Effect of early CO2 curing on the chloride transport and binding behaviors of fly ash-blended Portland cement. (21st June 2021)

• Record Type: Journal Article
• Authors: Song, Baixing; Shi, Caijun; Hu, Xiang; Ouyang, Kai; Ding, Yahong; Ke, Guojun
• Is Part Of: Construction & building materials. Volume 288(2021)
• Publication Date: 2021-06-21
• Subjects: Early CO2 curing -- Fly ash -- Chloride transport -- Compressive strength -- Chloride binding; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.123113
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlight: Early CO2 curing enhances the water infiltration and chloride permeability resistance of cement mortar. Early CO2 curing decreases the chloride binding capacity of cement paste. The addition of fly ash reduces the chloride binding of early CO2 cured cement paste. Abstract: Early CO2 curing has attracted a lot of attentions due to sequestration of carbon dioxide and rapid strength development for cement-based materials. This study investigates the chloride transport and binding properties of fly ash-blended cement-based materials with and without early CO2 curing. A comparison is made between the specimens exposed to early CO2 curing followed by subsequent water curing and those continuously cured in water. Results show that early CO2 curing decreases the water sorption and chloride migration coefficient of cement mortar. The replacement of cement with fly ash decreases the strength and permeability of mortar regardless of the curing regime. CO2 cured cement pastes show lower chloride binding capacity than water cured cement pastes after immersion in 0.1 M, 0.5 M and 1 M sodium chloride solutions due to the consumption of calcium hydroxide, presence of carbonates as well as lower contents of C-S-H gel. The presence of fly ash increases the contents of bound chloride in water cured cement pastes but decreases them in CO2 cured cement pastes.