sustainability Review Mechanical Properties and Durability of Polypropylene and Steel Fiber-Reinforced Recycled Aggregates Concrete (FRRAC): A Review Peng Zhang 1 , Yonghui Yang 1, Juan Wang 1,*, Shaowei Hu 1,2, Meiju Jiao 1 and Yifeng Ling 3 1 School of Water Conservancy Engineering, Zhengzhou University, Zhengzhou 450001, China;
[email protected] (P.Z.);
[email protected] (Y.Y.);
[email protected] (S.H.);
[email protected] (M.J.) 2 College of Civil Engineering, Chongqing University, Chongqing 400045, China 3 Department of Civil, Construction and Environmental Engineering, Iowa State University, Ames, IA 50011, USA;
[email protected] * Correspondence:
[email protected] Received: 7 October 2020; Accepted: 13 November 2020; Published: 15 November 2020 Abstract: With the development of concrete engineering, a large amount of construction, demolition, excavation waste (CDEW) has been produced. The treated CDEW can be used as recycled aggregate to replace natural aggregate, which can not only reduce environmental pollution and construction-related resource waste caused by CDEW, but also save natural resources. However, the mechanical properties and durability of Recycled Aggregates Concrete (RAC) are generally worse than that of ordinary concrete. Various fiber or mineral materials are usually used in RAC to improve the mechanical properties and durability of the matrix. In RAC, polypropylene (PP) fiber and steel fiber (SF) are two kinds most commonly used fiber materials, which can enhance the strength and toughness of RAC and compensate the defects of RAC to some extent. In this paper, the literature on PP fiber- and SF-reinforced RAC (FRRAC) is reviewed, with a focus on the consistence, mechanical performance (compressive strength, tensile strength, stress–strain relationship, elastic modulus, and shear strength), durability (water absorption, chloride permeability, carbonation, freeze–thaw cycling, and shrinkage), and microstructure.