete sand for total replacement of primary crushed sand and recycled concrete fines as partial cement replacement material is a promising option to produce cement mortars.
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Zhao, Ya Jun, Ying Gao, and Li Li He. "Effect of Admixed Recycled Aggregate on Properties of Recycled Concrete." Applied Mechanics and Materials 174-177 (May 2012): 743–46. http://dx.doi.org/10.4028/www.scientific.net/amm.174-177.743.
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The mixture proportion of recycled concrete was discussed by orthogonal design method. The influence of water-cement ratio, recycled aggregate quantity on workability, cube compressive strength of recycled concrete was analyzed. The experimental results indicated that，Recycled concrete mix proportion design should consider the impact of the water absorption of recycled aggregate. Unit water amount of recycled concrete should be plain concrete unit water consumption and recycled aggregate additional amount of water. Sand ratio should increase in the corresponding ordinary aggregate concrete sand ratio on the basis of 1 to 3 percent. When the water-cement ratio is 0.36 and construction waste content of 40% slag content of 20%, 28d compressive strength of concrete is 48.1MPa, slightly higher than the reference concrete (48.0MPa).
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Hamid, Roszilah, and M. A. Zubir. "The Flexural Properties of Reinforced Recycled Glass Concrete Beam." Materials Science Forum 803 (August 2014): 325–29. http://dx.doi.org/10.4028/www.scientific.net/msf.803.325.
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In this study, recycled glass is used to replace the natural fine aggregate in different mix proportions. The control samples are Grade 30 ordinary Portland cement concrete (OPCC) containing 100% natural sand and coarse aggregate. The recycled glass concretes contain 70% natural fine aggregate + 30% size 300 micron crushed glass (Sample 2), and 70% fine aggregate + 15% size 300 micron crushed glass + 15% size greater than 300 micron crushed glass (Sample 3).The recorded strength of the control, Sample 2 and 3 at 90 days are 47, 61 and 55 MPa. Although the compressive strength for the concrete samples with recycled glass are higher than the control samples, the flexural test results show that, concrete with recycled glass has less ability to be fully functioning as a reinforced concrete by exhibiting their flexural strength at 91 % and 84% of the theoretical flexural strength whereas for the control specimen, its flexural strength is 10% higher than the theoretical value. Nonetheless, the toughness index of recycled glass concrete with 30% replacement of fine sand with recycled glass powder is at par with the control samples, which shows the ductile behavior of the recycled glass concrete.
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Lin, Yuezhong, Xingxing Zhang, and Yachao Wang. "Research on the performance of recycled concrete powder self-leveling mortar based on orthogonal experiment." E3S Web of Conferences 198 (2020): 01011. http://dx.doi.org/10.1051/e3sconf/202019801011.
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Waste concrete in the construction waste is reprocessed into concrete sand and powder [1]. Recycled concrete sand with a particle size between 0.15 and 0.25mm partially replaces natural sand, and the recycled concrete powder with a particle size less than 0.075mm partially replaces cement. The five-factor four-level orthogonal experiment was used to study the replacement amount of recycled concrete powder, the replacement amount of recycled concrete sand, the amount of dispersible latex powder, the amount of polycarboxylate water-reducing agent, the ratio of bone cement, and the five factors on the fluidity of self-leveling mortar. The influence of the three performance indicators of bond tensile strength and dimensional change rate; through the range analysis of the above indicators. The analysis results show that the content of recycled concrete powder instead of cement has the greatest impact on the tensile bond strength and dimensional change rate of recycled concrete powder self-leveling mortar, and the content of Polycarboxylate Superplasticizer has the greatest influence on the fluidity.
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Nedeljković, Marija, Jeanette Visser, Siska Valcke, and Erik Schlangen. "Physical Characterization of Dutch Fine Recycled Concrete Aggregates: A Comparative Study." Proceedings 34, no. 1 (November 18, 2019): 7. http://dx.doi.org/10.3390/proceedings2019034007.
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In the Netherlands, yearly 20 Mt Construction- and Demolition waste (CDW) is being produced mainly consisting of concrete and masonry rubble. This is two third of the yearly production of concrete (33 Mt). Currently, less than 1 Mt/year of the 20 Mt/year CDW is recycled in new concrete (mainly as coarse recycled concrete aggregates). This preliminary study being part of a larger study, is aiming to increase that amount, amongst others by focusing on use of the fine recycled concrete aggregates. Fine recycled concrete aggregates (fRCA) appear promising for (partial) replacement of natural fine aggregates (sand) and cement in new concrete. Nevertheless, they can be expected to have adverse properties and components that may reduce the performance of the concrete. Their physical, chemical and mechanical properties, which thus may significantly differ from that of natural sand, are still far from being fully investigated. The present paper focusses on characterization of physical properties of fRCA for finding the most critical indicators for fRCA quality. The tests include particle size distribution, morphology, BET surface area, solid density and water absorption of individual and total fractions (0–0.25 mm, 0.25–4 mm and 0–4 mm). The tests are performed on three fRCAs with different origin. Natural river sand with 96 wt.% of SiO2 was also studied to provide a baseline for comparison. Experimental results showed that, on the one side, the particle size distribution, surface area and amounts of individual fractions of fRCAs are significantly different from that of natural sand and that there is a large difference between each other. This is caused by variations of the parent concrete properties and by the type of recycling technique and processes (one step or multiple steps crushing). On the other side, fRCAs have comparative solid densities, which were still lower than that of natural sand. It was also shown that difference in water absorption between fractions 0.25–4 mm and 0–4 mm is very small in all three fRCAs groups. The results of this study will be used for future correlations between investigated properties of fRCAs with properties of concretes with fRCAs. This will be investigated in the next stage of the project, such that these correlations can enable production of durable concretes with fRCAs and assist recyclers in optimization of their production processes based on quality control of fRCAs.
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Miyazaki, Yuji, Takeshi Watanabe, Yuji Yamada, and Chikanori Hashimoto. "Properties of Concrete Using Treated Low-Class Recycled Coarse Aggregate and Blast Furnace Slag Sand." Materials 13, no. 4 (February 13, 2020): 843. http://dx.doi.org/10.3390/ma13040843.
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Since high quality natural aggregates are becoming scarce, it is important that industrial recycled products and by-products are used as aggregates for concrete. In Japan, the use of recycled aggregate (RG) is encouraged. Since, strength and durability of recycled aggregate concrete is lower than that of normal aggregate concrete, the use of recycled aggregate has not been significant. In order to improve physical properties of concrete using recycled coarse aggregate, blast furnace slag sand has been proposed. Recently, blast furnace slag sand is expected to improve durability, freezing, and thawing damage of concrete in Japan. Properties of fresh and hardened concrete bleeding, compressive strength, and resistance to freezing and thawing which are caused by the rapid freezing and thawing test using liquid nitrogen is a high loader than the JIS A 1148 A method that were investigated. As a result, concrete using treated low-class recycled coarse aggregate and 50% or 30% replacement of crushed sand with blast furnace slag sand showed the best results, in terms of bleeding, resistance to freezing and thawing.
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Zhang, Yancong, Lingling Gao, and Wei Bian. "Mechanical Performance of Concrete Made with Recycled Aggregates from Concrete Pavements." Advances in Materials Science and Engineering 2020 (September 15, 2020): 1–8. http://dx.doi.org/10.1155/2020/5035763.
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This research aims at analysing the mechanical performance of concrete with recycled aggregates from concrete pavements. First, the characteristics of various natural and recycled aggregates used in the concrete were thoroughly analysed. The composition of the recycled aggregates was determined and several physical and chemical tests of the aggregates were performed. In order to evaluate the mechanical performance of recycled concrete, cube compressive strength and flexural tensile strength tests were performed. The effect of recycled aggregates on the strength of recycled concrete is related to the strength of recycled aggregates, the strength of natural aggregates, and the strength of old concrete. The strength of recycled concrete decreases with increasing water-cement ratio. However, due to the water absorption of the recycled aggregate, it has a certain inhibitory effect on the strength reduction. As the replacement rate of recycled aggregates increases, the optimal sand ratio decreases. The sand ratio is controlled between 32% and 38%, which is ideal for recycled concrete. With the increase of fly ash content, the 7 d strength of recycled concrete has decreased to some extent, but the 28 d strength has been slightly improved. In addition, for compressive strength and flexural tensile strength, the optimal content of fly ash is different.
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Wongkvanklom, Athika, Patcharapol Posi, Sahalaph Homwuttiwong, Vanchai Sata, Ampol Wongsa, Duangkanok Tanangteerapong, and Prinya Chindaprasirt. "Lightweight Geopolymer Concrete Containing Recycled Plastic Beads." Key Engineering Materials 801 (May 2019): 377–84. http://dx.doi.org/10.4028/www.scientific.net/kem.801.377.
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Utilizing recycled plastic beads (RPB) as lightweight waste aggregates in the concrete and geopolymer application is quite attractive. This study presented the mechanical behavior, density, porosity, water absorption, abrasion resistance, thermal conductivity, and ultrasonic pulse velocity (UPV) of geopolymer lightweight concrete containing RPB. River sand in each mixture was replaced by various proportions of RPB ranging between 0-100% by weight. Sodium hydroxide concentration of 15 M, activator solution to fly ash ratio (L/A) of 0.40, sodium silicate and sodium hydroxide ratio of 1.0, and aggregate to fly ash ratio of 1.0 were used throughout the experiment. The results indicated that the replacement of sand by 25% and 50% of RPB had a positive impact on the weight, density, water absorption, and thermal insulating property. The strength and density of the concretes met the minimum requirements of structural lightweight concrete according to ASTM C330.
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Cheng, Yong San, Ke Qiang Yu, and Shuang Xi Wang. "Research on Mixture Ratio of Recycled Concrete Aggregate in Concrete." Applied Mechanics and Materials 193-194 (August 2012): 1371–75. http://dx.doi.org/10.4028/www.scientific.net/amm.193-194.1371.
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In order to better understand the recycled concrete aggregate, it is essential to investigate the different mixture ratio in it. For determining the better mixture ratio of recycled concrete aggregate, the experimental investigation was conducted by making use of recycled concrete aggregate of different ratio instead of small stones in concrete, while maintaining the proportion of other raw materials of concrete unchanged. Its mechanical properties were also investigated. It is found that the better materials proportion of recycled concrete is that sand: recycled aggregate: water= 1: 1.8 : 2.1: 0.55.
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Zhang, Xue Bing, and Zhi Fang. "Effect of some Key Factors on the Strength of Recycled Concrete." Advanced Materials Research 503-504 (April 2012): 576–81. http://dx.doi.org/10.4028/www.scientific.net/amr.503-504.576.
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Because there exists a used cement mortar layer outside the recycled aggregate, there are more interfaces inside recycled concrete, which would result in recycled concrete has different properties from ordinary concrete. In this paper, the effect of such key factors for recycled concrete mix ratio as water-cement ratio, cement strength, sand rate, maximum granule diameter and gradation on the properties of concrete with recycled coarse aggregate was studied by experiment, and the some useful suggestion for mix ratio of recycled concrete was provided.
13
Lan, Wen Wu, Rong Fu Zhong, Bo Lv, Jing Yan Gan, and Jing Wei Ying. "Compressive Strength of Artificial Sand Recycled Concrete with Different Content of Stone Powder." Applied Mechanics and Materials 578-579 (July 2014): 464–68. http://dx.doi.org/10.4028/www.scientific.net/amm.578-579.464.
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This study examined the compressive behaviors of concrete with artificial sand that mixed with different content of stone powder (SP). Forty-five cubic specimens were prepared with two strength grades and five SP-content. Including 15 specimens (C35) of recycled coarse aggregate (RA) concrete with artificial sand (RCC35), 15 specimens (C45) of recycled coarse aggregate concrete with artificial sand (RCC45) and 15 specimens (C35) of natural aggregate concrete with artificial sand (NC35). The workability of concrete mixture and the compressive strength of the cubic specimens were tested. The results showed that the slump of concrete mixture decreased with the SP-content increased, and the coagulability and water retentivity of the concrete mixture were improved by using stone powder. The compressive strength of the concrete with artificial sand were increased by incorporating stone powder. The optimal SP-content of RCC35 and NC35 is 20%, while RCC45 is 10%.
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Iduwin, Tommy, Dicki Dian Purnama, Pratiwi Septyaning Putri, and Hastanto Siswo Martono. "Pengaruh Penggunaan Material Daur Ulang Terhadap Sifat Mekanik Beton Non Pasir." FORUM MEKANIKA 9, no. 1 (May 31, 2020): 11–19. http://dx.doi.org/10.33322/forummekanika.v9i1.1080.
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Infrastructure development is increasing every year making the need for concrete materials increases. Using alternative materials can reduce the scarcity of material and environmental damage caused by taking and dredging the material. This research is to find out how much influence the recycled material has on the compressive strength of no fines concrete. The variations used are recycled materials of 0%, 25%, 50%, 75% and 100%. Mechanical testing conducted is a compressive strength test to determine the compressive strength of no fines concrete at the age of 7, 14 and 28 days. The ratio of cement and aggregate used is 1: 4 with FAS 0.5. This research uses 15 x 30 cm cylindrical molds with 45 test specimens. The test results show the highest compressive strength value of non-sand concrete occurs at 0% recycled material by 10.47 Mpa and the lowest compressive strength on non-sand concrete 100% recycled material is 8.39 Mpa. The percentage of absorption of no fines concrete shows that the more recycled material is used, the smaller the value of water absorption. The highest absorption value in no fines concrete is 0% recycled material, which is 5.93% and the smallest value is in the variation of no fines concrete 100% recycled material recycled material that is equal to 4.99%.
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Šefflová, Magdaléna, and Tereza Pavlů. "The Durability of Fine Recycled Aggregate Concrete." Advanced Materials Research 1144 (March 2017): 59–64. http://dx.doi.org/10.4028/www.scientific.net/amr.1144.59.
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This paper is focused on the durability of recycled aggregate (FRA) concrete. The durability of FRA concrete is connected with many uncertainties and doubts. This paper presents results of long-term of compressive strength, freeze – thaw resistance and carbonation depth of FRA concrete. The FRA was originated from crushed old concrete structures. There were prepared a total four concrete mixture. The first mixture was reference with natural sand. In other concrete mixtures, natural sand was replaced by the FRA in various replacement ratios, specifically 10 %, 20 % and 30 %. All prepared concrete mixtures were designated with the same parameters for clear comparison. It is possible to say that according to the durability, the FRA concrete is possible to used in the same applications as conventional concrete. However it is necessary to verify this results.
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Yan, Han Dong, and Guo Hui Huang. "Study on Pervious Road Brick Prepared by Recycled Aggregate Concrete." Key Engineering Materials 302-303 (January 2006): 321–28. http://dx.doi.org/10.4028/www.scientific.net/kem.302-303.321.
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The influence of aggregate to cement ratio(A/C), sand to aggregate ratio(S/A) and water to cement ratio(W/C) on mechanical properties and pervious coefficient of pervious concrete prepared by recycled aggregate were systematically investigated in the paper. The optimum mix proportion by weight of pervious concrete prepared by recycled aggregate were 3.5 of aggregate to cement ratio, 0.15 of sand to aggregate ratio and 0.34 of water to cement ratio, resulted from an effect coefficient method. Flexural strength and compressive strength of pervious concrete road brick prepared by recycled aggregate concrete could satisfy the requirements of Chinese Standard for Concrete Road Brick (JC/T466-2000) and had good pervious performance.
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Chundupalle, Sashidhar, Nirmala Seeri, Sudarsana Reddy Veera, and Venkata Ramana Nelluri. "Strength and durability characteristics of self compacting concrete (SCC) with recycled aggregate and manufactured sand." Acta Polytechnica CTU Proceedings 33 (March 3, 2022): 92–97. http://dx.doi.org/10.14311/app.2022.33.0092.
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The investigations on self compacting concrete (SCC) with recycled coarse aggregate and Manufactured sand (M-Sand) were performed in this current study. The SCC mixtures were produced with the recycled coarse aggregate of proportions of 0 to 100% with step increment of 25% with a ratio of water binder at 0.36. In addition, the mixtures were also prepared by mixing it with M-Sand. The feasibility of utilizing the recycled coarse aggregate in SCC was evaluated through strength an durability studies. The obtained results demonstrated that the SCC produced from these materials can be effectively recommended for their usages in concrete industries.
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Nigussie, Lucy Feleke, Muge Mukaddes Darwish, and Tewodros Ghebrab. "Comparative Investigation of the Effect of Recycled Fine Aggregate from New and Old Construction Wastes in C-25 Concrete in Ethiopia." Sustainability 11, no. 24 (December 12, 2019): 7116. http://dx.doi.org/10.3390/su11247116.
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Wherever there are construction activities, there is waste generation. In Ethiopia, the popular material for wall construction is a hollow concrete block that can be broken on the production site or the construction site during loading and unloading and is also found abundantly in demolished buildings. This research aimed at searching for alternative construction materials through recycling and examined the properties of recycled fine aggregate from demolished (old) and construction (new) hollow concrete block (HCB) wastes. The study examined the effect of the recycled HCB on fresh and hardened C-25 concrete properties and the possible replacement percentage of river sand by those recycled fine aggregates. The research also examined the comparative properties of the two recycled fine aggregates. The replacement percentage was in steps of 25%, starting from 25% up to 100%, and 0% represented the reference mix. In general, the recycled fine aggregate exhibited relatively lower physical properties than natural river sand but satisfied the American Society for Testing and Materials (ASTM) standard requirements. The demolished recycled fine aggregate (DRFA) had slightly lower physical properties than the construction recycled fine aggregate (CRFA). The properties of fresh and hardened concrete were decreased as percentage replacement of DRFA and CRFA increased. The optimum percentage replacement of river sand by recycled fine aggregate was between 50% to 75% but was much closer to 75% for that of recycled from construction (new) and closer to 50% for that of recycled from demolished (old) HCB. Recycling wastes can reduce environmental impact due to sand mining and waste disposal as well as partially conserve the natural resource depletion.
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Abbas, Syed Nasir, Muhammad Irshad Qureshi, Malik Muneeb Abid, Muhammad Atiq Ur Rehman Tariq, and Anne Wai Man Ng. "An Investigation of Mechanical Properties of Concrete by Applying Sand Coating on Recycled High-Density Polyethylene (HDPE) and Electronic-Wastes (E-Wastes) Used as a Partial Replacement of Natural Coarse Aggregates." Sustainability 14, no. 7 (March 30, 2022): 4087. http://dx.doi.org/10.3390/su14074087.
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Plastic wastes are a major hazard for the environment and their use in the construction industry is increasing day by day. The major drawback of the use of plastic in concrete is an exceptional reduction in strength and workability. This research work explores the effect of sand coating on two types of recycled plastic aggregates, high-density polyethylene (HDPE) and electronic-wastes (E-wastes), as partial replacement of natural aggregates. The replacement ranged from 0% to 30% along with the use of super plasticizer SP-675 and wet lock sealant. Both recycled plastic aggregates are crushed, melted, and ground to convert them into aggregates of 20 mm size. The workability of concrete containing uncoated recycled plastic aggregates (HDPE and electronic wastes), SP-675, and wet lock sealant has been found to be higher than controlled concrete samples with 0% recycled aggregates. Compressive strength, split tensile strength, and flexural strength of such type of concrete is lower than the controlled concrete samples due to the weak bond between the plastic aggregates and Ordinary Portland Cement. After applying the sand coating to improve bonding, the workability is reduced compared to uncoated samples whereas the compressive strength, split tensile strength and flexural strength of the sand coated plastic aggregate concrete is higher than uncoated plastic aggregate concrete. There is a significant increase in workability of concrete after the addition of SP-675 when added as 2% by weight of cement. The wet lock sealant positively affects the strength properties of concrete. It is recommended that the durability of concrete containing uncoated and sand coated recycled plastic aggregates be further explored in future studies.
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Pan, Li Yun, Wen Jing Shao, Guang Xin Li, and Hai Feng Li. "Experimental Study on Flexural Resistance of Reinforced Recycled-Concrete Beams." Applied Mechanics and Materials 438-439 (October 2013): 789–93. http://dx.doi.org/10.4028/www.scientific.net/amm.438-439.789.
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Seven reinforced recycled-concrete beams were tested to study their flexural resistance considering the variations of the strength of recycled-concrete and the reinforcement ratio of longitudinal tensile rebar. The aggregates of recycled-concrete comprised the machine-made sand and the recycled coarse aggregate. The failure state of normal section and the flexural resistance of reinforced recycled-concrete beams affected by the strength of recycled-concrete and the reinforcement ratio were discussed. The results show that the failure states of reinforced recycled-concrete beams were similar with those of the ordinary reinforced concrete beams. The flexural resistance was controlled by the reinforcement ratio, and influenced increasingly by the strength of recycled-concrete with the increase of reinforcement ratio. The failure resistance of reinforced recycled-concrete beam can be calculated by the method for ordinary reinforced concrete beam specified in current design code GB50010-2010.
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Zha, Xiao Xiong, and Jian Wei Zhong. "The Research of Reliability on Recycled Concrete." Applied Mechanics and Materials 71-78 (July 2011): 5046–49. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.5046.
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With the rapid development of urban construction, the waste that construction brings is also increasing. The recycled concrete technology can solve the problems of waste concrete, but also save the natural sand. This paper gives the progress on the research about the reliability of recycled concrete. Because of the rough surface of the recycled concrete aggregates and large porosity, the apparent density, strength and durability of the recycled concrete are different from the ordinary concrete on many aspects. So the study of the reliability about the recycled concrete is very necessary. The page will research on the material subentry coefficient of fifty and sixty years.
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Zhang, Kaijian, Jianzhuang Xiao, Yiqing Hou, and Qingtian Zhang. "Experimental study on carbonation behavior of seawater sea sand recycled aggregate concrete." Advances in Structural Engineering 25, no. 5 (February 17, 2022): 927–38. http://dx.doi.org/10.1177/13694332211026221.
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The carbonation behavior of seawater sea sand recycled aggregate concrete (SSRAC) was investigated in this study. Considering different added water, fine aggregates, and coarse aggregates, the specimens were divided into 12 groups for the accelerated carbonation test by 7 days, 14 days, and 28 days. Among them, river sand, sea sand, and mixed sand (the proportion of sea sand and shell sand was 4:1) were used as fine aggregates. The results show that the carbonation depths of concretes with different mixtures all increase over time. When the replacement ratio of recycled coarse aggregate (RCA) is not less than 50%, sea sand is the most suitable fine aggregate to acquire best carbonation resistance, while river sand is the worst. On the contrary, when the replacement ratio of RCA is not more than 30%, river sand is the most suitable fine aggregate, while sea sand is the worst. It can also be speculated that the most appropriate replacement ratio of RCA is 50% when sea sand is applied as fine aggregates in SSRAC. At the same time, 30% replacement ratio of RCA is appropriate when mixed sand is applied as fine aggregates in SSRAC.
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Han, Qing, Zong Ming Jia, and Dong Ye Sun. "Recycled Aggregate Concrete Mixture Proportion Method Based on Pulp Content." Applied Mechanics and Materials 584-586 (July 2014): 1425–31. http://dx.doi.org/10.4028/www.scientific.net/amm.584-586.1425.
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Putting forward a new recycled aggregate concrete mixture proportion method based on the pulp content by researching the effect of pulp content on recycled coarse aggregate physical properties .Research on the cube compressive strength and splitting tensile strength of recycled aggregate concrete by the proposed method and results showed that:The proposed method can reduce the dosage of cement and sand, and increase the recycled aggregate concrete compressive strength and splitting tensile strength ;Establishing the relationship formula between splitting tensile strength and compressive strength of recycled aggregate concrete upon a large number of experimental data.
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Šefflová, Magdaléna, Tereza Pavlů, and Vladimír Hujer. "Behavior of Concrete Containing of Fine Recycled Aggregate." Key Engineering Materials 677 (January 2016): 260–65. http://dx.doi.org/10.4028/www.scientific.net/kem.677.260.
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The use of coarse recycled aggregate in concrete is already accepted in the Czech Republic but with specific restrictions. The problem is the use of fine recycled aggregate (FRA) in concrete. This paper is focused on behavior of concrete containing FRA. FRA, which originated from recycling plant in the Czech Republic, was used in an experimental part. FRA was obtained from demolished and crushed concrete structures. Four concrete mixtures were designed and prepared. The first concrete mixture was reference which did not include FRA. Natural sand was replaced by FRA in other concrete mixtures in varying ratio. There were tested physical, mechanical and deformation properties of concrete. According to test results it is possible to say that the use FRA as partial replacement of natural sand in concrete mixtures.
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Salahuddin, Hammad, Liaqat Ali Qureshi, Adnan Nawaz, Muhammad Abid, Rayed Alyousef, Hisham Alabduljabbar, Fahid Aslam, Summera Fahmi Khan, and Rana Faisal Tufail. "Elevated Temperature Performance of Reactive Powder Concrete Containing Recycled Fine Aggregates." Materials 13, no. 17 (August 24, 2020): 3748. http://dx.doi.org/10.3390/ma13173748.
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This study examines the effect of elevated temperature on various properties of reactive powder concrete (RPC) containing varying percentages of recycled fine aggregates as sand replacement. Recycled fine aggregates were collected from two sources, i.e., demolished normal strength concrete and demolished RPC. The specimens were prepared using 25%, 50%, and 75% replacement of natural sand with recycled fine aggregates, exposed to two different curing conditions and were subjected to four temperatures, i.e., 25, 200, 400, and 600 °C. Later, the specimens were tested for mass loss, compressive strength test, split-tensile strength test, flexural strength test, and water absorption test at all temperature ranges. Results determined that although the mechanical properties degraded with the temperature rise, the recycled aggregates can be employed as a partial replacement of natural sand in RPC without causing a significant decrease in the performance of RPC, and can help to produce more sustainable RPC by using recycled aggregates.
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Pizoń, Jan, Jacek Gołaszewski, Mohamed Alwaeli, and Patryk Szwan. "Properties of Concrete with Recycled Concrete Aggregate Containing Metallurgical Sludge Waste." Materials 13, no. 6 (March 22, 2020): 1448. http://dx.doi.org/10.3390/ma13061448.
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Sand has been considered to be something of an immeasurable quantity. There are many indications that this view is no longer valid and that the limiting of natural aggregates usage is doubly justified. Firstly, the extraction of natural aggregates is expensive and has a huge impact on the environment. The main issues in sand and gravel mining are the large areas that are affected, ground water level changes, illegal mining, unsuitability of desert and marine sand, and costs of transport. Secondly, metallurgical waste can be used as a substitute for natural aggregates. This is doubly beneficial—the waste is recycled and the use of natural aggregates is reduced. Waste is stored in landfills that take up large areas and there is also the possibility of ground and groundwater pollution by hazardous compounds. The research presented in this article focuses on the technological conditions of using metallurgical waste in its original form and as a component of recycled concrete aggregate (RCA). The use of metallurgical sludge waste or crushed or round RCA to produce concrete deteriorates the consistency and does not significantly affect the air content and density of the concrete mix. RCA lowers the density of hardened concrete. Metallurgical sludge waste or RCA usage adversely affect the absorbability and permeability of concrete. Concrete containing metallurgical sludge waste is of higher compressive strength after 7 and 28 days, with up to 60% of waste as a sand replacement. RCA concrete achieved higher compressive strength also.
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Larsen, Oksana, Viktoria Shvetsova, Ekaterina Patsenko, and Artyom Polozov. "Properties of sand concrete with recycled tyre polymer fibers." E3S Web of Conferences 263 (2021): 01015. http://dx.doi.org/10.1051/e3sconf/202126301015.
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Disposal of tyre waste is a major environmental problem in all over of the world. It has been estimated that more than 1.5 billion tyres are produced annually and almost one million end their service life. More than 50% of them are accumulated on landfills. The tyre fiber can be added to the concrete mixture to improve not only the strength properties, but also the crack resistance of the composition. The use of recycled tire polymer fibers as reinforcement component is a perspective view on the development of dispersed concrete technology. In this research the main characteristics of the fiber and the technological characteristics of the concrete mixture are presented. The effect of the polymer fiber on strength and performance properties of sand concrete are shown. It was found that the optimal dosage of fiber is 1 kg/m3, the adding of the fiber reduces at the range 3.6% of slump of the concrete mixture. It was found that each 10 kg/m3 of recycled polymer fiber reduce the density of samples by 4%. The addition of such amount of the polymer fiber reduces the compressive strength. The addition of 1 kg/m3 has the significant effect on the reduction of the compressive and flexural concrete strength with class B15, while the same characteristics of concrete with class B30 are higher. The results of this research allow to conclude that such fiber is suitable to use in concrete with class В30 and lower.
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Fořtová, Kristina, and Tereza Pavlů. "The Properties of Fine Recycled Aggregate Concrete Containing Recycled Bricks from Construction and Demolition Waste." Key Engineering Materials 760 (January 2018): 193–98. http://dx.doi.org/10.4028/www.scientific.net/kem.760.193.
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This paper presents research results of recycled fine aggregate concrete testing. The main aim of this contribution is verification of properties of fine aggregate concrete with partial replacement of fine natural aggregate by recycled masonry aggregate originated from construction and demolition waste. The influence of partial replacement of natural sand to mechanical properties and freeze-thaw resistance is described. The compressive strength and flexural strength were tested at the age of 28 and 60 days and after 25, 50, 75 and 100 freeze-thaw cycles. Partial replacement of natural sand was 0, 25 and 50 % for all these tests. Prismatic specimens were examined.
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Babafemi, Adewumi John, Nina Sirba, Suvash Chandra Paul, and Md Jihad Miah. "Mechanical and Durability Assessment of Recycled Waste Plastic (Resin8 & PET) Eco-Aggregate Concrete." Sustainability 14, no. 9 (May 9, 2022): 5725. http://dx.doi.org/10.3390/su14095725.
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The massive amount of plastic waste in our natural environment is a global concern. In this study, recycling plastic waste to partially replace natural sand in concrete is investigated. The performance of Resin8, a unique combination of all types of plastics and Polyethylene Terephthalate (PET) in concrete, has also been investigated. Replacement contents of 5%, 10%, and 15% for sand by volume were performed. The concrete mixes incorporating recycled plastic waste were tested against a reference concrete mix without plastic. The workability, compressive strength, tensile strength, oxygen permeability index (OPI), and effect of temperature were assessed. Scanning Electron Microscopy (SEM) analysis was conducted on the plastics and plastic concretes, pre- and post-temperature exposure. PET at a replacement content of 10% slightly increased the compressive strength by 2.4%. Regarding the OPI test, all the mixes incorporating recycled plastic waste are classified as “good”. When exposed to a temperature of 250 °C, no significant change in compressive strength was observed for the concrete mixes incorporating Resin8 at a replacement content of 15%, and the mixes incorporating PET at a replacement content of 5%, 10%, and 15%. It was clear from the results that both Resin8 and PET are suitable as a partial replacement for sand in concrete.
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Abass, Mohammed, and Yasuyuki Kanda. "Ceramics based on concrete wastes prepared by spark plasma sintering." Processing and Application of Ceramics 15, no. 1 (2021): 100–109. http://dx.doi.org/10.2298/pac2101100a.
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An effective utilization technique is required to recycle fine aggregate in concrete waste because the presence of residual waste cement reduces the quality of the recycled concrete. In this study, recycled aggregate powder (RAP) was prepared by milling Okinawan concrete waste and developing a ceramic compact with high flexural strength using the spark plasma sintering (SPS) method. The RAP raw material consisted mainly of calcite and quartz. The densification gradient of the sintered compact was uniform during sintering at 1123-1273K. At 1273K sintering temperature, Vickers hardness (HV) obtained a maximum of 393 along with 78.9MPa maximum flexural strength, which exceeded the porcelain stoneware tile ISO 13006 standards. Scanning electron microscopy with energy dispersive X-ray (SEM-EDX) element analysis suggested that the inner structure constituted unmelted silica-rich sand particles and melted calcium-rich particles containing waste cement and fine aggregate with limestone. Therefore, it can be concluded that SPS progressed by the liquid-phase sintering phenomenon between sand particles and calcium-rich particles, which contributed to flexural strength and modulus improvement.
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Fomina, Natalya, and Mikhail Polyanskiy. "Grain size distribution of aggregates of crushed concrete." E3S Web of Conferences 97 (2019): 02018. http://dx.doi.org/10.1051/e3sconf/20199702018.
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The results of studies of recycling aggregates obtained by crushing concrete scrap are presented. The heterogeneity of the material received as a result of crushing concrete scrap, complicates the task of selecting the fractional composition of aggregates. The presence of the mortar component in recycled aggregates significantly increases their water demand. This indicates the expediency of their use in a mixture with natural ones. This work aimed at optimizing the granulometry of recycling rubble and sand. Concrete scrap was used for the research. It was represented by destroyed samples of heavy concrete cubes. Standard methods for determining the grain composition and properties of aggregates of concrete, manufacturing and testing mortar mixes were used. It has been shown that recycling rubble of the 5-20 mm fraction has a minimum voidness when it contains 35% of the 5-10 mm grains and 65% of the 10-20 mm grains, which is close to the ratio of these fractions in the initial crushing product. Therefore, it is advisable to use recycling rubble fractions of 5-20 mm without separation into fractions. The rather high content in the recycling sand of grains with a particle size of more than 0.63 mm indicates the feasibility of using it in a mixture with natural fine and very fine sand. A grain-optimized mixture of natural very fine sand (46% of the total mass of mixed sand) and coarse fractions (0.63–5 mm) of recycled sand (54%) is proposed. Should be considered that recycled sand has increased water demand.
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Pavlů, Tereza. "The Comparison of Properties of Fine Recycled Aggregate Concrete from Different Sources of Recycled Aggregate." Key Engineering Materials 760 (January 2018): 176–83. http://dx.doi.org/10.4028/www.scientific.net/kem.760.176.
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The main aim of this contribution is comparison the properties of fine aggregate concrete with partial replacement of sand by fine recycled aggregate. The fine recycled aggregate originated from two different sources. The main topic of this article is the study of influence of the origin of FRA to fine aggregate concrete properties. The compressive strength, flexural strength and freeze-thaw resistance were tested. The mechanical properties and weight were examined after 28 and 60 days and after 25, 50, 75 and 100 cycles of freeze-thaw. Partial replacement of sand was 25 and 50 % for all these tests. The properties were investigated by using prismatic specimens.
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Joohari, Ilya, Nor Farhani Ishak, and Norliyati Mohd Amin. "Mechanical Properties of Lightweight Concrete Using Recycled Cement-Sand Brick as Coarse Aggregates Replacement." E3S Web of Conferences 34 (2018): 01029. http://dx.doi.org/10.1051/e3sconf/20183401029.
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This paper presents the result of replacing natural course aggregate with recycled cement-sand brick (CSB) towards the mechanical properties of concrete. Natural aggregates were used in this study as a control sample to compare with recycled coarse aggregates. This study was also carried to determine the optimum proportion of coarse aggregates replacement to produce lightweight concrete. Besides, this study was conducted to observe the crack and its behaviour development during the mechanical testing. Through this study, four types of concrete mixed were prepared, which were the control sample, 25%, 50% and 75% replacement of CSB. The test conducted to determine the effectiveness of recycled CSB as coarse aggregates replacement in this study were slump test, density measurement, compression test, and flexural test and. The strength of concrete was tested at 7 days and 28 days of curing. From the results obtained, the optimum proportion which produced the highest strength is 25% replacement of recycled CSB. The compressive and flexural strength has decreased by 10%-12% and 4%-34% respectively compared to the control sample. The presence of recycled coarse aggregates in sample has decreased the density of concrete by 0.8%-3% compared to the control sample.
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Mallikarjuna Reddy, Dr V., and M. Manikanta Sai Swaroop. "Effect of Recycled Aggregates on Strength and performance of Recylced Aggregate Concrete." E3S Web of Conferences 184 (2020): 01085. http://dx.doi.org/10.1051/e3sconf/202018401085.
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This study is taken up to utilise the recycled coarse aggregate and recycled fine aggregate as replacement of natural aggregate in concrete mix. It is required to find the percentage of recycled coarse aggragate and recycled fine aggregate, as the strength of concrete can not be achieved by using higher percentaged. The purpose of study is to compare between recycled coarse aggregate and recycled fine aggregate with natural coarse aggregate and sand in terms of specific gravity, water absorption, particle size distribution. Further, this stydy will also consider the difference between the performance of Recycled Aggregate Concrete for different percentages of recycled coarse aggregate and recycled fine aggregate i.e for 0%, 10%, 15%, 20%, 25%, 30%, 35% replacement. The present study is an experimental investigation on the behaviour of recycled aggregate concrete (coarse& fine aggregates) with respect to the strength and performance.
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Mustafy, Tanvir, Md Maruf Hasan, Nayeem Ahmed Shuvo, and Joarder Md Sarwar Mujib. "Characterization of Mechanical Properties of Concrete Recycled Ceramic and Glass Powder Exposed to Elevated Temperatures." MIST INTERNATIONAL JOURNAL OF SCIENCE AND TECHNOLOGY 10 (June 26, 2022): 01–14. http://dx.doi.org/10.47981/j.mijst.10(01)2022.350(01-14).
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Systematic reuse of industrial debris is a crucial component that helps shape the sustainable construction system and green technology. The effective optimization of waste ceramic and glass fines into concrete mixes, as partial replacements of natural sand by volume, has been used in this study to explore the mechanical properties of ceramic recycled aggregate (CRA) and glass recycled aggregate (GRA) concrete at higher temperatures. The study comprises 17 types of concrete mixtures comprised of normal concrete (NC) along with 8 different mixes from both GRA and CRA concrete. In both types of GRA and CRA concrete, the sand replacement (by volume) ratios are similar. This paper highlights NC along with the volumetric replacements of sand as 5%, 10%, 15%, 20%, 25%, 30%, 35%, and 40% in other mixes. A total of 306 cylinders were made whereas 18 cylinders for NC and each group (GRA and CRA) included n=18 cylinders. Selected temperatures were 25°C, 100°C, 200°C, 400°C, 600°C, and 800°C to determine the overall mechanical and chemical alterations in NC and recycled concrete. The study reveals that increasing the addition of recycled glass and ceramic fines improves the overall compressive strength, and tensile strength compared to normal concrete. Higher replacement of ceramic and glass fines reduces the cracks and enhances the durability of concrete. In addition, more strength reduction was noticed in NC with increasing temperatures, while the reduction rate was slower in both GRA and CRA concrete. Furthermore, the study expounds that, by exploiting the ceramic and glass wastes (as fines) into concrete would result in two-way environmental advantages. One is, it would reduce the hazardous ceramic and glass landfills while the other is, it would minimize the frequency of sand mining.
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Gerges, Najib Nicolas, Camille Amine Issa, Samer Ahmad Fawaz, Jacques Jabbour, Johnny Jreige, and Aiman Yacoub. "Recycled Glass Concrete: Coarse and Fine Aggregates." European Journal of Engineering Research and Science 3, no. 1 (January 19, 2018): 1. http://dx.doi.org/10.24018/ejers.2018.3.1.533.
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Conventional concrete aggregate consists of sand (fine aggregate) and various sizes and shapes of gravel or stones (coarse aggregate). However, there is a growing interest in substituting alternative aggregate materials, largely as a potential use for recycled materials. While there is significant research on many different materials for aggregate substitutes such as granulated coal ash, blast furnace slag or various solid wastes including fiberglass waste materials, granulated plastics, paper and wood products or wastes, sintered sludge pellets and others. Recycled waste glasses were used as coarse and fine aggregates replacement in concrete. Coarse aggregates were replaced with Green Bottles coarse aggregates at third, half, two thirds, and 100% replacement ratios. The replacement of a third coarse aggregate was established as being the most suitable for retaining the properties of the concrete mix design. As for fine aggregates, in order to account for the numbers of variables and clearly establish a bench mark, the sand grading, color of glass, source of waste glass (bottles and non-bottles), and design mix strength were used as parameters. Fine aggregates from green, brown, and transparent bottles in addition to clear window waste glass were used. Concrete properties were tested in fresh and hardened states. The incorporation of glass sand regardless of the ratios of replacement showed no significant influence on fresh or mechanical properties of concrete except for the case of transparent bottles. Transparent bottles due to the wide source of obtainability have introduced a non-uniform factor that caused discrepancy compared to the rest of the group.
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Gerges, Najib Nicolas, Camille Amine Issa, Samer Ahmad Fawaz, Jacques Jabbour, Johnny Jreige, and Aiman Yacoub. "Recycled Glass Concrete: Coarse and Fine Aggregates." European Journal of Engineering and Technology Research 3, no. 1 (January 19, 2018): 1–9. http://dx.doi.org/10.24018/ejeng.2018.3.1.533.
Full textAbstract:
Conventional concrete aggregate consists of sand (fine aggregate) and various sizes and shapes of gravel or stones (coarse aggregate). However, there is a growing interest in substituting alternative aggregate materials, largely as a potential use for recycled materials. While there is significant research on many different materials for aggregate substitutes such as granulated coal ash, blast furnace slag or various solid wastes including fiberglass waste materials, granulated plastics, paper and wood products or wastes, sintered sludge pellets and others. Recycled waste glasses were used as coarse and fine aggregates replacement in concrete. Coarse aggregates were replaced with Green Bottles coarse aggregates at third, half, two thirds, and 100% replacement ratios. The replacement of a third coarse aggregate was established as being the most suitable for retaining the properties of the concrete mix design. As for fine aggregates, in order to account for the numbers of variables and clearly establish a bench mark, the sand grading, color of glass, source of waste glass (bottles and non-bottles), and design mix strength were used as parameters. Fine aggregates from green, brown, and transparent bottles in addition to clear window waste glass were used. Concrete properties were tested in fresh and hardened states. The incorporation of glass sand regardless of the ratios of replacement showed no significant influence on fresh or mechanical properties of concrete except for the case of transparent bottles. Transparent bottles due to the wide source of obtainability have introduced a non-uniform factor that caused discrepancy compared to the rest of the group.
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Šefflová, Magdaléna, and Tereza Pavlů. "The Carbonation Depth of Fine Recycled Aggregate Concrete." Key Engineering Materials 722 (December 2016): 228–32. http://dx.doi.org/10.4028/www.scientific.net/kem.722.228.
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This paper is focused on carbonation resistance of fine recycled aggregate (FRA) concrete. Durability of FRA concrete is connected with uncertainties and doubts. One of the most unknown aspects of FRA cocnrete is carbonation resistance. This paper presents results of carbonation depth of FRA concrete. The FRA was originated from crushed construction and demolition (C&D) waste. There were prepared a total four concrete mixture. The first mixture was reference, did not include the FRA. In other concrete mixtures, natural sand was replaced by the FRA in various replacement ratios, specifically 10%, 20% and 30%. All prepared concrete mixtures were designated with the same parameters for clear comparison. From the test results it is possible to say that the use of the FRA as partial replacement of natural sand in concrete influences carbonation resistance of concrete. The carbonation depth was higher for concrete samples with the use of FRA. However it is possible to say that according to the carbonation resistance, the FRA concrete is possible to be used in the same applications as conventional concrete but it is necessary to verify this results.
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Mohan das, Dr K., Dr N. Sundar, S. Harishankar, A. Raj Kumar, SPM Kannan, and Dr K. Ramesh. "An experimental study on strength characteristics of replacement of fine aggregate with stone dust and coarse aggregate with demolished concrete waste." YMER Digital 21, no. 02 (February 26, 2022): 683–700. http://dx.doi.org/10.37896/ymer21.02/64.
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The report presents a comparative examination of the experimental results of the characteristics of fresh and cured concrete with various natural with recycled coarse and fine aggregate replacement ratios. Crushing leftover concrete from laboratory test cubes and precast concrete columns yielded recycled coarse aggregate. Stone dust was used in place of recycled fine aggregate. One of the most significant components of a reinforced structural part is concrete. Concrete has an inextricable influence on reinforced concrete constructions. Concrete that isn't strong enough puts the entire structure in harm. Many structures nowadays fail as a result of a lack of strength. The mechanical properties of concrete changed by stone dust as a fine aggregate replacement material are investigated in this work. A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse and fine aggregate are presented in the paper. Recycled coarse aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Recycled fine aggregate was replaced by stone dust. Concrete is one of the most important components in reinforced structural member. In reinforced concrete structures concrete have some inseparable influence. Lacking in concrete strength endanger the whole structure. Now a day it is seen that many structures fails due to lack of strength. In this paper investigate experiment is reported on the mechanical properties of concrete modified by stone dust as replacing material of fine aggregate and demolished concrete waste as replacing material of coarse aggregate and a study is conductto determine the engineering properties of compressive strength, tensile strength, flexural strength and water absorption capacity of partially replacement of natural sand and natural aggregate. In recent days the demand of river sand is increasing due to its lesser availability. Hence the practice of partially replacing river sand with stone dust is taking a tremendous growth. Due to critical stage of natural aggregate the availability of demolished concrete as recycled aggregate. Using discarded concrete as recycled aggregate conserves natural aggregate, lowers landfill impact, reduces energy use, and potentially saves money. The materials of the future are recycled aggregate. Stone dust and destroyed concrete waste were used to replace 25 percent, 50 percent, 75 percent, and 100 percent of fine and coarse aggregate, respectively. After a 28-day curing period, concrete samples (cubes, cylinders, and beams) are cast and evaluated. To produce the effect on mortar, several members were built utilising the above percentage. Modified concrete is compared to regular concrete in terms of strength. The strength parameters of concrete employing stone dust as fine aggregate and demolished concrete debris as coarse aggregate are observed to increase in compressive strength, flexural strength, and tensile strength. It was discovered that the concrete may be used as structural members in buildings and other structures.
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Corbu, Ofelia, Attila Puskás, Andrei Victor Sandu, Adrian M. Ioani, Kamarudin Hussin, and Ioan Gabriel Sandu. "New Concrete with Recycled Aggregates from Leftover Concrete." Applied Mechanics and Materials 754-755 (April 2015): 389–94. http://dx.doi.org/10.4028/www.scientific.net/amm.754-755.389.
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We live in an era where people should be more aware of pollution and its consequences. The present paper reveals a way protecting the environment while producing high quality concrete. What make this type of concrete environmentally friendly are the recycled aggregates in the concrete composition amongst with eliminating the ecological impact by saving large amounts of natural aggregates resources. Recycling concrete comes with many other advantages that lead to waste reduction, economy in waste transportation and storage taxes, which are becoming increasingly expensive. This research is based on mix design and experimental tests carried out on C20/25 strength class concrete with uncontaminated leftover concrete aggregates (LCAgg). It reveals favorable results in order to militate for recycled concrete aggregate uses in regular concrete strength classes respectively for common structural elements, mainly for slabs. River sand (0/4 mm) and coarse aggregates (4/8 mm and 8/16 mm): natural sources or recycled concrete type-alternatively used in several mixes-were utilized in concrete mixes.
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Ghorbel, Elhem, George Wardeh, Hector Gomart, and Pierre Matar. "Formulation parameters effects on the performances of concrete equivalent mortars incorporating different ratios of recycled sand." Journal of Building Physics 43, no. 6 (December 27, 2019): 545–72. http://dx.doi.org/10.1177/1744259119896093.
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The present research investigates the feasibility of manufacturing masonry mortars with recycled sand. The primary aim is to study the effect of fine recycled aggregates on fresh and hardened states with properties. Two series of mortars were designed by substituting natural sand with recycled sand, with variable sand replacement ratios ranging from 0% to 100%. One series, named variable workability series, has variable workability with constant water to cement ratio ( W/C), while the other series, called constant workability series, has a constant workability with variable W/C. The density, air content, and slump of mortars in fresh state were measured with a special attention devoted to the effect of pre-saturation of recycled sand on the slump. In the hardened state, the microstructure was studied by means of water accessible porosity test and mercury intrusion porosimetry test. Flexural and compressive strength as well as the dynamic modulus of elasticity were also examined and the correlations between these properties and the microstructure have been established. It was found that the properties of mortars with recycled sand are lower than those obtained for the natural sand mortar (−20% for variable workability series and −45% for constant workability series at the age of 28 days). For the series with variable workability, mechanical properties decrease to a step starting from 30% replacement ratio, while linearly decrease for the mortars with constant workability. The difference between the two series lies in the difference in total porosities and the pore size distribution.
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Chu, Hongyan, Yu Zhang, Fengjuan Wang, Taotao Feng, Liguo Wang, and Danqian Wang. "Effect of Graphene Oxide on Mechanical Properties and Durability of Ultra-High-Performance Concrete Prepared from Recycled Sand." Nanomaterials 10, no. 9 (August 30, 2020): 1718. http://dx.doi.org/10.3390/nano10091718.
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Ultra-high-performance concrete (UHPC) has been used as an advanced construction material in civil engineering because of its excellent mechanical properties and durability. However, with the depletion of the raw material (river sand) used for preparing UHPC, it is imperative to find a replacement material. Recycled sand is an alternative raw material for preparing UHPC, but it degrades the performance. In this study, we investigated the use of graphene oxide (GO) as an additive for enhancing the properties of UHPC prepared from recycled sand. The primary objective was to investigate the effects of GO on the mechanical properties and durability of the UHPC at different concentrations. Additionally, the impact of the GO additive on the microstructure of the UHPC prepared from recycled sand was analysed at different mixing concentrations. The addition of GO resulted in the following: (1) The porosity of the UHPC prepared from recycled sand was reduced by 4.45–11.35%; (2) the compressive strength, flexural strength, splitting tensile strength, and elastic modulus of the UHPC prepared from recycled sand were enhanced by 8.24–16.83%, 11.26–26.62%, 15.63–29.54%, and 5.84–12.25%, respectively; (3) the resistance of the UHPC to penetration of chloride ions increased, and the freeze–thaw resistance improved; (4) the optimum mixing concentration of GO in the UHPC was determined to be 0.05 wt.%, according to a comprehensive analysis of its effects on the microstructure, mechanical properties, and durability of the UHPC. The findings of this study provide important guidance for the utilisation of recycled sand resources.
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Khalid, Faisal Sheikh, Nurul Bazilah Azmi, Puteri Natasya Mazenan, Shahiron Shahidan, and Noorwirdawati Ali. "The mechanical properties of brick containing recycled concrete aggregate and polyethylene terephthalate waste as sand replacement." E3S Web of Conferences 34 (2018): 01001. http://dx.doi.org/10.1051/e3sconf/20183401001.
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This research focuses on the performance of composite sand cement brick containing recycle concrete aggregate and waste polyethylene terephthalate. This study aims to determine the mechanical properties such as compressive strength and water absorption of composite brick containing recycled concrete aggregate (RCA) and polyethylene terephthalate (PET) waste. The bricks specimens were prepared by using 100% natural sand, they were then replaced by RCA at 25%, 50% and 75% with proportions of PET consists of 0.5%, 1.0% and 1.5% by weight of natural sand. Based on the results of compressive strength, only RCA 25% with 0.5% PET achieve lower strength than normal bricks while others showed a high strength. However, all design mix reaches strength more than 7N/mm2 as expected. Besides that, the most favorable mix design that achieves high compressive strength is 75% of RCA with 0.5% PET.
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Stuerwald, Simone, Ronny Meglin, Susanne Kytzia, and Sabrina Gilg. "Use of recycled concrete fines in cement and as aggregate." Acta Polytechnica CTU Proceedings 33 (March 3, 2022): 591–96. http://dx.doi.org/10.14311/app.2022.33.0591.
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The research project focused on investigating and optimizing the processing and use of recycled crushed sand 0/4 from concrete demolition waste, as an alternative raw material in the cement and concrete industry. Crushed sand is produced during the processing of concrete demolition waste. The goal was to identify the optimum way of using the processed material along the entire process chain so that greenhouse gas emissions, waste volumes are reduced, and natural resources are conserved. Different samples of laboratory and real crushed concrete fines were collected and examined in relation to various possible applications in accordance with the applicable standards. Results highlight, that crushed concrete fines can be used in various applications in the concrete value-chain. However, for an optimal usage, additional processing is needed.
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Prošek, Zdeněk, Andrej Osvald, Jaroslav Topič, Jan Valentin, Jan Trejbal, and Pavel Tesárek. "Influence of Recycled Concrete Composition on its Elastic Stiffness." Key Engineering Materials 677 (January 2016): 288–91. http://dx.doi.org/10.4028/www.scientific.net/kem.677.288.
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The presented study was focused on the influence of the micronized recycled a concrete sleeper on the mechanical properties of fine-grained concrete, specifically on dynamic modulus of elasticity. The tested material consisted of cement CEM I 42.5R (Radotín), crushed bricks fraction 2-5 mm, 0-4 mm sand and micronized recycled concrete fraction 0-0.125 mm. Individual material samples differed in the quantity of cement and finely ground recycled concrete (milled at Ltd. Lavaris, Libčice – Czech Republic). Cement was replaced by the recycled concrete in an amount of 30, 50 and 70 weight percent. Testing was performed on beams of dimensions 40 × 40 × 160 mm by using non-destructive testing – pulse method. The article compares the values obtained between 2-nd and 28-th day.
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Łój, Grzegorz, and Wiesława Nocuń-Wczelik. "Use of Prefabrication, Construction and Demolition Wastes as an Aggregate in Vibropressed Precast Concrete Blocks Production." Journal of Civil Engineering and Construction 11, no. 1 (February 15, 2022): 20–28. http://dx.doi.org/10.32732/jcec.2022.11.1.20.
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The aim of current study was to determine the recycled concrete aggregate (RCA) applicability in the production of concrete mixture for vibropressed concrete blocks. The experiments were focused especially on the crushed waste material from the same concrete elements producing plant. For this type of precast elements only some finer fractions can be implemented and the “earth-moist” consistency of fresh mixture is required. The series of samples was prepared in which the mixture of natural aggregates was partially or totally substituted by recycled concrete aggregate. The 0/4 RCA fraction, which is usually rejected in ready mix concrete technology, plays a role of 0/2 sand. The substitution of sand fraction was from 20% to 100% respectively. The substitution of the coarser aggregate fractions by 4/16 RCA was also done. The standard properties of vibropressed elements, such as the degree of densification, the density of material, the compressive and splitting tensile strength and the water absorption capacity according to the relevant standards were determined. The parameters of materials with the natural aggregate substitution by RCA are affected by the ratio of recycled concrete aggregate. In most cases the results do not decline specially from those for reference samples, when only the natural sand (0/2) fraction is substituted by the 0/4 recycled aggregate. As one could expect, as lower the substitution, as better the test results. The partial substitution of natural aggregate by coarser fractions requires experimental verification; over 20% substitution of natural aggregate by 4/8, 8/16 or 0/16 RCA should be excluded.
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Hanganu, Dumitru-Dragos. "Notes About Crushing Sand from Bituminous Schist." Bulletin of the Polytechnic Institute of Iași. Construction. Architecture Section 67, no. 1 (March 1, 2021): 103–8. http://dx.doi.org/10.2478/bipca-2021-0009.
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Abstract People have used sand and stone for foundations for thousands of years. Significant refinement of the production and use of aggregate occurred during the Roman Empire, which used aggregate to build its vast network of roads and aqueducts. The invention of concrete, which was essential to architecture utilizing arches, created an immediate, permanent demand for construction aggregates. Construction aggregate, or simply “aggregate”, is a broad category of coarse to medium grained particulate material used in construction, including sand, gravel, crushed stone, slag, recycled concrete and geosynthetic aggregates. Aggregates are the most mined materials in the world. Aggregates are a component of composite materials such as concrete and asphalt concrete; the aggregate serves as reinforcement to add strength to the overall composite material. Due to the relatively high hydraulic conductivity value as compared to most soils, aggregates are widely used in drainage applications such as foundation and French drains, septic drain fields, retaining wall drains, and roadside edge drains. Aggregates are also used as base material under foundations, roads, and railroads. In other words, aggregates are used as a stable foundation or road/rail base with predictable, uniform properties (e.g. to help prevent differential settling under the road or building), or as a low-cost extender that binds with more expensive cement or asphalt to form concrete. Preferred bituminous aggregate sizes for road construction are given in EN 13043 as d/D (where the range shows the smallest and largest square mesh grating that the particles can pass). The same classification sizing is used for larger armour stone sizes in EN 13383, EN 12620 for concrete aggregate, EN 13242 for base layers of road construction and EN 13450 for railway ballast. Aggregates themselves can be recycled as aggregates. Unlike deposits of sand and gravel or stone suitable for crushing into aggregate, which can be anywhere and may require overburden removal and/or blasting, “deposits” of recyclable aggregate tend to be concentrated near urban areas, and production from them cannot be raised or lowered to meet demand for aggregates. Supply of recycled aggregate depends on physical decay of structures and their demolition. The recycling plant can be fixed or mobile; the smaller capacity mobile plant works best for asphalt-aggregate recycling. The material being recycled is usually highly variable in quality and properties.
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Hamid, Roszilah, and M. A. Zubir. "Compressive Strength of Concrete with Recycled Glass as Partial Aggregate Replacement." Materials Science Forum 803 (August 2014): 21–25. http://dx.doi.org/10.4028/www.scientific.net/msf.803.21.
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In this study, recycled glass is used to replace the natural fine aggregate in different mix proportions to obtain the optimum combination that will produce the highest strength. The control samples are Grade 30 ordinary Portland cement concrete (OPCC) containing 100% natural sand and coarse aggregate. The recycled glass concretes contain 70% natural fine aggregate + 30% size 300 micron crushed glass (Sample 2), and 70% fine aggregate + 15% size 300 micron crushed glass + 15% size greater than 300 micron crushed glass (Sample 3). The compressive strengths of the concrete samples with recycled glass are higher than the control samples at all ages of 7, 28, 56 and 90 days. At age 60 days, the strength gain of the control samples shows no significant increment but both samples that include recycled glass still show significant increment in strength. It is found that recycled glass performed better when utilised at size 300 microns and less. The recorded strength of the control, Sample 2 and 3 at 90 days are 47, 61 and 55 MPa.
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Rafiza, Abdul Rahman, Ahmad Fazlizan, Atthakorn Thongtha, Nilofar Asim, and Md Saleh Noorashikin. "The Physical and Mechanical Properties of Autoclaved Aerated Concrete (AAC) with Recycled AAC as a Partial Replacement for Sand." Buildings 12, no. 1 (January 7, 2022): 60. http://dx.doi.org/10.3390/buildings12010060.
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The application of AAC has increased considerably in Malaysia since the 1990s. The usage of AAC has some advantages, but it also has negative environmental impacts since rejected concrete will become landfill. This study aimed to use AAC waste powder as a material that would partially replace the sand content to produce a new form of Autoclaved Aerated Concrete (AAC). The physical and mechanical properties of the newly developed AAC were investigated. This paper presents improved mechanical and physical properties of the new form of recycled AAC concrete. Besides these improvements, using recycled AAC could lower production costs. Furthermore, the usage of this recycled waste powder is both economically and environmentally advantageous. This study found that when recycled AAC was substituted for sand, AAC with a fine recycled powder content of 30% had a compressive strength that was around 16% higher than conventional AAC and between 29% and 156% higher than any value attained utilizing an industrial waste product. This study also confirmed that the greater strength could be identical to a higher tobermorite phase and that the recycled AAC surface showed a finer crystalline morphology.
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Lan, Wen Wu, Zhi Peng Yao, Yi An, and Li Chen. "Experimental Study on the Shear Behavior of Recycled Concrete with Artificial Sand." Applied Mechanics and Materials 405-408 (September 2013): 2538–43. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.2538.
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This study examines the shear behaviors of concrete structure with recycled concrete and artificial sand (AS). Thirty-six beams were prepared with two strength grades (C35, C45) and different artificial sand replacement rates (0%, 30%, 50%, 70%, and 100%). They were submitted to four-point static stress test in order to distinguish the shear behaviors of ASCRC (AS-containing recycled concrete) and of natural concrete that is fabricated using original coarse aggregate and natural sand. Experimental results found the shear strengths values of the ASCRC were lower than the nature ones, with decreasing extents less than 20%. When AS-containing level ranged from 30% to 70%, the cube compressive and shear strengths were more lower than other replacement ratios. Shear force-shear strain curve of the ASCRC was found similar to that of the nature concrete. The peak strain of the ASCRC rose with the increase of the shear strength, but the slope of the curves was lower.