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


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

Author(s): L. Z. Hales and D. E. Wilson

Publication: Special Publication

Volume: 163


Appears on pages(s): 423-446

Keywords: breakwaters; compressive strength; durability; grouting; freeze thaw durability; harbor structures; jetties; nondestructive tests; portland cement; Materials Research

Date: 8/1/1996

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, Maine) for the eight-year period 1987 to 1995. Nondestructive tests (ultrasonic pulse velocity and transverse flexural frequency) were conducted periodically during the eight-year evaluation period. Long-term durability exposure field tests revealed spalling of the Buhne Point Mixture due to freezing and thawing. However, nondestructive tests indicated the integrity of all specimens was maintained, as there appeared to be minimal changes in the properties of these cementitious grouts. Grout laced within the core of rock structures may not actually be exposed to the extreme conditions on the weathering platform at Treat Island. Either the WES Mixture or the Buhne Point Mixture may be used as grouting materials to rehabilitate existing Corps rubble-mound breakwaters and jetties by filling voids to prevent passage of excessive wave energy and sediment through such structures.