Title: Deterioration and Repairs of Navigation Lock Concrete
Author(s): Ernest Schrader, James Dikeou, and Dwight Gill
Publication: Symposium Paper
Appears on pages(s): 557-576
Keywords: concrete durability; deterioration; fiber reinforced concretes; freeze-thaw durability; latex-(plastic); locks (waterways); mix proportioning; permeability; protective coatings; shotcrete; repairs; strength; tests; walls.
Deterioration of navigation lock wall concrete due to freeze/thaw cycles is a serious problem usually attributed to ineffective or a lack of air entrainment in the concrete. Most affected structures were made many years ago before air-entrained concrete was widely used. But, one of the largest locks in the world, Lower Monumental in Washington State, has been in service for only 10 years and also has serious surface deterioration. Conventional repair techniques of deteriorated surfaces call for removal of about 1 ft of face concrete, placing anchors and a reinforcing steel mat, and replacing the excavated concrete with new high-qualfty air-entrained concrete. However, at Lower Monumental, costs and repair time had to be taken into consideration. A coating which could be applied in a short period of time, could prevent continued freeze/thaw damage,.and be permanent under the adverse service conditions was needed. Six coatings of various portland cement and fine aggregate mixes were pneumatically applied to a section of the lock wall for evaluation. An accurate account of construction equipment, procedures, and production time was kept and "constructability" by these methods was evaluated. Total coating of the interior lock wall with a suitable latex-modified fiber-reinforced material was to be done in March 1980. This repair technique may be applicable to other structures, saving millions of dollars in construction costs and lost shipping time.