Porous ConcretePrepared By: Ravi Kumar

BEDM CBRI, Roorkee

Contents1. Introduction

2. Mix Proportion

3. Properties

4. Variation In Strength & Rupture

5. Application

6. Conclusion

Introduction

Porous (pervious) concrete is a special type of concrete with a high porosity used for concrete flatwork applications that allows water from precipitation and other sources to pass directly through, thereby reducing the runoff from a site and allowing groundwater recharge .

The high porosity is attained by a highly interconnected void content.

Contd.

It is a mixture of Cement, Corse aggregate and with or without sand (Fine aggregate) and has enough cementitious paste to coat the coarse aggregate while preserving the interconnectivity of the voids.

This concrete is being used as paving material to solve or reduce the storm water runoff to the drainage system and minimize water logging problems.

Porous Concrete Porous Concrete: when it rains, it drains.

Mix Proportion

Materials Proportion Range

Cementitious Material 270 - 415 Kg/m3

Water/cementitious Ratio

0.20 - 0.45

Coarse Aggregate 1190 - 1600 Kg/m3

Void Content 15% - 35 %

Note: Retarders are often used to control the normal rapid setting of pervious concrete.

Contd.Pervious concrete mix proportion used in various geographic areas:

Materials Florida Massachusetts

Colorado

Cementitious Material

355 kg/m3 370 kg/m3 360 kg/m3

Water 75 to 90 kg/m3

105 kg/m3 80kg/m3

Water/Cementitious 0.21 - 0.25 0.28 0.22

Coarse Aggregate 1540 kg/m3

1600 kg/m3 1365 kg/m3

Voids Content 22% to 25%

18% 35%

Properties

Density: In place densities on the order of 1600 kg/m³ to 2000 kg/m³.

Void: Concrete with a high volume of voids (20% to 35%)

Permeability: Typical flow rates for water through pervious concrete are 120 L /m2/min, or 0.2 cm/s to 320 L /m2/min, or 0.54 cm/s.

Compressive Strength: 3.5 MPa to 28 Mpa

Contd.

Flexural Strength : 1 Mpa to 3.8 Mpa

Shrinkage : Drying shrinkage of pervious concrete develops sooner, but is much less than conventional concrete in order of 200 10-6 have been reported.

Freeze-Thaw : Entrained air in the paste dramatically improves freeze-thaw protection for pervious concrete.

Relationship Between Age & Compressive Strength

Relationship Between Age & Modulus of Rupture

Applications

Low-volume pavements

Residential roads, alleys, and driveways

Parking lots

Well linings

Foundations/floors for greenhouses, fish hatcheries, aquatic amusement centers, and zoos

Pervious Pavement-It’s a System.

Conclusion

Saving in materials- As no-fines concrete contains no sand and consequently requires considerably less cement per cubic yard of concrete, there is a direct saving in materials.

High thermal insulation value-Because of its nature, which allows the formation of large voids, it has better insulating characteristics than conventional concrete.

Environmental Benefits: Reduces storm water runoff

Contd.Eliminates need for detention ponds and other

costly storm water management practices.

Replenishes water tables and aquifers.

highways generally are not suitable for pervious concretes. pervious concrete pavements allow snow to melt faster, requiring less plowing.

References

1. Yang J, Jiang G. Experimental study on properties of pervious concrete pavement materials. Cem Concr Res 2003;33:381–6.

2. Malhotra VM. No-fines concrete: Its properties and applications. ACI 1976;73(11):628–644

3. Technical Bulletin-0111 “Design and Control of ConcreteMixtures” PCA,2002

4. Tennis D. Paul et al. “Pervious Concrete Pavements” PCA,2004

5. Chindaprasirt .P, Cement paste characteristics and porous concrete properties, Elesvier, Construction and Building Materials 22 (2008) 894–901