Research On Anti-crack And Impermeability Of Fiber Expansive HPC In Deep Freezing Wall

With the exploitation of depth coal seams in the middle and eastern regions of China, the new shafts will encounter an increasing number of deep alluvium problem. The thickness of the single wall has reached more than 1.0m in order to resist strong external load in freezing and using HPC method, so the single wall is mass concrete. The wall s conceret can produce temperature cracks easily for great temperature difference between inside and outside it in low temperature in freezing method.In addition, currently mining projects require faster construction and early strength concrete leading to concentrated heat of hydration and followed significant cooling. Wherefore the wall often appear temperature constraints crack and leakage accident after thawing.In this paper, it has advanced a method which mix polypropylene fibers and expansive agent into the wall's HPC in order to enhance impervious and anti-cracking, through the study on cracking mechanism of HPC and water seepage mechanism of concrete materials. In the theory aspect, it has analyzed components, micro-structure, stress and temperature environment, deformation and cracking condition of HPC in depth freezing mine, and physical and chemical properties of polypropylene fibers and expansive agent compatible with concrete. In the experiments, it has accomplished the orthogonal assortment experimentation of polypropylene fibers and expansive agent which obtaind the optimal dosage of polypropylene fibers and expansive agent as to the concrete strength, moreover, it has completed cracks evaluation test of concrete while it was plastic phase and hardening afterwards as well as shrinkage test, impervious test, the bending toughness test of concrete. In conclusion, The optimal dosage of polypropylene fibers and expansive agent is acquired through comprehensive evaluation.The results show that doped with a proper proportion of polypropylene fiber and micro-expansive agent is favored to impervious and anti-cracking performance of high-performance concrete in depth freezing shaft wall Without affecting early compressive strength of concrete. The research results acquired from this paper can be used for one method to settle water Leakage problem in freezing wall with thick alluviumFigure [50] table [33] reference [54]...