Abstract: Through syneresis rate and uniaxial compressive test, the paper studied the grout ratio that the main experimental materials were PO42.5 ordinary portland cement and superfine cement in different water cement ratio and bentonite proportion, and the grouting experiment of destructive mudstone specimens using independent development MYZJ-2 hydraulic pressure grouting system, analyzed the grouting effect. The results showed that superfine cement grout with water cement ratio 1：0.6 and bentonite in 4% of cement weight which the syneresis rate was 6% and uniaxial compressive strength after curing 28d was 8.87MPa met the requirements of lab grouting to destructive specimens with standard size. After grouting reinforcement of destructive mudstone specimens in triaxial compression test by ratio optimized grout, the uniaxial compressive strength recovery value was the 14.7% of original uniaxial compressive strength. The grouting effect was better.

Key words: syneresis rate, superfine cement, optimization of grout ratio, MYZJ-2 hydraulic pressure grouting system, uniaxial compressive strength