Date of this Version
Heyen, W., and Halsey, L. (2019). "Effect of Moisture Condition on Concrete Core Strengths". Nebraska Department of Transportation Research Report.
The main purpose of this study was to determine if there would be any major differences between curing methods of cores taken for acceptance testing from a highway slab on a project. The comparison provided data to determine the effect of the moisture gradients created by these different curing treatments on core strength and core permeability. The strengths were measured of moist cured cores and sealed plastic bag cured cores from the day cores were obtained (14, 21 and 26 days) until they reached 28 days. Permeability was also measured at 26, 28 and 32 days. According to ASTM C42, it is current practice to allow the cores to remain in a sealed condition with a plastic bag or non-absorbent containers for at least 5 days prior to testing unless otherwise specified by the engineer. Currently, Nebraska Department of Transportation (NDOT) follows the ASTM C42 with the exception that all cores obtained for compressive strength testing must be delivered to the PCC Lab in a sealed bag, un-bagged and stored immediately in a moist cure room until the required 28-day testing. The findings from this study show no significant difference in strength nor in permeability between curing concrete core samples in bags versus storing them in a moist room.