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The excessive impurities in the no single water can
affect the time of setting and the concrete resistance of, if not also they can
be efflorescence cause, stained, corrosion of the effort, volumetric instability
and a smaller durability. The water that contains less than 2.000 parts of
million (ppm) of solids dissolved total generally can be used of satisfactory
way to elaborate concrete. The water that contains but of 2.000 ppm of dissolved
solids will have to be tried to investigate its effect on the resistance and the
time of setting.
ALKALINE CARBONATES AND BICARBONATES
The sodium carbonate can cause very fast settings, whereas the bicarbonates can
accelerate or slow down the setting. In strong concentrations these salts can
reduce of significant way the resistance of the concrete one. When the sum of
1.000 the dissolved salts exceeds ppm, tests will be due to make to analyze
their effect on the time of setting and the resistance to the 28 days. Also the
possibility will be due to consider that appears reactions alkali - added
serious.
CHLORIDES
The restlessness with respect to an elevated chloride content in the mixed water
of, must to the possible adverse effect mainly that the chloride ions could have
in the corrosion of the steel of reinforcement, or the stumps of the preeffort.
The ions chloride attack the layer of I oxidizes protector formed in the steel
by the average alkaline chemistry (pH 12,5) highly present in the concrete one.
The chlorides can be introduced in the concrete one, or with the separated
ingredients - additives, aggregates, cement, and water - or atraves of the
exhibition to the antifreeze salts, the water of sea, or the loaded air of salts
near the coasts. The water that is used in concrete reinforced or in a concrete
one which it is going to have contracted aluminum will not have to contain
injurious amounts of ion chloride. The chloride contributions of the ingredients
different from the water also will be due to take in consideration. The calcium
chloride additives will be due to use with much precaution. The Regulation of
Construction of the American Concrete Institute, ACI 318, limits the content of
ion soluble chloride the water in the concrete one, to the following percentage
in weight of the cement. Concrete reinforced. Concrete reinforced exposed to
chlorides during its service.
Types of water
WATER OF SEA
Even though a concrete fact with water of sea can have an early resistance
greater than concrete a normal one, their resistance to greater ages (after 28
days) can be inferior. This reduction of resistance can be compensated reducing
to the relation water - cement. The water of sea is not adapted to produce
concrete reinforced with steel and it will not have to be used in concrete
reinforced due to the risk of corrosion of the effort, particularly in warm and
humid atmospheres. The water of sea that is used to produce concrete also tends
to cause to efflorescence and humidity in exposed surfaces of concrete to the
air and the water.
ACIDS WATER
In general, the water of mixed that contains acids hydrochlorate, sulfuric and
other inorganic acids common in 10.000 inferior concentrations to ppm does not
have an adverse effect in the resistance. The acids waters with values pH
smaller than 3,0 can cause handling problems and they are due to avoid as far as
possible.
ALKALINE WATERS
The waters with concentrations of hydroxide of 0,5% sodium the weight of the
cement, does not affect to a great extent to the resistance of the concrete one
every time they do not cause a fast setting. Nevertheless, greater
concentrations can reduce the resistance of the concrete one. The hydroxide one
of potassium in concentrations smaller to 1,2% by weight of cement has little
effect in the resistance of the concrete one developed by certain cements, but
the same concentration to the being used with other cements can substantially
reduce the resistance to the 28 days.
RINSING WATERS
The Agency of Environmental Protection and the state agencies of the U.S.A.
prohibit to unload in the fluvial routes, not treated waters of rinsing that
have been used to take advantage of the sand and the gravel concrete returned or
to wash the mixer ones.
WATERS OF INDUSTRIAL WASTES
Most of the waters that take industrial wastes has less than 4.000 ppm of total
solids. When use becomes of this water as waters of mixed for the concrete one,
the reduction in the compressive strength is not generally greater than from 10%
to 15%.
BLACK WATERS
Approximately 400 the typical black waters can have ppm of organic matter. As
soon as this waters have been diluted in a good system of treatment, the
concentration is reduced approximately 20 ppm or less. This amount is too small
to have effect of importance in the resistance. |
