scholarly journals Factorial Design for Studying the Properties of Recycled Aggregate Concrete Exposed to Aggressive Media

2021 ◽  
Vol 9 (ICRIE) ◽  
Author(s):  
Ammar Ali Abed ◽  
◽  
Ibtisam Mustafa Kamal ◽  
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
Standard Procedure ◽  
Operating Parameter ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Fine Aggregate ◽  
Aggregate Concrete ◽  
Immersion Period ◽  
The Impact

Recycled Aggregate Concrete (RAC) mixes (1.15: 2.3: 4.6) cement: fine aggregate (sand): coarse aggregate (demolition concrete waste), water / cement (0.5), and 50 % demolition aggregates were prepared according to standard procedure. The resistance of the recycled aggregate concretes towards chemicals was investigated throughout the attack of (Acid: acetic Acid HAC, and salt: Sodium Chloride NaCl) solutions. The test was carried out based on adopted experiments designed using Response Surface Methodology (RSM). A 2-operating parameter central composite design was adopted to study the impact of concentration of the HAC and NaCl solutions (0.1-0.45) Molar, and immersion period (0.57-6.9) day of the (RACs) specimens on weight loss, compressive strength and density. The results obtained confirmed that weight loss increases, but both compressive strength and density decreases after the aggressive solutions attack, however HAC seemed more aggressive. The decrease in compressive strength was (2.8-42) % and (3.2-10.8) %, while the decrease in density was (0.72-2.05) % and (0.6-1.8) % for the samples immersed in HAC and NaCl solutions respectively. The mathematical models presenting the effect of concentration of the aggressive media and immersion duration on weight loss, compressive strength and density were estimated, and the effects were optimized and modeled. The Analysis of Variance (ANOVA) revealed that an optimum compressive strength (37.8 and 34.8) MPa is obtained for the RACs immersed for 0.56 day at 0.1 Molar HAC and NaCl respectively.

scholarly journals Compressive Strength Study on the Freeze-thaw Resistance of Recycled Aggregate Concrete Members

2017 ◽  
Vol 11 (1) ◽  
pp. 270-280 ◽  
Author(s):  
Haicheng Niu ◽  
Yonggui Wang ◽  
Xianggang Zhang ◽  
Xiaojing Yin
Keyword(s):  
Compressive Strength ◽  
Mass Loss ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Fine Aggregate ◽  
Replacement Rate ◽  
Aggregate Concrete ◽  
Freeze Thaw ◽  
Surface Scaling

Introduction: Freeze-thaw resistance of recycled aggregate concrete with partial or total replacement of recycled aggregate compared with that of natural aggregate concrete was investigated in this paper. Method: Ninety specimens were fabricated to study the influence of different recycled aggregate replacement ratios on the surface scaling, mass loss, and residual compressive strength after 100 freeze-thaw cycles. Results: The experiment results indicate that the type of recycled aggregate and its replacement ratio have significant effects on the freeze-thaw performance. The cubic compressive strength of recycled aggregate concrete is overall slightly lower than that of normal concrete. After 100 freeze-thaw cycles, the compressive strength decreases and the reduction extent increases with increasing replacement rate of recycled aggregate. The surface scaling of reinforced recycled concrete prisms tends to be more severe with the increase of freeze-thaw cycles. Conclusion: Furthermore, a notable rise in mass loss and the bearing capacity loss is also found as the substitution ratio increases. Under the same replacement rate, recycled fine aggregate causes more negative effects on the freeze-thaw resistance than recycled coarse aggregate.

The Comparison of Properties of Fine Recycled Aggregate Concrete from Different Sources of Recycled Aggregate

2018 ◽  
Vol 760 ◽  
pp. 176-183 ◽  
Author(s):  
Tereza Pavlů
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Aggregate Concrete ◽  
Freeze Thaw ◽  
Concrete Properties ◽  
Different Sources

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.

scholarly journals Compressive Strength of Concrete with Recycled Concrete Aggregate as Coarse Aggregate and Recycled Paving Block Aggregate as Fine Aggregate Partially Substituted by Recycled Brick Aggregate

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Idi Priyono ◽  
Meiske Widyarti, Erizal
Keyword(s):  
Compressive Strength ◽  
Residential Buildings ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Fine Aggregate ◽  
Aggregate Concrete ◽  
Concrete Mix

An excessive extraction of natural resources for aggregate in concrete mix can caused an environmental degradation.  According to Indonesia ministry of industry in 2017, the use of cement is predicted will reach 84,96 million tons, that can affected the use of aggregate for concrete mix are quadruplet to 250 – 350 million tons. Opimally, the use of recycled material is green method that can reduce an excessive extraction of natural aggregates and keep an environmental sustain. The aim of this study is to obtain recycled aggregate concrete compressive strength and examine recycled aggregate concrete quality in days 3, 7, 28, 35, and 90 along with a proposal of the use of recycled aggregate concrete as a building construction material. This research used experimental method of SNI 03-2834-2002 the standard of normal concrete mix design for f’c 25 MPa then built five types of concrete mix of REC B, REC C, REC D, REC E, and REC F with every types of concrete has four sample are used for compressive strength test. The fine recycled paving block aggregate (RPA) were used partially to substituted a fine recycled brick aggregate (RBA) at 0%, 25%, 50%, 75%, and 100% by weigth. The result of this study showed the mixed concrete REC D with RCA 100%, RPA 50% and RBA 50% in 28 days is generate highest compressive strength than other recycle aggregates concrete mixes. Compressive strength at 28 days in a mix codes REC B, REC C, REC D, REC E and REC F are 18,12 MPa; 18,36 MPa; 19,35 MPa;16,69 MPa; and 16,39 MPa. The results show that it is feasible to replace a natural aggregate entirely by recycled aggregates. With compressive strength over 17 MPa at 28 days, mix codes REC B, REC C and REC D are recommended to use the recycled aggregate concrete for structure of residential buildings but mix codes REC E and REC F aren’t recommended and only allowed for non-structural concrete such as separate wall (SNI 8140:2016). Based on SNI 03-0691-1996 about solid brick concrete (paving block), recycle aggregate concrete with mix code of REC B, REC C, and REC D are able to use on paving block with B quality such as parking lot. While, recycled aggregate concrete with mix code of REC E and REC F are able to use on paving block with C and D quality which used for pedestrian, garden and other use. 

scholarly journals Experimental Study on the Mechanical Properties and Compression Size Effect of Recycled Aggregate Concrete

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2323
Author(s):  
Yubing Du ◽  
Zhiqing Zhao ◽  
Qiang Xiao ◽  
Feiting Shi ◽  
Jianming Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Size Effect ◽  
Compressive Stress ◽  
Failure Modes ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Substitution Ratio ◽  
The Impact

To explore the basic mechanical properties and size effects of recycled aggregate concrete (RAC) with different substitution ratios of coarse recycled concrete aggregates (CRCAs) to replace natural coarse aggregates (NCA), the failure modes and mechanical parameters of RAC under different loading conditions including compression, splitting tensile resistance and direct shear were compared and analyzed. The conclusions drawn are as follows: the failure mechanisms of concrete with different substitution ratios of CRCAs are similar; with the increase in substitution ratio, the peak compressive stress and peak tensile stress of RAC decrease gradually, the splitting limit displacement decreases, and the splitting tensile modulus slightly increases; with the increase in the concrete cube’s side length, the peak compressive stress of RAC declines gradually, but the integrity after compression is gradually improved; and the increase in the substitution ratio of the recycled aggregate reduces the impact of the size effect on the peak compressive stress of RAC. Furthermore, an influence equation of the coupling effect of the substitution ratio and size effect on the peak compressive stress of RAC was quantitatively established. The research results are of great significance for the engineering application of RAC and the strength selection of RAC structure design.

Recycling of Waste Concrete and Fly Ash for Recycled Aggregate Concrete: Fundamental Characteristics Evaluation

2009 ◽  
Vol 620-622 ◽  
pp. 255-258 ◽  
Author(s):  
Cheol Woo Park
Keyword(s):  
Fly Ash ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Experimental Program ◽  
Concrete Aggregate ◽  
Fine Aggregate ◽  
Recycled Concrete Aggregate ◽  
Aggregate Concrete ◽  
Waste Concrete

As the amount of waste concrete has been increased and recycling technique advances, this study investigates the applicability of recycled concrete aggregate for concrete structures. In addition fly ash, the industrial by-product, was considered in the concrete mix. Experimental program performed compressive strength and chloride penetration resistance tests with various replacement levels of fine recycled concrete aggregate and fly ash. In most case, the design strength, 40MPa, was obtained. It was known that the replacement of the fine aggregate with fine RCA may have greater influence on the strength development rather than the addition of fly ash. It is recommended that when complete coarse aggregate is replaced with RCA the fine RCA replacement should be less than 60%. The recycled aggregate concrete can achieve sufficient resistance to the chloride ion penetration and the resistance can be more effectively controlled by adding fly ash. It I finally conclude that the recycled concrete aggregate can be successfully used in the construction field and the recycling rate of waste concrete and flay ash should be increased without causing significant engineering problems.

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.

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