Effect of OPC-SAC Composite Cementitious System on the Properties of Ultra-high Performance Concrete
Based on the problems such as long setting time and slow development of early strength of ultra-high performance concrete(UHPC)in reinforcement and restoration engineering,sulphoaluminate cement(SAC)was incorporated into ultra-high performance concrete,the effect of OPC-SAC composite cementitious system on the mechanical and working properties of UHPC under different compounding ratios were studied.Scanning electron microscopy(SEM),X-ray diffractometry(XRD)and isothermal calorimetry were used to analyze the effects of OPC-SAC composite cementitious system on the hydration process and mechanism of UHPC in terms of the microstructure of the hydration products,the hydration rate and the hydration heat release,respectively.Experimental results showed that the significant decrease in UHPC setting time and fluidity was due to the incorporation of SAC.When the SAC content was 10％,the initial setting time of UHPC was 329 min less than that of the baseline group,the final setting time was reduced by 365 min,and the slump was decreased by 20 mm.The 1 d compressive strength of UHPC increased first and then decreased with the increase of SAC content,when 10％SAC was added,the 1 d strength of UHPC was the highest,and 4.6％higher than that of the base group.After the addition of SAC,the early hydration rate and heat release of UHPC were higher than that of the reference group,and the hydration rate and heat release of UHPC in early stage showed an increasing trend with the increase of SAC content.The incorporation of SAC increased the generation of Aft and decreased the generation of Ca(OH)2 in the composite cementitous system,resulting in excessive generation and uneven distribution of hydration products within a short time,which affected the strength of UHPC.The output of this work can provide a theoretical basis for sprayability of UHPC in restoration and reinforcement engineering.
ultra-high performance concretecompound cement systemsetting timehydration process
万方数据
维普
