Trilinear tensile stress–strain constitutive model for high ductility cementitious composite with totally recycle fine aggregate

Abstract

In this paper, the crushed waste concrete particles with original particle grade were adopted as recycled fine aggregate (RFA) to completely substitute the natural fine aggregate in preparing high ductility cementitious composite (HDCC) for fully utilizing waste concrete, simplifying the sieving steps, reducing the environmental pollution and obtaining better tensile performance. The tensile stress–strain behavior of HDCC with 100% RFA (termed as R-HDCC) was explored by the uniaxial tensile test and compared with that of HDCC with totally natural fine aggregate. Then the effects of RFA-binder ratio, water-binder ratio, fly ash content and fiber volume fraction on the properties of R-HDCC were investigated in detail. The test results showed that the increase of both water-binder ratio and fly ash content reduced the tensile strength of R-HDCC but improved the strain capacity significantly. The increase of fiber volume fraction was beneficial to both tensile strength and strain capacity. As RFA-binder ratio increased, the strain capacity of R-HDCC decreased continuously while the tensile strength increased first and then decreased. Most notably, there was apparently three stages on the tensile stress–strain curve of R-HDCC, which was very different from the bilinear tensile response of ordinary HDCC. Therefore, a new trilinear tensile stress-train constitutive model was proposed for R-HDCC and validated in comparation with test results in this study and relevant literatures. It demonstrated that the trilinear model could well match with the measured curves of HDCC with PVA fibers and recycled fines crushed from concrete or clay brick.