配合比对PVA-FRCC长期自生收缩性能的影响

Effect of Mix Proportion on the Long-Term Autogenous Shrinkage of PVA-FRCC

基于聚乙烯醇(PVA)纤维增强水泥基复合材料(PVA‑FRCC)试件的收缩试验,研究了纤维体积分数、水胶比、砂胶比对PVA‑FRCC自生收缩性能的影响.结果表明:PVA纤维的掺入减小了水泥基材料的自生收缩,但效果有限;低水胶比/低砂胶比(LW/LS)组试件的自生收缩明显大于高水胶比/高砂胶比(HW/HS)组试件;水胶比在小范围内变化时,PVA‑FRCC自生收缩随水胶比增大而增大,随砂胶比增大而降低;HW/HS组试件自生收缩占比(ε_(a)/ε_(t))随龄期的增加而增大,LW/LS组试件ε_(a)/ε_(t)随龄期的增加先增大后降低;解除密封后,HW/HS组PVA‑FRCC试件的总收缩仍有较大增长,LW/LS组试件则增长较少.

Based on the shrinkage experiment of polyvinyl alcohol fiber(PVA)reinforced cementitious composite(PVA-FRCC)specimens,the effects of the fiber volume fraction,water-binder ratio and sand-binder ratio on the autogenous shrinkage of the PVA-FRCC were studied.The results show that the addition of PVA fiber reduces the autogenous shrinkage of the cement-based materials,but the effect is limited.The autogenous shrinkage of low water-binder ratio/low sand-binder ratio(LW/LS)specimens is much larger than that of high water-binder ratio/high sand-binder ratio(HW/HS)specimens.When the water-binder ratio changes in a small range,the autogenous shrinkage of PVA-FRCC increases with the increasing of the water-binder ratio,and decreases with the increasing of the sand-binder ratio.With the increasing of the age,proportion of autogenous shrinkage(ε_(a)/ε_(t))of HW/HS specimens increases,whileεa/εt of the LW/LS specimens increases first and then decreases.After unsealing,the shrinkage of HW/HS specimens increases greatly,while that of the LW/LS specimens increases less.