Durability of Cementitious Mixtures Used for Sealing Voids in Rubble-Mound Breakwaters and Jetties

Abstract

Many Corps of Engineers rubble-mound breakwaters and jetties have become permeable to sand transport and wave transmission, resulting in increased dredging costs, risks and delays to navigation, and damage to moored vessels by excessive wave activity. Some Corps coastal districts have applied grouting techniques for sealing these structures by using cementitious and chemical grouts for creating a vertical barrier through a series of vertical holes drilled along the centerline of the structure. To ascertain the effective useful life of such grouts, durability time-dependent tests were conducted by U.S. Army Engineer Waterways Experiment Station (WES) to determine how the materials would endure under near-actual field conditions. A cementitious mixture previously used at Buhne Point, California (Buhne Point Mixture), and a new mixture design (WES Mixture) developed by the WES Structures Laboratory (SL), were evaluated. Specimens were exposed at three weathering stations (including Treat Island, ME) for the 8-year period 1987-1995. Long-term durability exposure field tests revealed spalling of the Buhne Point Mixture due to freezing and thawing.