Study On The Effect Of Dispersants On The Dispersibility Of Glass Fibers In Cement Matrix

Fiber concrete works better compared to ordinary concrete,especially it can improve the tensile properties,bending properties and alkali resistance of concrete,etc.Glass fiber is widely used to make fiber concrete because of its high strength,high alkali resistance and low cost.However,in the process of preparing glass fiber concrete,there are difficulties in the uniform dispersion of glass fibers in the concrete,and even the phenomenon of fiber "dough",resulting in the work of glass fiber concrete performance instead of rising.Therefore,in this paper,glass fiber dispersant types(polymer type hyperdispersant(B193),polyether modified polymer(S-3101B)and sodium carboxymethyl cellulose(CMC)),dispersant mass fraction(0,0.2%,0.5%,0.8% of the cementitious material)are used as variables to investigate the compressive strength,splitting tensile strength,impermeability,microstructure,energy loss of glass fiber concrete and finite element models were investigated.Based on the above study,the admixtures of the three dispersants were determined,and then the dispersant admixtures were quantified(0.5% mass fraction of B193,0.2% mass fraction of S-3101 B,0.5% mass fraction of CMC)and the replacement rate of recycled coarse aggregate(0,15%,25%,35%)were used as variables to further investigate the effects of the three dispersants on glass fiber in glass fiber recycled concrete the effect of dispersibility.The main research of this paper is:(1)The effect of dispersants on the dispersibility of glass fibers in glass fiber concrete and glass fiber recycled concrete was characterized by studying the changes in compressive strength and splitting tensile strength of glass fiber concrete specimens.It was found that: dispersant B193 and dispersant CMC have less effect on the compressive strength and splitting tensile strength of glass fiber concrete;dispersant S-3101 B will generate gas when added to the cement matrix,resulting in more internal holes and 17.5%reduction in compressive strength;9.4% reduction in splitting tensile strength after the members are hardened and formed.(2)To characterize the dispersion of glass fibers in concrete by macroscopically and microscopically exploring the effect of dispersants on the impermeability of glass fiber concrete and glass fiber recycled concrete.The test results show that all three dispersants can improve the dispersion of glass fiber in concrete,but the concrete with dispersant S-3101 B added,the internal pores become more and the pore size increases.The type of hydration products inside the concrete did not change with the addition of different dispersants,and the proportion of products was different.The relationship equation between the dispersant admixture of glass fiber concrete and the percolation height was established through porosity and impermeability tests;the relationship equation between the porosity of glass fiber recycled concrete and the percolation height was established.(3)Based on the Najar theory and stress-strain relationship,a model for compressive damage of glass fiber concrete was established.When the same strain occurs in the specimen,the specimen with dispersant B193 has the smallest compressive damage value,and the specimen with dispersant S-3101 B has more internal holes and loose space structure,and the specimens have the largest damage value under pressure.(4)Based on the stress-strain relationship between glass fiber concrete and glass fiber recycled concrete obtained from the tests,a finite element model was established to simulate the damage changes when the specimens were subjected to compression.