Porous ConcretePrepared By: Ravi Kumar

M.Tech 2nd Semester

Contents1. Introduction

2. Mix Proportion

3. Properties

4. Variation In Strength & Rupture

5. Application

6. Conclusion

IntroductionPorous (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 ProportionMaterials Proportion RangeCementitious 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 Massachusett

sColorado

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%

PropertiesDensity: 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 MpaShrinkage : 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

ApplicationsLow-volume pavementsResidential roads, alleys, and drivewaysParking lotsWell liningsFoundations/floors for greenhouses, fish

hatcheries, aquatic amusement centers, and zoos

Pervious Pavement-It’s a System.

ConclusionSaving 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.

ReferencesYang J, Jiang G. Experimental study on properties of

pervious concrete pavement materials. Cem Concr Res 2003;33:381–6.

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

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

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

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