scholarly journals Residual Compressive Strength of Recycled Aggregate Concretes after High Temperature Exposure

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1981 ◽  
Author(s):  
Francisco B. Varona ◽  
Francisco Baeza-Brotons ◽  
Antonio J. Tenza-Abril ◽  
F. Javier Baeza ◽  
Luis Bañón
Keyword(s):  
Compressive Strength ◽  
Construction Industry ◽  
Residual Strength ◽  
Raw Materials ◽  
Environmental Benefits ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Residual Properties ◽  
Negative Effect ◽  
Temperature Exposure

Sustainability requirements are gaining importance in the construction industry, which needs to take specific measures in the design and construction of concrete structures. The use of recycled aggregates in concrete may be of special interest. Recycling a construction waste will close the life cycle of the original materials (e.g., concrete). Thus, environmental benefits would come from the lower waste generation, and from a lower necessity of raw materials for new structures. The current Spanish code for structural concrete considers the use of recycled aggregates in replacement rates up to 20% by aggregate mass, assimilating their properties with those of concretes without aggregate replacement. Higher substitution percentages would require further testing. In this work, substitution of coarse aggregate for recycled aggregates (with replacement percentages of 25%, 50% and 100%) has been studied, and the concrete’s residual properties after exposure to high temperatures (between 350 °C and 850 °C) have been assessed. Compressive strength and capillary water absorption tests were made after heating, and the experiments showed higher residual strength in concretes with the greatest content of recycled aggregates. However, a statistical analysis made with additional data available in the literature seemed to predict otherwise, and the recycled aggregate replacement would have a negative effect on the residual strength.

scholarly journals Mechanical characteristics of concrete containing basalt fiber and recycled aggregate

2021 ◽  
Vol 889 (1) ◽  
pp. 012044
Author(s):  
Hemant ◽  
Rachit Sharma ◽  
Ankush Thakur ◽  
Tiwary Kumar Aditya
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Mechanical Characteristics ◽  
Basalt Fiber ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Split Tensile Strength ◽  
Coarse Aggregates ◽  
Concrete Production ◽  
Negative Effect

Abstract The potential of construction waste as an alternative to the constituents of concrete has been generally examined to demonstrate their utility and ensure the climate and/or environment of its otherwise ill effects. The mechanical characteristics of concrete are investigated to comprehend its behaviour under compressive, tensile, and flexural loads. This experimental study investigates the effect of supplanting proportions of river aggregates with waste coarse aggregates in addition to the effect of basalt fiber additions on concrete mixes with (25 and 50%) substitutions of recycled waste coarse aggregates (RWCA). The workability of concrete mixes was negatively affected with recycled aggregates and/or basalt fiber inclusions. Using recycled aggregates with 25 and 50% replacements decreases the strength of concrete. On utilizing discrete proportions of basalt fiber with natural coarse aggregates, the strength was higher as compared to control mix however increasing the percentage of basalt fiber from 1% to 3% the compressive strength was reduced. On incorporating additions of basalt fiber with different proportions of RWCA, the strength of concrete was deteriorated as the percentage of fiber was increasing. For natural aggregates, the inclusion of fibers has negative effect on compressive strength however the tensile strength was increased with higher percentage of fibers. The inclusions of fibers to 25% recycled aggregate mixes, split tensile strength was much higher as compared to control mix. It was concluded that addition of basalt fibers provides a viable option to recycle recycled aggregate in concrete production.

scholarly journals Predicting Compressive Strength of Concrete Containing Recycled Aggregate Using Modified ANN with Different Optimization Algorithms

2021 ◽  
Vol 11 (2) ◽  
pp. 485
Author(s):  
Amirreza Kandiri ◽  
Farid Sartipi ◽  
Mahdi Kioumarsi
Keyword(s):  
Compressive Strength ◽  
Optimization Algorithms ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Tree Model ◽  
Grasshopper Optimization Algorithm ◽  
Compressive Strength Of Concrete ◽  
Grasshopper Optimization ◽  
Artificial Neural Network Ann ◽  
Industry Needs

Using recycled aggregate in concrete is one of the best ways to reduce construction pollution and prevent the exploitation of natural resources to provide the needed aggregate. However, recycled aggregates affect the mechanical properties of concrete, but the existing information on the subject is less than what the industry needs. Compressive strength, on the other hand, is the most important mechanical property of concrete. Therefore, having predictive models to provide the required information can be helpful to convince the industry to increase the use of recycled aggregate in concrete. In this research, three different optimization algorithms including genetic algorithm (GA), salp swarm algorithm (SSA), and grasshopper optimization algorithm (GOA) are employed to be hybridized with artificial neural network (ANN) separately to predict the compressive strength of concrete containing recycled aggregate, and a M5P tree model is used to test the efficiency of the ANNs. The results of this study show the superior efficiency of the modified ANN with SSA when compared to other models. However, the statistical indicators of the hybrid ANNs with SSA, GA, and GOA are so close to each other.

scholarly journals Effect of Fly Ash on Compressive Strength, Drying Shrinkage, and Carbonation Depth of Mortar with Ferronickel-Slag Powder

2021 ◽  
Vol 11 (3) ◽  
pp. 1037
Author(s):  
Se-Jin Choi ◽  
Ji-Hwan Kim ◽  
Sung-Ho Bae ◽  
Tae-Gue Oh
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Construction Industry ◽  
Bituminous Coal ◽  
Raw Materials ◽  
Drying Shrinkage ◽  
The Other ◽  
Test Results ◽  
Slag Powder ◽  
Ferronickel Slag

In recent years, efforts to reduce greenhouse gas emissions have continued worldwide. In the construction industry, a large amount of CO2 is generated during the production of Portland cement, and various studies are being conducted to reduce the amount of cement and enable the use of cement substitutes. Ferronickel slag is a by-product generated by melting materials such as nickel ore and bituminous coal, which are used as raw materials to produce ferronickel at high temperatures. In this study, we investigated the fluidity, microhydration heat, compressive strength, drying shrinkage, and carbonation characteristics of a ternary cement mortar including ferronickel-slag powder and fly ash. According to the test results, the microhydration heat of the FA20FN00 sample was slightly higher than that of the FA00FN20 sample. The 28-day compressive strength of the FA20FN00 mix was approximately 39.6 MPa, which was higher than that of the other samples, whereas the compressive strength of the FA05FN15 mix including 15% of ferronickel-slag powder was approximately 11.6% lower than that of the FA20FN00 mix. The drying shrinkage of the FA20FN00 sample without ferronickel-slag powder was the highest after 56 days, whereas the FA00FN20 sample without fly ash showed the lowest shrinkage compared to the other mixes.

Predicting Compressive Strength of Recycled Aggregate Concrete by Multiple Regression Analysis

2012 ◽  
Vol 253-255 ◽  
pp. 546-549 ◽  
Author(s):  
Yoon Seok Shin ◽  
Gwang Hee Kim
Keyword(s):  
Compressive Strength ◽  
Regression Analysis ◽  
Multiple Regression Analysis ◽  
Multiple Regression ◽  
Construction Industry ◽  
Multiple Regression Model ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Average Error ◽  
Aggregate Concrete

Today, efforts are underway in a number of areas to conserve the environment and protect natural resource. In the construction industry, many researchers have studied the development of new concrete using recycled aggregate (RA). This research proposes a multiple regression model (MRM) for predicting the compressive strength of recycled aggregate concrete (RAC). The compressive strength data of 85 specimens of RAC strengths were used for constructing and evaluating the prediction model. The average error rate of the constructed MRM evaluation is 7.18 percent. This result will be useful for predicting the compressive strength of RAC using multiple regression analysis.

scholarly journals Effect of Recycled Coarse Aggregates in Properties of Concrete

2008 ◽  
Vol 3 (4) ◽  
pp. 130-137 ◽  
Author(s):  
R Kumutha ◽  
K Vijai
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Modulus Of Elasticity ◽  
Coarse Aggregate ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Split Tensile Strength ◽  
Coarse Aggregates ◽  
The Cost

The properties of concrete containing coarse recycled aggregates were investigated. Laboratory trials were conducted to investigate the possibility of using recycled aggregates from the demolition wastes available locally as the replacement of natural coarse aggregates in concrete. A series of tests were carried out to determine the density, compressive strength, split tensile strength, flexural strength and modulus of elasticity of concrete with and without recycled aggregates. The water cement ratio was kept constant for all the mixes. The coarse aggregate in concrete was replaced with 0%, 20%, 40%, 60%, 80% and 100% recycled coarse aggregates. The test results indicated that the replacement of natural coarse aggregates by recycled aggregates up to 40% had little effect on the compressive strength, but higher levels of replacement reduced the compressive strength. A replacement level of 100% causes a reduction of 28% in compressive strength, 36% in split tensile strength and 50% in flexural strength. For strength characteristics, the results showed a gradual decrease in compressive strength, split tensile strength, flexural strength and modulus of elasticity as the percentage of recycled aggregate used in the specimens increased. 100% replacement of natural coarse aggregate by recycled aggregate resulted in 43% savings in the cost of coarse aggregates and 9% savings in the cost of concrete.

Investigation of the mechanical properties of concrete containing recycled aggregate and scrap crumb rubber and polypropylene fibers

2020 ◽  
pp. 147776062097750
Author(s):  
Moein Khoshroo ◽  
Ali Akbar Shirzadi Javid ◽  
Nima Rajabi Bakhshandeh ◽  
Mohamad Shalchiyan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Polypropylene Fiber ◽  
Crumb Rubber ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Fine Aggregate ◽  
Mixture Ratio ◽  
Coarse Aggregates

In this study, the effect of using crumb rubber and recycled aggregates on the mechanical properties of concrete has been evaluated as areplacement of fine and coarse aggregates In order to add the admixtures and evaluate their combined effect, 20 different types of concrete mixture ratio were prepared. The results indicated that in those samples containing crumb rubber and recycled aggregates the compressive strength is reduced and adding fiber up to 0.1%. to these concrete samples can improve the compressive strength Also, the tensile strength of the samples mixed with crumb rubber and recycled aggregates were decreased, and with the addition of propylene fiber up to 0.4%. the tensile strength slightly increased Moreover by adding the crumb rubber to the samples the elasticity modulus was reduced but by adding fiber to samples about 0.1% and 0.2.% the modulus of elasticity of concrete in all samples were increased. According to the results, it can be said that using the combination of 5% of crumb rubber as a replacement of fine aggregate, and the combination of 35% of recycled aggregates as a replacement of coarse aggregate, and also by adding 0.1% polypropylene fiber in volumetric percentage of concrete along with adding 7% of micro silica as a replacement of cement led to the best effect on the mechanical properties of concrete.

Experimental Study on Compressive Strength of Recycled Aggregate Concrete with Different Replacement Ratios

2012 ◽  
Vol 174-177 ◽  
pp. 1277-1280 ◽  
Author(s):  
Hai Yong Cai ◽  
Min Zhang ◽  
Ling Bo Dang
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Failure Mode ◽  
Failure Process ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Replacement Ratio ◽  
Aggregate Concrete

Compressive strengths of recycled aggregate concrete(RAC) with different recycled aggregates(RA) replacement ratios at 7d, 28d, 60d ages are investigated respectively. Failure process and failure mode of RAC are analyzed, influences on compressive strength with same mix ratio and different RA replacement ratios are analyzed, and the reason is investigated in this paper. The experimental results indicate that compressive strength of recycled concrete at 28d age can reach the standard generally, it is feasible to mix concrete with recycled aggregates, compressive strength with 50% replacement ratio is relatively high.

scholarly journals Internal Curing Effect and Compressive Strength Calculation of Recycled Clay Brick Aggregate Concrete

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1815
Author(s):  
Feng Chen ◽  
Kai Wu ◽  
Lijian Ren ◽  
Jianan Xu ◽  
Huiming Zheng
Keyword(s):  
Compressive Strength ◽  
Recycled Aggregate Concrete ◽  
Strength Calculation ◽  
Internal Curing ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Clay Brick ◽  
Significant Drop ◽  
Aggregate Concrete ◽  
Curing Age

In order to investigate the internal curing effect of recycled brick aggregate (RBA) in recycled aggregate concrete (RAC) and calculate its contribution to the final compressive strength, two RAC groups with different recycled aggregates and 6 replacement ratios (r) under 4 curing ages were tested. Results show that the compressive strengths of RACI and RACII decrease steadily with the increase of r when below 40%, and that there is a significant drop once the r is higher than 60%. The internal curing effect for RAC with a low RBA ratio is mainly reflected during the curing age of 14–21 days, while for RAC with a high RBA ratio, this internal curing effect appears earlier, during 7–14 days, and becomes very obvious after 14 days. In addition, the actual tested compressive strength of RAC replaced by 100% RBA exceeds around 40% of the expected compressive strength at the age of 28 days. When the age of RAC entirely with RBA is 28 days, the compressive strength caused by the internal curing effect accounts for around 28% of the actual tested compressive strength. The most appropriate r of RBA for RAC production is between 40% to 60%. Finally, the equations for calculating the compressive strength of RAC are presented considering the curing ages, the replacement ratios and the internal curing effect of RBA. Further, a unified equation is suggested for convenience in calculation.

scholarly journals Reusing of Construction Debris in Plain Concrete Elements

2021 ◽  
Vol 9 (3) ◽  
pp. 81-87
Author(s):  
A. Abdelrahman Abuserriya ◽  
B. Bashir H. Osman ◽  
C. Salma Y. Mahmoud
Keyword(s):  
Compressive Strength ◽  
Sea Water ◽  
Plain Concrete ◽  
Absorption Capacity ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Content ◽  
Concrete Production ◽  
Concrete Blocks

Construction is a serious environmental problem and a challenge for people who concerned with sustainability in the construction field. Previous studies showed positive results for the use of recycled aggregates in the concrete production. This study portrays the results for utilizing construction debris for casting different types of concrete blocks. The recycled concrete debris was used in different ratios (0%, 50%, and 100%) in replacement for natural coarse aggregates for different targeted compressive strength (B250, B300, B350 and B400). Two types of water (pure and sea water) were used for curing the blocks. In addition, hollow block and paving block were casted with different ratios of recycled aggregate (0%, 20%, 45% and 100%) and cured with two types of water. The results showed a decrease in compressive strength with the increase recycled aggregate content. It was also noticed that the absorption capacity increases with high recycled aggregate content.  

scholarly journals Recycled aggregate amount variation of fraction 4/8 mm and 8/16 mm in the concrete mixture

2020 ◽  
Vol 15 (2) ◽  
pp. 49-54
Author(s):  
Jozef Junák ◽  
Natália Junáková
Keyword(s):  
Compressive Strength ◽  
Reference Sample ◽  
Point Of View ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Economic Point ◽  
Aggregate Fractions ◽  
Aggregate Amount

AbstractThe introductory part of the paper is devoted to the classification of aggregates according to various criteria, one of them is the geographical origin of aggregates. From the point of view of the circular economy, the use of recycled aggregates comes to the fore, mainly from the ecological point of view but also from the economic point of view.The paper summarizes the results of research focused on the variation of the amount of 2 Recycled concrete aggregate fractions in concrete, followed by an evaluation of the effect of the presence of recycled material in the mixture on the selected property, specifically compressive strength. The highest compressive strength 34.7 MPa after 28 days hardening reached sample containing 100% recycled fraction 4/8 mm, and 60% recycled fraction 8/16 mm. This value is only slightly different from the compressive strength of the reference sample (34.4 MPa).

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