This manuscript presents a review of the potential and challenge of using recycled concrete aggregate (RCA) as the substitute for natural aggregate (NA) in concrete mixtures. Using RCA in concrete preserves the environment by reducing the need for opening new aggregate quarries and decreases the amount of construction waste that goes into landfill. The properties of RCA such as specific gravity, absorption, and the amount of contaminant present in it contribute to the strength and durability of concrete. The quality of RCA depends on the features of the original aggregate and the condition of the demolished concrete. Some researchers have reported that the use of RCA degrades concrete properties while others have successfully produced RCA concrete with a performance that matched normal concrete (NC). In addition to the influence of RCA to concrete properties, this paper also evaluates multiple techniques to improve the performance of RCA concrete, reported cost savings in concrete production and recommendations regarding the application of RCA in concrete.

Properties of recycled concrete aggregate and their influence in new concrete production

Green concrete: Prospects and challenges

Effect of incorporation of high volume of recycled concrete aggregates and fly ash on the strength and global warming potential of concrete

This paper presents a literature review and experimental results on the effect of high incorporation levels of fly ash (FA) and recycled concrete aggregates (RCA), individually and jointly, on the pore system of concrete that remarkably influences its durability. For that purpose, apart from an extensive literature review, three tests were performed, including electrical resistivity (ER) test, which indirectly measures the interconnected porosity of concrete, and water absorption (WA) by capillarity and immersion tests that both depend on the pores number and size but in a different way. A comparison between the experimental results and the literature is also presented to show the main findings and the research needs. The results show that WA increases and ER decreases with increasing incorporation level of RCA, and the opposite occurs with the addition of FA for both tests. The reduction percentage of WA was higher in mixes with both RCA and FA when compared to the sum of reductions in mixes with only RCA or FA. Thus, it is advisable to produce concrete with both mentioned non-traditional materials in terms of WA and ER of concrete. In addition, the benefit of incorporating of FA and RCA in concrete increased even more when superplasticizers was used.

Davoud Jafari

Papers

RETRACTED: Comparative study on effects of Class F fly ash, nano silica and silica fume on properties of high performance self compacting concrete