纳米SiO2和聚乙烯醇纤维对混凝土抗弯拉性能的影响

通过坍落扩展度试验和抗弯拉性能试验,采用4种不同纳米SiO2质量掺量和4种不同聚乙烯醇(PVA)纤维体积掺量,探讨纳米SiO2和PVA纤维对混凝土拌合物流动性及抗弯拉性能的影响.结果表明,随着纳米SiO2或PVA纤维掺量的逐渐增加,混凝土拌和物的流动性逐渐降低.纳米SiO2掺量不超过5％时,随着纳米SiO2掺量的增加,混凝土抗弯拉弹性模量以及抗弯拉强度均不断增大;但当纳米SiO2的掺量从5％继续增加到7％时,混凝土抗弯拉弹性模量和抗弯拉强度均有一定下降.当PVA纤维体积掺量低于0.1％时,PVA纤维对纳米混凝土抗弯拉性能的增强作用随纤维体积掺量增加逐渐增大,但当纤维体积掺量超过0.15％时,纳米混凝土抗弯拉强度和抗弯拉弹性模量均有下降趋势,抗弯拉强度和抗弯拉弹性模量分别在纤维体积掺量为0.15％和0.1％时达到最大值.

Effect of Nano-SiO2 and PVA Fiber on Flexural Performance of Concrete

Through the slump flow test and flexural performance test, the effects of PVA fiber and nano-SiO2 on the flowability of fresh concrete and the flexural performance of concrete were discussed. Four different nano-SiO2 contents and four different PVA volume contents were adopted. The results show that the workability of fresh concrete decreases with the increasing content of nano-SiO2 or PVA fibers. When the amount of nano-SiO2 is less than 5%, the flexural elastic modulus and flexural strength increase with the increase of the amount of nano-SiO2. However, when the amount of nano-SiO2 increases from 5% to 7%, the flexural elastic modulus and flexural strength decreases. When the volume content of fibers is low, the reinforcement of PVA fibers on flexural performance of concrete is increasing with increment in fiber dosage. While the fiber dosage is large, the flexural performance of concrete has decreasing tendency. Flexural strength and elastic modulus reach the maximum on condition that fiber volume dosages of 0.15% and 0.1% were used, respectively.