纳米SiO2对再生骨料混凝土的抗冻性能影响研究

Study on the Effect of Nano SiO2 on the Anti-freezing Property of Recycled Aggregate Concrete

为探讨纳米SiO2对再生骨料混凝土的抗冻性能影响,通过对加入不同掺量和粒径的纳米SiO2再生骨料混凝土进行快速冻融循环试验,研究了冻融循环作用下纳米SiO2对再生骨料混凝土的抗压强度、质量损失率及相对动弹性模量的影响规律。试验结果表明:(1)再生骨料混凝土的坍落度随着纳米SiO2掺量的增大逐渐减小;(2)随着冻融循环次数和纳米SiO2粒径的增加,再生骨料混凝土的抗压强度和相对动弹性模量均逐渐减小,随着冻融循环次数和纳米SiO2掺量的增加,混凝土的质量损失率则均呈先减小后增大趋势;(3)随着纳米SiO2掺量的增大,再生骨料混凝土的抗压强度和相对动弹性模量均呈先增大后减小趋势;随着纳米SiO2粒径增大,再生骨料混凝土的坍落度和质量损失率则逐渐增大;(4)适量的纳米SiO2有利于提高再生混凝土的抗冻性能,而过量则导致其抗冻性消弱。

In order to investigate the effect of nano Si O2 on the frost resistance of recycled aggregate concrete,the effects of nano Si O2 recycled aggregate concrete with different content and particle size on compressive strength,mass loss rate and relative dynamic elastic modulus of recycled aggregate concrete under freeze-thaw cycle were studied by rapid freeze-thaw cycle test. The experimental results show that: 1) the slump of recycled aggregate concrete decreases with the increase of nano Si O2 content;2) With the increase of freeze-thaw cycle times and nano SiO2 particle size,the compressive strength and relative dynamic elastic modulus of recycled aggregate concrete decrease gradually,and with the increase of freeze-thaw cycle times and nano SiO2 particle size,the compressive strength and relative dynamic elastic modulus of recycled aggregate concrete decrease gradually. With the increase of freeze-thaw cycle times and nano SiO2 content,the mass loss rate of concrete decreases at first and then increases. 3) With the increase of nano Si O2 content,the compressive strength and relative dynamic elastic modulus of recycled aggregate concrete increase and then decrease,and the slump and mass loss rate of recycled aggregate concrete increase with the increase of nano SiO2 particle size.4) Proper amount of nano Si O2 is beneficial to improve the frost resistance of recycled concrete,while excess leads to the weakening of frost resistance of recycled concrete.