Study On Synergistic Activation Of Cementitious Activity By Steel Slag And Slag

Cement clinker needs to go through"two grinding and one burning",which consumes a lot of energy and emits a lot of environmental pollutants such as CO₂.The mineral composition of steel slag,slag and cement clinker,alternative preparation of cement clinker cementing materials,but the steel slag containing the compact structure of C₃S and C₂S,also including calcium ferrite and olivine difficult ground mineral composition,make its gelling activity is low,limiting the steel slag to replace the proportion of cement clinker,thus the steel slag activity became the focus of the study.According to the mineral characteristics and cementitious activity of steel slag and slag,the optimal dosage and proportion of steel slag and slag in steel slag-slag composite cementitious material and the activation method of composite cementitious material are explored in this paper,and the hydration process,hydration mechanism and activation mechanism of steel slag-slag composite cementitious material are studied.1)By changing the total amount of steel slag and slag and the mass ratio of steel slag and slag in the composite cementing material,the influence on the activity of the steel slag-slag composite cementing material was explored,and the optimal material ratio was determined:steel slag 40%,slag 40%,cement clinker 16%,gypsum 4%.2)The changes of specific surface area,sieve allowance and gelling activity index of steel slag under different grinding time were obtained by physical excitation of steel slag.The optimal grinding time of steel slag is 80min,the specific surface area is 509m²/kg,the screen allowance of 45μm is 21%,80μm is 7.2%,the 28d compressive strength of steel slag-slag composite cementing material is 31.3MPa.3)Na₂CO₃,Na₂SO₄,Na OH and sodium silicate were selected to chemically stimulate the cementing activity of steel slag-slag composite cementing material.The four activators all improved the 3d strength of the test block,but Na₂CO₃,Na₂SO₄ and Na OH reduced the 28d compressive strength of the cementing material.The addition of sodium silicate greatly improved the 28d strength of the sample,which reached 43MPa.4)The effect of high temperature curing on the cementing activity of composite cementing materials was studied in view of the low 3d strength caused by the addition of steel slag.It was found that the high temperature curing excitation promoted the hydration degree of the composite cementing material system 3d,which greatly improved the 3d strength of the sample,and the compressive strength of 3d increased from 2MPa to20.5MPa under normal temperature curing.5)The hydration mechanism of steel slag and slag composite cementing material was investigated.Various substances in the system had synergistic effect.The Ca（OH）₂generated by hydration of steel slag reacted with Si O₂ in slag to form C-S-H gel and C-A-S-H gel.The sodium silicate in sodium silicate condensed the hydration products and improved the strength of the composite cementite system.Figure 37;Table 6;Reference 80...