Study on the Modification Mechanism of Soap-Free Latex on the Microstructure and Mechanical Properties of Cement Paste

ABSTRACT In view of problems such as the decline in strength of cement paste and latex exudation caused by the addition of conventional latex, JAS soap-free latex (JAS latex) was prepared by soap-free emulsion polymerization technology. JAS latex had the characteristics of low viscosity, uniform particle size, good dispersity of particles, and good compatibility with cement admixtures. JAS latex had little impact on the fluidity of oil-well cement paste. The free liquid of the cement paste with 10 % JAS latex was 0 %, and its liquid-loss content was 43 mL. When the JAS cement paste was cured at 90°C, its compressive strength was 34.08 MPa. When the curing temperature was 70°C, the bond strength between the paste and metal casing reached 4.95 MPa. Combining the results tested by X-ray diffraction, scanning electron microscopy, and atomic force microscopy showed that JAS latex did not affect the hydration process of oil-well cement, had good film-forming ability in cement paste, and improved the density and impact resistance of the cement paste. It is helpful to improve the sealing integrity and sealing ability of cement sheath in cementing engineering and ensure the safe and efficient development of oil and natural gas resources.