Microstructural evolution and durability performance of MgO-modified calcium aluminate cement

Abstract

Calcium aluminate cement (CAC) has been used as an alternative for Portland cement (PC) under some extreme conditions and for specific purpose such as rapid strength gain, even at temperatures approaching 0°C, the ability to customize fresh property characteristics, high abrasion resistance, and resistance to chemical corrosion. Despite various advantages, CAC is vulnerable to phase conversion and strength loss over a period of time or exposure to elevated temperature and humidity. Due to phase conversion, CAC also becomes vulnerable against extreme condition. However, this dissertation mainly focuses on the features of CAC incorporated with reactive MgO in order to cater/minimize the microstructure instability and strength loss due to phase conversion along with durability against extreme conditions.This dissertation investigates the fundamentals of phase conversion and strength loss of CAC along with the effect of MgO on phase conversion, microstructure modification, and strength loss mitigation before and after exposure to expedited curing. Furthermore, MgO-modified CAC was exposed to extreme conditions involving CO$_2$, high temperature, and acid rich environment. The structural evolution of binder phases in MgO-modified CAC exposed to extreme conditions was investigated using multi analytical tools. The obtained results will provide new insights into the phase conversion, microstructural alteration, and durability of MgO-modified CAC. The thesis is concluded by summarizing implications of the results.