INTRODUCTION
Erosion is defined in this report as the progressive disintegration of a solid by cavitation, abrasion, or chemical action. This report is concerned with: 1) cavitation erosion resulting from the collapse of vapor bubbles formed by pressure changes within a high-velocity water flow; 2) abrasion erosion of concrete in hydraulic structures caused by water-transported silt, sand, gravel, ice, or debris; and 3) disintegration of the concrete in hydraulic structures by chemical attack. Other types of concrete deterioration are outside the scope of this report.
Ordinarily, concrete in properly designed, constructed, used, and maintained hydraulic structures will undergo years of erosion-free service. However, for a variety of reasons including inadequate design or construction, or operational and environmental changes, erosion does occur in hydraulic structures. This report deals with three major aspects of such concrete erosion:
Part 1 discusses the three major causes of concrete erosion in hydraulic structures: cavitation, abrasion, and chemical attack.
Part 2 discusses the options available to the designer and user to control concrete erosion in hydraulic structures.
Part 3 discusses the evaluation of erosion problems and provides information on repair techniques. Part 3 is not comprehensive, and is intended as a guide for the selection of a repair method and material.

INTRODUCTION
Erosion is defined in this report as the progressive disintegration of a solid by cavitation, abrasion, or chemical action. This report is concerned with: 1) cavitation erosion resulting from the collapse of vapor bubbles formed by pressure changes within a high-velocity water flow; 2) abrasion erosion of concrete in hydraulic structures caused by water-transported silt, sand, gravel, ice, or debris; and 3) disintegration of the concrete in hydraulic structures by chemical attack. Other types of concrete deterioration are outside the scope of this report.
Ordinarily, concrete in properly designed, constructed, used, and maintained hydraulic structures will undergo years of erosion-free service. However, for a variety of reasons including inadequate design or construction, or operational and environmental changes, erosion does occur in hydraulic structures. This report deals with three major aspects of such concrete erosion:
Part 1 discusses the three major causes of concrete erosion in hydraulic structures: cavitation, abrasion, and chemical attack.
Part 2 discusses the options available to the designer and user to control concrete erosion in hydraulic structures.
Part 3 discusses the evaluation of erosion problems and provides information on repair techniques. Part 3 is not comprehensive, and is intended as a guide for the selection of a repair method and material.