Restrained Shrinkage Behavior of High-Strength Concrete with Various Synthetic Fiber and Cellulose Fiber Proportions

This study investigated the effect of synthetic fibers, specifically glass fibers (GFs), polypropylene fibers (PPF), and cellulose fibers (CF), derived from wastepaper pulp on the restrained shrinkage and cracking behavior of high-strength concrete. The research employed guidelines from a recent standard to conduct restrained shrinkage tests on concrete ring samples, analyzing factors such as restrained shrinkage, residual stress, and cracking age. The findings reveal that incorporating GF, PPF, and CF at 1% by weight of cement can significantly prolong the crack age in high-strength concrete, with improvements of 43%, 29%, and 14%, respectively. Moreover, the addition of these fibers effectively reduced the residual stress in the concrete rings by up to 66%, 60%, and 50%, respectively. This consistent trend across all fiber-reinforced concrete types indicates a direct relationship between the strain in steel rings and the residual stress in high-strength concrete. Additionally, the compressive strength and density were assessed following recent standards. The results indicate that adding 0.5% GF, CF, and PPF by weight of cement enhances the compressive strength by 13.4%, 1.5%, and 3%, respectively, and the density increases by 4.1%, 1%, and 0.4%, respectively.