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早强外加剂和养护温度对混凝土早期性能的影响
作者：姜骞1，刘加平2，杨斌3，于诚1，余鑫1，严涵1，张茜1
（1.江苏苏博特新材料股份有限公司 高性能土木工程材料国家重点实验室，江苏 南京 211103；
2.东南大学 材料科学与工程学院，江苏 南京 211189；3.中国铁路总公司，北京 100844）
摘要：选取4种典型早强外加剂（早强聚羧酸减水剂、亚硝酸钙、三异丙醇胺和纳米晶核）配制C30预制构件混凝土，考察了混凝土工作性能、不同温度下的早期凝结硬化性能和净浆水化热，并分析了早强外加剂对混凝土早期性能的影响机理。结果表明：1%亚硝酸钙造成混凝土初始坍落度减小并且30 min后坍落度损失殆尽；早强聚羧酸减水剂则显著增大混凝土的振动黏度，且增幅随坍落度减小而逐渐增大。纳米晶核混凝土从硬化至养护3 d始终具有最佳的早强效果，1 d内优势最明显，且受低温影响较小；三异丙醇胺的早强效果仅次于纳米晶核；亚硝酸钙在低温下早强效果优于早强聚羧酸减水剂，但常温时与其相当。
关键词：早强外加剂；养护温度；混凝土；早期性能；水化热
中图分类号：TU528.042 文献标识码：A 文章编号：1001-702X（2020）02-0009-05
Influence of early strengthening agent and curing temperature on early age performance of concrete
JIANG Qian1，LIU Jiaping2，YANG Bin3，YU Cheng1，YU Xin1，YAN Han1，ZHANG Qian1
（1.Jiangsu Sobute New Materials Co. Ltd.，State Key Laboratory of High Performance Civil Engineering Materials，
Nanjing 211103，China；2. School of Materials Science and Engineering，Southeast University，Nanjing 211189，China；
3.China Railway Corp.，Beijing 100844，China）
Abstract：C30 pre-cast concrete was prepared using four types of typical early strengthening agent（early-strength polycarboxylic acid water reducer，calcium nitrite，tri-isopropanolamine and nanocrystal nucleus）. Fresh properties，early age setting and hardening performance under different kinds of temperatures of concretes and hydration heat of pastes were compared and influence mechanism of each early strengthening agent on early properties of concrete were analyzed. The results showed，that one percent of calcium nitrite in fresh concrete led to decrease of initial slump and quick slump loss in 30 min. Vibration viscosity coefficient of concrete rose significantly as early-strength polycarboxylic acid water reducer was used，and the extent of the increase was negative related to the slump value. Nanocrystal nucleus exhibited the most excellent hardening accelerating effect in concrete from setting to curing for 3 days，especially in 1 day regardless of temperature influence. Tri-isopropanolamine showed second effective in early strengthening among the four agents. Calcium nitrite was clearly superior to early-strength polycarboxylic acid water reducer at low temperature but almost the same at normal temperature.
Key words：early strengthening agent，curing temperature，concrete，early age performance，hydration heat