Constitutive model and reinforcing mechanisms of uniaxial compressive property for reactive powder concrete with super-fine stainless wire

Abstract

Super-fine stainless wire (SSW) is an excellent reinforcing filler for reactive powder concrete (RPC) due to its high mechanical property, favorable dispersibility, strong interface bonding with matrix, and micron diameter and high aspect ratio. In this paper, the uniaxial compressive strength, deformation and stress-strain curves of SSW reinforced RPC under different curing conditions are studied. Meanwhile, an uniaxial compressive constitutive model is established based on continuum damage theory and the reinforcing mechanisms are revealed through macroscopic, microscopic and Ca(OH)2 orientation analysis. The uniaxial compressive strength, elastic modulus and Poisson's ratio of RPC are increased by 85.3%, 58.2% and 114.8% respectively and the cyclo-hoop effect is weakened due to the addition of SSW. The ascending-stage of uniaxial compressive stress-strain curves of SSW reinforced RPC shows obvious elastic-plastic region and the longitudinal peak strain is enhanced by 73.8%. The established theoretical uniaxial compressive constitutive model can well describe the stress-strain relationship of SSW reinforced RPC. The change of damage variable demonstrates the delaying effect of SSW on cracks. The reinforcing mechanisms of SSW to RPC include interface effect, overlapping network effect, inter-anchor effect, bridging effect, torsion, stripping and snapping effect and decrease in crystal orientation index of Ca(OH)2.