Onsite strength determination for early-opening decision making of high early strength concrete pavement

High early strength(HES)concrete pavements are commonly opened to traffic within the first 24 h after construction,making early-opening decisions critical for pavement quality and traffic operations.Currently,most state departments of transportation rely on compressive strength testing for early-opening decision making.However,there laboratory tests are labor intensive,costly and not always representative of field strength development.In this study,non-destructive testing(maturity and ultrasonic tomography)was explored for faster and reliable in-situ strength estimations.An experimental section constructed using HES concrete was routinely monitored using compressive testing,maturity,and ultrasonic tomography in the first 24 h after construction.The shear wave velocity,measured using ultrasonic tomography,was able to capture the strength-gain variability within a single slab and between different slabs due to the ability to monitor several locations in a short period of time.Maturity results were consistently conservative in the first 24 h of monitoring.Results show that both maturity testing and ultrasonic tomography are able to replace or add to conventional strength testing for HES concrete pavements to facilitate making the opening decision within the first 24 h.Ultrasonic tomography proved more beneficial as a result of the device's portability,increased speed of testing,and accurate estimations of HES concrete strength for the entire pavement length.