Effect Of Water Film Thickness In Cement Paste,Mortar And Concrete With Mineral Admixtures

The heavy use of concrete puts great pressure on the environment,the main ingredient in concrete,cement is the main source of environmental pollution.To protect the environment and reduce the cost of producing concrete,the practice of using suitable mineral admixtures replace cement has been widely promoted.In order to fundamentally control the fluidity and strength of cement paste,mortar and concrete,mortar and concrete,in this experiment,quartz sand,ground granulated blast furnace slag(GGBS),silica fume,metakaolin(MK),zeolite powder and other mineral admixtures were respectively added to cement paste,mortar and concrete.On the basis of measuring the fluidity,cohesion and strength of each sample,the water film thickness of the sample was calculated by measuring the packing density of the cementitious material,the effect of water film thickness on cement paste,mortar and concrete was analyzed,and the conclusions are as follows:1.The flowability of cement paste increases with the increase of the content of quartz sand,however,the 28 days compressive strength of cement paste decreases with the increase of the content of quartz sand,the sieving rate of 0.63 mm of cement paste increases with the increase of the content of quartz sand,the addition of quartz sand has little effect on the packing density of cementitious materials.The water film thickness doesn't change much with the content of quartz sand.2.The addition of proper amount of GGBS is added can improve the flowability and compressive strength and weaken a little cohesion of cement paste,The optimal ratio of cement paste appears when the content of GGBS is 5%,and GGBS can increase packing density of cementitious material.The water film thickness increases at first and then decreases with the increase of content of GGBS.3.The addition of silica fume and MK can improve the adhesion and compressive strength of cement paste,but decrease its flowability and porosity,the maximum compressive strength and the minimum porosity were occurs when thedosage is silica fume: MK = 15: 10,and the water film thickness were calculated,the packing density of cementitious materials increases with the increase of the amount of silica fume and MK.The addition of silica fume and MK can significantly reduce the thickness of water film in slurry,and gradually decrease with the increase of total content.4.When the water-binder ratio and cement-sand ratio are constant,the flowability of mortar increases first and then decreases with the increase of the content of zeolite powder,and reaches to the maximum at 5%,the chesion increases with the increase of zeolite content,and reaches to the best at the content of zeolite powder is 15%;The strength of mortar can be improved by mixing zeolite powder with not more than 10% of the total cementitious material,when the content of zeolite powder exceeds 10%,the strength decreasing;The effect of zeolite powder on the packing density of solid phase materials is consistent with the strength of mortar,the water film thickness curve changes with the increase of the content of zeolite powder.The slump,slump flow and 7 days compressive strength of concrete decrease with the increase of the content of zeolite powder,the packing density of solid phase materials increases with the increase of the content of zeolite powder.5.The effect of mineral admixture on the packing density and the coarse aggregates of solid phase materials are comprehensively reflected by the water film thickness.Finally,it is found that the water film thickness is the major controlling factor of flowability and adhesion,the flowability of cement paste,mortar and concrete increases and the adhesion decreases with the increase of water film thickness;The porosity is the major controlling factor of compressive strength,compressive strength increases with the decrease of porosity,the relationship between water film thickness and compressive strength is weak.The basic factors affecting the working performance of cement paste,mortar and concrete were mastered,which provide the basis for the prepare ideal concrete.