Effect of admixtures on mechanical properties of cement

The hard brittle of traditional cement was not only causing the damage of integrity of oil well in the course of work and subsequent construction, but also the main cause of failure of inter-zonal isolation. In order to study and improve the performance of cement further and solve practical problems of well cementation, the admixtures, such as styrene-butadiene latex, silica fume and asbestos, were added to the ordinary cement (G-pure cement), which formed latex cement (a combination of G-pure cement and styrene-butadiene latex), binary compound cement (a combination of G-pure cement, styrene-butadiene latex and silica fume), and ternary compound cement (a combination of G-pure cement, styrene-butadiene latex, silica fume and asbestos). The effect of admixtures on nine kinds of mechanical properties of those cements were investigated, including compressive strength, Young's modulus, Poisson's ratio and bulk modulus, etc. The results showed that four types of cement, including traditional cement, latex cement, binary compound cement, and ternary compound cement had similar Poisson's ratio values with about 0.2. Furthermore, compared with the traditional cement, the compressive strength of latex cement and binary compound cement enhanced 24.6% and 12.3% while that of ternary compound cement reduced 11.2%, respectively. Young's modulus and bulk modulus of elasticity of binary compound cement increased 11.8% and 12.9%, respectively, while those of latex cement decreased 2.9% and 8.2%, and those of ternary compound cement decreased 14.7% and 18.6%. Binary compound cement showed more strength. On the contrary, latex cement and ternary compound cement showed better bending property and good flexibility. In addition, latex cement showed good impact toughness, which was the best choice for well cementation.