Time-Temperature Implications of Curing on Mechanical Properties of Ultra-High-Performance Concrete

In this paper, variable temperature (VT) curing was used on ultra-high-performance concrete (UHPC) specimens to determine the effects of early-age temperature histories on UHPC mechanical property development. A systematic test plan evaluated 16 programmed VT profiles with different target temperatures as well as VT start and end times. VT curing profiles were intentionally exaggerated from typical time-temperature curves of hydrating concrete to expose the effects of timing on mechanical property development. Specimens that were placed into VT curing immediately after molding produced higher maximum temperatures compared with specimens that were exposed to VT curing 1 day after molding. However, specimens that were cured at room temperature for 1 day prior to VT curing had significantly higher compressive strength and elastic modulus. These findings show the importance of predicting in-place temperatures that develop in UHPC structures as mechanical properties can be drastically altered based on when high temperatures occur. Keywords: curing temperature; curing time; mechanical properties; ultra-high-performance concrete (UHPC); variable temperature (VT) curing.