Study On The Influence Of Calcium Carbonate On The Performance Of Sulphoaluminate Cement-based Grouting Materials

Sulphoaluminate cement-based grouting materials（SCGM）are widely used in roadway surrounding rock reinforcement projects,and their performance directly affects project quality.In order to further improve the performance of sulphoaluminate cement-based grouting materials,including mechanical properties and durability of carbonation resistance.Therefore,this study aims to use different types of calcium carbonate（including limestone powder produced by physical methods,calcium carbonate produced by gas-liquid carbonation）to sulfur the aluminate cement-based grouting material is modified.The results are as follows:（1）After limestone powder replaces natural anhydrite,the fluidity of material B gradually increases,the initial and final setting time after mixing A and B slurry becomes shorter,and the mechanical properties of each age increase first and then decrease.The best replacement material is 20%,its 6 h,28 d and 90 d compressive strength increased by 146.41%,22.33%and 33.57%respectively,and the 90 d compressive strength continued to increase without shrinkage.As the replacement amount of limestone powder increases,the linear expansion rate of the cement stone body gradually decreases.When the replacement amount is 20%,the linear expansion rate at 1 day of hydration decreases from 0.35%to 0.13%.After limestone powder replaced natural anhydrite,the hydration heat release curve of the system showed a second exothermic peak.The porosity and average pore size of the grouted stone bodies after hydration 6 h and 28 d decreased.（2）Using calcium hydroxide and calcium carbide slag as raw materials,calcium carbonate is synthesized by carbonation.The calcium carbonate synthesized from the two raw materials under the same conditions has almost no difference in other properties except for the difference in the color of the macro powder.The two kinds of calcium carbonate have certain effects on the setting time,mechanical properties,expansion performance and hydration heat release performance of SCGM slurry,and the influence rules and degrees are basically the same.With the increase of calcium carbonate content,the mechanical properties of SCGM grouting stone body first increase and then decrease.When the optimum dosage was 3%,the mechanical properties at 6 h,28 d and 90 d were increased by 29.4%,26.43%and25.42%respectively.A.After mixing with B slurry,the initial and final setting time is shortened by 21.05%and 14.49%respectively.At the same time,calcium carbonate can reduce the linear expansion rate of SCGM grouting stone,improve the hydration heat release rate and optimize the pore structure.（3）The possibility of CO₃^2-replacing SO₄^2-in ettringite is calculated by first principles.When a CO₃^2-replaces SO₄^2-at the S3 position,the unit cell volume of ettringite decreases.This result is consistent with XRD the test results are consistent.At the same time,the stability of ettringite is increased,which improves the carbonation resistance of SCGM.This paper studies the influence of limestone powder and gas-liquid carbonation method on the hydration and hardening performance and anti-carbonation performance of SCGM,providing a certain reference value for the further improvement of the performance of the grouting material,and at the same time,it is a solid waste of calcium carbide slag application in SCGM provides a new method.