The Cementitious Activity Of Mineral Powder And Its Effect On Chloride Ion Permeability Of Concrete

Mineral powder and cement has a similar chemical composition, with potential activity,and it is a kind of green, environmentally friendly, cheap building material. With the replacement of cement, mineral powder can reduce the production cost of concrete and reduce the pollution of cement production. This paper systematically researches the cement and mineral powder mixed cementitious system activity and the mineral powder content are 40%, 50%, 60%. This paper also systematically studies the chloride ion permeability of concrete with mineral powder. The activity of the mixed cementitious system is studied by adding compound activator(Na2CO3 and Na2SO4) and the increasing of curing temperature. This paper tests the concrete' strength and resistance to chloride ion permeability under different conditions which is mixed with lots of mineral powder, and analyzes the microstructure of concrete with lots of mineral powder. The main research contents as follows:By measuring the strength of mortar to indirectly evaluate the activity of the gelling system, the experiment shows that the best ratio of compound activator(Na2CO3 and Na2SO4) is 1:1, the optimum content is 3%. The compound activator(Na2CO3 and Na2SO4) can improve the flexural strength, so as to improve the toughness of mortar. This paper studies the excitation effect of curing temperature on the activity of mineral powder, when the curing temperature was 20?, 30?, 40?. The results show that the optimal curing temperature is 30? and the effect of curing temperature on activation of excitation effect is better than adding the compound activator.By testing the compressive strength of concrete with lots of mineral powder and the electric flux test under different conditions, it is found that the compressive strength of concrete is not lost and the resistance to chloride ion penetration is better, when the curing temperature is 30? without adding any activator. Compound activator(Na2CO3 and Na2SO4) can improve the resistance to chloride ion penetration of concrete with lots of mineral powder.This paper studies the microstructure of concrete with lots of mineral powder by Rapid Air 457 Air void analyzer. Compared with no mineral admixture of concrete, mineral admixture concrete internal closed porosity content is relatively higher, and the distance between the pores is larger. At the same time, there is a certain correlation between the Air Content and the Spacing Factor and the compressive strength of concrete with lots of mineral powder.