Hui Xie , Xin Liu , Haochuan Wang , Zhenqi Yu , Lijing Shao , Wei Wang , Jinxiang Hong , Chong Wang , Pan Feng
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引用次数: 0
Abstract
The use of aluminum sulfate (Al2(SO4)3)-based alkali-free accelerators in shotcrete often impeded tricalcium silicate (C3S) hydration, leading to poor ultra-early strength development. To address this, a novel stage-wise kinetic control strategy was proposed to regulate the sequential formation of ettringite and C-S-H gel through the delayed addition of C-S-H nano seeds. The dosage of C-S-H nano seeds, delayed time, addition sequence of Al2(SO4)3 and C-S-H nano seeds were carefully examined in this study, and the effects of addition sequence on the hydration kinetic, hydration products, and pore structure of cement pastes were systematically investigated. Results demonstrated a significant enhancement in 6 h compressive strength, achieving a 35% increase when C-S-H nano seeds (4% dosage) were added 1 h after initial mixing compared to simultaneous addition. Hydration heat, XRD, TG, SEM, and BSE-EDS analyses revealed that the delayed addition promoted C3S hydration at later stages by staggering intensive ettringite formation and C-S-H gel precipitation, mitigating competition for calcium ions. This stage-wise approach facilitated C-S-H gel integration into the pre-constructed porous ettringite skeleton, refining the pore structure and enhancing ultra-early mechanical performance. These findings highlight an effective strategy to optimize hydration kinetics and strength development in shotcrete applications.
期刊介绍:
Cement and Concrete Research is dedicated to publishing top-notch research on the materials science and engineering of cement, cement composites, mortars, concrete, and related materials incorporating cement or other mineral binders. The journal prioritizes reporting significant findings in research on the properties and performance of cementitious materials. It also covers novel experimental techniques, the latest analytical and modeling methods, examination and diagnosis of actual cement and concrete structures, and the exploration of potential improvements in materials.