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PERVIOUS CONCRETEANNAMACHARYA INSTITUTE OF TECHNOLOGY AND SCIENCES

PRESENTED BY G. GURU LATHA

13701A0115

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Topics To Be Discussed• What is pervious concrete• History• Mix design• Composition• Subgrade applications• Compaction methods• Applications• Advantages• Disadvantages• conclusion

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What Is Pervious Concrete

• Pervious concrete is a special type of

concrete with a high porosity used

for concrete flatwork applications

that allows water from precipitation

and other resources to pass through

it, thereby reducing the runoff from a

site and recharging ground water

levels.

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History Of Pervious Concrete Pervious concrete was first used

in the 1800s in Europe. It became

popular again in the 1920s for

two story homes in Scotland and

England. It became increasingly

viable in Europe after the Second

World War due to the Scarcity of

cement. It did not become as

popular in the US until the 1970s

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Mix Design• Aggregates• Cementious Materials• Water• Admixtures Ranges Of Materials Design Void Content: 15% to 30% Water to Cement Ratio: 0.28 to 0.40 Binder to Aggregate Ratio: below 0.25

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A mix design with little water can create a very

weak binder. This will create a very dry mix that

is susceptible to spalling and crumbling.

Correct amount of water

A mix design with too much water can collapse

the void space, making an almost impenetrable

concrete surface

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Aggregates• Pervious concrete has little or no fine aggregates in the

mixture. Aggregate size is typically between 3/8 to1/2 inch

maximum

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Cementious materials• Typically type-I cement is used for the production of pervious concrete.

• Supplementary cementious materials such as fly ash or slag can be used in

exchange up to about 25% (fly ash) and up to about 50%(slag) of cement.

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Water• Water meeting standard requirements for conventional

concrete can be used for the production of pervious concrete

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Admixtures• Air entraining admixtures may be used to improve the

freeze/thaw durability of the paste/mortar.

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Typical composition of pervious concrete

• The Pervious Concrete Layer• Sub-grade Layer• Drainage

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Sub-grade Layer

• This is the undisturbed soil underneath the sub-base layer. Sub-grade layer

infiltration rate determines how much water can be absorbed within a given time.

This directly affects the size of the sub-base layer. If the infiltration rate is too low,

larger sub-base or drainage should be considered. If the sub-grade is too fine, it

may be necessary to place geo-textile in between the sub-base and sub-grade to

minimize the migration of fine soil particles into the sub-base. Omitting this could

lead to clogging and reduced retention capacity

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Pervious Concrete Layer

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Drainage• A drainage system is not always necessary but may be needed

when the infiltration rate of the sub-grade layer is low and water

contained in the sub-base cannot be absorbed by soil quickly

enough.

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Sub Grade Applications

• Leveled subgrade

• Elevated subgrade

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Leveled Subgrade Layer

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Elevated sub grade layer

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Compaction Methods1. Roller compaction

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2. Compaction by plate compactors

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3. Mechanical / manual vibrating screeds Commonly used technique, which is simple and fast.

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Keep in mind….• Maintenance such as vacuuming or sweeping may be required in certain

areas to preserve pervious properties

• Pervious concrete is only as good as its design and installation.

vacuum for sweeping

pervious pavements

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APPLICATIONS

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ADVANTAGES

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Environmental benefits• Reduces storm water runoff• Water management practices• Mitigation surface pollutants pervious water allows recharging the ground level

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Safety

• Reduce tire sound• Prevents glare

Economics• Low maintenance cost• More life span

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DISADVANTAGES

• Extended curing time

• Limited use in heavy vehicle traffic areas

• Frequent maintenance is required

• Compressive strength is low

• Special care in expansive soils & high ground water

conditions

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CONCLUSION• The pervious concrete helps the water to

infiltrate• Cities with pervious pavements would be safer

for traffic, be cleaner and less pollution

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