The Effect Of Mineral Admixture On The Corrosion Process Of Steel In Concrete

The concrete structures under the environment of coastal saline soil suffer from chemical sulfate,chlorine salt and other environmental factors which cause damage to concrete and steel corrosion,resulting in the lack of durability of concrete structure,which lead to the safety of the structure the concrete structure reduced and the service of the engineering structure failed in advance,in order to seriously affect the safety and reliability of engineering structures.At the same time,fly ash,slag,silica fume and other mineral admixtures have be used for the preparation of the superior performance of concrete.Therefore,the research of effect of admixture on corrosion process of reinforced concrete is significant to enhence the safety and reliability of the pile foundation concrete structure in the saline soil environment.Some experiments are designed to carry out the electrochemical measurements in the corrosion process of the different dosage and mixed ratio of mineral admixture composite cement paste reinforced concrete,respectively.The different mineral admixtures influence on the corrosion process of reinforced concrete in different corrosive environment is analyzed.The main research results are as follows:(1)To some extent,the existence of sulfate slows down the corrosion rate of the specimens in the environment of chloride corrosion,but the corrosion rate is accelerated in the late stage of corrosion,and the corrosion degree is more serious.(2)The corrosion rates of the composite cement paste with single slag,fly ash and double mixed slag and fly ash are all reduced,significantly,with the obvious improvement of corrosion resistance of chloride and compound chloride and sulfate.The phenomenon of the fly ash cement paste and reinforced steel repassivation has occurred in single chloride solution and chloride and sulfate compound solution.The second hydration of fly ash has a significant effect on the repassivation of steel.(3)The corrosion resistance of chloride of the paste-steel specimens with 20%slag is better than that of compound chloride and sulfate.The corrosion resistance of chloride of the paste-steel specimens with 40%slag is little better than that of compound chloride and sulfate.The corrosion resistance of both chloride and compound chloride and sulfate of the paste-steel specimens with 20%slag is better than that of 40%slag.(4)The corrosion resistance of chloride of the paste-steel specimens with 10%fly ash is basically equivalent to that of compound chloride and sulfate.The corrosion resistance of both chloride and compound chloride and sulfate of the paste-steel specimens with 10%fly ash is better,not obviously,than that of 20%fly ash.(5)The corrosion resistance of compound chloride and sulfate of the paste-steel specimens with 10%fly ash and 10%slag is better than that of chloride.The corrosion resistance of chloride of the paste-steel specimens with 20%fly ash and 20%slag is basically equivalent to that of compound chloride and sulfate.The corrosion resistance of both chloride and compound chloride and sulfate of the paste-steel specimens with 20%fly ash and 20%slag is slightly better than that of 10%fly ash and 10%slag.