scholarly journals Verification of a Torsional Behaviour Prediction Model for Reinforced Recycled Aggregate Concrete Beams

2022 ◽  
Vol 2022 ◽  
pp. 1-13
Author(s):  
Aqeel H. Chkheiwer ◽  
Mazin A. Ahmed ◽  
Zahir M. N. Hassan

This study shows the torsional conduct of aggregate streaming beams of reinforced concrete recycling. Pure torsion was perceived for 15 reinforced concrete beams containing recycled concrete aggregates. The beams were grouped into five lengths and cross-sectional groups. The study’s principal parameters were the various percentages of longitudinal steel reinforcement and the proportions of recycled aggregates. The beams were purely twisted until failure and investigated for torsional and crack behaviour. The findings show that the beams with maximum steel enhancement and standard aggregate exhibited maximum cracking power and ultimate torsional strength. Recycled aggregates increased the presence of splitting and the ultimate strength, and the effects of steel strengthening in recycled beams were apparent. In a second analysis, the whole torsional reaction of the beams was analytically predicted. A soft truss model was used and matched with test results for standard beams. A strong compromise was generally reached.

2012 ◽  
Vol 517 ◽  
pp. 601-605
Author(s):  
Zhao Hua Du ◽  
Tong Hao ◽  
Li Xin Liu

This paper presents the test results of 6 reinforced concrete beams with recycled aggregates of construction waste under flexure, the beams were made of two strength grade concrete of and with different recycled aggregate replacement rate. The results indicate: the ultimate bearing capacity of recycled concrete beams with natural aggregate concrete beams are almost the same, and can meet the requirements of chinese code; The cracking resistance of the reinforced recycled concrete beams is slightly less than that of the beams with natural aggregates, the influence of recycled aggregate replacement rate to cracking resistance is not obvious. Recycled concrete beam crack load the calculated value is greater than the measured value, should carry out the theoretical value adjustment. Reinforced concrete beams is one of concrete structures, its the most common and most important component, Study of flexural property of reinforced concrete for recycled concrete structure component in the popularization and application to have the important significance [. This paper presents the test results of 6 reinforced concrete beams with recycled aggregates of construction waste under flexure, the beams were made of two strength grade concrete of C30 and C40 and with different recycled aggregate replacement rate of 0%, 50% and 70%. These results may be as a reference for the application of the concrete with recycled aggregates of construction waste in engineering [2,3,.


2019 ◽  
Vol 262 ◽  
pp. 06010
Author(s):  
Marek Węglorz ◽  
Andrzej Ajdukiewicz ◽  
Alina Kliszczewicz

Assessment of recycled aggregate concrete (RAC) properties by laboratory tests is still required due to lack of precise guidelines and with taking into account slightly different behaviour of such concretes in comparison with natural aggregate concretes (NAC). It is especially important when recycled concrete aggregates are used for the structural elements. In this paper, the following rules for the whole concrete recycling cycle were defined: (1) rules for examination of original concretes selected for recycling and (2) rules for aggregate preparation and their fractionize as well as design rules for recycled aggregate concrete mixtures (including required tests of recycled aggregates and concrete properties). Requirements towards recycled aggregate concrete formulated in this paper are based on the long term experience and research works on the RAC which were held by A. Ajdukiewicz and A. Kliszczewicz in the Department of Structural Engineering of the Silesian University of Technology, practically since 1995.


2021 ◽  
pp. 136943322110262
Author(s):  
Haiyan Zhang ◽  
Keyue Wan ◽  
Bo Wu ◽  
Zhonghao Hu

Geopolymer recycled aggregate concrete (GRAC) is a new green construction material, which uses geopolymer as the binder and recycled concrete as aggregates. To compare the flexural performance of GRAC and ordinary recycled aggregate concrete (RAC) beams, static loading tests were conducted on seven GRAC beams and three RAC beams. The effects of the replacement ratio of recycled aggregates (RAs), the replacement patterns, and the reinforcement ratio on the flexural behavior of GRAC beams are evaluated. The test data show that the replacement ratio has no significant effect on the cracking pattern, failure mode, or bending capacity of GRAC beams, but the replacement pattern does have an effect. Under a given replacement ratio, replacing only the larger fraction of natural aggregates (NA) with RA improves the concrete strength and crack resistance of both RAC and GRAC beams, compared to that using same replacement percentage for all fractions. Due to the lower elastic modulus and strength of GRAC prepared in this study, the GRAC beams have lower height of neutral axis and greater deflection than RAC beams at the same load level and possess slightly lower cracking load, bending capacity, and ductility. The bending capacity of GRAC beams can be predicted by the formulas proposed for ordinary reinforced concrete beams in the Chinese code GB50010-2010, ACI 318-11, or BS EN 1992-1-1:2004 codes, but the safety margin is generally lower than that of ordinary reinforced concrete beams.


Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 930 ◽  
Author(s):  
Xiaoke Li ◽  
Songwei Pei ◽  
Kunpeng Fan ◽  
Haibin Geng ◽  
Fenglan Li

To promote the engineering application of recycled aggregate for concrete production with good adaptability and economic efficiency, this paper performed a campaign to investigate the flexural performance of steel fiber reinforced composite-recycled aggregate concrete (SFR-CRAC) beams matched with 500 MPa longitudinal rebars. The composite-recycled aggregate has features of the full use recycled fine aggregate and small particle recycled coarse aggregate, and the continuous grading of coarse aggregate ensured by admixing the large particle natural aggregate about 35% to 45% in mass of total coarse aggregate. The properties of SFR-CRAC have been comprehensively improved by using steel fibers. With a varying volume fraction of steel fiber from 0% to 2.0%, 10 beam specimens were produced. The flexural behaviors of the beams during the complete loading procedure were experimentally studied under a four-point bending test. Of which the concrete strain at mid-span section, the appearance of cracks, the crack distribution and crack width, the mid-span deflection, the tensile strain of longitudinal rebars, and the failure patterns of the beams were measured in detail. Results indicated that the assumption of plane cross-section held true approximately, the 500 MPa longitudinal rebars worked at a high stress level within the limit width of cracks on reinforced SFR-CRAC beams at the normal serviceability, and the typical failure occurred with the yield of 500 MPa longitudinal rebars followed by the crushed SFR-CRAC in compression. The cracking resistance, the flexural capacity, and the flexural ductility of the beams increased with the volume fraction of steel fiber, while the crack width and mid-span deflection obviously decreased. Finally, by linking to those for conventional reinforced concrete beams, formulas are suggested for predicting the cracking moment, crack width, and flexural stiffness at normal serviceability, and the ultimate moment at bearing capacity of reinforced SFR-CRAC beams.


2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Haifeng Yang ◽  
Zhiheng Deng ◽  
Yinghong Qin ◽  
Liangsheng Lv

This paper investigated bond-slip characteristics of chloride-induced corroded reinforced concrete incorporating different levels of recycled concrete aggregates (RCA). Pullout tests were adopted to evaluate the bonding and debonding behaviors of the embedded rebar experiencing different corrosion levels. Both high- and low-strength concrete were considered. Bond-slip curves were recorded to determine the influences of rebar corrosion levels and RCA replacements on the bond strength and debonding energy of the specimens. Test results indicate that increasing rebar corrosion level gradually weakens the antisliding ability of reinforced recycled aggregate concrete (RAC) except for a small level corrosion and the degradation rate of ultimate bond strength increases with a decrease of compressive strength at 0.5% rebar corrosion. The results also demonstrate that the ultimate bond strength of reinforced RAC slightly decreases with an increase of RCA replacement. However, the relative bond strength between uncorroded rebar and RAC is little affected by RCA content, while it decreases with an increase of RCA replacement in high-strength specimens after rebar corrosion. The debonding energy between deformed rebar and RAC is found decreasing with the increment of the rebar corrosion level and increasing with an increase of RAC content.


2005 ◽  
Vol 2 (2) ◽  
pp. 49
Author(s):  
Ahmad Ruslan Mohd Ridzuan ◽  
Azmi Ibrahim ◽  
Abdul Manaff Mohd Ismail

The effects of using crushed waste concrete as course aggregates upon compressive strength and carbonation were investigated. Waste concrete cubes, which had been tested for compressive strength in compliance with construction specification, were crushed and utilized as coarse recycled aggregates in new concrete. It is important to mention that, in order to simulate the real life conditions, waste concrete with very minimal information about its originality was used in its natural moisture condition. Tests on the aggregates showed that the recycled concrete aggregates have lower specific gravity and bulk density but have higher water absorption capacity than the natural aggregates. The resistance to mechanical actions such as impact and crushing for recycled concrete aggregates is also lower. Concrete mixes with design strength of 30 N/mm2, 35 N/mm2 and 40 N/mm2 were prepared using this recycled aggregates as coarse aggregates and tested. From the strength point of view the recycled aggregate concrete compared well with natural aggregate concrete. Therefore, it could be considered for various potential applications. With respect to resistance to carbonation the recycled aggregate concrete shows comparable performance.


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