高石粉含量人工砂水工混凝土抗冻性的试验研究

摘要

The effects of the stone powder content in the artificial sand on the frost resistance of the secondary pump concrete with two water cement ratio was researched,and by taking the flexural strength loss rate,the relative dynamic modulus and the mass loss rate as evaluation indexes.The mechanism of powder effect on frost resistance of concrete was discussed by means of SEM testing technology.The results show that the flexural strength loss rate and the relative dynamic modulus of elasticity can reflect the deterioration of concrete performance more accurately which relative to the mass loss rate.The frost resistance of concrete first increases and then decreased with stone powder content increases,on one hand the stone powder micro aggregate filling effect and activity effect can improve the concrete density,and it is favorable to improve the concrete frost resistance.On the other hand,the air content decreased with increasing of powder content,and it is unfavorable frost resistance.From the frost-resistant performance point of view,there is an optimal range of stone powder content.Under the conditions of this test,the optimum range of the stone powder content in the artificial sand used for the secondary pump concrete is 20%~25%.%以抗折强度损失率、相对动弹性模量、质量损失率作为评价指标,研究了人工砂中石粉含量对两种水胶比的二级配泵送混凝土的抗冻性能影响,借助SEM测试技术分析探讨了石粉对混凝土抗冻性的影响机理.结果表明:相对于质量损失率,抗折强度损失率和相对动弹性模量能更准确地反映冻融循环对混凝土性能劣化的程度.混凝土的抗冻性随石粉含量增大而呈现先提高后下降的趋势,这是由于一方面石粉颗粒的微集料填充效应和活性效应能提高混凝土密实度,对改善混凝土抗冻性有利,另一方面,混凝土的含气量随石粉含量的增大而降低,从而对抗冻性不利.因此,从抗冻性的角度,石粉含量存在一最佳范围值.在本试验研究条件下,二级配泵送混凝土所用人工砂中石粉含量的最佳范围为20%~25%.