Iowa State University
Iowa Department of Transportation
Bridge decks, Concrete curing, Contraction joints, Cracking, Hydration, Joint spacing, Portland cement concrete, Shrinkage, Warping, Water cement ratio
Internal curing is a relatively new technique being used to promote hydration of Portland cement concretes. The fundamental concept is to provide reservoirs of water within the matrix such that the water does not increase the initial water/cementious materials ratio to the mixture, but is available to help continue hydration once the system starts to dry out. The reservoirs used in the United States (US) are typically in the form of lightweight fine aggregate that is saturated prior to batching. There has been considerable work conducted both in the laboratory and in the field to confirm that this approach is fundamentally sound, and yet practical for construction purposes. A number of bridge decks have successfully been constructed around the US including one in Iowa in 2013. The application where this technology has not been investigated to any depth is in the area of pavements. It is believed that inclusion of about 20% to 30% lightweight fine aggregate will not only improve strength development and potential durability, but more importantly will significantly reduce shrinking and warping, thus reducing cracking risk, particularly in thinner pavements or those with relatively large panel sizes. The aim of the work described in this proposal is to investigate the feasibility of such an approach, and to monitor and evaluate a section of pavement built using such a system.