Study On The Effect Of Stearate On The Performance Of Alkali-activated Slag Cement Mortar

Alkali-activated slag cement is a new type of cementitious material with excellent comprehensive technical performance,which conforms to the direction of economic and social sustainable development.Nonetheless,research and application in recent years have shown that alkali-activated slag cement stone has greater water absorption,which has a greater negative impact on its performance and durability.It is of theoretical significance and practical value to study the technology for effectively improving the water absorption of alkali-activated slag cement stone to promote the further development of the research and application of alkali-activated slag cement and concrete.In this paper,the water absorption of alkali-activated slag cement stone is improved by adding stearate to improve the water resistance of alkali-activated slag cement stone.The main research contents include: the effect of admixture on the stearate’s action efficiency in the alkali-activated slag cement system;the effect of stearate on the performance of the alkali-activated slag cement new mixing slurry;the influence of salt on the carbonization behavior and chloride ion permeability of alkali-activated slag cement mortar.The main laws revealed by the study and the main results achieved are as follows:(1)Mixed grinding with slag effectively improves the efficiency of stearate in alkali-activated slag cement.At low dosage(0.5%),it significantly reduces the capillary water absorption coefficient of alkali-activated slag cement mortar and causes less compression Loss of strength.In the range of 0.5% to 1.0%,the compressive strength and capillary water absorption coefficient of alkali-activated slag cement mortar specimens decrease with the increase of stearate content.When the mixing time is within20 min,the alkali-activated slag cement mortar’s compressive strength loss and capillary water absorption coefficient decrease as the mixing time increases.Among them,calcium stearate has the greatest influence on compressive strength,and sodium stearate has the least influence at high dosage(1.0%).Potassium stearate achieves the highest efficiency at a dosage of 0.5%: the alkali-activated slag cement mortar has a compressive strength loss of less than 10% and a water absorption coefficient reduced by more than 80%.(2)Under the condition of mixed grinding,the shear yield stress,plastic viscosity and air entrainment of alkali-activated slag cement slurry increase with the increase of stearate content.The mobility of freshly mixed alkali-activated slag cement mortar decreases with the increase of stearate content.The addition of stearate will form competitive adsorption with slag and affect the retardation effect of YP3 retarder on alkali-activated slag cement.(3)The addition of stearate will cause the alkali-excited slag cement mortar 3d carbonation depth to increase relative to the baseline group.Its 28 d cumulative carbonation depth is comparable to the reference group.The depth of carbonation is not significantly affected by the amount of stearate.The calcium stearate test group had a lower 28 d carbonation depth than other test groups.(4)The mixed grinding of stearate and slag can significantly improve the resistance to chloride ion penetration of alkali-activated slag cement mortar.The evaluation of chloride ion permeability of alkali slag cement mortar specimens with0.5% stearate reached “very low”;the evaluation of chloride ion permeability of alkali slag cement mortar specimens with 1.0% stearate reached “negligible”.The alkali-activated slag cement mortar chloride permeability coefficient decreased with the increase of stearate content,which is not significantly affected by the type of stearate.