“The Relations Between the Strains
and Constitution of Cements and Col-
loidal Structured Materials” (1926-
1929).
14
Freyssinet’s motivation was primar-
ily to understand structures made of
concrete rather than the structure of
concrete. Indeed, he ends this treatise
with the conclusion that “arches with
spans in excess of 1000 meters” can
be built “at a far lower cost than a sus-
pension bridge of the same span.”
15
His major work did not, however, lie
in that direction.
By 1928, with the Plougastel Bridge
well under way, Freyssinet had recog-
nized the more general significance of
prestressing, patenting his ideas in
France, Britain, and the United
16
devoted his full attention to the poten-
tials of prestressing.
In November of 1932, Freyssinet
sat down and wrote out his progress at
the request of the editor of a new
journal Science et Industrie. In one of
its early issues, dated January 1933,
Freyssinet’s article “New Ideas and
Methods” appeared.
17
Beginning with his ideas on the
“thermodynamic theory of binders,”
he proceeded to analyze the behavior
of cement, concrete, and reinforced
concrete, all from the perspective of a
scientist. He described tests and their
results and further explained how
stresses over a cross section arise from
shrinkage, from axial compression and
from bending. Finally, in the fourth of
his six chapters, he outlined the “con-
ditions for the practical use of pre-
stressing.”
18
1. Using metals with a very high
elastic limit.
2. Submitting them to very strong
initial tensions, much greater than
70,000 psi (500 MPa).
3. Associating them with concretes
of a very low, constant and well-
known rate of deformability, which
offer the additional advantage of very
high and regular strengths of resis-
tance.
In present-day terms, Freyssinet had
established the need for high strength
steel, for tensioning it to a high initial
stress, and for high strength concrete
to reduce to a minimum the loss of
initial prestress.