聚乙烯醇纤维对盐冻混凝土抗折强度的影响

Improved Flexural Strength Resistance of PVA Fiber-reinforced Concrete Subjected to Freezing and Thawing Cycles in Chloride Environment

通过聚乙烯醇纤维增强混凝土(PVA-FRC)试件和素混凝土试件28d弯曲抗折试验和300次盐冻后弯曲抗折试验,考察盐冻对混凝土试件弯曲抗折强度的损伤和纤维对盐冻前后混凝土试件弯曲抗折强度的增强作用。设置了3种纤维体积掺量的PVA-FRC试件,并在纤维体积掺量为1.5%的基础上,分别以10%硅灰和20%粉煤灰替代等量水泥试图提高PVA-FRC试件盐冻前后抗折强度。结果表明,PVA-FRC试件盐冻前后抗折强度均大于素混凝土试件盐冻前后抗折强度,纤维体积掺量为1.5%的PVA-FRC试件盐冻前后增益比最大;PVA-FRC试件盐冻后抗折强度损伤量远小于素混凝土试件抗折强度损伤量,纤维体积掺量为1.5%的PVA-FRC试件损伤量最低;硅灰和粉煤灰的掺加没有提高PVA-FRC试件盐冻前后的抗折强度,也没能降低PVA-FRC试件盐冻后抗折强度损伤量。

Flexural strength of PVA fiber reinforced concrete（PVA-FRC）specimens and plain concrete specimens were cured for 28 days and exposed to 300 cycles of freezing and thawing in chloride environment were tested.Effect of salt-freezing and PVA fiber-reinforcement on flexural strength of concrete was studied.PVA-FRC specimens with fiber volume fraction of three kinds of proportion were used for this test.With 10% silica fume and 20%fly ash instead of the isometric cement respectively based on PVA-FRC specimens with fiber volume of 1.5% and expected to improve flexural strength of PVA-FRC before and after salt-freezing.It showed that the flexural strength of PVAFRC specimens before and after salt-freezing was greater than plain concrete specimens.Gain ratios of PVA-FRC specimens were greater than 113%,and PVA-FRC specimens with fiber volume of 1.5% before and after salt-freezing was greater than all others.Damage of flexural strength of PVA-FRC specimens after salt-freezing was much less than plain concrete specimens,PVA-FRC specimens with fiber volume of 1.5% was less than all others.Resistance of PVA fiber-reinforced concrete with silica fume and fly ash before and after salt-freezing wasn′t improved,and damage of PVA-FRC specimens wasn′t reduced.