Optimization of the fresh and hardened properties of cement grouting material for semiflexible pavement using polypropylene fiber

To enhance the cracking resistance of semiflexible pavement, short polypropylene fibers with lengths of 3 mm and 6 mm were incorporated into cement grouting material, and their effect on fluidity, mechanical properties, drying shrinkage, and pore structures was systematically investigated. When polypropylene fiber dosage is less than 0.9 vol%, the reduction in fluidity is relatively minor. Polypropylene fiber can not only improve toughness, but also inhibit water loss and reduce drying shrinkage, which is related to the distribution of polypropylene fiber and the bonding performance between fiber and matrix. However, excessive polypropylene fiber can lead to uneven distribution of the porosity along vertical direction. With a 0.9 vol% of 3 mm polypropylene fiber, the 28d flexural strength of the grouting material increased by 38%, and the drying shrinkage decreased by 22%. This article provides some guidance for enhancing the overall performance of cement grouting material using polypropylene fiber.