Experimental Study On Adding Chloride Ion Transport Blocking Materials In Cement Concrete

There are many factors that affect the durability of cement concrete.In this paper,the performance of cement concrete in the addition of chloride ion transport retardation materials was studied.The experimental results of dispersion test of silica fume show that the maximum Zeta potential of silica fume is-46 mv in the range of pH 7~12 in the water dispersion system.In the silica fume concentration of 300 g/L,adding silica fume 3wt% poly carboxylate water-reducing agent and grinding and dispersing 24 h,the prepared silica fume dispersion has good stability,and the average particle diameter D50 was 237.3 nm.The effects of different additives on the chloride ion transport and mechanical strength of cement concrete were further studied.The results show that the prepared silica fume suspension can improve the mechanical properties of cement paste and cement mortar.The compressive strength of 28 days of cement paste sample and mortar sample with 6wt% dispersed silica fume instead of the same quality of cement were respectively increased 22.2% and 19.14% compared with those without silica fume.The compressive strength of 28 days of mortar sample with 6wt% dispersed silica fume instead of the same quality of cement and 0.4wt% sodium methyl silicate external addition of cement quality was increased 34.32% compared with those without silica fume.Chloride ion permeation of 60 days of free chlorine ions and total chloride ion content were respectively decreased 80.01% and 82.86% at the 12~16mm of permeation layer.The compressive strength of 28 days of mortar sample with 1wt% carbon nitride external addition of cement quality was increased 17.16% compared with not adding carbon nitride group.Chloride ion permeation of 60 days of free chlorine ions and total chloride ion content were respectively decreased 14.83%% and 20.18%% at the 12~16mm of permeation layer.The compressive strength of 28 days of mortar sample with 6wt% dispersed silica fume instead of the same quality of cement and 1wt% carbon nitride external addition of cement quality was increased 23.43% compared with with non-doped carbon nitride group.Chloride ion permeation of 60 days of free chlorine ions and total chloride ion content were respectively decreased 82.31% and 80.09% at the 12~16mm of permeation layer.The compressive strength of 28 days of mortar sample with 20wt% aluminate glass powder external addition of cement quality was decreased 9.72% compared with non-admixture group.Chloride ion permeation of 60 days of free chlorine ions and total chloride ion content were respectively decreased 32.8%and 10.36% at the 12~16mm of permeation layer.The splitting strength of 28 days of concrete specimen with 2wt% strongly basic anion exchange resin external addition of cement quality was increased 13.83% compared with not adding anion exchange resin group.The carbonization depth of the concrete with anion exchange resin after 28 days of carbonation was decreased 21.18% compared with not adding anion exchange resin group.The influence of silica fume on the high temperature and freeze-thaw performance of concrete shows that the mechanical properties of 6wt% dispersed silica fume instead of the same quality is the best at any temperature of 25~800?.The relative strength of adding dispersed silica fume and without silica fume were respectively 95.3% and 88.7% after 100 cycles of freeze-thaw cycles.