Mechanical Performance and Microstructure of Ultra-High-Performance Concrete Modified by Calcium Sulfoaluminate Cement

High autogenous shrinkage property is one of the disadvantages ultra-high-performance concrete (UHPC), which may induce early age cracking and threaten safety structure. In present study, different dosages calcium sulfoaluminate (CSA) cement were added in UHPC as an effective expansive binder. Hydration mechanism, property, compressive strength carried out to investigate effect CSA addition on mechanical properties UHPC. Scanning electron microscopy was also employed characterize intrinsic microstructural reasons relating changes macroproperties. Based XRD diagram, increasing formation ettringite Ca(OH)2 can be found with content up 15%. heat flow results 10% addition, maximum release increases 2.6 mW/g, 8.3% higher than reference UHPC, suggesting a degree hydration addition. The show that expansion agent plays significantly beneficial role improving corresponding ?59.66 ? ? , ?131.11 id="M2"> ?182.31 id="M3"> respectively, at 7 d 5%, 10%, 15% 108%, 117%, 123% reduction compared specimen without CSA. terms strength, 15%, 20% has 10.5%, 17.4%, 30.2%, 22.1% for 28 d. Microstructural study shows there extremely dense microstructure both bulk matrix interfacial transition zone attributed therefore result performance.