纤维混凝土冻融损伤试验研究

Experimental study on the damage of fiber concrete in freeze-thaw cycles

对普通素混凝土、掺加钢纤维或聚丙烯纤维的混凝土进行了快速冻融循环试验,经过对试件进行强度测试,分析研究了冻融循环后掺加不同纤维的混凝土的力学损伤规律,依据损伤破坏的相关理论,对纤维混凝土的冻融损伤破坏机理进行了分析。以动弹性模量来定义损伤变量,依据试验数据对损伤演变模型进行了拟合。分析和计算结果表明:混凝土中掺加纤维有助于减小冻融循环对试件动弹性模量的影响,提高了混凝土的抗冻性;掺加钢纤维和聚丙烯纤维的混凝土抗压强度和抗弯拉强度损失远小于普通素混凝土,尤其是抗弯拉强度大大提高;结合试验数据对冻融损伤演变方程进行拟合,发现纤维混凝土冻融损伤演变模型有较高的拟合精度,说明该模型能较好地表征本试验的纤维混凝土冻融损伤演变过程。

Common concrete, steel fiber concrete, polypropylene fiber concrete are tested by freeze-thaw cycles. Through the strength test of specimens, rules of mechanical damage of fiber reinforced concrete after freezing and thawing cycles are studied. On the basis of the relevant theories of damage, mechanism of damage from freeze-thaw on fiber reinforced concrete are analyzed. Damage variable is defined by the dynamic elastic modulus. According to the experimental data, the model of damage evolution is fitted. Test analysis and calculation indicate that concrete adding fiber helps to reduce the influence of freezing and thawing cycles on the dynamic elastic modulus of specimens and improves the freeze-thaw resistance of concrete. Compressive strength loss and flexural tensile strength loss of concrete mixed with steel fiber and polypropylene fiber are far less than ordinary concrete. Especially, the flexural tensile strength of concrete is greatly improved. Based on test data, the equation of freeze-thaw damage evolution is fitted. And the accuracy of the model of damage evolution of fiber reinforced concrete freezing and thawing is high. The model can better characterize the process of freeze-thaw damage evolvement of fiber reinforced concrete.