高温-干湿循环作用下混凝土分区抗硫酸盐的侵蚀性能OA

To address the damage and deterioration of concrete materials in a sulfate environment in marine engineering,a concrete erosion test and microscopic test under different concentrations of sulfate solution and high temperature in the semi-immersed environment were carried out.By analyzing the mass change,dynamic elastic modulus,composition and content of eroded products,and sulfate ion content of concrete specimens and conducting the microscopic test,the damage and deterioration law of concrete under the high temperature and dry-wet cycle in semi-immersed and sulfate environment was revealed.The results show that in the early stage of sulfate erosion,sulfate invades the interior of concrete in the immersion zone and promotes hydration.The ettringite(AFT)and gypsum inside the concrete fill the initial gap,and the products play a filling and skeleton role.However,the continuous increase of the product amount in the later stage causes damage to the concrete,and the dynamic elastic modulus decreases by 12%-30%.The concrete in the adsorption zone is subjected to both the dry-wet cycle and the thermal cycle.The two cycles aggravate the capillary and diffusion effects so that the salt is easy to crystallize inside the concrete.Additionally,the thermal cycle accelerates the separation of aggregate and cement matrix,forming more pores,which is conducive to the continued intrusion of salt.The filling effect in the early stage of sodium sulfate crystallization improves the strength,and the mass increases by 0.5%-1.75%.However,the damage effect in the later stage is more serious.