Experimental Study On Effects Of High Silicon Iron Tailings On The Concrete Carbonation And Frost Resistance

This paper selected high silicon iron tailings from Anshan Qida Mountain for study,discussed the mechanochemical activation effects of high silicon iron tailings and effects of high silicon iron tailings after mechanochemical activation on concrete carbonation and frost resistance were studied.Based on the basic principle of mechanochemical,analysis on particle size and SEM particle morphology observation and the XRD crystallization degree of high silicon iron tailings grinded different time were carried out.The results showed that within 3.5h,with increasing grinding time,the particle size decreases,specific surface increases;SEM showed that the particle size decreases,smoothness and degree of sphericity were raised;XRD showed that crystallization degree of SiO2 decreases.In this paper,the high silicon iron tailings after mechanochemical activation were used as supplementary cementitious materials of concrete.Through lots of experiments,discussed the impact of the supplementary cementitious on the concrete carbonation and frost resistance.Concrete were designed in 9 groups,a group of reference concrete,the design strength grade was C30,tailings partially replace cement in concrete 8 groups,not mixed with air-entraining agent and with air-entraining agent all four groups,which replacement of cement were 10%,20%,30% and 40% respectively.The test results showed that when cement was partially replaced by the tailings,concrete anti-carbonation properties was lower than the reference concrete,and with the replacement increased,concrete carbonation resistance reduced;mixing air entraining agent can improve the carbonation resistance of concrete;Given the actual needs of the project,when not mixed with air-entraining agents,the amount tailings replace cement capacity up to 20%,when mixed with air-entraining agent,the amount up to 30%.Tailings partially replace cement in concrete,whose frost resistant is roughly equal to the reference concrete,when the replacement is 30%,concrete frost resistance is better than the reference concrete;entraining agent can greatly improve the performance of concrete frost,when tailings replace cement is 10%,20% and 30%,the maximum number of the concrete freeze-thaw cycles can reach 300 times.DTA-TG analysis were carried out on cement paste and cement-tailings slurry (20% and 30% substitution)of 28d hydration,the results show that the incorporation of tailings have little effect on the hydration product type of slurry and calcium hydroxide was found gradually reduced.