超硫水泥混凝土抗盐冻性能及提升研究

Salt Frost Resistance and Improvement of Supersulfated Cement Concrete

通过测试不同盐冻循环次数后超硫水泥混凝土的表面剥落质量和超声波相对动弹性模量,并对气泡结构参数进行表征,系统探究了引气剂对超硫水泥混凝土抗盐冻性能的影响规律,以及弱碱性激发剂——乳酸钠对超硫水泥混凝土抗盐冻性能的提升效果。研究结果表明,添加引气剂可有效提高超硫水泥混凝土抗盐冻性能,但会降低强度,复合掺加乳酸钠可避免强度降低。加入胶凝材料质量0.3%的引气剂,剥落质量仅为919.7 g/m^(2),较基准组降低了36.8%,且超声波相对动弹性模量未明显降低。引气剂的加入,改善了超硫水泥混凝土的气孔结构,降低了内部气孔间距系数和弦长大于100μm的气孔数占比。这可以减缓冻融作用下内部微裂纹的发展速率,延缓冻融破坏过程。此外,乳酸钠通过促进超硫水泥水化使得混凝土抗盐冻性能得到增强,但提升效果主要体现在测试后期,且对混凝土气孔结构参数影响不大(28 d龄期)。

The influence of air-entraining agent,and the enhancement effect of one weak alkaline activator—sodium lactate on the salt frost resistance of supersulfated cement concrete were systematically investigated.Specifically,the surface spalling mass and relative dynamic elastic modulus of ultrasonic of concrete after different cycles of salt freezing were periodically tested,and the air-void structure characteristic was characterized.The results indicate that adding air-entraining agent effectively improves the salt frost resistance of supersulfated cement concrete but with the loss of strength,and the compound addition of sodium lactate avoids strength loss.Adding 0.3%(mass fraction)air-entraining agent of cementitious material,the spalling mass is only 919.7 g/m^(2),which is 36.8%lower than that of the reference group,and the relative dynamic elastic modulus of ultrasonic is not significantly reduced.The addition of air-entraining agent ameliorates the air-void structure of supersulfated cement concrete,including the reduce of internal pore spacing ecoefficiency and proportion of pore with string length greater than 100μm.This can slow down the development rate of internal microcracks and delay the failure under freeze-thaw cycles.In addition,sodium lactate promotes the hydration of supersulfated cement and enhances the salt frost resistance of concrete.However,the enhancement effect mainly appears in the late test period.Meanwhile,sodium lactate has little influence on the air-void structure parameters of concrete(28 d).