19 June 2001
REPAIR OF CONCRETE STRUCTURES
CONCRETE FOR REPAIRS. Quality, lasting concrete for repair of
waterfront facilities depends on the quality of the concrete mix, and careful
attention to preparation and construction techniques. Both factors are important
in making and placing conventional Portland cement concrete and the special
types of repair concretes.
Some of the information in this section was extracted from the
NAVFAC MIL-HDBK-1025/6, General Criteria for Waterfront
Survey of Techniques for Underwater Maintenance/Repair of
Waterfront Structures, Revision No.1, Childs Engineering
Corporation, December 1985.
NCEL TM-43-85-01CR UCT Conventional Inspection and Repair
Techniques Manual, October 1984.
CEL CR 81.009, Survey of Techniques for Underwater
Maintenance/Repair of Waterfront Structures, Childs Engineering
Corporation, February 1981.
Portland Cement Concrete
Durability. Concrete of low permeability is important for waterfront
facilities. The objective is to keep salt and water out of the concrete
to protect the reinforcing steel from corroding, which result in the
concrete spalling. The most important factors are a low water-to-
cement ratio (0.40) in the mix, use of 25% Class F fly ash, and
proper curing of the concrete when placed.
Strength. 35 MPa (5000 psi) concrete is recommended for most
repairs. Design of the mix and proper curing will determine the final
Workability. Concrete must be easily handled and placed. A dense
concrete is important. This workability must be obtained without
increasing the water content beyond the mix design. Enhanced
workability is obtained by using 25% Class F fly ash. Use of
admixtures conforming to ASTM C-494, Standard Specification for