中文摘要：

制备水灰比为0.4和0.5的普通混凝土和掺引气剂混凝土,通过冻融循环试验、楔形劈裂试验,及CONSOFT软件逆向分析和拟合,研究了冻融循环损伤对混凝土断裂能及其应变软化的影响。结果表明,100次冻融循环后水灰比为0.4和0.5的普通混凝土相对动弹性模量分别下降30%和55%,而掺加引气剂混凝土几乎无动弹性模量损失;冻融循环后,混凝土断裂能显著下降,水灰比为0.5的普通混凝土100次冻融循环后断裂能损失71%,水灰比0.4时下降超过50%,极大削弱了混凝土的软化韧性;掺加引气剂混凝土具有良好的抗冻能力,虽然断裂能也随冻融次数的增大而降低,但基体内部大量气泡的存在使混凝土弹性变形能力增大,从应变软化性能来看,其抗拉强度较普通混凝土高得多,呈现较好的韧性。

英文摘要：

Both normal concrete and concrete with addition of air entraining agent with water cement ratio of 0.4 and 0.5 have been prepared. Through freeze-thawcycle test and wedge-splitting test,the influence of frost damage on fracture properties of concrete has been studied. The fracture energy and the strain softening curves under different conditions have been analyzed by the program CONSOFT in particular. The results indicate that after 100 freeze-thawcycles,the relative dynamic elastic modulus of normal concrete with water cement ratio of 0.4 and 0.5 was reduced by 30% and 55%,respectively; while as for concrete with addition of air entraining agent,the relative dynamic elastic modulus showed no decrease. After a certain number of cycles of freezing and thawing,the fracture energy of concrete decreased significantly. The fracture energy of normal concrete with water cement ratio of 0.5 loss 71% after 100 cycles; concrete with water cement ratio of 0.4 loss higher than 50%. With addition of air entraining agent,concrete had good frost resistance. The fracture energy also decreased with the increasing of freeze-thawcycles,however,the big amount of small air bubbles introduced by entraining agent lead to increasing of elastic deformation capacity of concrete. Therefore,concrete with air entraining agent had much higher toughness than normal concrete after freeze-thawcycles.