The construction of a pyrament bridge deck overlay (FHWA-OK-91-04)

Abstract

The Oklahoma Department of Transportation (ODOT) has been using .High Density Portland Cement (HDPC) overlays on reconstruction of bridge decks smce 1977. At the time of introduction, the HDPC (Iov;a method) was considered the best method to prevent or minimize bridge deck deterioration. Although many of the overlays have performed well, some have experienced severe cracking and delamination within ten years of service. Pyrament was chosen to be evaluated on a two inch bridge deck overlay as part of a bridge deck rehabilitation project. The performance of the overlay will be compared to the presently used HDPC overlays. Pyrament is a rapid setting, low permeability, high strength concrete developed by Lonestar Industries. Pyrament cement is a blend of 65~10 Portland cement, 30% fly ash, and 5% trademark additive. The 4-hour and 28-day compressive strengths were 2700 psi and 9600 psi respectively, Proper curirrg of Pyramcnt was found to be critical. Phase I of the project developed severe shrinkage cracking. Five percent of the Phase I overlay had to be replaced due to shrinkage cracking accompanied by dclaminations. The curing procedures in Phase I I were changed to resin curing compound, fogging, wet burlap, cotton blankets, and plastic all kept in place for 24 hours. The Phase 11 overlay shows no signs of cracking. The overlay will be tested annually and a performance report will be written in 1993.