Influence of Silica Fume on The Rheological Properties and Autogenous Shrinkage of UHPC Paste
High amount of cementitious material and low water/binder (W/B) ratio increase shrinkage strain which also increases the crack formation risk of ultra-high performance concrete (UHPC). The effects of silica fume replacement ratio on the rheological properties and autogenous shrinkage of UHPC paste were investigated in this study. Four pastes with a very low W/B ratio (0.20) were produced. Besides the rheometer with a ball measuring system, mini slump-flow and V-funnel tests were applied to determine rheological properties. Moreover, autogenous shrinkage was measured by using a laser system at early-age, whereas a mechanical comparator was used for long-term measurements. As a result, the pastes which have SF up to 20% showed dilatant behavior. It was found that early-age shrinkage is much higher than long-term shrinkage. Both early-age and total autogenous deformation was increased as a result of SF replacement. The long-term and total deformations were significantly increased as a result of increasing SF replacement from 20% to 30%.
Index Terms- Rheology, Shrinkage, Silica Fume, UHPC.