During recent decades, alkali-free accelerators have appeared on the market as setting accelerator additives for shotcrete. In this work, copolymers poly(AANa-co-DMAA) with a variation of their charge densities (monomeric molar ratios) were synthesised by aqueous solution polymerisation and characterised by Fourier transform infrared spectroscopy. Then the copolymers were used to optimise the setting behaviour of cement paste in the presence of alkali-free accelerator. The setting times of cement pastes with a combination of alkali-free accelerators and copolymers were tested. Isothermal calorimetry, X-ray diffraction, thermal gravimetric analysis and total organic carbon were also performed to obtain the comprehensive optimisation effects of poly(AANa-co-DMAA). The results clearly show that the capacity of the alkali-free accelerator for shortening the setting time of cement paste was enhanced significantly by introducing poly(AANa-co-DMAA). More AA units in the copolymers have better adsorption capacity, leading to a faster dissolution rate of tricalcium aluminate and the formation of massive ettringite crystals, thus finally the setting time of the cement paste with a combination of alkali-free accelerators and copolymers was shortened markedly compared with that containing alkali-free accelerators alone. The good synergy effect of the copolymers and alkali-free accelerator indicates great potential for practical applications.

中文翻译：

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优化含有聚（AANa-co-DMAA）的加速水泥浆的凝结行为

近几十年来，市场上出现了无碱促进剂作为喷射混凝土的促凝剂添加剂。在这项工作中，通过水溶液聚合合成了具有不同电荷密度（单体摩尔比）的共聚物聚（AANa-co-DMAA），并通过傅里叶变换红外光谱进行表征。然后使用共聚物来优化水泥浆在无碱促进剂存在下的凝结行为。测试了结合无碱促进剂和共聚物的水泥浆的凝结时间。还进行了等温量热、X射线衍射、热重分析和总有机碳分析，以获得聚(AANa-co-DMAA)的综合优化效果。结果清楚地表明，通过引入聚(AANa-co-DMAA)，无碱促进剂缩短水泥浆凝结时间的能力显着增强。共聚物中AA单元越多，吸附能力越好，导致铝酸三钙溶解速度更快，形成块状钙矾石晶体，最终使无碱促进剂与共聚物结合的水泥浆的凝结时间显着缩短与单独使用无碱促进剂相比。共聚物与无碱促进剂的良好协同作用表明具有巨大的实际应用潜力。导致铝酸三钙溶解速度更快，形成块状钙矾石晶体，最终与单独使用无碱促进剂相比，无碱促进剂与共聚物结合的水泥浆的凝结时间明显缩短。共聚物与无碱促进剂的良好协同作用表明具有巨大的实际应用潜力。导致铝酸三钙溶解速度更快，形成块状钙矾石晶体，最终与单独使用无碱促进剂相比，无碱促进剂与共聚物结合的水泥浆的凝结时间明显缩短。共聚物与无碱促进剂的良好协同作用表明具有巨大的实际应用潜力。