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WATER
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Dr. Adeel Zafar , CE-803 , Fall 2013
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Necessity of Water in Concrete
Minimum quantity of mixing water
required for hydration of cement
Water in excessrequired to act
lubricant between aggregates toproduce workable and economical
concrete
Lesserwater makes it difficult to
work with concrete and non-uniformmixing makes it weaker in strength
Water is also used for curingand
aggregate washing
Dr. Adeel Zafar , CE-803 , Fall 2013
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Water Quality
A safe drinking water is safe for concrete
Dr. Adeel Zafar , CE-803 , Fall 2013
Fit for drinking.
No taste.
No odour.
Some water with
some impurities can
be acceptable
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Water Basic Requirements
ASTM C-191 (AASHTO T-131) tests should be madeto ensure that impurities in the mixing water do notadversely shorten or extend the setting time of thecement
Water of questionable suitability can be used formaking concrete if mortar cubes (ASTM C-109 orAASHTO T-106) made with it have 7-day strengthsequal to at least 90%of companion specimens made
with drinkable or distilled waterAcceptable criteria for water to be used in concreteare given in ASTM C-94 (AASHTO M-157) andAASHTO T-26
Dr. Adeel Zafar , CE-803 , Fall 2013
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Limits for Wash water as Mixing water
Dr. Adeel Zafar , CE-803 , Fall 2013
* parts per million
Water containing less than 2000 parts per million (ppm) of total dissolved solids can
generally be used satisfactorily for making concrete. Water containing more than 2000
ppm of dissolved solids should be tested for its effect on strength and time of set.
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Analysis of some City water vs Seawater
Dr. Adeel Zafar , CE-803 , Fall 2013
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Alkali Carbonate and Bicarbonate
Carbonates and bicarbonates of sodium and
potassium have different effects on the setting
times of different cements
Sodium carbonate can cause very rapid setting,bicarbonates can either accelerate or retard the
set
In large concentrations, these salts can materially
reduce concrete strength
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Chlorides in Water
Concern over a high chloride content in mixing water is
chiefly due to the possible adverse effect of chloride ions
on the corrosion of reinforcing steel
Chloride ions attack the protective oxide film formed on
the steel
Placing an acceptable limit on chloride content for any
one ingredient, such as mixing water, is difficult
considering the several possible sources of chloride ions
in concrete.
An acceptable limit in the concrete depends primarily
upon the type of structure and the environment to which it
is exposed during its service life.
Dr. Adeel Zafar , CE-803 , Fall 2013
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Chloride content limits by ACI
Dr. Adeel Zafar , CE-803 , Fall 2013
The ACI 318 building code limits water soluble
chloride ion content in reinforced concrete to the
following percentages by mass of cement:
Prestressed concrete 0.06% Reinforced concrete exposed to chloride in service
0.15%
Reinforced concrete that will be dry or protected from
moisture in service 1.00% Other reinforced concrete construction 0.30%
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Sulfates
Dr. Adeel Zafar , CE-803 , Fall 2013
Concern over a high sulfate content in mix water
is due to possible expansive reactions and
deterioration by sulfate attack, especially in areas
where the concrete will be exposed to highsulfate soils or water
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Sea Water
Dr. Adeel Zafar , CE-803 , Fall 2013
About 78% of the salt is sodium chloride, and15% is chloride and sulfate
Although concrete made with seawater may have
higher early strength than normal concrete,strengths at later ages (after 28 days) may belower
This strength reduction can be compensated for
by reducing the water-cement ratio in plaincement concrete (PCC)
If aggregates are known to have alkali-reactivity,sea water should not be used in even PCC
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Sea Water
Dr. Adeel Zafar , CE-803 , Fall 2013
Seawater is not suitable for use in making steel
reinforced concrete and it should not be used in
prestressed concrete due to the risk of corrosion
of the reinforcement, particularly in warm andhumid environments
For PCC, Types-II or MS, should be used along
with a low water-cement ratio
Seawater used for mix water also tends to cause
efflorescence and dampness on concrete
surfaces exposed to air and water
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Acid Waters
Dr. Adeel Zafar , CE-803 , Fall 2013
Acceptance of acid mixing water should be based onthe concentration (ppm) of acids in the water
Occasionally, acceptance is based on the pH, whichis a measure of the hydrogen-ion concentration on alog scale
The pH value is an intensity index and is not the bestmeasure of potential acid or base reactivity
The pH of neutral water is 7.0; values below 7.0indicate acidity and those above 7.0 alkalinity (abase)
Organic acids, such as tannic acid, can have asignificant effect on strength at higher concentrations
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Acid Waters
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Alkaline Waters
Dr. Adeel Zafar , CE-803 , Fall 2013
Waters with sodium hydroxide concentrations
dictates alkalinity of water
Higher concentrations of hydroxides may reduce
concrete strength
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Organic Impurities / Algae impurities
Dr. Adeel Zafar , CE-803 , Fall 2013
Presence of organic substances effects the setting
timeof OPC and the ultimate strength of concrete
Highly colored waters, waters with a noticeable odor,
or those in which green or brown algae are allindications of high organic impurities
Water containing algae is unsuited for making
concrete because the algae can cause an excessive
reduction in strength.Algae in water leads to lower strengths either by
influencing cement hydration or by causing a large
amount of air to be entrained in the concrete
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Sugar / Sucrose
Dr. Adeel Zafar , CE-803 , Fall 2013
Small amounts of sucrose, as little as 0.03% to
0.15% by mass of cement, usually retard the
setting of cement
The upper limit of this range varies with differentcements
The 7-day strength may be reduced while the 28-
day strength may be improved Sugar in quantities of 0.25% or more by mass of
cement may cause rapid setting and a substantial
reduction in 28-day strength
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Oils
Dr. Adeel Zafar , CE-803 , Fall 2013
Mineral oil (petroleum) has less effect on strength
development if in less quantities / concentration
Mineral oil in concentrations greater than 2.5% by
mass of cement may reduce strength by morethan 20%
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Tolerable limits
for Impurities
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