Frost Resistance of Recycled Aggregate Concrete: A Critical Review

Recycled aggregate concrete (RAC) offers a green, sustainable answer to handle the increasing pile-up of construction and demolition waste. However, a big issue, especially in colder areas, is the durability of RAC against freeze-thaw cycles (FTCs). This paper rolls out a systematic literature review concerning RAC’s frost resistance. It examines how RAC gets worn down during FTCs, focusing on the underlying deterioration mechanisms. Then, key factors impacting RAC’s frost resistance are identified, including the type of recycled aggregate (RA), the characteristics of parent concrete, the replacement ratio, the moisture state of RA, and the coupling effects between FTC and other factors (such as mechanical loading, salt solution, dry-wet cycles, carbonation, among others). Approaches to enhance RAC’s frost resistance are categorized into two main strategies: improving the RA itself and upgrading the new mortar mix. The paper also scopes out the current models for predicting RAC’s freeze-thaw durability, looking at both models driven by the mechanisms and those crunched by data. Beyond that, real-world challenges and what is next in the research pipeline are discussed. Those include: nailing down a standard method to gauge RA’s frost resistance, uncovering how compressive stress affects RAC’s frost resistance, developing eco-friendly, cost-effective ways to improve RAC’s durability, and widening the experimental data pool on RAC’s frost resistance.