EFFECTS OF LIMESTONE FILLER ON EARLY-AGE PROPERTIES OF ULTRA-HIGH PERFORMANCE CONCRETE

Ultra-high performance concrete (UHPC) is characterized by a very low water-to-cement ratio, which causes a substantial portion of cement to remain unhydrated. As emissions from cement production are harmful to the environment, greener concrete can be achieved by partially replacing the unhydrated cement in UHPC with more environmentally friendly materials, such as ground limestone. This dissertation evaluates the effects of various particle sizes and dosages of fine limestone on the early-age properties of UHPC. Workability, setting time, heat of hydration, compressive strength, and drying shrinkage are among the properties that have been examined. Results indicate an improvement in the hydration process along with enhanced mechanical properties when incorporating fine limestone in UHPC. It was found that up to 20% of cement can be partially replaced by fine limestone while maintaining similar engineering properties to that of mixtures without limestone. Therefore, fine limestone allows for the production of greener concrete with potentially improved characteristics, while reducing energy consumption and greenhouse gas emissions from cement production