低温条件下硅酸盐水泥基钢筋连接用套筒灌浆料试验研究

通过研究环境温度、拌和水温度、预养护时间及外加剂对套筒灌浆料工作性和力学性能的影响,探索了常温套筒灌浆料在低温环境下性能变化的趋势,为利用硅酸盐水泥制备低温套筒灌浆料提供试验基础。试验结果表明:常温套筒灌浆料不适宜用于低于5℃的温度环境;低温时,升高拌和水温度有助于提高灌浆料的早期强度,但处于负温时,灌浆料强度发展缓慢;预养护有助于提高低温时套筒灌浆料的早期强度;适量掺加防冻剂和早强剂可以提高套筒灌浆料早期强度,流动度随其掺量的增加而逐渐下降。综合考虑,4种外加剂中亚硝酸钠效果最好,其合理掺量为2.0%,碳酸锂效果最差。对于硅酸盐水泥基套筒灌浆料,在负温时难以通过单掺外加剂来获得较高的早期强度。

Experimental study on cementitious grout for sleeve of rebar splicing based on Portland cement at low temperature

By studying the influence of ambient temperature,mixing water temperature,pre curing time and additives on the workability and mechanical properties of cementitious grout for sleeve,the performance change trend of normal temperature type cementitious grout for sleeve in low temperature environment is explored,which provides experimental basis for the preparation of low temperature type cementitious grout for sleeve with Portland cement.The test results show that the normal temperature type cementitious grout for sleeve is not suitable for the temperature environment below 5 ℃.At low temperature,increasing the mixing water temperature is helpful to improve the early strength of cementitious grout for sleeve,but at negative temperature,the strength develops slowly.The pre curing system is helpful to improve the early strength of cementitious grout for sleeve at low temperature.The early strength of cementitious grout for sleeve can be improved by adding antifreeze and early strength agent,and the fluidity gradually decreases with the increase of its content.Comprehensive consideration,the sodium nitrite effect is the best in the four kinds of additives,its reasonable content is 2.0%,lithium carbonate effect is the worst.For Portland cement-based cementitious grout for sleeve,it is difficult to obtain higher early strength by adding only admixtures at negative temperature.