Experimental Studies On Durabilities Of Concretes With Different Binder Systems

This thesis presents experimental studies on the resistance to chloride ion permeability and sulfate erosion of concretes with different binder systems. Electrical conductivity of concrete at different ages is tested by ASTMC1202-97. By comparing the experiment result, the most optimum binder system is identified. Besides, a formula predicting chloride diffusion coefficient is used to evaluate the resistance to chloride ion permeability of concrete with different binder system, and the data obtained from this calculation are taken to compare with the experiment results. The resistance of sulfate erosion of concrete is also evaluated. When cured to different ages, specimens are put into two different sulfate environments, dipped in solution of sodium sulfate or subjected to wet-dry cycle. Loss of weight and compressive strength are considered as referenced index.It can be concluded from data of electrical conductivity tested that mineral admixture can improve the resistance to chloride ion permeability of concrete obviously without loss of strength. In all binder system adopted in this paper, compound of slag and silica fume is most effective. Moreover, compound of slag and fly ash can be better than each of them mixed into concrete separately. The best ratio of slag to fly ash in this experiment is 1:1. In the process of this testing program, the final electrical quantities are linearly dependent on electrical current in initial stage, therefore, initial current can instead of electrical quantities and become referenced index to evaluate the resistance to chloride ion of concrete under some conditions, but the sphere of application is not identified.The formula can predict the resistance to chloride ion permeability of concrete approximately by calculating chloride diffusion coefficient. However, it still leaves much to be desired. To measure the effect arising from different kinds of mineral materials system accurately, not only the dosage of mineral admixtures, but the physical property parameter should be taken into consideration.When cured to different ages, specimens are put into two different sulfate environments; Subjecting to wet-dry cycle is more severe than dipping, and increasing the concentration of solution is anther effective way to accelerate the deterioration rate of concrete. As the referenced index, Loss of strength is more sensitive to sulfate...