Supervised by Dr. Sami Hijjawi Prepared by Hamza Saifan Abdul-Rahman Easa

Supervised by

Dr. Sami Hijjawi

Prepared by

Hamza SaifanAbdul-Rahman Easa

Civil Engineering Department

Soil Improvement and Design of PavementFor

Sanour – Maythaloon Street – Jenin

Supervised by

Dr. Sami Hijjawi

Prepared by

Hamza SaifanAbdul-Rahman Easa

2010 –2011

Project OutlineTypes of Pavement

Study Area

Pavement Condition Description

Soil Improvement

Pavement Design Using AASHTO Method

Approximate Quantities and Costs

Conclusions and Recommendations

Types of PavementTypical stress distribution under a rigid

and a flexible pavement.

• Asphalt concrete Surface• Basecourse layer• Subbase layer (Rock Fill)• Subgrade

Flexible Pavement

• Sanour –Maythaloon Street .

Study Area

Pavement Distresses Description

1 .Longitudinal Cracking

Cracks parallel to the pavement's centerline or lay down direction,

usually a type of fatigue cracking.



2. Alligator Cracking

Series of interconnected cracks caused by fatigue failure of the Pavement surface under repeated traffic loading.





3. Raveling

The progressive disintegration of an Pavement layer from the surface downward as a result of

the dislodgement of aggregate particles.


Soil Improvement

Types of Soil Improvement

Lime Stabilization

SubgradeReplacement

Geosynthetics

Cement Stabilization

1. Lime Stabilization

Lime stabilization involves the use of burned lime products, quicklime, hydrated lime (oxides and hydroxides, respectively) and Codel.

Lime is a strong alkaline base which reacts chemically with clays, causing a base exchange Calcium ions displace sodium and hydrogen cations and combine with available silica and alumina in the soil to form complex silicates and aluminates .

1. Lime Stabilization

The principal changes to a soil stabilized with lime include: reduction in plasticity index (PI) and volume change; increase in optimum moisture content, permitting compaction under wetter conditions and allowing the soils to dry out more rapidly; increase in strength and stability through a cementing action; and resistance to water absorption and capillary rise.

2. Cement Stabilization

Portland cement is one of the older materials used for stabilization. The cement hardens the soil material and structural strength .

Soil cement is a mixture of Portland cement, water and soil compacted to a high density. When cured, the soil cement mixture becomes a hard, rigid base material.

2. Cement Stabilization

Soil cement is used as a base course, a subbase course and a subgrade treatment for flexible and rigid pavements. Almost all types of soils can be used for cement stabilization except highly organic soils and heavy clay soils.

Four fundamental factors control the construction of soil cement : moisture content, curing duration, compaction, and cement content.

3 .Subgrade Replacement

This method can be practical and economical where soft deposits are shallow and are located above groundwater levels.

A common approach taken where soft subgrade soils are encountered is to remove and replace the in situ soils with stronger, usually granular, materials.

4 .Geosynthetics

Geosynthetics have been found to provide significant improvement in pavement construction and performance.

Geotextiles placed at the subgrade increase stability and improve performance of pavement constructed on high fines subgrade soils.

4 .Geosynthetics

Without using geosynthetics, these tensile stresses will cause tension cracks to develop within the bottom of the base course.

Due to dynamic traffic loads these cracks allow fines from the subgrade to migrate upward into the base course layer while base course aggregate simultaneously migrates downward into the subgrade.

PAVEMENT DESIGN USING AASHTO METHOD

5 - Determine thicknesses of pavement layers

2 -Collect Traffic Data

3 -Determine Average Annual Daily Traffic AADT

4 -Calculate Equivalent Single Axial load ‘ESAL’

Eiiirndi FNAADTGfESAL 365

1 -Determine the type oftreatment: Reconstruction


Flexible Pavement Design with 10 Years Design Period

So the ESAL = 0.451*106

ESAL Values

Passenger Cars (Class A)

Taxi van (class B)

Su2 axle (class C) Bus (class C) Su 3 axle

(class C) Truck/ Trailer

(class D) Total

total number

1248 1232 229 50 126 21 2906

% 0.429456297 0.42395045 0.078802478 0.01720578 0.043358568 0.00722643 1

ESAL factor

0.0004 0.02 0.02 0.21 0.73 0.98

ESAL 1473.411977 72726.104 13518.08264 30991.2375 271483.2405 60742.8255 450934.902

Thicknesses


Thicknesses of layers (cm)

Surface (asphalt layer) , divided in two layers 10

Base course layer 15

Rock Fill layer 80

Costs


material unit quantity unit cost cost ($)

Excavation m3 18200 4 72800

Rock Fill m3 11200 35 392000

Base coarse m2

140005 70000

MC (prime coat ) m2 9800 2 19600

Asphalt (2 layers ) m2 9800 15 147000

701400

Total Cost = 701,400 $


Flexible Pavement Design with 20 Years Design Period

So the ESAL = 1.044*106

ESAL Values

Passenger

Cars (Class A)

Taxi van (class B)

Su2 axle (class C) Bus (class C) Su 3 axle

(class C) Truck/ Trailer

(class D) Total

total number

1248 1232 229 50 126 21 2906

% 0.429 0.424 0.079 0.017 0.043 0.007 1

ESAL factor

0.0004 0.02 0.02 0.21 0.73 0.98

ESAL 3412.235 168424.432 31306.165 71771.775 628720.749 140672.679 1044308.035

Thicknesses


Thicknesses of layers (cm)

Surface (asphalt layer) , divided in two layers 12

Base course layer 20

Rock Fill layer 80

Costs


Total Cost = 764,400 $

material unit quantity unit cost cost ($)

Excavation m3 18200 4 72800

Rock Fill m3 11200 35 392000

Base coarse m2 14000 6 84000

MC (prime coat ) m2 9800 2 19600

Asphalt (2 layers ) m2 9800 20 196000

764400

The subgrade layer consists mostly of silty clay materials with classification of A-7. The high plasticity of the encountered silty clays indicates a high possibility of soil volume change. This could be the sole explanation of the pavement condition.

Due to weak and swelling soil of subgrade layer , it is recommended to use soil improvement which is soil replacement with Rock Fill layer to reduce the effect of subgrade moisture content on the road layers .


It has been noticed that the difference in cost between two scenarios is too small so it is recommended to use 20 year Design period than 10 year Design period .

Visual inspection of the pavement surface reveals the existence of several types of distresses (longitudinal cracks, alligator cracks, …etc.) .

Upon to visual examination and record of distresses , it is recommended to reconstruct the pavement and its layers after removing the existing one .


Thank You!

Documents

Supervised by Dr. Sami Hijjawi Prepared by Hamza Saifan Abdul-Rahman Easa