This presentation discusses temperature control in mass concrete structures. It defines mass concrete as any concrete with dimensions too large to prevent cracking from the heat generated during curing. Temperature control is necessary to limit cracking from uneven thermal expansion. Methods of temperature control include using low heat materials, pre-cooling the concrete, post-cooling with pipes, and insulating surfaces to reduce temperature differentials. The presentation covers the specific techniques involved in each method to effectively control temperatures in mass concrete projects.

1. Presentation on
“Temperature Control in Mass
Concrete (Major Works)”
BY
SATISH AWARE (M.Tech Civil)
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2. INTRODUCTION
 Experiment of one Construction
Techniques Of Major Works.
 We were going to introduction about
mass concrete.
 Methods of controlling temperature in
mass concrete
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3. CONTENTS
What is mass concrete ?
Why is temperature control
necessary?
Methods of temperature control
Low-heat materials
Pre cooling of concrete
Post-cooling of concrete
Surface insulation
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4. What is mass concrete ?
 According to ACI mass concrete is
defined as “any volume of concrete with
dimensions large enough to require that
measures be taken to cope with generation
of heat from hydration of the cement and
attendant volume change, to minimize
cracking.”
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5.  Mass concrete is defined by some
agencies as “any concrete element having
a least dimension greater than 3 ft (0.9 m).
What is mass concrete ?
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6. Applications of mass
concrete…
 In metropolitan cities
 High rise buildings
Columns & foundations
 Metro railways
 Other infrastructural developments
◦ Peirs , bed blocks, flyovers etc.
 Dams, reservoirs, retaining walls and
maritime structures etc.
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7. Concrete is thermally very poor conductor.
Heat transfer
(heat of hydration)
Results in unequal thermal expansion
Tensile stress at the free surface due to
expansion of core exceeds the tensile
strength
Then surface cracking will develop
Temp. difference betn interior & outer surface
of more than 200 C cause cracks.
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Why is temperature control
necessary?

8.  Coefficient of thermal expansion of
concrete αc= 10 x 10-6 per 0C
 if ∆t=200C
. ’. e = αc x ∆t =10 x 10-6 x 20 =200x10-6
This amount of strain is realistic tensile
strain @ cracking.
 Most mass concreting specifications call
for an absolute maximum temperature
value of not more than 160F(710C), and a
core-to-face differential of never more than
35F.
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9.  Cracks generated due to thermal gradients
may cause
◦ loss of structural integrity,
◦ loss in monolithic action,
◦ excessive shrinkage,
◦ loss in durability &
◦ aesthetically objectionable.
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 Cracks may cause -

10. Methods of temperature control
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Methods of controlling mass concrete
temperatures range from relatively
simple to complex, and from
inexpensive to costly. Depending on a
particular situation, it may be
advantageous to use one or more
methods over another.
Low-heat materials
Pre cooling of concrete
Post-cooling of concrete
Surface insulation

11. 1. Low-heat materials
 Select low heat of hydration cement or
mixture cement
 Use low cement contents(120 to 225 kg/M3)
 Class F fly ash generates about half as much
heat as the cement that it replaces and is often
used at a replacement rate of 15 to25%.
 Ground granulated blast-furnace slag is often
used
at a replacement rate of 65 to 80% to reduce
heat.
 Use large sized aggregates 75-120 mm high
aggregate contents up to 80% of total 11

12. 2. Pre cooling of concrete
 Use of chilled mix water.
 And some times replacement of mix water by
ice.
 Efforts to cool aggregates have the most
pronounced effects on the concrete
temperature because they represent 70 to 85%
of the weight of the concrete.
 Liquid nitrogen can also be used to precool
concrete or concrete constituents. But this
option can significantly increase the cost of
concrete
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13. 3. Post-cooling of concrete
 Cooling pipes in mass concrete are
sometimes used to reduce maximum
concrete temperatures and to quickly reduce
interior temperatures.
 This method can have high initial and
operating costs, but benefits can often.
 It is important to emphasize again that
significant internal and surface thermal cracking
can result if post-cooling is improperly designed
or performed.
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14. 4. Surface insulation
 Insulation or insulated formwork is often used
to warm the concrete surface and reduce the
temperature difference, which in turn
minimizes the potential for thermal cracking.
 Insulation often has to remain in
place for several weeks or longer.
 Removing it too soon can cause the surface
to cool quickly and crack.
 Many types of insulation materials are
available, and insulation levels can be
optimized to meet required temperature
differences and maximize the rate of cooling.
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