Experimental Study On Working Performance Of Sepiolite Concrete

Cement as one of the necessary raw materials for concrete,generates a large amount of carbon dioxide during its production process,which poses serious environmental hazards.In order to build a green and sustainable society,it is imperative to strengthen research and development and explore new cementitious materials.Sepiolite is a clay minerals containing magnesium silicate,which has a large specific surface area,adsorption and high temperature resistance.At present,it is widely used in agriculture,medicine,chemical industry,catalysis,building materials and other fields.Through studying the influence of sepiolite on concrete performance,this paper explores the feasibility of sepiolite replacing part of cement as a new cementing material.The main research contents and conclusions are as follows:Through compression and splitting tensile tests,it is found that in terms of mechanical properties of concrete,with the increase of sepiolite content,the mechanical properties of concrete are gradually reduced,and the extent of reduction is also gradually reduced with the increase of concrete curing age.When the sepiolite content is 3% and 6%,the mechanical properties of concrete are reduced by about 5% in the later period,with little impact.When 6%of sepiolite,which has been calcined at high temperature,is added into the concrete,it is found that the calcination temperature of sepiolite at 600℃ and 800℃ has little effect on the later mechanical properties of concrete,but when the calcination temperature is 1000℃,the effect is greater,and the mechanical strength at each age is reduced by more than 10%;By comparing the influence of sepiolite added to concrete under different water binder ratios on the mechanical properties,it is found that the greater the water binder ratio,the smaller the mechanical properties will be.When the water binder ratio is 0.45 and the sepiolite content is6%,the mechanical strength of concrete in the later period will decrease by about 3%,and the influence can be almost ignored;Comparing the impact of 100 mesh and 325 mesh sepiolite on the mechanical properties of concrete,it is found that the larger the mesh number,the smaller the impact.In the tests of electric flux,capillary water absorption and drying shrinkage of concrete,it is found that when the content of sepiolite is 6%,the durability of concrete can be effectively improved,electric flux and drying shrinkage both decrease,and capillary water absorption increases mainly because of the water absorption of sepiolite;After being calcined at 600℃and 800℃,sepiolite improves the durability of concrete more than normal temperature,and the maximum electric flux value decreases by more than 20%.The increase of capillary water absorption is due to the increase of internal pores of sepiolite caused by high temperature,which strengthens the water absorption capacity;By comparing the influence of sepiolite with different water binder ratios on concrete performance,it is found that when the sepiolite content is 6%,the greater the water binder ratio is,the more obvious the improvement of concrete durability will be.The electric flux of concrete at the water binder ratio of 0.45 has more than doubled compared with 0.35 at each age,the capillary water absorption has increased by half,and the drying shrinkage has also decreased significantly;At the same time,it is also found that the mesh size of sepiolite ranges from 100 mesh to 325 mesh,and the larger the mesh size,the greater the increase in concrete durability.Based on the above analysis,sepiolite can have little impact on the mechanical properties on the premise of improving the durability of concrete.