摘要
以溴化钙、溴化锂和三异丙醇胺制备一种无碱、无氯、不含SO_(4)^(2)的新型低温早强剂,研究了5℃下新型低温早强剂对混凝土工作性、强度及耐久性的影响.结果表明:低温早强剂对混凝土工作性影响不大,但低温早强效果显著,且在不同粉煤灰掺量(10%、20%、30%)体系中具有良好的适应性.5℃养护下,掺低温早强剂C50混凝土1、3、7 d抗压强度比分别达157%、132%、123%,28~120 d抗压强度比均超过了110%,混凝土各龄期下强度已接近对比样20℃下强度.掺低温早强剂混凝土干缩略有增大,56 d前混凝土的电通量增大6%~14%;但可减小混凝土90 d后电通量,并能改善混凝土抗冻性能.在早强剂中复配2%膨胀剂+3%硅灰,使混凝土120 d干缩率较对比样减小23%,56 d电通量小于1000 C,该方法并不损失混凝土强度。
A new type of low-temperature early-strength accelerator,without alkali,chlorine and sulfate ions,was prepared with calcium bromide,lithium bromide and triisopropanolamine,and its effects on the workability,strength and durability of concrete at 5℃were studied.The results show that,the low-temperature earlystrength accelerator had little influence on the workability of concrete,but it hada significant low-temperature early-strength performance and a good adaptability to different fly ash contents(such as 10%,20%,30%).The 1 d,3 d and 7 d compressive strength ratios of the C50 concrete mixed with early strength acceleratorscured at 5℃,reached 157%,132%and 123%respectively,and the retention rates from 28 d to 120 d all exceeded 110%.The strength of concrete at each age was already close to that of the contrast sample cured at 20℃.The incorporation of low-temperature early strength accelerators would increase the dry shrinkage of concrete slightly,and the electric flux of concrete before 56 d would increase by 6%to 14%.However,the electrical flux of concrete after 90 d could be reduced and the frost resistance of concrete could be improved.The method of compounding 2%expansion agent and 3%silica fumein the early strength accelerator could reduce the dry shrinkage of concrete by 23%compared with that of the contrast sample at 120 d,and the electric flux at 56 d was less than 1000 C.By the way,this method did not lose the strength of concrete.
作者
张丰
白银
蔡跃波
ZHANG Feng;BAI Yin;CAI Yuebo(Nanjing Hydraulic Research Institute,State Key Laboratory of Hydrology-Water Resourcesand Hydraulic Engineering,Nanjing 210029,China)
出处
《混凝土》
CAS
北大核心
2021年第6期98-102,111,共6页
Concrete
基金
国家重点研发计划项(2018YFC0406702)
国家自然科学基金项目(51739008)
中央级公益性科研院所基本科研业务费专项(Y419004)
云南省交通运输厅行业科技攻关项目(云交科教[2016]56号)。
关键词
低温
早强剂
混凝土
强度
耐久性
low temperature
early strength accelerator
concrete
compressive strength
durability
