of Los Angeles has been accomplished by observing established facts 
regarding concrete, applying the best constructional procedures, and 
adhering to principles of good workmanship, all of which necessitated 
correctly written specifications and assiduous inspection. 
Service records of 27 specific American concrete waterfront struc- 
tures, built during the period 1904 to 1951, have been briefly presented 
in geographic sequence (Mather, 1957). The north and central Atlantic 
Coast, from Canada to North Carolina, is a zone in which the dominant 
influence on durability is characterized by freezing and thawing. The 
south Atlantic Coast, the Gulf Coast, and most of the Pacific Coast are 
zones where chemical factors are dominant relative to influencing 
concrete durability. 
Service records of 105 concrete structures in seawater were studied 
from 1922 to 1924 and certain conclusions deduced (Atwood and Johnson, 
1924). Maritime structures included 31 facilities in foreign nations 
(built during the period 1855 to 1911) and 74 American structures (built 
during the period 1889 to 1919). The evidence showed great variations 
in the serviceability of both plain and reinforced concrete waterfront 
structures. The durability of the cementitious matrices in general use 
as of 1924 seemed to be questionable. Plain concrete in seawater may 
deteriorate as the result of chemical action of sulfates (in the seawater) 
on the constituents of the concrete and mechanical action of water, ice, 
and debris. Reinforced concrete in seawater may deteriorate not only 
because of such chemical and mechanical actions, but also because of the 
splitting and spalling brought about by the corrosion of the steel 
reinforcement. The rate of deterioration is related to the permeability 
and porosity of the concrete. Most of the deterioration, in both plain 
and reinforced concrete, occurs above low tide level; good concrete 
seldom suffers below this level. "Deterioration of well built rein- 
forced concrete does not often indicate its presence by rust stains in 
much less than 10 years.'' Disintegration by the chemical action of mag- 
nesium sulfate in seawater can be prevented by incorporating siliceous 
materials in the concrete; such materials (volcanic origin) are pozzolana 
from Italy, Santorin earth from Greece, trass from Germany, and tuff 
from California. Other siliceous materials are diatomaceous earth from 
Denmark and California, certain blast furnace slags, and some burned 
clays. 
In Norway, during the period from 1962 to 1968, comprehensive 
field inspections of 219 reinforced concrete wharves (among a total of 
716 concrete maritime structures erected since about 1910) disclosed 
that deterioration developed very slowly within the tidal zone. Above 
high tide level the deck beams were especially vulnerable to corrosion 
of steel reinforcement. However, neither the deck slabs nor seawalls 
underwent any serious impairment of strength during a half century of 
service. The wharves inspected involved over 2,000,000 square feet of 
reinforced concrete decks supported by more than 5000 reinforced con- 
crete pillars. Evidence indicated that deck beams should be either very 
shallow or, preferably, avoided altogether in order to assure good per- 
formance of concrete wharves under severe marine environment (Gjorv, 1969). 
x3} 
