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Concrete Under The Effects Of SeawaterConcrete under the effects
of seawater has many items , one of them is sodium hydroxide
dissolved by water in the seawater , it would reduce the value
of pH , increasing void ratio and permeation ,result in
increasing reinforce bar corrosion velocity , those factors
cause to reduce the strength, durability , lifecycle of concrete
structure, and increase additional maintenance cost ,finally due
to waste earth resources and more pollution. For the purpose to
understand the concrete in the marine conditions under the
seawater what will be affected ,and try to observe concrete what
will occur under those conditions of circumstances ,so using
cylinders which made from different types of cement and w/c
ratio to put it on seashore , seabed , between high and low
tide, and in the laboratory, those are in the Port of Kaohsiung
(Nos.81). Applying Fick''s Second Low of Diffusion converted to
programs to find the diffusion factors with the known content of
chlorine, then use the found diffusion factors to estimate the
among of chlorine by different values of time, depth from
concrete surface, and discuss the relations between the time, w/
c ,pores and so on ,expect to construct some referent data which
could be used in marine engineering for designing ,construction,
maintain, and research.It is showed cylinders of concrete at
high w/c in the early date could get more higher strength but
doesn''t increase the final compress strength after 180th day ,
cylinders of concrete at lower w/c was put on seabed is weaken
about 0.1 times compress strength of cylinders of concrete at
same w/c put in laboratory at the 180th day. The value of
chlorine of diffuse factors are not constant , it is changed
with the age of cylinders ,location, materials , environments
and so on .The among of content of chlorine in concrete is
decreased with w/c, increased with pores , increased when pH of
concrete is decreased. Cylinders of concrete were immersed in
seawater is made from type II cement had contained more chlorine
than type I cement but it was opposite to the cylinders of
concrete put on between high and low tide . After measuring pH
values of cylinders of concrete that we could know seawater
making pH values decreased with age of concrete.To conclude The
sum of all tests shown seawater would penetrate into concrete
and produce interactive reactions between physics and chemistry
, those interactive reactions would direct or indirect
influence the durability of concrete. If we want to use more
exact and accurate data with more reasonable and perfected to
describe and explain in fixed analysis of quantity that we
should need to make more tests and more the work of surveying .
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