【摘要】 本研究主要对比了减缩剂和高性能混凝土膨胀剂(HCSA)单掺以及复掺时,对超高性能混凝土(UHPC)强度、收缩性能的影响。结果显示,减缩剂会延缓水泥水化,延长水泥凝结时间,不利于UHPC早期强度的发展。随着减缩剂掺量(0%～2%,质量分数)增加,UHPC的自收缩降低,当减缩剂掺量为0.5%时可有效降低UHPC的干燥收缩。而HCSA膨胀剂缩短UHPC的凝结时间,早期强度的发展快;HCSA膨胀剂具有降低UHPC内部有害孔数量、减小总孔隙率的作用,能够降低UHPC的自收缩和干燥收缩;但HCSA膨胀剂过量时,无法获得足够的水分参与反应,且有破坏UHPC结构的风险。减缩剂和HCSA膨胀剂复掺时,UHPC的抗压、抗折强度均大于单掺减缩剂时的强度,且小于单掺HCSA膨胀剂时的强度。2%减缩剂和10%HCSA膨胀剂复掺对UHPC收缩的抑制作用最好,同时UHPC具有较高的力学性能。更多还原

【Abstract】 In this paper, we mainly compared the effects of ultra high performance concrete(UHPC) on strength and shrinkage when the shrinkage redu-cing agent and high performance concrete expansion agent(HCSA) were combined and mixed. The results show that the shrinkage reducing agent will delay the hydration of cement and increase the setting time, which is not conducive to the development of early strength of concrete. As the amount(0 wt%—2 wt%) of shrinkage reducing agent increases, the autogenous shrinkage of UHPC decreases. When the amount of shrin-kage reducing agent is 0.5 wt%, the drying shrinkage can be effectively reduced. The HCSA expansion agent will accelerate the UHPC setting time and develop the early strength. HCSA expansion agent can reduce the number of harmful pores inside the concrete and reduce the total porosity, which can reduce the autogenous shrinkage and drying shrinkage of UHPC; When the agent is in excess, sufficient moisture cannot be obtained to participate in the hydration, and there is a risk of damaging the structure. When the shrinkage reducing agent and the HCSA expansion agent are compounded, the compressive strength and flexural strength of the UHPC are greater than those of the single anti-shrinkage agent, and less than the strength when the HCSA expansion agent is directly doped. When the 2 wt% shrinkage reducing agent and the 10 wt% HCSA expansion agent are compounded, the inhibition of UHPC shrinkage is the best and the mechanical properties of UHPC are high.更多还原