关键词: 矿渣, 强度, 弹性, 晶核, 渗透率, 微裂隙, 水化产物

Abstract: Using Blast Furnace Slag (BFS) to convert drilling fluid into cementing fluid system (MTC) mainly exists two limitations in producing application: one is it has less antiseepage ability, second is the strength regression of solid state under high temperature (T>70℃). Through SEM analysis the main reason of strength regression of BFS solid state under high temperature is due to the uneven growth of crystallization of hydrates of silicon calcic rock and calcium alumna rock and finally occurs under the high stress condition at the later period of solid state. After applying hydrated heat analysis, contract rate test, permeability test, analysis of strength increase curve, regular physical test and microstructure analysis to BFS, the strength increase and elastic increase of BFS solid state were improved by the crystal kern induced and thus propose a theory that crystal kern induced mechanism of BFS system is a part chemical of kern forming of heterogeneity phase. The microfracture in the BFS solid state induced by crystal kern could be closed, the gas permeability is lower than 1×10^-3umsup>2.After BFS solid state have been maintained in water bath of 75℃ for half year, the compression strength is higher than 25MPa, with no strength regression phenomenon.

Key words: slag cement, strength, elasticity, crystal grain, permeability, microfracture, hydrated mineral