冻融时间对早期混凝土抗压性能的影响试验

为研究冻融前养护时间和冻融时间对早期混凝土抗压性能的影响，采用混凝土冻融试验机冻融循环和冬季室内外自然冻融循环，对不同冻融前养护时间和冷冻时间的混凝土立方体试块进行抗压性能试验．冻融循环后混凝土表面不再光滑，表面剥落情况越严重，混凝土疏松、起皮，甚至脱皮，空洞现象也随之增多．龄期越早、冻融时间越长表面破坏越严重．混凝土冻融试验机和室内外自然冻融受冻试块的冻融时间与质量损失率的关系曲线大致相同，受冻时间为6h的试块均比受冻时间为12h的质量损失大，且冻融前养护3d和7d的质量损失较大，7d后质量损失较小，斜率趋于平缓．混凝土冻融试验机和冬季室内外自然冻融受冻12h的试块比受冻6h的抗压强度低，抗压强度损失率要大．

Experimental Research on Compressive Property of Crumb Rubber Concrete Based on Freezing and Thawing Time

In order to research compression behavior of concrete cubes based on the time of freezing and thawing, the compression tests of concrete cube test blocks in two kinds of freeze-thaw-cycle condition of concrete freeze-thaw test machine and natural state in winter are made. The results show that after the freeze-thaw cycles, the concrete surface is no longer smooth, the surface flakes seriously, and the concrete is loose, peeling, or even scaling, the number of concrete hollows is also increased. Erosion damage of concrete is more serious with the decrease of concrete maintenance time before freezing and thawing and the increase of the time of freezing and thawing. The relation curves of freeze-thaw time and mass loss of two kinds of freeze-thaw-cycle condition are roughly the same. The loss of quality of the test block which got frozen for 6 h was more than that got frozen for 12 h. And the quality loss of the blocks conserved for 3 d or 7 d before freeze-thaw was larger than after 7 d, the slope was leveling off. The compressive strength of the test block that was frozen in concrete freeze-thaw testing machine and the natural freeze-thaw indoor and outdoor in winter for 12 h is lower than that for 6 h; the loss rate of compressive strength is larger.