This study aimed to investigate the influence of natural cellulose fibers (NCFs) on improving the hydration characteristics of cementless ultra-high performance concrete (UHPC) using CaO-activated ground granulated blast furnace slag (GGBFS). The NCFs were added in a saturated condition as an internal-curing agent so as to supply additional water to the UHPC matrix and subsequently increase the reactivity of unhydrated phases. To evaluate the hydration characteristics, saturated NCFs were added at 0 to 1.5 wt% of the GGBFS plus CaO. TGA and FTIR analyses showed that, as the amount of NCFs increased, the formation of hydration products was improved as evidenced by an increase in heat of hydration, indicating that more reactions of unhydrated phases occurred. Similarly, morphologies of the samples revealed the formation of hydration products on and near the surfaces of the NCFs due to the additional water exerted during the process of internal curing. Moreover, the compressive and tensile strengths were not compromised by the incorporation of weak and flexible NCFs, but rather a slight improvement was observed with a certain content of NCFs.
This study proposes an innovative approach to develop cementless ultra-high performance concrete (UHPC) by activating ground granulated blast furnace slag (GGBFS) without an alkaline-activating solution. To develop cementless UHPC, calcium oxide (CaO) (5% by weight) was used to activate GGBFS, and calcium formate (CF) was used as an accelerator at concentrations ranging from 0 to 6 wt%. The results showed that CF significantly improved the mechanical properties until 5 wt% and all the samples, including CF, exhibited a compressive strength of over 150 MPa. Uniaxial tensile tests revealed strain-hardening behavior, similar to typical cement-based UHPC. The addition of CF led to an increase in hydration products and pore size refinement, resulting in improved mechanical properties. The life cycle assessment results indicated that the developed UHPC mixture had nearly 70% lower CO 2 emission than cement-based UHPC. The experimental results highlight the potential of this method for sustainable UHPC development.
危险品化学品经营许可证（带存储）