The negative effect of sulfate to the concrete and reinforced concrete elements
Abstract
One of the reasons deteriorations constitute at the
concrete and reinforced concrete structures in the
time is the effect of sulfate.Naturally occuring
sulfates in soils and groundwater, after a series of
chemical processes, may lead to durability problems
causins expansion and disintegration of the
hardened concrete. Concrete that expose to sulfate
ions at high-density may destroy completely. Effect
of fly ashes (FA) and blast furnace slag (BFS) on
properties of superplasticizer (SP) added concrete
was investigated against to sufate effect. FA and
BFS were added to Portland cement (PÇ 42,5) 20 %
by weight of the cement. FA and BFS replacement
concretes were compared with each other as well as
with Portland cement concrete. 15 cm cube
specimens were prepared with produced concrete
and cured at 7, 28, 90 and 150 days For this
purpose, high density sulfate of soils were examined
by comparing the ratio of TS 12457-4 Standards. In
this study, pozzolanic additions were added to
changing in ratio 20 % by weight of the (PÇ. 42.5)
portland cement. The 0.56 water/cement ratio and
300kg/m3
cement dozage are selected as reference. A
control concrete sample is also produced having the
same dozage. The performance of mineral
additives concrete was obtained both in the
sulphate and water cures. In this context, three
series of concrete samples was produced; in two
concrete samples series the certain ratio of fly
ash and granulated blast furnace slag was used
as additives, and one series of sample was used
without additives. In order to see the effect
strength and durability of concrete at high-rate
sulfate, concrete samples were rested in a
solution of Na2SO4(150 g / l) in accordance
with ASTM C 1012. One group of specimens
was kept continuously in sodium sulphate
solution with concentration of 150 g/l for 5
months.. The other group samples were rested
in water and compressive strengths are
presented as a comparatively. At the end of each
curing period, a total of 3 specimens were tested
for each concrete property. Surface hardness
and compressive strength of Concrete samples
exposed to Sulphate effect were measured
regularly. At the same time, the surface
distortions and changes of weight of the
samples were observed periodically. As a
result, sulfate is determined to decrease upon
the strength and durability of concrete
structures. Moreover, The results showed that
use of %20 FA(Fly Ash) as replacement of
portland cement increased the strength
properties of concrete samples. Economical
benefit can be achieved by using pozzolanic
additions in the concrete mixture. As a
conclusion use of such additions, waste
materials, provide both durable and economic
concrete structures and ecologic balance for.
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