硫酸盐侵蚀环境下混凝土断裂参数衰减规律  

Decay of Fracture Parameters of Concrete under Sulfate Environments

作　　者：高原[1,2] 张君[1,2] 韩宇栋[1,2] 

机构地区：[1]清华大学结构安全与耐久教育部重点实验室,北京100084 [2]清华大学土木工程系,北京100084

出　　处：《建筑材料学报》2011年第4期465-472,477,共9页Journal of Building Materials

基　　金：国家重点基础研究发展计划(973计划)项目(2009CB623200)

摘　　要：采用三点弯曲试验测取荷载-裂纹口张开位移(P-CMOD)曲线,逆推得到混凝土抗拉软化关系(σ(应力)-w(裂纹宽度))以及开裂强度、抗拉强度和断裂能等断裂参数的方法,研究了C30,C50和C80这3种强度等级混凝土在10%(质量分数)硫酸钠、10%(质量分数)硫酸镁和清水3种侵蚀环境中断裂参数的衰减规律.8个月浸泡结果表明,在硫酸盐侵蚀环境中,低强度等级混凝土(C30)的开裂强度、抗拉强度和断裂能均呈现先增加后减小的变化特征,脆性指数呈现先减小后增加的变化趋势;高强度等级混凝土(C50,C80)的开裂强度、抗拉强度、断裂能和脆性指数均呈现小幅变化特征,这与高强度混凝土水灰比低、孔隙率小,硫酸盐侵入混凝土内部需要较长时间有关.A method to solve tension softening relationship of concrete from three point bending test was used to evaluate the variation of fracture parameters,including cracking strength,tensile strength and fracture energy,of concrete under sulfate environments（10%（by mass） MgSO4 and Na2SO4） and clean water.The results of 8 months attack test show that the variation of fracture parameters under sulfate environments is influenced by the compressive strength.Along with the duration of sulfate attack,for normal strength concrete（C30）,the cracking strength,tensile strength and fracture energy increase at first and then decrease,and the characteristic length decreases at first and then increases.For the high strength concrete（C50,C80）,during the attack period,the cracking strength,tensile strength,fracture energy and characteristic length change a little.The above performance may be related to the water to cement ratio and the porosity of cement paste.The lower the water to cement ratio and/or the smaller the porosity,the lower the rate of sulfate attacking.

关 键 词：硫酸盐侵蚀 混凝土 软化关系 开裂强度 抗拉强度 

分 类 号：TU528.0[建筑科学—建筑技术科学]