Influence of fly ash, slag cement and specimen curing on shrinkage of bridge deck concrete.

PDFTech ReportFHWA/MS-DOT-RD-14-247Project No. 106266 167000Fly ashSlag cementConcrete curingConcrete bridgesBridge decksShrinkageCrackingMississippiMississippi. Dept. of TransportationVarner, Robert L.Burns Cooley Dennis, Inc.United States. Federal Highway AdministrationUS Transportation CollectionCracks occur in bridge decks due to restrained shrinkage of concrete materials. Concrete materials shrink ascementitious materials hydrate and as water that is not chemically bonded to cementitious materialsmigrates from the high humid environment of the concrete to an environment with lower humidity.Reinforcing steel and structural supporting members provide restraint to this shrinkage which causes tensilestress in the concrete. When these tensile stresses exceed the tensile strength of the concrete, cracks occurand provide relief for these stresses. MDOT engineers wanted to determine the usefulness of supplementarycementitious to reduce shrinkage of concrete materials and subsequent cracking. This research projectinvestigates length change of concrete as influenced by supplementary cementitious materials includingClass C fly ash, Class F fly ash, and slag cement. The use of liquid membrane and 7-day, 14-day, and 28-day moist curing periods were also investigated to determine the influence of curing on length change ofstandard prism specimens