The reinforcement effects of PVA, PE, and steel fibers on AAS material

This paper employs PVA, PE, steel fibers, as well as the hybrids of two of the three fibers to reinforce alkali-activated slag (AAS) material, aiming to prepare strain-hardening and clinker-free composites. The flexural strength, compressive strength, uniaxial tensile performance of the composites and bond behavior between fibers and the matrix were tested to clarify the rein-forcement effects of different fibers on the matrix. Strain-hardening AAS materials are obtained with compressive strengths of 116 MPa -137 MPa (with fibers contributions of 17%-38%) and strain capacities over 0.8% at 60 d. The results indicate that there are several kinds of rein-forcement effects of fibers on the matrix, namely bridging effect, lapping effect (for steel fibers), synergetic effect (for hybrid fibers) and static effect (for flexible fibers). Deterioration of PVA and PE fibers are found, indicating that these two fibers have poor adaptability in AAS material with a high alkalinity. This paper specially distinguishes the difference of the crack numbers during the strain-hardening stage only with the ones during the whole period including the following strain -softening stage. A new relationship is established between the crack numbers and the strain-stress curves, which provides a more reasonable way to characterize the strain-hardening property of fiber-reinforced composites.