scholarly journals Behaviour of recycled aggregate concrete under combined compression and shear stresses

2018 ◽  
Vol 68 (331) ◽  
pp. 162
Author(s):  
K. Liu ◽  
J. Yan ◽  
C. Zou
Keyword(s):  
Failure Criterion ◽  
Coarse Aggregate ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Shear Stresses ◽  
Aggregate Concrete ◽  
Model Code ◽  
Eurocode 2 ◽  
Model Code 2010 ◽  
Normal Strength

To investigate the behaviour of recycled aggregate concrete (RAC) under combined compression and shear stresses, 75 hollow cylinder specimens prepared with various replacement ratios of recycled coarse aggregate (RCA) were tested with a self-designed loading device. The results showed that the failure pattern was similar for RAC with different replacement ratios of RCA. The ultimate shear stress improved with an increasing axial compression ratio of less than 0.6 and declined after exceeding 0.6. A modified failure criterion for RAC with normal strength under combined compression and shear stresses was proposed. A new procedure to predict the shear strength for RAC beams without stirrups was developed based on the proposed failure criterion, showing a better correlation with the experimental results than the predictions calculated by GB50010, Eurocode 2, fib Model Code 2010 and ACI 318-11.

Mechanical properties of recycled aggregate concrete under multiaxial compression

2020 ◽  
Vol 23 (12) ◽  
pp. 2529-2538
Author(s):  
Yumei Wang ◽  
Zhiheng Deng ◽  
Jianzhuang Xiao ◽  
Jun Sheng
Keyword(s):  
Mechanical Properties ◽  
Stress State ◽  
Failure Criterion ◽  
Stress Ratio ◽  
Coarse Aggregate ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Replacement Ratio ◽  
Aggregate Concrete ◽  
Multiaxial Compression

The mechanical properties of recycled aggregate concrete under multiaxial compression were tested by servo-controlled setup (TAWZ-5000/3000). Properties of strength and stress–strain relation were obtained, and the influence factors of stress ratio and recycled coarse aggregate replacement ratio were analyzed. The results show that the strength of recycled aggregate concrete under multiaxial compression is higher than that of under uniaxial state, the stress ratio and recycled coarse aggregate replacement ratio have obvious effect on strength, and the shape of stress–strain curve is also varied with different levels of the two factors. Failure criterion can reflect the strength relation for recycled concrete under multiaxial stress state. Kupfer’s failure criterion is selected to describe strength properties under biaxial stress state, and the failure envelope reflects the energy absorption of different mix series. Based on octahedral stress theory, the tensile and compressive meridians have been proposed to analyze the strength characteristics under triaxial compression, and the theoretical values are well coherent with the test data.

scholarly journals Recycled Aggregate Concrete including Various Contents of Metakaolin: Mechanical Behavior

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Khaleel H. Younis ◽  
Abdulfattah A. Amin ◽  
Hemin G. Ahmed ◽  
Shelan M. Maruf
Keyword(s):  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Modulus Of Elasticity ◽  
Coarse Aggregate ◽  
Recycled Aggregate Concrete ◽  
Construction And Demolition Waste ◽  
Recycled Aggregate ◽  
Demolition Waste ◽  
Aggregate Concrete ◽  
Eurocode 2

This experimental research investigates the effect of utilizing metakaolin (MK) on the behavior of recycled aggregate concrete (RAC). The RAC incorporates recycled coarse aggregate (RCA) originated from crushing construction and demolition waste. The investigated parameters were RCA and MK contents. Tests of workability and mechanical properties such as compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity were conducted to evaluate the influence of MK on workability and mechanical behavior of RAC. In total, 19 mixes were prepared. These mixes are divided into four groups. Group zero (G0) includes a reference mix containing normal coarse aggregate (NCA) and 3 mixes made with 35%, 70%, and 100% of RCA. Each one of the other three groups (G1, G2, and G3) was made with one content of the three contents of RCA, and each group includes five mixes made with the contents of 4%, 8%, 12%, 16%, and 20% of MK. Empirical models among the mechanical properties of the RAC mixes were developed and compared with models of standard codes of practice such as ACI 318, BS 8110, and Eurocode 2. It was found that MK reduces the workability of the RAC mixes. Nonetheless, the outcomes reveal that MK can improve the compressive, splitting tensile, and flexural strengths and the elastic modulus of RAC. This strength improvement enhances as the content of MK increases. The proposed models for the mechanical properties of RAC made with MK showed good correlations. The developed model for modulus of elasticity is quite close to the Eurocode 2 model, whereas the models of ACI 318 and BS 8110 underestimate the values of the modulus of elasticity.

scholarly journals Prediction of Shear Strength of Reinforced Recycled Aggregate Concrete Beams without Stirrups

2021 ◽  
Author(s):  
Monthian Setkit ◽  
Satjaphan Leelatanon ◽  
Thanongsak Imjai ◽  
Suchart Limkatanyu ◽  
Reyes Garcia
Keyword(s):  
Shear Strength ◽  
Shear Failure ◽  
Coarse Aggregate ◽  
Concrete Beams ◽  
Reduction Factor ◽  
Recycled Aggregate Concrete ◽  
Reinforced Concrete Beams ◽  
Recycled Aggregate ◽  
Shear Stresses ◽  
Aggregate Concrete

The brittle shear failure of reinforced concrete beams is complexed and unfavorable. For decades, research on the mechanical properties and durability of recycled coarse aggregate (RCA) to make recycled aggregate concrete (RAC) has been widely investigated. However, test results on the shear strength of reinforced recycled aggregate concrete beams are still limited and contradictory. This paper reports the shear strength of reinforced recycled aggregate concrete beams without stirrups. Eight RAC beams and two controlled beams with natural coarse aggregate (NCA) were tested under the four-point flexural test with the shear span-to-effective depth ratio (a/d) of 3.10. Parameters in this study were the replacement percentage of RCA (0%, 25%, 50%, 75%, and 100%) and longitudinal reinforcement ratio (w) of 1.16% and 1.80%. It was found that the normalized shear stresses of RAC beams with w = 1.80% at all levels of replacement percentage were quite similar to that of the NAC counterparts. Normalized shear stress of the beam with 100% RCA and w = 1.16% was lower than that of the NAC beam by 5%. Database of 128 RAC beams without shear reinforcement from literature was analyzed to evaluate the ability of the most recent ACI 318-19 shear provisions in shear strength prediction. A reduction factor of 0.75 is proposed to the current ACI code provision to account for the physical variations of RCA such as replacement percentage, RCA source and quality, density, amount of residual mortar, and physical irregularity.

Study on Performance of Recycled Aggregate Concrete

2011 ◽  
Vol 477 ◽  
pp. 280-289 ◽  
Author(s):  
Shao Wei Yao ◽  
Zhen Guo Gao ◽  
Chang Rui Wang
Keyword(s):  
Mechanical Properties ◽  
Coarse Aggregate ◽  
Physical And Mechanical Properties ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Chemical Solution ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Natural Aggregate ◽  
Strength And Durability

The properties of recycled coarse aggregate and the slump, the physical and mechanical properties and durability of recycled aggregate concrete were studied through tests. The results indicate that the slump, compressive strength and durability of concrete with recycled aggregate are lower than that of concrete with natural aggregate when recycled coarse aggregate fully absorbs water. However, the slump can be similar to that of concrete with natural aggregate. The properties of recycled aggregate concrete can be improved by strengthening the recycled coarse aggregate, and it is also found that the recycled coarse aggregate strengthened by grinding is superior to that soaked by chemical solution.

Experimental Study on Compressive Strength of Recycled Aggregate Concrete

2008 ◽  
Vol 385-387 ◽  
pp. 381-384 ◽  
Author(s):  
Wei Wang ◽  
Hua Ling ◽  
Xiao Ni Wang ◽  
Tian Xia ◽  
Da Zhi Wang ◽  
...  
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Coarse Aggregate ◽  
Recycled Aggregate Concrete ◽  
Time Dependent ◽  
Recycled Aggregate ◽  
Experimental Investigations ◽  
Aggregate Concrete ◽  
Cement Ratio ◽  
Practical Engineering

With the increase in the use of recycled aggregate concrete (RAC), it is necessary to clearly understand its behavior and characteristics. In this paper, experimental study on compressive strength of RAC with same water/cement ratio is conducted. Firstly, influence of recycled coarse aggregate contents on cube compressive strength of RAC is studied. Secondly, experiment on time-dependent strength developing process of RAC is conducted with different solidification ages. Finally, based on above experimental investigations, empirical formula for compress strengths of RAC with different ages is presented. The result of this paper is helpful to theoretical analysis and practical engineering design of RAC structures.

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