National Concrete Pavement Technology Center

Project description

Coarse aggregate, depending on intended usage, constitutes roughly 20–45% of portland cement concrete as well as being a major component in the construction of granular surface roads and shoulders for paved roads. However, coarse aggregate quality greatly varies among sources based on its petrophysical properties. Therefore, it is important to understand how these properties emerge from the depositional and diagenetic history of a deposit in order to accurately predict pavement durability, which can be negatively impacted by oscillating freeze/thaw cycles. To derive more information about a coarse aggregate’s pore system, this study used a “third generation” Iowa Pore Index (IPI) device capable of measuring the volume of intruded water at various time intervals ranging from 0.1–2.0 seconds, as well as measuring intrusion at variable pressures up to 70 psi (480 kPa). Using this new device, 21 carbonate samples (10 dolostones and 11 limestones) were compared to “traditional” IPI measurements. The new method gave slightly higher primary loads.