Study On The Effect Of Activator On The Performance Of Aeolian Sand Powder Cementitious System

With the transformation and upgrading of concrete and cement products industry,it is developing towards low-carbon and high-efficiency green,more and more solid wastes are used as the materials and the production of cement which is supplementary and cementitious.This project is aimed to activate the aeolian sand,which is low activity and difficult to use of aeolian sand in the Xiangsha Bay of Dalate Banner,Ordos City,Inner Mongolia,combined with modern excitation technology.The activated aeolian sand powder was used as supplementary cementitious materials in water cement concrete,and the hydration mechanism of aeolian sand powder composite cementitious material was analyzed,the contents and results are as follows:（1）It is found that the compressive strength of glue sand increased and then decreased with the increase of grinding time of aeolian sand.When grinding 50 minutes,the compressive strength of aeolian sand powder glue sand at different ages is the largest.（2）Three types of activators were separately pulverized with aeolian sand for 50 min,and the activated aeolian sand powder was used to replace the 30%cement to make the glue sand,and the compressive strength test was carried out.Preferably,two kinds of sulfate-based activators and two kinds of alkali-based activators and one type of alcohol-amine activator are used,and orthogonal tests are carried out under appropriate dosages.The optimal ratio was selected:0.25%for Na₂SO₄,0.65%for CaSO₄,0.25%for Na₂SiO₃,0.05%for Ca（OH）₂,and 0.03%for TEA.（3）Active aeolian sand powder prepared by integrally grinding the orthogonally preferred composite activator with aeolian sand for 50 min,the same quality replaces 30%cement to make the glue sand.The compressive strength and hydration heat test of the aeolian sand powder before and after the excitation were carried out,and the hydration products of aeolian sand powder composite cementitious material for 3d,7d and 28d were analyzed by field emission scanning electron microscopy（SEM）.The results show that the compressive strength of aeolian sand powder is improved after excitation,and compressive strength of 28 day is the most significant,increased 14%.It was found that there were abundant interlaced fiber cluster C-S-H gel and slender columnar AFt crystal in the product of aeolian sand powder sand.A spatial reticular structure is formed and pores are filled,which compacts the structure of the cemented sand specimen.The composite activator can improve the early hydration rate of the aeolian sand micro-powder composite cementitious material and accelerate the exothermic peak time.（4）To study the effect of composite activator on the compressive strength,chloride ion penetration resistance,wear resistance,shrinkage and frost resistance of aeolian sand concrete,we replaced 30%cement with active aeolian sand powder prepared by integrally grinding the orthogonally preferred composite activator with aeolian sand for50 min.The results show that under the same water binder ratio,compared with Aeolian sand powder concrete before activation,the compressive strength of the aeolian sand powder concrete after the excitation is improved,and the 7d compressive strength is the most significant.The wear resistance and resistance to chloride ion erosion are also correspondingly improved,and these are larger than that of fly ash concrete.However,Activated Aeolian Sand powder Concrete shrinkage deformation is larger than the Aeolian sand powder concrete before activation and fly ash concrete;Compared with fly ash concrete,two types of aeolian sand micro-powder concrete have poor frost resistance and have been destroyed after 100 cycles of freeze-thaw cycles.