DURABILITY AND TESTING OF STONE FOR USE IN RUBBLEMOUND STRUCTURES

Abstract

Rubblemound structures protected from wave action by a layer of quarried rock (stones) are the most common form of breakwaters. While extensive guidelines and procedures exist to select the size of stone there is very little information available on procedures to be followed to assure the quality of the in-place stone. This subject is not covered in depth in the principal breakwater design manuals such as the U.S. Army Corps of Engineers Shore Protection Manual (1984). However, review of existing breakwaters show that deterioration of the stone is a common problem and some projects have experienced very serious difficulties in assuring the placement of durable stone. Review of construction specifications used throughout the world shows considerable variability in testing procedures required to define properties of the stone and different criteria to measure acceptability of a stone. In response to these issues a two-day seminar was held in Cleveland, Ohio on 22 and 23 May 1991, sponsored by the Rubblemound Structures Committee of the Waterways, Port, Coastal, and Ocean Division of the American Society of Civil Engineers. Cleveland was an important location because of the serious deterioration of some of the stones placed on the Cleveland breakwater.