Some Remarks towards a Better Understanding of the Use of Concrete Recycled Aggregate: A Review

Abstract

Research on recycled concrete aggregates (RCAs) has been progressively advanced. Beyond replacing natural aggregates with RCA, discussions have been held on the effect of the parent concrete and repeatedly recycled aggregate concrete. Although it has been reported that RCA can be technically used for structural concrete, due to several other factors, RCA is mainly used for sub-bases. Therefore, identifying these factors is the key to promoting the use of RCA. Therefore, this review study first briefly summarizes the physical and chemical characteristics of RCA compared to natural aggregate, and reviews the effects of parent concrete and repeatedly recycled aggregate on next generation concrete. This study also briefly discusses the RCA standards of various countries and the factors that hinder the widespread use of RCA. The results show that there is a correlation in properties between parent concrete and the next generation concrete, and the properties of concrete decrease when RCA is used repeatedly. In addition, on the basis of the literature review, factors hindering the use of RCA were found to be unstable supply and demand, economic feasibility, and negative perceptions.

An Experimental Study on Structural Concrete Containing Recycled Aggregates and Powder from Construction and Demolition Waste

“…In addition, technologies and methods for improving the performance of recycled aggregate concrete (RAC) have been developed mainly based on RCA. Therefore, the knowledge system on the effects of RCA on concrete is well-established [ 13 , 14 ], and guidelines for the use of RCA have been suggested by several countries [ 8 , 15 , 16 ]. Some researchers pointed out that research on concrete recycling has been relatively limited to RCA [ 17 , 18 ].…”

Scaled concrete beams containing maximum levels of coarse recycled aggregate: Structural verifications for precast‐concrete building applications

“…However, these aspects were partially compensated by increasing the amount of plasticizing admixtures. Regarding mechanical behavior, the difference in compressive strength between both mixes was minimal, with mix CR even showing a higher strength than mix C at 180 days (62.4 vs. 59.9 MPa). A behavior made possible due to the non‐modification of the water content when adding coarse RA, which balanced the expected decrease in strength, 21 as well as due to the good mechanical strength of the parent concrete 55 . Both mixes were designed to have practically identical compressive strengths, so the structural‐feasibility analysis was focused on the aggregate type and not on the compressive strength of SCC. The mix‐design strategy was not as effective in relation to splitting tensile strength, although the difference between the two mixes remained small (less than 5%).…”

“…Thus, the parent concrete of the RA could be considered of a high quality. 55 Company machinery was used to produce the RA, by means of hydraulic clamping, followed by jaw and impact crushing. Finally, sieving produced a coarse RA 4/12.5 mm.…”

“…A behavior made possible due to the non-modification of the water content when adding coarse RA, which balanced the expected decrease in strength, 21 as well as due to the good mechanical strength of the parent concrete. 55 Both mixes were designed to have practically identical compressive strengths, so the structural-feasibility analysis was focused on the aggregate type and not on the compressive strength of SCC. • The mix-design strategy was not as effective in relation to splitting tensile strength, although the difference between the two mixes remained small (less than 5%).…”

“…The RA was produced from precast‐concrete beams and columns manufactured at the precast company plant with compressive strengths higher than 45 MPa that had been rejected due to faulty sizes or geometrical defects. Thus, the parent concrete of the RA could be considered of a high quality 55 . Company machinery was used to produce the RA, by means of hydraulic clamping, followed by jaw and impact crushing.…”