Studies on Frost Resistance of Concrete by Making Dense Surface Layr Using Permeable Sheets and Surface Coating

(1)密实面层的制作及其评价以高密度聚酯纤维为主要材料，采用4种透水片材制作混凝土密实面层。使用该片材后，由于自由水的排出和大的空隙率，混凝土表面的麻点减少，表面外观得到很大改善。随着水灰比的降低，回弹值和表层强度也随之增加。(2)透水片材和表面涂层对提高混凝土抗冻融性的作用，透水片材和表面涂层的使用，大大提高了混凝土的抗冻融性和表层强度。表层强度与相对动态弹性模量之间存在高度的相关性，表层强度与初始值的比值与相对动态弹性模量之间的相关性最强。因此，混凝土表层拔出强度是衡量混凝土表层冻害程度的一个很好的指标，通过对混凝土表层进行表面处理，如涂层、透水板等，可以大大改善混凝土表层的冻害程度。

(1) Making dense surface layr and its estimation.A total of four permeable sheets, mainly composed of high density and span bond fabric of polyester were examined to make tight surface layr of concrete. When using these sheets, the pits on concrete surface deceased and the surface appearance was greatly improved because of discharge of free water and large air void. Then, the rebound number and the surface layr strength also increased by lowering the water cement ratio.(2) Effect of permeable sheet and surface coating to improvefreeze-thaw resistance of concrete.Using permeable sheets and surface coating, the freeze-thaw resistance and surface layr strenth were greatly improved. A high relationship between the surface layr strength and relative dynamic modulus of elasticity was found, and the strongest correlation was observed between ratio of surface layr strength to initial value and relative dynamic modulus of elasticity. Therefore, the surface layr pull out strength was found to be an excellent index to evaluate the degree of surface layr of concrete due to frost damage.From the facts described above, It was found that the surface treatment such as coating and the use of permeable sheet could greatly improve the damage of the surface layr of concrete due to frost action.