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

关键词:  聚乙烯醇纤维增强水泥基复合材料  自生收缩  纤维体积分数  水胶比  砂胶比

Key words:  polyvinyl alcohol fiber reinforced cementitious composite  autogenous shrinkage  fiber volume fraction  water-binder ratio  sand-binder ratio

摘要:

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.

Abstract:

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， while ε_a/ε_t 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.