Influence of sisal fibers on mechanical properties and thermal conductivity of fully recycled aggregate concrete

Abstract

To reduce greenhouse gas emission and utilize construction solid waste, fully recycled aggregate concrete (FRAC) with plant fiber was proposed and investigated in this study. The effects of sisal fiber contents (0 %, 0.5 %, 1 %, and 2 %) and fiber lengths (5 mm, 10 mm, and 20 mm) on the mechanical properties and thermal conductivity of FRAC were intensively tested. The compressive strength, splitting tensile strength, axial tensile strength, flexural strength, thermal conductivity and porosity of concrete specimens were analyzed. The results show that with the increase of fiber contents, the mechanical strength of FRAC first increased and then decreased. The splitting tensile strength and flexural strength of FRAC have been enhanced by 33.00–37.54 % and 4.31–24.43 %, respectively. The lowest thermal conductivity of FRAC occurred at the fiber content of 0.5 %. With the variation of the fiber length, the maximum mechanical strength, flexural toughness and thermal conductivity of FRAC appeared at the length of 10 mm. The incorporation of sisal fibers at a volume fraction of 2 % or with a length of 20 mm led to a noticeable increase in porosity, both by more than 45 %. Compared to conventional concrete, FRAC has a 16.34 % reduction in carbon emission when the sisal fiber content is 2 %. Through the analysis of carbon intensity ratio, the optimal fiber content is 1 % and fiber length is 10 mm. This study shows that FRAC mixed with proper amount of sisal fibers has better mechanical properties, thermal insulation performance and lower carbon emission.