Comparing mechanical properties of concrete with recycled aggregates using different mixing methods

This study addresses the growing use of recycled coarse aggregate (RA) from construction and demolition waste (CDW) as a sustainable alternative in concrete production. It evaluates the influence of varying RA by 0%, 25%, 50%, 75% and 100% by natural coarse aggregate (NA) on the mechanical properties of M20 grade concrete. Additionally, the study compares four mixing methods: Normal Mixing Approach (NMA), Treated Aggregate Mixing Approach (TAMA), Two-Stage Mixing Approach (TSMA), and Mortar Mixing Approach (MMA). Results reveal that increasing RA content reduces the workability and strength of recycled aggregate concrete (RAC). The performance in workability, compressive strength, splitting tensile strength, and flexural strength of RAC by four mixing methods was compared. Among them, TSMA showed significant improvement of 27.27, 15.55, 9.3, and 12.22% compared to NMA for a 100% RA mix. TSMA enhances these properties by promoting better mortar coverage around aggregate particles, reducing pores and strengthening the interfacial transition zone. This study highlights that optimizing mixing techniques can improve RAC's performance, making it an environmentally responsible option for the construction industry.