Effect of Carbonation on Microstructure Evolution of Alkali-Activated Slag Pastes

Xie, Xiao Ying; Wei, Hao; Zuo, Xiao-Bao; Cui, Dong

doi:10.4028/p-hp6t1t

Cited by 2 publications

(2 citation statements)

References 17 publications

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“…First, the gray-scale value of the carbonated area was “pulled down” by the crack network, as it acquired a relatively lower gray-scale value. Secondly, unlike C-S-H formed during cement hydration, the structure of alkali-activated products (e.g., C-(A)-S-H, N-S-H) was less stable, and a larger amount of water would release during its carbonation [ 14 , 25 , 28 ]. If the increase of gray-scale vale by CO 2 binding was counterbalanced by the moisture loss, a decrease of the gray-scale value would then be inevitable.…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, for the purpose of achieving the carbon neutralization, a potential substitute of the Portland cement, such as the alkali-activated materials (AAM), is gaining increased concentration in recent years [ 13 , 14 ]. Compared with the ordinary Portland cement (OPC), the strength of AAM develops more rapidly [ 15 , 16 ], and the resistance against the invasion of chloride [ 17 , 18 ] and sulfate ion [ 19 , 20 ] are better.…”

Section: Introductionmentioning

confidence: 99%

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Investigation on the Carbonation Behavior of Alkali-Activated Pastes Served under Windy Environments

Cui

Shen²,

Shen³

et al. 2023

Materials

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Most reinforced concrete structures serve under windy environments, and the carbonation resistance under that circumstance exhibits significant difference from that under the steady (no wind) environment. In this study, a windy environment was simulated using one self-developed wind tunnel, and alkali-activated slag/fly ash paste specimens were adopted for the carbonation under variant windy environments. Meanwhile, to reveal the effect of inner humidity on the carbonation, sliced alkali-activated materials (AAM) were mass-balanced first to variant humidity, and were then carbonated under a 2.5 m/s windy environment. With the assistance of computed tomography (CT), the structure of AAM at variant carbonation ages was rendered. The experimental result showed that wind is capable of promoting the exchange of moisture between the sample inside and the outer atmosphere, leading to faster carbonation as compared to that under no wind environment. When preconditioned to lower inner humidity, the carbonation rate of AAM was faster because the larger gaseous space benefited the intrusion of both CO2 and moisture. Furthermore, when preconditioned to lower humidity, the cracking extent of AAM was severer, which also contributed to the faster carbonation. Moreover, compared with ordinary Portland cement (OPC), the carbonation front on each instant 1D gray-scale value profile was broader, which suggested that the carbonation progress of AAM under windy environments was no longer controlled solely by diffusion. In addition, the gray-scale value on instant 1D profile fluctuated drastically, which verified cracking in AAM carbonated under windy environments. The current work not only deepens the understanding of the carbonation mechanism in-site (mostly under windy environments), but also helps to develop more environment-friendly construction material, with better durability performance.

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Section: Resultsmentioning

confidence: 99%