Mechanical and microstructural characterization of bio-concrete prepared with optimized alternative green binders

Abstract

Due to their high alkaline natrure, ordinary Portland cement and lime based traditional binders show poor compatibility with the bio-aggregates. As a results, produced bio-concretes show prolonged setting time, poor mechanical and durability properties. In order to use the traditional binders in preparing the bio-concrete, the use of expensive treatment methods to improve bio-comptability of these binders become inevitable. In this regards, this research aims to solve the bio-compatibility issues of traditional binders and develop new green binders to prepare bio-concrete. In the first part, mechanical and chemical characterization (through XRD, DTG/TGA and SEM) of Portland cement (OPC), geopolymer (GP) and magnesium phosphate cement (MPC) binders was carried out. Optimized binders from each group were then further used to produce bio-concretes. In the second part, influence of type of binder and pretreament on the properties of bio-concrete was examined. It was observed that hydrophobic treatment was most efficient and increased the amount of hydration products (studied through XRD, FTIR and SEM) and bio-compatibility of OPC and GP binders. However, MPC binder was naturally compatible with the bio-aggregates due to its low pH value and do not necessarily demand any pretreatment of bio-aggregate. It was concluded that, MPC based bio-concrete shows high performance as compared to OPC and GP based bio-concrete.