Impact of coarse aggregate gradation on PCC performance properties : final report.

Final reportPDFTech ReportFHWA-SC-13-03SPR 689Portland cement concreteTypes of concreteAggregatesUnited StatesSouth CarolinaClemson University. Glenn Department of Civil EngineeringRangaraju, Prasada RaoBalitsaris, MarcusKizhakkumodom, HarishClemson University. Glenn Department of Civil EngineeringSouth Carolina. Dept. of TransportationUnited States. Federal Highway AdministrationUS Transportation CollectionIncreasingly, aggregates in South Carolina are failing to meet the standard requirements for gradation for use inportland cement concrete. The effect of such failed aggregate gradations on concrete properties and theconsequent effect on short- and long-term performance of the structures are poorly understood. Furthermore, arational basis to accept or reject concrete containing such out-of-specification aggregate is not available at thepresent time. The goal of this project was to provide SCDOT with guidance on determining whether concretecontaining aggregate with an out-of-specification gradation should be accepted or rejected. The principalobjective of this investigation was to study the influence of variations in aggregate gradations on selectedproperties of concrete. The experimental methodology for this research study consisted of using aggregates sizefractions that are sieved into individual size fractions and recombining them in definite proportions to create arange of gradations, some within the bounds of the acceptable gradation (Control-1, Control-2, Control-3) andsome out-of-specification gradations. Concrete specimens were prepared with such aggregate gradations and arange of fresh and hardened properties of concrete were evaluated. Results from these studies indicated thatdeviations in fine aggregate gradation from the Control-2 gradation had relatively larger influence on propertiesof concrete compared to coarse aggregate. Also, the differences in gradations of aggregates within controlgradations (i.e. between Control-1 and Control-3 gradation) had more significant influence on properties ofconcrete, compared to the out-of-specification gradations. In general, the effects of deviations in gradations fromthe Control-2 gradation had minimal influence on compressive strength and modulus of elasticity of concrete.However, properties such as slump of fresh concrete, split tensile strength and rapid chloride ion permeabilitywere more significantly influenced by the deviations in the gradations