Study On Some Properties Of Supersulphated Cement And Cement Stabilized Gravel

Supersulphated cement (SSC) with low hydration heat, micro expansion, longsetting time, high final strength as well as sulfate resistant property shows specialadvantage in the construction of high-grade highway basement layer.In this paper, the effect of clinker, gypsum and additive on the mechanicalbehavior of the SSC was analyzed, optimum proportion or species of eachcomposition was determined by a series of experiments, the final proportion ofSSC was10%P.O42.5+75%slag+15%gypsum+0.6%additive.Physical and mechanical properties of the cement were tested, it is shown thatboth the compressive strength and flexural strength of the SSC were better thanordinary Portland cement. The expansion of the Portland cement cured at roomtemperature and humidity was-1.36‰, the expansion of the water curing rate of-0.71‰, while the inflation rate of SSC are–0.33‰and0.55‰respectively.From microscopic analysis it is seen that the hydration products of SSC aremainly ettringite crystal and C-S-H gel etc. the ettringite crystal grows in capillarypore enhanced the density and good tightness which ensured the strengthadvantage of sulfate cement.For the research of the cement stabilized gravel, a continuous gradationskeleton dense structure was studied through analysis to obtain the optimalaggregate gradation：30~20mm of gravel:20~10mm of gravel:10~5mm stone:stone chips=22:28:15:35. Under this grading, through the compaction test andunconfined compressive strength test, dosage of SSC was determined as4.5%,therefore, in this paper, the mix proportion of SSC/aggregate ratio for cementstabilized gravel=4.5:95.5.Cement stabilized gravel with ordinary portland cement was also tested andcompared with SSC, results showed that the8d compressive strength of SSCstabilized gravel is6.1MPa,28d is8.7MPa while the compressive strength ofordinary cement stabilized macadam is5.4MPa and4.9MPa respectively. This isbecause the water cured SSC is expansive, therefore, good curing of this cementstabilized macadam should also be ensured.