Preliminary investigation of the relationship between capillary pore pressure and early shrinkage cracking of concrete.

36647147Final report.PDFTech ReportVTRC 97-R12VirginiaVirginia Transportation Research CouncilScott, M. LLane, D. StephenWeyers, Richard EVirginia. Dept. of TransportationVirginia Transportation Research CouncilUS Transportation CollectionThe purpose of this study was to design experimental laboratory equipment and perform experiments to investigate the basic physical processes that occur in concrete for periods of several hours to several days after mixing. The study was conducted in the laboratory, with controlled variations in concrete materials, mixture proportions, and curing regimes. Mortar was used because concrete containing aggregates produces less measurable shrinkage. The development of capillary pore pressure at early stages in a concrete mass appears to be a basic physical parameter controlling the occurrence of plastic cracking. Equipment was designed to monitor capillary pore pressure and shrinkage strains developing in setting mortar or concrete. Five tests were conducted using the equipment, and the results were interpreted with respect to the physical-chemical processes occurring in the hydrating mortar. The results show that the equipment can monitor capillary pore pressure and shrinkage strains that develop in hydraulic cement-based materials in the early ages after mixing. The equipment will be used in future experiments to investigate the interrelationships between materials properties and environmental factors and their effect on the occurrence of plastic cracking of concrete