普通聚羧酸减水剂在超高性能混凝土中的应用研究

Application of common polycarboxylic acid water reducing agent in ultra-high performance concrete

研究了采用普通聚羧酸减水剂制备超高性能混凝土(UHPC)的技术方法,对比分析了普通聚羧酸减水剂PT、UHPC专用聚羧酸减水剂GK和MI、早强剂、消泡剂等对UHPC力学性能及氯离子渗透系数的影响。结果表明,采用PT制备UHPC可以满足流动度的要求,但流动度达到220 mm时PT的掺量比GK增加43%,凝结时间延长,1 d无法脱模;28 d抗压与抗折强度较掺GK的分别降低34.6%和35.3%,氯离子渗透系数增加到0.7×10^(-12)m^(2)/s。通过蒸汽养护并不能提高掺PT的UHPC早期强度,PT与早强剂和消泡剂复掺可使UHPC的力学性能和氯离子渗透系数符合T/CECS 10107—2020《超高性能混凝土(UHPC)技术要求》的要求。

This paper studies the technical method of preparing ultra-high performance concrete(UHPC)with common polycarboxylic acid water reducing agent.The influence of common polycarboxylic acid water reducing agent PT,UHPC special polycarboxylic acid water reducing agent GK and MI,early strength agent,antifoaming agent on UHPC mechanical properties and chloride ion permeability coefficient were relatively analyzed.The results show that the UHPC prepared using PT can meet the requirements of flowability,but when the flowability reaches 220 mm,the content of PT increases by 43%compared to GK,and the setting time increases,resulting in the inability of the concrete to demould for one day.The compressive and flexural strength at 28 days decreased by 34.6%and 35.3%respectively compared to that with GK.The rapid chloride ion permeability coefficient increases to 0.7×10^(-12) m^(2)/s.Steam curing cannot increase the early strength of UHPC with the addition of PT.The combination of PT and early strength agent and defoamer can make the mechanical properties and rapid chloride ion permeability coefficient of UHPC meet the requirements of T/CECS 10107—2020"Technical Requirements for Ultra High Performance Concrete".