Application of Internal Curing to Improve Concrete Bridge Deck Performance

US Transportation Collection2020PDFTech ReportAbdigaliyev, ArmanKim, Yong-RakHu, JiongUniversity of Nebraska--Lincoln. Dept. of Civil EngineeringPeter Kiewit InstituteNebraska. Department of TransportationNebraska. Department of TransportationUnited StatesBridge decksConcrete bridgesConcrete curingCrackingDurabilityFine aggregatesLaboratory studiesMechanical propertiesMix designPavement performanceShrinkagelightweight fine aggregateinternal curingSPR-P1(19) M083Due to the relatively high cement content and low water-to-cement ratio (w/c) used, bridge deck concrete is prone to premature cracking. Internal curing has been found to greatly reduce the chance of premature cracking as well as concrete deterioration. This research project was intended to develop internally cured bridge deck concrete based on a local mix design in Nebraska. Four different lightweight fine aggregate (LWFA) as internal curing agents were evaluated, and their effects on fresh, mechanical, durability, and shrinkage properties of concrete were studied. To identify the most effective LWFA dosage for shrinkage reduction, different replacement rates of sand and gravel with LWFA were adopted to account for the moisture loss during the construction and drying period. Aggregate blends of internally cured mixes were also optimized to account for the disturbed aggregate gradations due to the introduced LWFA. The research study demonstrated that it is possible to develop a local internally cured concrete mix that is both technical and economically feasible. Even though the replacement of fine aggregates by LWFAs results in decreases of 28-day modulus of elasticity, and modulus of rupture, the overall mechanical properties still meet bridge deck criteria. As the curing age decreases, internally cured mixes were found to be less affected owing to the curing water from within the concrete matrix provided by the saturated LWFAs, which demonstrated that internal curing could potentially decrease the required amount of curing period in the field. The developed internally curing mixes were also found to have comparable chloride penetrability compared to the control mix and were also categorized as either very low or low chloride ion penetrability based on lab study.120