Evaluation Of High Slump Concrete For Bridge Deck Overlays

Download or read book Evaluation of High-slump Concrete for Bridge Deck Overlays written by Brian Keierleber and published by . This book was released on 2005 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Iowa Method for bridge deck overlays has been very successful in Iowa since its adoption in the 1970's. This method involves removal of deteriorated portions of a bridge deck followed by placement of a layer of dense (Type O) Portland Cement Concrete (PCC). The challenge encountered with this type of bridge deck overlay is that the PCC must be mixed on-site, brought to the placement area and placed with specialized equipment. This adds considerably to the cost and limits contractor selection, because not all contractors have the capacity or equipment required. If it is possible for a ready-mix supplier to manufacture and deliver a dense PCC to the grade, then any competent bridge deck contractor would be able to complete the job. However, Type O concrete mixes are very stiff and generally cannot be transported and placed with ready-mix type trucks. This is where a "super-plasticizer" comes in to use. Addition of this admixture provides a substantial increase in the workability of the concrete - to the extent that it can be delivered to the site and placed on the deck directly out of a ready-mix truck. The objective of this research was to determine the feasibility of placing a deck overlay of this type on county bridges within the limits of county budgets and workforce/contractor availability.