Assessment of the durability of cement-bound granular mixtures using reclaimed concrete aggregate and coconut fiber

Abstract

In transport infrastructures, the cement-bound granular mixtures (CBGM) for base and sub-base of pavement layers can be built using mostly recycled materials. Recycled aggregates (RA) can replace the natural aggregates (NA) and coconut fiber (CF), obtained from discarded coconut husk, can be introduced to promote a reinforcement effect. Currently, the use of CF in CBGM is new, and regarding the use of RA in CBGM, the literature about its durability is still limited. Thus, there is a gap in knowledge regarding the durability of these solutions.Building on previous validation of mechanical performance, this work is among the first to evaluate the durability of CBGM incorporating RA and CF. For a comprehensive evaluation, three test methods were selected: wetting-and-drying, freezing-and-thawing, and a strength ratio using the indirect tensile strength test. The results highlight the feasibility of RA to replace NA, as both led to similar CBGM durability levels. The introduction of CF promoted gains in durability (on average reducing the mass loss by 42 % in the wetting-and-drying tests and by 20 % in the freezing-and-thawing tests), enhanced toughness, and allowed for a better response of the CBGM in the post-cracking phase.