Experimental Research on Properties of UHPC Based on Composite Cementitious Materials System

As concrete damage occurs frequently in the transition zone of bridge expansion joints, this paper discussed ultra-high-performance concrete (UHPC) based on composite cementitious materials system for the repair of the bridge expansion joint transition zone. The performance of UHPC based on composite cementitious materials system was studied by combining the macroscopic properties and microstructure of the material with the hydration mechanism of the cementitious material. The influence of sulphate aluminum cement (SAC) on composite cementitious materials system was studied. The experimental results showed that the appropriate amount of SAC can effectively reduce the setting time in the composite cementitious materials system. While SAC caused the strength to decrease, it has little effect on the mechanical properties of the composite cementitious materials system. When the ratio of SAC is 0.1 in the composite cementitious materials system, the setting time is shortened with maintaining the dense micro-structure observed by the SEM images. It can achieve fast hardening and have good early mechanical performance while retaining excellent long-term properties. Therefore, the addition of SAC can effectively make it possible to apply the excellent performance of UHPC for the repair of highway and bridge.