Study on the mechanical and microscopic properties of steel fiber reinforced reactive powder concrete under different curing methods

Abstract

In order to investigate the effects of different curing regimes on the mechanical properties and hydration products of micro steel fiber (MSF) reinforced reactive powder concrete (RPC), three curing methods were selected: spraying curing (SPC), standard curing (SC) and (90 °C hot water + spray) curing (H + SPC). The variation rules of MSF content and age on the compressive and splitting tensile strength of RPC were analyzed, and the MSF strengthening mechanism and microscopic morphology were studied using scanning electron microscopy and X-ray diffraction microscopy techniques. Prediction models were subsequently developed for 28-day compressive and splitting tensile strength of micro steel fiber reinforced reactive powder concrete (MSF-RPC). The experimental results showed that the mechanical properties of RPC were significantly improved due to the incorporation of MSF. Under the three curing regimes, the optimal fiber volume content of MSF-RPC was 1.65%, with the improvement rates in 28-day compressive strength of MSF-RPC under SPC, SC, and H + SPC to be 33.38%, 32.22%, and 30.65%, respectively, compared with that of plain RPC. The corresponding improvement rates in splitting tensile strength were 236.24%, 211.29%, and 238.66%. The strength obtained under H + SPC was slightly higher than that obtained under SC, while its later growth rate was lower than that obtained under SC or SPC. Although the strength obtained under SPC was slightly lower than that obtained under SC, the engineering requirements were basically met, and SPC can be easily promoted in engineering practice.