Synthetic Polypropylene Fiber Content Influence on Cement Strength at High-Temperature Conditions

This study evaluates the use of the synthetic polypropylene fibers (SPF) to mitigate Class G cement strength retrogression under high-temperature conditions. Cement samples with different SPF concentrations were prepared, half of the samples were cured at 38°C for 28 days to represent a base of comparison, while the other half was cured for 25 days at 38°C and for additional 3 days at 300°C. The changes in the compressive strength, tensile strength, and permeability of the cement samples were evaluated under both conditions. At low-temperature conditions, incorporating the SPF improved the compressive and tensile strengths of the cement, and the rate of improvement increases with the increase in the SPF concentration. Adding 0.125% BWOC of SPF into the cement decreased the cement permeability to 0.0013 mD compared with 0.0036 mD for the base cement. Subjecting the cement samples to 300°C during the last 3 days of curing considerably affected the compressive and tensile strengths of the base sample which decreased by 11.9% and 13.7%, respectively. Incorporating 0.125% of the SPF decreased the base cement strength retrogression at 300°C. The cement sample containing 0.125% of SPF has compressive and tensile strengths greater than those of the base cement by 19.3% and 18.7%, respectively.