Influence of polyoxymethylene fibers on autogenous shrinkage, tensile creep, and cracking resistance of ultra-high performance concrete

Supersulfated cement (SSC) has been utilized in ultra-high performance concrete (UHPC) to replace Portland cement to reduce carbon dioxide emissions and energy consumption. Polyoxymethylene fibers (POMF) have been added in UHPC to decrease shrinkage and increase tensile strength. Autogenous shrinkage and tensile creep are important factors in evaluating the cracking resistance of UHPC. However, investigations on the impact of POMF on the autogenous shrinkage, tensile creep, and cracking resistance of UHPC prepared by SSC (UHPC-SSC) remain insufficient, which limits the application of POMF on UHPC-SSC. Therefore, investigations on the impact of POMF on the autogenous shrinkage, tensile creep, and cracking resistance of UHPC-SSC by using temperature stress test machine (TSTM) were systematically carried out in this study. Meanwhile, the workability and mechanical properties tests were also conducted. Test results indicated that the splitting tensile strength and compressive strength of UHPC-SSC first increased and then decreased with the increase of the contents of POMF. In addition, the autogenous shrinkage of UHPC-SSC decreased by 31.87 % when the content of POMF was 3 %. Furthermore, the basic tensile creep, creep-shrinkage ratio, and specific tensile creep of UHPC-SSC decreased with the increase of the contents of POMF. Incorporating POMF delayed the cracking time of UHPC-SSC, and the cracking resistance first increased and then decreased with the increasing contents of POMF.