Investigation on Bond Stress-slip Behavior of Concrete Containing Poly-lactic Acid Aggregate

Abstract

The performance of Composites Structural Assemblies (CSAs) depends on the bond strength of the embedded components, namely composite panels and infill materials. A new type of eco-friendly ultra-lightweight concrete with Expanded Poly-Lactic Acid (EPLA) was prepared to assess the possibility of using biopolymer concrete as a replacement for expanded polystyrene (EPS) lightweight concrete. The bond properties of EPLA and EPS concrete for the parameters compressive strength, strip locking patterns, as well as elastic and inelastic interlocking areas were assessed. The results indicate that the application of biopolymers significantly changed the mechanical and bond properties of concrete. The chemical reactivity of EPLA and its degradation in the alkaline environment of cement causes bond failure at the interfacial transition zone of the aggregate-paste. Two different failure modes consisting of splitting cracks and pullout failure were observed. A bond stress-slip model for EPS and EPLA concrete was found to give a reasonable estimation of experimental results of bond-slip behaviour. Also, a new method is proposed to estimate the elastic and inelastic length of embedded components in ultra-lightweight concrete.