溶蚀混凝土的表征及应力-应变关系

溶蚀作用导致水泥基材料的孔隙率增加从而影响材料的传输及力学性能.对于结构中的既有混凝土,采用非破损和局部破损方法测量和评估溶蚀混凝士的承载力是非常重要的.采用酚酞指示剂法、孔隙溶液pH测量法、超声波无损检测法,对溶蚀混凝土进行了溶蚀损伤程度表征;试验测试了溶蚀混凝七的单轴应力一应变关系:采用XRD和压汞分析研究了混凝土...

Characterization and Stress-Strain Relationship of Leached Concrete

Leaching of ccmentitious materials leads to an increase in porosity,which has important consequences on transport and mechanical properties.It is thus important to investigate the methods that can be used in unleached concrete to evaluate the residual bearing capacity of leached concrete.In this paper,the degradation degree of leached concrete was characterized by three methods (i.e,spraying phenolphthalein,pH value of pore solution,velocity of supersonic).The stress-strain curve of leached concrete under unaxial loads was examined by a material test system.The kinetics of degradation Was analyzed by X-ray diffraction and mercury intrusion test.The results show that spraying phenolphthalein is an effective way to characterize the leaching degradation related to attenuation of compressive strength.The dissolution happened both in portlandite and C-S-H gel during the leaching duration and the dissolution of portlandite is a main cause of mass loss at the early stages of leaching.A number of harmful pores with the size above 200 nm increased in the leaching of portlandite,affecting the durability of leached concrete.The stress-strain behaviors for all the leached concrete were similar to that for unleaehed concrete.The unleached concrete showed a better ductility,compared to unleached concrete.