Influence of mix composition on the properties of recycled aggregate concrete

Abstract

There is an increasing trend towards using recycled aggregate (RA) in concrete due to the shortage of high quality natural aggregates. The use of RA in concrete results in the conservation of natural resources, protects the environment and encourages sustainable construction. Though some studies have been conducted on the use of recycled aggregate concrete (RAC), the effect of mixture composition on its properties has not been well addressed. In the reported study, the effect of mixture composition, namely cement content and water/ cement ratio and the proportion of RA on the mechanical properties of RAC was evaluated, with the intention of developing varying grades of RAC. As reported in earlier studies, the properties of RAC were generally inferior to that of normal aggregate concrete (NAC). Notwithstanding this, RAC with acceptable mechanical properties can be produced utilizing RA, for example RAC with low strength can be used in non-structural applications. The construction industry should be encouraged to use RAC in building construction; as its use will lead to technical, economic and environmental benefits. Further, the use of RAC will lead to a sustainable development of the construction industry, particularly in regions that lack good quality natural aggregates.Based on the data developed in the reported study, the following quantities of RA are recommended to produce RAC: (i) 20% to produce low strength (20--30 MPa) concrete, (ii) 40% to produce medium (30-50 MPa) concrete and high strength (more than 50 MPa) concrete. Mathematical correlations between the mechanical properties of RAC with varying mix design parameters, such as cement content and water cement ratio and the quantity of RA, are also reported. These correlations can be used to predict the properties of RAC prepared with other proportions of RA and mix design parameters.bond strength, compressive strength, mixture proportions, modulus of elasticity, morphology, recycled aggregate concrete, tensile strength Discussion on this paper must be submitted within two months of the print publication. The discussion will then be published in print, along with the authors' closure, if any, approximately nine months after the print publication.

Punching shear capacity of flat slabs with recycled aggregate

“…Reductions in both the compressive and tensile strengths occurred when the RCA amount increased because of the presence of attached cement mortar in RCA which has a lower strength than that of NCA. The results revealed that RCA can be efficiently used with a percentage of up to 30% as it has an insignificant effect on the compressive strength of concrete, as previously concluded in several studies (Bidabadi et al , 2020) and (Zaben et al , 2021). However, the concrete with RCA of 70% suffered from a significant reduction in the compressive strength, which might not be inappropriate for some applications.…”

Retracted: Predicting the compressive strength of modified recycled aggregate concrete

“…In addition to the destruction of natural resources, it imposes a lot of solid waste in the environment. 19,29,32,33,38,39,42,56,62 Abbreviations: AC, curing age; ADR, additive regression; B, total binder; BAG, bagging predictors; CA, coarse aggregate; CS, compressive strength; DT, decision table; GF, glass fiber; GPR, Gaussian process regression; LWL, locally weighted linear; M5R, M5-Rules; MLP, multilayer perceptron; RA, recycled aggregates; RAC, recycled aggregate concrete; REPT, reduced-error pruning tree; RF, random forest; SF, silica-fume; SSD, saturated surface dried; SVR, support vector regression; W, water.…”

“…Most of the solid waste of countries is usually caused by construction and demolition in the construction industry. In addition to the destruction of natural resources, it imposes a lot of solid waste in the environment 19,29,32,33,38,39,42,56,62 …”

Microstructural analysis of recycled brick aggregate concrete modified by silane

“…RAC has great application potential. 2 However, Noaman et al 3 found that compared with natural aggregate (NA), RA has smaller density and higher water absorption. Cachim 4 also pointed out that RA could be used as partial replacement of NAs in concrete without reduction of concrete properties for 15% replacement and with reductions up to 20% for 30% replacement.…”

“…RBA and RCA are called recycled aggregate (RA), RBAC and RCAC are called recycled aggregate concrete (RAC). RAC has great application potential 2 . However, Noaman et al 3 found that compared with natural aggregate (NA), RA has smaller density and higher water absorption.…”