Microstructural alteration of accelerated carbonation-cured calcium sulfoaluminate cement exposed to harsh environments

Abstract

This dissertation investigates the microstructural and mechanical alteration of accelerated carbonation-cured calcium sulfoaluminate (CSA) cement exposed to the several harsh environment conditions. The CSA cement, which can be an option for replacing the ordinary Portland cement (OPC), has been extensively explored due to its potential for reducing the environmental issues associated with the $CO_2$ emission related to the cement industry. In addition, the accelerated carbonation curing (ACC) a straightforward technique to actualize the carbonation capture and storage (CCS) strategy in an effective manner, which can store a large amount of $CO_2$ in the cementitious materials. However, it is not sufficient to only produce the cementitious materials in a more environmentally friendly method. To produce a more sustainable cementitious materials, it should be involved the enhancement of durability, otherwise the benefits will be offset due to the shorter service life of cementitious materials. The understanding of deterioration process of cementitious materials upon exposure to the harsh environments should be proceeded to assess the durability performance. This dissertation explores the microstructural alteration of accelerated carbonation-cured CSA cement exposed to the different harsh environments. This dissertation can be categorized into four aspects as follows: 1) identifying the effect of temperature of ACC on microstructural and mechanical properties of CSA cement, 2) investigating the microstructural alteration of accelerated carbonation-cured CSA upon exposure to high temperature, 3) identifying the microstructural alteration of accelerated carbonation-cured CSA cement under chloride-rich environment exposure, 4) inspecting the microstructural alteration of accelerated carbonation-cured CSA cement exposed to acidic mediums, and 5) evaluation of carbon footprint via $CO_2$ uptake results to assess the environmental impact of accelerated carbonation-cured CSA cement. The results provide new insights into the properties of accelerated carbonation-cured CSA cement exposed to the numerous harsh environments, which can establish the fundamental knowledge of deterioration process of CSA cement upon exposure to harsh environments. In addition, the environmental impact obtained through adoption of CSA cement and ACC and effect of temperature of ACC on the microstructural and mechanical properties of CSA cement were provided. The dissertation provides implications related to CSA cement based on the experimental results and deals with future research topics.