Durability of Calcium Aluminate Cement Concrete: Assessment of Concrete From a 60-Year Old Marine Structure at Halifax, NS, Canada

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Title: Durability of Calcium Aluminate Cement Concrete: Assessment of Concrete From a 60-Year Old Marine Structure at Halifax, NS, Canada

Author(s): P. C. Aitcin, F. Blais and C. M. George

Publication: Special Publication

Volume: 154

Issue:

Appears on pages(s): 145-168

Keywords: calcium aluminates; durability; freeze thaw durability; harbor structures; mechanical properties; permeability; porosity; Materials Research

Date: 5/1/1995

Abstract:
Pier B in the port of Halifax, NS, Canada, was built in 1930-32 using 18,000 tons of calcium aluminate cement (CAC, Ciment Fondu), sea-dredged sand and aggregates and mixing water pumped from an inland freshwater lake. The climatic conditions at Halifax are extremely severe; it is estimated that exposed concrete is subjected to about 100 freezing and thawing cycles per year. Pier B is over sixty years old and in regular service as a container terminal for ocean-going ships. The main structure is permanently submerged in sea water. A protective layer of facing concrete made of both CAC and normal portland cement, cast over the outside faces in the tidal zone, has needed periodic repair. The CAC concrete displays excellent durability with cylinder compressive strengths of 29 to 49 MPa, modulus of elasticity of about 30 GPa, and a Poisson's ratio typical of normal weight concrete. Records indicate that the CAC concrete was cast with a water-cement ratio of 0.5 to 0.6 and a cement content of about 330 kg/m 3. Volume porosity is of the order of 10 percent. The investigation reported here of cores taken from Pier B in 1993 provides a broad characterization and guide for more detailed examinations in a collaborative program, the results of which will be reported as they become available. A particular focus of interest will be the speculative existence of zones of enhanced impermeability on the exposed faces of the concrete, an effect which has been observed in other old CAC structures.