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This study is aimed at exploring the mechanism of the reinforcement of aligned steel fibers on the mechanical properties of cement-based composite by acoustic emission (AE) signal analysis. Flexural tests were carried out and the results shown that the flexural strength of aligned steel fiber reinforced cement-based composite (ASFRC) increases by around 50% over that of conventional steel fiber reinforced cement-based composite (SFRC) with randomly distributed steel fibers inside. In the flexural tests, the interior deterioration of the specimens was monitored by AE. AE signal analysis results show that, compared to the conventional SFRC, the ASFRC specimens with aligned steel fibers have larger number of signals originated by the steel fiber pullout on the fracture sections, which indicates that there are more steel fibers working. It is also found that in the specimens with aligned steel fibers the local damage of matrix around the fibers in the fracture section caused by the pullout of steel fibers is less than that in the specimens with randomly distributed steel fibers. The difference in the local crushing of matrix and the number of steel fibers (AE signals) in fractured sections between the ASFRC and SFRC specimens may be the main reasons that ASFRC is superior to SFRC in mechanical performance.

In this paper, the effect of fiber types such as steel fiber, polyvinyl alcohol (PVA) fiber, polypropylene (PP) fiber and basalt fiber, on the creep of concrete after one-year-loading was studied and the principle of fiber’s effect on concrete creep was analyzed. The elastic modulus of fibers is shown to be the most significant factor influencing concrete creep. Fibers with elastic modulus much higher than plain concrete can clearly restrict creep, while fibers with lower elastic modulus have the opposite effect. For example, 2% volumetric blending of steel fiber reduces specific creep by 25.1%, compared with plain concrete, while 0.9 kg/m3 mass blending of PVA fibers increases it by 19.9%. The internal defects introduced by fiber addition, i.e., the fiber-concrete interfacial zone and non-uniform fiber distribution, weakens its creep resistance. There is a clear correlation between the 28 days elastic modulus of fiber reinforced concrete (FRC) and its long-term creep behavior, indicating that they are influenced by similar factors. Larger elastic modulus at 28 days tends to yield less specific creep at 1 year.