Transport Properties and shrinkage of UHPC Containing Presoaked Scoria Sand

The demand for tall buildings and important structures has transformed concrete technology, leading to the development of ultra-high performance concrete (UHPC). Known for its exceptional strength and durability, UHPC is produced with optimized granular materials, lower water-to-cement ratio, and higher percentage of cementitious materials, often reinforced with micro steel fibers. UHPC has remarkable mechanical properties, including superior compressive and tensile strengths and exceptional toughness. However, a major challenge is its considerably high autogenous shrinkage, caused by the high cement content and low water-to-cement ratio. To effectively reduce this shrinkage, we explored the use of lightweight scoria sand in varying proportions as an internal curing agent. Our experimental research involved testing UHPC specimens to assess autogenous shrinkage, compressive strength and also water absorption and capillary water absorption as transport properties. The results were promising where increasing lightweight scoria sand content significantly reduced autogenous shrinkage, though it slightly decreased strength properties. We also found that higher replacement ratios of scoria sand led to increased water absorption and capillary water absorption in the specimens. We identified an optimal amount of lightweight scoria sand that effectively lowers autogenous shrinkage while minimizing impacts on strength and transport properties, providing a valuable strategy for enhancing UHPC performance in modern construction.

Keywords:

Ultra-high performance concrete (UHPC) , Autogenous shrinkage , water absorption , Capillary water absorption , Internal curing , Presoaked lightweight scoria sand