Study Of Sea Sand Concrete Resist Chloride Permeability Under Recombination Action

With the extensive construction of the city, some places has emerged a shortage of river sand. So the resourses of sea sand has been gradually used for the construction, as the advantages of abuandance and low-cost. But there are many differences between sea sands and river sands in basical performances, especially if the Chloride ion and some other harmful substances in the sea sand were infiltrated into concrete, may it can affect the durability of concrete seriously. So it is essential to study the durability of sea sand-concrete.This passage mainly researches the Chloride ion Penetration of sea sands mortar specimens and washed sea sand mortar specimens,when they are loaded by both four point load and NaCl solution of 3%. And study the effect of silane waterproofing treatment on the chloride diffusion in the specimen. Concrete with strength class of C30,C40,C50and C60 were prepared from sea sand, washed sea sand and river sand. The experimental test series were described by accelerated carbonation and combined carbonation and chloride penetration. Finally carbonation depth and free chloride content of concrete in different depths were determined. and compared with river sand concrete. So as to get the degradation mechanism of sea sand concrete under combined environmental loads. By comparative study,found the durability of washed sea sand.The results show that: sea sand mortar, sand mortar, and washed sea sand mortar test block under load, the amount of free chloride ion penetration increases with the load. Generally, the chloride content is the highest in specimen surface, after a certain depth, chloride ion content stabilized. The chloride ion permeability in mortar specimen coated with silane waterproofing agent is effectively reduced. In generally, the free chloride content in different depths is lower than the untreated specimen about 65%, while free chlorine ions penetration depth is also significantly reduced. Under the same conditions, the longer the penetration time is, the greater the concentration of chloride ions is, the longer the carbonation time before soaking is, the lower the concrete strength grade, the free chloride ion content in different depths of concrete is higher. And the soaking solution concentration of chloride ion content in concrete is the largest influence, followed by soak time, carbonization time.It can be seen that sea sands can not directly used for reinforced concrete as the overproof chloride. And after the dilution of sea sand, the content of choride is on the verge of river sand, and washed sea sand has good gradation, the silt concentration is low, and the mechancial property and durability of concrete is as good as river sand concrete. So washed sea sand is good building material.