蒸养条件下硅灰对钢渣-水泥基材料力学性能和耐久性能的影响

Influence of Silica Fume on the Mechanical and Durability Properties of Steel Slag-cement-based Materials Under Steam Curing Conditions

为研究蒸养条件下硅灰对钢渣-水泥基材料力学性能和耐久性能的影响,通过试验测试了不同硅灰掺量的钢渣-硅灰-水泥复合材料的抗压强度、抗折强度、干缩性能、抗氯离子渗透性和抗冻性能。试验结果表明:蒸汽养护对钢渣-硅灰-水泥复合材料的力学性能和耐久性能有负面影响;复掺硅灰对钢渣-水泥基材料的力学性能、抗氯离子渗透性和抗冻性能有正面影响,对干缩性能有负面影响。蒸养条件下,相较于单掺30%钢渣,复掺2%~10%硅灰后:胶砂28 d抗压强度增加6.8%~25.5%,6%为硅灰最佳掺量;胶砂干缩率增加3.4%~32.6%,干缩率随硅灰掺量增加而增大;混凝土氯离子扩散系数降低12.2%~84.3%,100次冻融循环后的相对动弹性模量增加23.3%~39.9%,抗氯离子渗透性和抗冻性能随硅灰掺量增加而提高,但硅灰掺量超过6%后,性能提升有限。

To explore the effects of silica fume on the mechanical and durability properties of steel slag-cement-based materials under steam curing conditions,this paper conducts experimental tests on the compressive strength,flexural strength,shrinkage,chloride ion permeability,and frost resistance of steel slag-silica fume-cement composite materials with varying silica fume contents.The results indicate that steam curing adversely affects the mechanical and durability properties of steel slag-silica fume-cement composite materials.The addition of silica fume positively influences the me-chanical properties,chloride ion permeability,and frost resistance of the steel slag-cement-based materials,while negatively affecting shrinkage.Under steam curing conditions,compared to the sole addition of 30%steel slag,the inclusion of 2%to 10%silica fume results in:a 6.8%to 25.5%increase in the 28-day compressive strength of the mortar,with 6%being the optimal silica fume content;a 3.4%to 32.6%increase in shrinkage rate,which rises with the amount of silica fume;a 12.2%to 84.3%reduction in the concrete's chloride ion diffusion coefficient,and a 23.3%to 39.9%increase in the rel-ative dynamic modulus of elasticity after 1oo freeze-thaw cycles,indicating that chloride ion permeability and frost resist-ance improve with the addition of silica fume.However,the performance gains are limited when the silica fume content ex-ceeds 6%.