a new look at pervious concrete

A New Look at Pervious Concrete

MUHANNAD T. SULEIMANAssistant Professor

Uses of Pervious concrete

All are surface applications….

How about underground applications?

Foundation Issues

Sandy Soil

Soft/Loose Soil

Bed Rock

Sandy Soil

Soft/Loose Soil

Bed Rock

Large Settlement Non-uniform

Settlement

Sandy Soil

Soft/Loose Soil

Bed Rock

Soil supporting foundations of structures or embankments need to satisfy two conditions:

Bearing capacity: can resist applied loads without failure

Allowable settlement: does not experience excessive settlement

Foundation Issues

Sandy Soil

Soft/Loose Soil

Bed Rock

Sandy Soil

Soft/Loose Soil

Bed Rock

Large Settlement Non-uniform

Settlement

Sandy Soil

Soft/Loose Soil

Bed Rock

5

When saturated soils are loaded, the water will be squeezed out This process is very very slow in fine (clay or silt) soils This process is called consolidation Engineers can make this process happen faster during construction, if

allowed by construction schedule If not, soil can be improved or deep foundations could be used

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Some Soil Mechanics

http://www.youtube.com/watch?v=qmVYbjiNWds

Settlement of Structures - Liquefaction Under earthquake loading, saturated sands can liquefy (form a quick sand)

This mainly happened because water can not flow quickly out of the soil (has no place to go)

Settlement of Structures - Liquefaction

But, how do we avoid these problems? --- ground improvement methods that allow water to flow through

Ground Improvement

Vertical drains Granular piers

Bio-modification

Ground Improvement – Vertical Drains

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Ground Improvement – Granular Piers

Ground Improvement – Granular Piers One major limitation is that their behavior depend on the confinement

provided by surrounding soil

Main Topics

Pervious Concrete Piles

Bio-Modification of Soil

Energy Piles

Ground Improvement Granular Piers (stone column, sand compaction pile and

aggregate pier) are widely used to increase bearing capacity, accelerate the consolidation, and reduce the settlement

The capacity of granular columns, however, depends on the confinement provided by surrounding soil, which limits their use in very soft clays and silts, and organic and peat soils

Pervious Concrete has higher stiffness and strength that are independent of the surrounding soil confinment, and offer permeability comparable to granular piers

Modulus MPa (ksi)

Permeability cm/sec (in./hour)

Granular Piers

25 – 190(3.6 – 27.6)

0.05 – 2.0 (71 – 2,835)

Pervious Concrete

13,800 – 27,600(2,000 – 4,000)

0.03 – 2.0(43 – 2,835)

Pervious Concrete vs. Granular Piers


Porosity

0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

28-d

ays

Com

pres

sive

Stre

ngth

(psi

)

1000

2000

3000

4000

5000

6000

Per

mea

bilit

y (in

ch/h

our)

1000

1500

2000

2500

3000

3500Compressive stengthPermeability

:Pile Mixing


Compressive Strength

18.3 – 22.2 MPa2650 – 3200 psi

Modulus 15.4 –16.2 GPa2235 – 2350 ksi

Permeability 1.2 – 1.6 cm/sec1700 – 2270 inch/hour

Testing Facility

Guiding system

Pile Driver

Guiding system

Cone tip

Mandrel

Vibrator

Pervious Concrete Piles - Installation

Testing Program

Four vertical load tests and two lateral load tests were performed

Two vertical load tests compared a granular pier to a pervious concrete pile

Vertical Loading (lb)

0 500 1000 1500 2000 2500

Ver

tical

Dis

plac

emen

t (in

.)

0

1

2

3

4

5

Aggregate pierPervious concrete pile 2200 lb

500 lb

2.5 D

Maximum load, N(lbs)

Granular pier 2,225(500)

Pervious pile 9,786(2,200)

Vertical Load Test Results

Capacity of pervious concrete piles is ~ 4.4 times the aggregate pier

Main Topics

Ground Improvement


Energy Piles

Bio-modification of Soil Ground improvement methods such as compaction and grouting have been

used to improve soil properties

However, these methods utilize significant mechanical energy and consume large amounts of fossil fuel

RECENTLY, a sustainable green method, which uses indigenous bacteria in the soil to turn sand into sandstone, has been studies

This process mimic a naturally occurring process over a long time

Bio-modification of Soil

Bio-modification of Soil So far, the applications of bio-modification have focused on small sand

samples with limited large-scale or field tests Large-scale or field tests encountered practical problems due to bio-plugging Bio-plugging limits the distribution of cementation around the injection point,

which limits the extent of soil improvement zone Therefore, stabilization large areas of soil using bio-modification remains

problematic Bio-modification could be used in combination with pervious concrete piles

where only a limited zone of improvement is needed to provide stronger foundation system

Pervious Concrete Pile with Bio-modification

Treatment and Vertical Load Tests

Four vertical load tests: Two subjected to axial tension and two subjected to axial compression

The two tests compared the response of pervious concrete pile with bio-modification to a pervious concrete pile with no modification

Untreated TreatedVertical Load Test Results

Vertical Load Test Results

Uplift load (N)

0 500 1000 1500 2000 2500 3000 3500 4000 4500

Upl

ift d

ispl

acem

ent (

mm

)

0

10

20

30

40

50

60

70

Uplift load (lbs)

0 200 400 600 800 1000

Upl

ift d

ispl

acem

ent (

inch

)

0.0

0.5

1.0

1.5

2.0

2.5UntreatedMICP-treated

205 lb

870 lb

Capacity of bio-modified-pervious concrete piles is ~ 4.25 times the pervious pile with no bio-modification

Main Topics

Ground Improvement


Energy Piles

The majority of energy consumed worldwide is currently obtained from fossil fuel sources (approximately 81%), which is related to global warming through increased carbon dioxide (CO2).

One of the major sources of CO2 emission is heating and cooling of buildings.

For example, heating and cooling of buildings is responsible for about 50% of the carbon emission in the UK.

One of the energy sources that could reduce CO2 emission resulting from heating and cooling is shallow geothermal energy.

Deep foundations used to support the structural loads of buildings can also be used as heat exchangers with the surrounding soil (Energy Piles).

Energy Demand

Geothermal Energy

Energy Piles

Heat Pump

Soil

Air Conditioning (Heating and Cooling)

Energy Pile for Heating and Cooling of Buildings

Energy Pile for Bridge Deicing

Energy Piles

Energy Piles

Pervious concrete energy pile

Heat exchanger

Ground water flow

Conventional concrete energy pile

Comparison of the Conventional and Pervious Energy Piles

Thermal conduction only in the concrete

Thermal conduction + convection in the concrete

• Geotechnical Engineering Program of the CMMI Division at the

National Science Foundation (Grant No. 0927743) and (Grant No.

1233566)

• Ph.D. Graduate Students: Lusu Ni, Hai Lin (Thomas), and Suguang

Xiao (Sean); M.S. Student: Hanna Jabbour

• Undergraduate Students: Pierre Bick, Caleb Davis

• Several photos presented in this presentation were obtained from

several websites

Thanks!Q&A