Improvement of early mechanical properties and mechanism of zeolite powder cement mortar

To reduce the weakening effect of large dosage of zeolite powder on early strength, further improve the efficiency of zeolite powder in cementitious materials and promote its application in cementitious materials. The experiments aimed to investigate the effect of zeolite powder dosing on the strength of composite mortar under two effects, which were Electric curing (EC) and early-strengthening agent (Sodium sulfate, sodium silicate). And through the hydration exotherm and pore structure test analysis, to explore its corresponding mechanism. The effects of electric curing, early-strengthening agent and the coupling of the two methods on the strength at the later stage were evaluated by testing the compressive strength of cement mortar at 28 d. The results are shown as follows. The strength of mortar increases and then decreases with the dosage of zeolite powder. Compared with the reference mortar, the 1 d and 28 d compressive strengths of mortar doped with 10% zeolite powder increases by about 19% and 8%. Both electric curing and sodium sulfate can significantly improve the early strength of zeolite powder cement mortar, but the improvement effect of direct electric curing is slightly lower than that of sodium sulfate. Under the coupling effect of electric curing and sodium sulfate, the early strength of mortar with high zeolite powder dosage is improved. The 1 d compressive strength of specimens dopes with 30% zeolite powder can be increased up to 25%. The results of hydration heat show that, with the increase of zeolite powder doping, the cumulative hydration exotherm of the slurry 72 h appeared to be reduced to different degrees, zeolite powder can promote hydration to a certain extent, zeolite powder and sodium sulfate together can significantly increase the rate of hydration exotherm of the system and the amount of exotherm. The admixture of zeolite powder has a certain refining effect on the pores of the system, and the cumulative pore content at the age of 28 d of the specimens with electric curing is slightly higher than that of standard curing. This results can provide ideas for improving the early mechanical properties of cement mortar with large dosage of zeolite powder, which is of great significance in promoting the application of zeolite powder in cement concrete. © 2024, Central South University Press. All rights reserved.