National Concrete Pavement Technology Center

Project description

Air content is a crucial component of hardened concrete that is directly linked to the durability and lifespan of structures. A widely known phenomenon of air loss occurs when pumping air-entrained concrete through a pump truck. To get a sample with the most accurate air content, the Arkansas Department of Transportation (ARDOT) specifications require samples to be taken at the pump truck hose discharge. This process is often difficult and relatively dangerous. Air loss can cause the ’concrete’s air content to fall below the specified limits of the specification and, therefore, cause issues for ARDOT engineers, contractors, and concrete producers. The objectives of this project are to determine the correct location for sampling air-entrained concrete. Evaluate the theory that entrained air returns to the concrete after pumping and before the initial set. Evaluate the ability of the Super Air Meter (SAM) to predict entrained air bubble size and spacing through petrographic analysis. Evaluate the durability of current concrete mix designs. Determine optimized concrete curing methods through comparison to current methods by using test decks. Test hardened concrete's resistivity and chloride penetration to establish a baseline of current concrete mix designs. Evaluate fly ash variability with air entrainment efforts through the use of the foam index test. This research will also evaluate the durability of current concrete mix designs and the variability of fly ash’s impact on air entrainment. The research will be conducted as a series of test decks cast alongside Department bridge construction projects. These test decks will be cast and cured identically to the bridge deck being poured.