The influence of sulfonated asphalt on the mechanical properties and microstructure of oil well cement paste

In this work, sulfonated asphalt was chosen as an admixture, and the influence of the quantity (1%, 2%, 3%, 4% of the weight of the cement) of sulfonated asphalt on the mechanical properties of hardened cement slurry was studied. Moreover, the micro-morphology and porous structure characteristics were examined using the SEM and nitrogen adsorption-desorption method, respectively. Studies showed that the addition of asphalt had great potential to improve the tensile strength and toughness of cement paste. The tensile strength of cement paste with 3% sulfonated asphalt increased by 45% at 7 days and 17% at 28 days in comparison with that of specimens without sulfonated asphalt. In addition, 2-3% sulfonated asphalt levels were advantageous for improving the toughness of oil well cement paste. Asphalt particles caused crack bending and deflection as well as toughened oil well cement paste. The addition of 3% asphalt had a positive good effect on the pore size distribution in cement paste. The addition of asphalt decreased the compressive and flexural strength of cement paste at the same curing age. The content of 4% asphalt increased the pore size and caused deterioration of the mechanical properties of cement paste. It is necessary to balance the mechanical properties of cement paste and the amount of asphalt in the range 2-3% to be beneficial for this application.