干燥大温差环境下砂浆抗冻临界强度试验研究

Experimental Research on Frost-resistant Critical Strength of Mortar in Dry Environment with Large Temperature Difference

为研究不同养护方式对砂浆试件抗冻临界强度的影响规律,在室内模拟温度-20~15℃、相对湿度50%的干燥大温差环境,并制备不同预养护时间的砂浆试件,测试其在受冻7 d后移入标准环境中养护至28 d的抗压强度,分析干燥大温差环境不同养护方式对砂浆预养护时间及抗冻临界强度的影响规律。研究结果表明:相较于恒低温环境,相同预养护龄期下,干燥大温差环境下砂浆28 d抗压强度更大;5种不同养护方式下,纳米保温隔热涂层养护效果最好,28 d抗压强度最高,所需预养护时间最短,其次为薄膜养护、双掺膨胀剂与内养护剂、自然养护、单掺膨胀剂;膨胀剂对砂浆早期强度发展有负面影响,而掺加内养护剂后,其抗压强度随预养护时间增加而显著增大,最终超过自然养护。

For the purpose of studying the influence of different curing methods on frost-resistant critical strength of mortar specimens, a dry environment with large temperature difference was simulated indoors, with a temperature of -20~15 ℃ and a relative humidity of 50%. Mortar specimens with different pre-curing times were prepared to test their compressive strength after being frozen for 7 days and moved into the standard curing environment for 28 days, so as to analyze the influence of different curing methods on mortar pre-curing time and frost-resistant critical strength in the dry environment with large temperature difference. The results show that compared with constant low-temperature environment, under the same pre-curing period, the 28 d compressive strength of mortar in dry environment with large temperature difference is greater;under five different curing methods, the nano thermal insulation coating has the best curing effect, the 28 d compressive strength is the highest and the required pre-curing time is the shortest, followed by film curing, double-doped expansion agent and internal curing agent, natural curing and single-doped expansion agent;the expansion agent has a negative impact on the early strength development of mortar, while after internal curing agent is doped, the compressive strength of mortar increases significantly with the increase of pre-curing time, and finally exceeds that of natural curing.