干燥失水对混凝土徐变的影响

Creep of concrete due to desiccation

干燥不仅引起混凝土收缩增加,也导致徐变增加。通过试验研究混凝土失水干燥与徐变增加的相关性,分析了干燥过程中骨料、外加剂对徐变的影响,验证失水改变孔隙充水程度进而影响混凝土力学性能、宏观表现出徐变增加的机理。研究结果表明,混凝土徐变随干燥失水程度线形增加,粗骨料本身质地是骨料影响徐变的主要原因;外加剂改变了混凝土孔溶液的表面物化性能,导致孔溶液与孔壁相互作用变化及干燥过程改变,是外加剂影响徐变的根本原因。

The drying causes the increase in shrinkage as well as creep of concrete.In this paper, the creep of concrete due to moisture lost is observed.The theory that moisture lose changes the mechanical behaviour of concrete and hence causes the extra creep is experimentally verified.In the experimental tests, the influence of the types of coarse aggregate and chemical admixtures on the extra creep due to drying and the relevant mechanisms are investigated.The test results show that the creep of concrete increases with moisture loss proportionally.The change in creep with the category of coarse aggregate is mainly due to the difference in the rigidity of coarse aggregates.The chemical admixture may modify the surface physic-chemical properties of pore liquid and hence the drying process as well as the interaction between the liquid in pores and the pore surfaces are changed, which accounts for the influence of chemical admixtures on creep of concrete.