Experimental Study On Tensile Property Of Concrete Exposed To Simulated Acid Rain Environment

Since the acid medium take complex chemical and physical actions with concrete and reinforcing steel, the concrete structures servicing in the acid rain environment always deteriorated gradually, even fails much earlier than its design servicing life. Therefore, it has significant theoretical and practical value to discover the damage mechanism of concrete, which will build a solid foundation for the study on durability of concrete structures in acid rain environment.Funded by the National Science Foundation of China (Grant No.50708010), "Study on mechanical response of reinforced concrete bridge under marine environment and vehicle loadings", the deterioration mechanism of the tensile property of concrete in the acid rain environment is studied.64 dumbbell shaped concrete specimen were cast. Viewing to the composition of acid rain in typical city of China, pH 1.0 acid solutions were deposed to simulate acid rain environments in the laboratory. The cast concrete specimens were exposed to the simulated acid rain solutions for certain periods. Then, comprehensive experiments were conducted on the concrete specimens at different damage states on macro, mesco and micro scale. The main contents of the research are listed as follows:Firstly, tensile test are performed on the concrete specimen under various corrosion states. Some results on macro-scale which inclusive of appearance, mass loss, tensile stress-strain relationship are achieved. Relations between the mechanical indices (such as mass loss ratio, relative deterioration ratio of tensile strength, relative deterioration ratio of peak strain, relative deterioration ratio of elastic modulus, etc.) and the corrosion states are discussed in detail. Received the law such as tensile strength,peak strain,elastic modulus; 4 damage indices(mass loss ratio, relative tensile strength variation ratio, relative peak strain variation ratio, relative elastic modulus variation ratio) to appraise the damage of concrete. Discuss inside structure deterioration principium of concrete been corroded by acid rain.To determine the meso-level structure of concrete specimen at different damage states, Computerized tomography (CT) was used herein. Based on the scanning images, the internal meso-level structure of the specimen is described. Then, the specimens were conditioned in the simulated acid rain for different period and scanned again.To better understand the internal cracks in the specimen, microstructure of the deteriorated concrete specimen was studied by SEM analysis. Microstructures of concrete sample cut from concrete specimen being exposed to the simulated acid solutions are compared.To discover tensile property of concrete in acid rain environment, experiments of marco-level, meso-level, and micro-level are fulfilled. The testing resulted achieved on different scales are compared and discussed. The macro phenomena of the damaged concrete specimen are explained by CT and SEM tests.