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Effect of K/Na on the alkali silica reaction of seawater and sea sand concrete
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NETL
NSTL
Springer Nature
Abstract In recent years, research into the properties of seawater and sea sand concrete (SWSSC) has emerged as a prominent area of investigation, and the alkali silica reaction (ASR) of SWSSC is an urgent issue to be solved. However, little attention has been paid to the effect of K/Na on the ASR of SWSSC. In order to fill this gap, the effects of different K/Na on ASR products, pore structure, pH and alkali ion content, and expansion of SWSSC were measured. The findings demonstrated that the composition of the amorphous product ASR-P1 (K0.52Ca1.16Si4O8(OH)2.84–1.5H2O) of SWSSC exhibited an inverse relationship with K/Na, whereas the crystalline product K-shlykovite (NaCaSi4O8(OH)3–2.3H2O) displayed a direct correlation with K/Na. The increase of K+ concentration leads to the decrease of silica dissolution, which is the main reason for the lowest ASR degree in the high K/Na group. The transformation of ASR-P1 to K-shlykovite also resulted in different main ASR products in different K/Na groups. The experimental data show that increasing the K/Na from 0.85 to 1.85 reduced the 14d expansion from 0.248 to 0.22% and 28d ASR expansion from 0.415 to 0.350%. Notably, the most significant suppression occurred in the high K/Na group, which exhibited the lowest expansion values at all ages. The findings of this study provide a foundation for the theoretical application of SWSSC in the field of ocean engineering. These results suggest that adjusting K/Na ratios could serve as a viable strategy to mitigate ASR induced damage in marine concrete structures. For such structures, this implies that material selection should prioritize potassium-rich binders, such as blended cements or SCMs like potassium feldspar, to naturally elevate the K/Na ratio. In mix design, controlled additions of KOH during mixing can adjust the alkali balance, while leveraging seawater with inherently higher K/Na ratios or supplementing seawater with potassium salts can help achieve the target K/Na ratio. The findings of this study provide a foundation for the theoretical application of SWSSC in the field of ocean engineering to enhance long-term durability in ocean engineering applications.
Seawater and sea sand concreteAlkali silica reactionASR-P1K-shlykoviteExpansion
Qizhi Zhang、Qingnan Gong、Rong Chen、Ming Wang、Ran Chen、Lincheng Weng、Dehui Wang
NETL
NSTL
Springer Nature
