Properties of Green, Lightweight, and High-Strength Reactive Powder Concrete Incorporating Modified Expanded Polystyrene Beads: Fid-Bau Portal

Properties of Green, Lightweight, and High-Strength Reactive Powder Concrete Incorporating Modified Expanded Polystyrene Beads

Azimi, Seyed Amin / Allahverdi, Ali / Alibabaie, Mehdi

Abstract

This work presents green lightweight reactive powder concrete (GLRPC) as a novel lightweight composite with improved properties by incorporating modified expanded polystyrene beads (MEPS) into green reactive powder concrete (RPC). It provides the advantages of both RPC and lightweight concrete (LWC). Because incorporation of the conventional expanded polystyrene (EPS) beads into the concrete mix results in a considerable loss of mechanical properties, it is necessary to find effective methods to preserve RPC properties as much as possible. The present work is devoted to the thermal modification of EPS. Various mixtures with different replacement levels of total RPC binder paste volume (0%, 15%, 30%, and 45%) with MEPS under different curing conditions (both standard water curing and heat curing conditions) were investigated in terms of their physical and mechanical properties. The results of the experimental study showed that MEPS beads had appropriate distribution into the GLRPC matrix without any considerable segregation. Replacement levels up to 30% of RPC paste volume by MEPS beads result in the development of high-strength lightweight concrete. Further replacement levels lead to lightweight concretes that drop into structural class. The water absorption shows a stronger dependency to curing temperature than replacement level of RPC paste volume with MEPS. The value of water absorption for all the studied mixtures, however, remained less than 2% that is relatively small. The microstructure analysis showed a very dense and uniform interfacial transition zone microstructure (ITZ) with good bonding of cement paste to MEPS beads. The relatively higher compressive strength of GLRPC cured at 200°C could be attributed not only to the development of a denser microstructure, but also to the development of hollow spherical polystyrene beads with hard and stiff shells resulting in an innovative high-tech plastic/cement-paste bonding.