Investigation of the Mechanical Properties of Self-compacting Concretes Containing Mineral Additives Produced by Substituting Fine Recycled Aggregate in Different Rates

Abstract

In the study, the effect of fine recycled concrete aggregate (FRCA) replaced by natural fine aggregate on some mechanical properties of self-compacting concrete (SCC) containing different types and amounts of mineral additives was evaluated. In the concretes produced for this purpose, natural fine aggregate was replaced with FRCA at the ratios of 35%, 70% and 100% by weight. For comparison, concretes without FRCA were also produced. Three different mineral additives, namely fly ash (FA), metakaolin (MK) and silica fume (SF), were used in different ratios. In order to determine the fresh state properties of concretes, unit weight, slump-flow, T₅₀₀ time, J-ring and sieve segregation tests were carried out, while compressive strength, splitting tensile strength, flexural strength, Böhme abrasion and dynamic elasticity modulus determination tests were carried out on hardened concretes. Based on the findings obtained, there is no significant adverse effect on the mechanical properties of concrete with 35% FRCA replacement. However, when FRCA is used at higher ratios, the negative effect on mechanical properties becomes evident. In particular, Böhme abrasion is quite high at high FRCA replacement ratios. Provided that the conditions in which the research was carried out are valid, the negative effects of FRCA substitution on the mechanical properties of concrete can be eliminated by changing the type and combination ratios of mineral additives used.