硅粉掺量对低水胶比混凝土收缩特性及水化产物的影响

Effects of the Silicon Powder Dosage on the Shrinkage Properties and Hydration Products of Low w/c Concrete

低水胶比混凝土(LWCC)因收缩变形较大,限制了其工程应用。硅粉是影响LWCC收缩变形的重要因素。本文系统地研究了不同硅粉掺量对LWCC化学收缩、自生收缩、干缩、抗压强度和水化产物的影响。研究表明,硅粉可减小LWCC化学收缩,掺量越大,则降低幅度越大。硅粉掺量对LWCC自收缩与干缩的影响规律相似,随着硅粉掺量的增大,自收缩或干缩先增大后减小,30%硅粉掺量使得两种收缩出现最大值。此外,硅粉可与水泥水化产物Ca(OH)2发生反应产生更多的承重物质CSH,从而可提高LWCC抗压强度,掺量越大,抗压强度提高幅度越高。

Low w/c concrete(LWCC)commonly has a much larger shrinkage,leading to a limited application.Silicon powder is one of the important factors affecting the shrinkage of LWCC.To reveal the effect of silicon powder on the shrinkage properties,this paper conducted several tests.Results showed that the chemical shrinkage of LWCC could be directly reduced by adding the silicon powder.The effects of silicon powder on the autogenous shrinkage and drying shrinkage enjoyed a similar result that 30%dosage is the peaks of both the autogenous shrinkage and drying shrinkage.Moreover,the compressive strength of LWCC could be improved through the production of more CSH by the reaction of silicon powder and the cement hydration product Ca(OH)2.