Effect of early CO2 curing on the chloride transport and binding behaviors of fly ash-blended Portland cement

Published on Jun 21, 2021in Construction and Building Materials6.141
· DOI :10.1016/J.CONBUILDMAT.2021.123113
Yahong Ding2
Estimated H-index: 2
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.
#1Daguan Huang (Xi'an University of Architecture and Technology)H-Index: 5
#2Ditao NiuH-Index: 15
Last. Qiang FuH-Index: 13
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Abstract This study investigates the chloride transport performance of coral aggregate concrete (CAC) in a marine environment. The effects of the aggregate type, strength grade, and fly ash (FA) content on the chloride concentration distribution, surface chloride concentration (Cs), chloride diffusion coefficient (Da), and porosity are discussed. The results show that the higher the strength grade of CAC is, the lower the Cs and Da will be. The Cs and Da of CAC initially decrease and then increa...
#1Zhiqiang Yang (SEU: Southeast University)H-Index: 5
#2Shiyu Sui (SEU: Southeast University)H-Index: 2
Last. Jinyang Jiang (SEU: Southeast University)H-Index: 22
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Abstract Chloride ingress is one of the main causes for the degradation of reinforced concrete structures. Increasing the chloride binding capacity of concrete is generally thought as a feasible way to restrain the chloride ingress. In our previous study, the γ-phase nano-Al2O3 (NA) was found to be beneficial for improving the chloride binding of plain Portland cement paste as a result of the formation of additional Friedel’s salt. Herewith, the cases of blended cement pastes were further invest...
#1Honglei Chang (SDU: Shandong University)H-Index: 6
#2Pan Feng (SEU: Southeast University)H-Index: 16
Last. Jian Liu (SDU: Shandong University)H-Index: 136
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Abstract The binding of chloride can retard the penetration process and is of important significance for the durability of concrete structures. The previous researches calculated the content of C-S-H absorbed chloride mainly through chemical synthesized C-S-H and thermodynamic modeling, rather than in real cement pastes. This study proposed a feasible method for assessing C-S-H adsorbed chloride in real cement pastes by utilizing the order of decomposition of Friedel’s salt, Kuzel’s salt and C-S...
#1Baojian Zhan (PolyU: Hong Kong Polytechnic University)H-Index: 22
#2Dongxing Xuan (PolyU: Hong Kong Polytechnic University)H-Index: 27
Last. Chi Sun Poon (PolyU: Hong Kong Polytechnic University)H-Index: 102
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Abstract Old cement mortars attached on recycled concrete aggregates (RCA) seriously affects the durability of the recycled aggregate concrete (RAC). Revealing the variation of the transport properties of cement mortar after subjecting to accelerated carbonation treatment is crucial with respect to understanding the effects of carbonated RCA on the durability of RAC. In this paper, cement mortars were used to study the transport properties after they were treated by accelerated carbonation. The ...
#1Zbigniew Giergiczny (Silesian University of Technology)H-Index: 11
Abstract Low-calcium (FA) and high-calcium (HCFA) fly ash and granulated blast furnace slag (GBFS) are the most widely known, standardized and used SCMs in the composition of cement and concrete. In the last 4 years, scientific work has focused on improving binder properties (e.g. long setting time, low early strength etc.) containing large quantities of FA, HCFA and GBFS. The main directions of activity are the introduction of high-level additives to concrete composition, such as nano-materials...
#1Baojian Zhan (PolyU: Hong Kong Polytechnic University)H-Index: 22
#2Dongxing Xuan (PolyU: Hong Kong Polytechnic University)H-Index: 27
Last. Caijun Shi (Hunan University)H-Index: 73
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Abstract A coupled CO2-water curing regime was employed on Ordinary Portland cement (OPC) paste samples immediately after casting, which allowed carbonation and hydration of OPC to proceed simultaneously. The strength development and microstructural evolution was evaluated by using multiple-techniques. The results indicated that, compared to the normal hydrated counterpart, a lower porosity, higher amorphous phase content and overall reaction degree can be achieved in the coupled CO2-water cured...
#1Chunyu QiaoH-Index: 11
#2Prannoy Suraneni (UM: University of Miami)H-Index: 17
Last. Jason Weiss (OSU: Oregon State University)H-Index: 57
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Abstract In cementitious materials exposed to solutions containing chloride, chloride binding typically results from the chemical reactions between chloride ions and aluminate phases to form Friedel's salt, and the interaction between chloride ions and calcium silicate hydrates (C S H). Calcium oxychloride can also form when Ca(OH)2 in cementitious materials reacts with CaCl2 solutions. This paper examines the chloride binding of hydrated cement pastes containing fly ash exposed to CaCl2 solutio...
#1Junxiao Wei (China University of Geosciences)H-Index: 3
#2Kuang Cen (China University of Geosciences (Beijing))H-Index: 11
Abstract Cement industry is a large emitter of carbon dioxide (CO2), taking up 5–8% of anthropogenic CO2 emissions. China is the largest developing country in the world. With the fast urbanization rate, economic growth and rapid development of industry, China's cement production is soaring year by year. Also, cement CO2 emissions increased year by year and aroused the rising attention. However, the historical province- and nation-level cement production situations, driving forces of cement outpu...
#1Duo Zhang (McGill University)H-Index: 12
#2Yixin Shao (McGill University)H-Index: 29
Abstract Surface scaling of concrete is one of the major durability issues for cold-region concrete materials. This study presents a solution of using CO 2 curing to mitigate the concrete surface salt scaling induced by the freeze-thaw exposure. A laboratory freeze-thaw cyclic test was performed on the concrete made with Portland cement and fly ash. To understand the underlying mechanism, the pore structure of cement paste was evaluated by mercury intrusion porosimetry (MIP) and nitrogen adsorpt...
#1Warda Ashraf (UMaine: University of Maine)H-Index: 10
#2Jan Olek (Purdue University)H-Index: 36
Abstract This paper presents a study on the carbonation activated binders prepared from pure calcium silicate phases, which included tricalcium silicate (3CaO.SiO2, [C3S]), β-dicalcium silicate (β-2CaO.SiO2, [β-C2S]), γ-dicalcium silicate (γ-2CaO.SiO2, [γ-C2S]), tricalcium disilicate (rankinite, 3CaO.2SiO2, [C3S2]), and monocalcium silicate (wollastonite, CaO.SiO2, [CS]). The overall study consisted of three experimental parts, with individual focus on the following issues: (i) reaction kinetics...
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#1Tiefeng Chen (HIT: Harbin Institute of Technology)H-Index: 2
#2Mengjie Bai (HIT: Harbin Institute of Technology)H-Index: 1
Last. Xiaojian Gao (Zhengzhou University)H-Index: 2
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Abstract null null Carbonation treatment of fly ash (FA) is proposed as a promising method for stabilization of hazardous residues and CO2 sequestration. This paper aims to investigate the performance of cement mortar incorporating carbonated FA and the synergistic effect with carbonation curing. The results show that the content of free CaO and the hydration heat were reduced apparently by carbonation treatment. The synergy of carbonation treatment and carbonation curing compensated for the str...
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