11-13. week rigid pavement [وضع...

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Prof. Dr. Eng Shafik Jendia

Rigid Pavement

Lectures of 11., 12. Week11. Week 16. 11 - 22. 11 . 201312. Week 23. 11 - 29. 11 . 201313. Week 30.11 – 06.12. 2013

Prof. DR. Eng. Shafik Jendia

Islamic University of Gaza


ReferencesHighway Engineering, Structural Design, Shafik Jendia (Arabic Version) AASHTO, Guide for Design of Pavement Structures.

Concrete Pavement Design,Construction, and Performance. Norbert Delatte

RIGID PAVEMENT DESIGN MANUAL.PUBLISHED BY FLORIDA DEPARTMENT OF TRANSPORTATION PAVEMENT MANAGEMENT OFFICE

Concrete Pavement Design, Guidance Notes, Geoffrey Griffiths and Nick Thom

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Rigid Pavement

IntroductionAdvantages and disadvantages of rigid pavementStresses of rigid pavement Design and construction of pavement jointsReinforcementDesign of rigid pavementDiscussion


Introduction

Rigid Pavements have been used for highways, airports, local roads, parking lots, industrial facilities,

and other types of infrastructure.When properly designed and built out of durable materials, concrete pavements can provide many decades of service with little or no maintenance.

Concrete generally has a higher initial cost than asphalt but lasts longer and has lower maintenance costs.

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IntroductionRigid Pavement or

Cement Concrete Pavementcan be paved as reinforced or unreinforced slabs

with certain dimensions. Longitudinal and transverse joints separate the slabs from each

other .


IntroductionCement Concrete consists of

Aggregates, Cement and Water

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Produce of Rigid (Cement Concrete) Pavement

Introduction


Flexible (Asphalt) and

Rigid (Cement Concrete) Pavements

Introduction

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binder

wearing

Introduction


Other Example For Rigid Pavement

Introduction

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Rigid Pavement has specific advantageswhen compared with asphalt pavement:• It lasts longer due to its rigidity and strength.

• It consists of a system of stiff plates (slabs)connected together to form a continuous, hingedslab system.

• The specific advantage of a rigid pavement isthat the relatively rigid plates apply load over awide area.

Advantages and disadvantages of rigid pavement



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• Because of its high skid resistance andbrightness, it is safer than asphalt pavement.Brightness provides the night drivers with bettersight and safety.

• No rutting and no/ or slight deformation.

• The binder (cement) isn't affected by temperature(unlike bitumen).



Rigid Pavements have specific disadvantageswhen compared with asphalt pavements:

• Rigid Pavement has a higher initial cost thanasphalt, thus it has been used for airports, heavilyloaded highways, industrial facilities and otherspecial types of infrastructure.

• The Joints between the slabs can be considered asa source for failures.

• It is not preferable to be used in urban roads,because of maintenance difficulties of infrastructurefacilities.


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Stresses of Rigid PavementThe concrete slab of the rigid pavement faces different types of stresses caused by repeated traffic load, temperature, moisture etc. which lead to: buckling, expansion, contraction and warping of the slab.Thus the designed slab must have high strength to resist all these effects. This means that the design Engineer should take into consideration in addition to traffic load and weather conditions: type of concrete, dimension of slabs, joints and their construction, the necessity of reinforcement and base type below.


Stresses of Rigid Pavement

• Wheel Load Stress

• Warping Stress

• Frictional Stress

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Stresses of Rigid Pavement / Wheel Load StressCritical Location of Loading

according Westergard

Interior Loading Edge Loading Corner Loading


Stresses of Rigid Pavement / Wheel Load StressStresses at Critical Location of Loading modified by

Westergard, Teller, Sutherland and Kelly.

Interior Loading

Edge Loading

Corner Loading

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Stresses of Rigid Pavement / Wheel Load Stress

Where:



Example 1: Calculate

the stresses caused by a vehicle

wheel (P) at all critical

locations of a cement concrete

pavement.

Given:

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Example 2: Calculate the

stresses caused by a vehicle wheel (P) at corners of cement concrete

slabs with the thicknesses:

h = 10 cm, 15 cm, 20 cm, 22 cm,

for the data given in example 1

Solution



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stresses caused by a vehicle wheel

(P) at edges of cement concrete


h = 10 cm, 15 cm, 20 cm, 22 cm,


Solution



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stresses caused by a vehicle wheel

(P) interior of cement concrete


h = 10 cm, 15 cm, 20 cm, 22 cm,


Solution



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Stresses of Rigid Pavement / Wheel Load StressRelationship between slab thickness and wheel load

stresses at the three critical locations

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Stresses of Rigid Pavement / Wheel Load StressConclusions

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Stresses of Rigid Pavement / Wheel Load StressSlab Deflection W

here:


Stresses of Rigid Pavement / Wheel Load StressExample 5: Calculate

the deflections caused by a vehicle

wheel (P) at all critical

locations of a cement concrete

pavement.

Given:

α = 200 mm

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Stresses of Rigid Pavement / Wheel Load StressSlab Deflection/ solution


Stresses of Rigid Pavement / Warping Stresses

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Stresses of Rigid Pavement / Warping StressesSummer Midday

Temperature Distribution over the slab thickness

Slab Deformation Summer Midday



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Stresses of Rigid Pavement / Warping StressesWinter Midnight

Temperature Distribution over the slab thickness

Slab Deformation Winter Midnight



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Stresses of Rigid Pavement / Warping StressesExample 6: Calculate

the warping Stresses at interior and

edgelocations of a cement concrete

pavement.

Given:



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Given:

= 15 cmExample 7: Calculate

the warping Stresses at interior and

edgelocations of a cement concrete

pavement.



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Stresses of Rigid Pavement / Frictional Stress


Stresses of Rigid Pavement / Frictional Stress

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Stresses of Rigid Pavement / Frictional Stresses


frictional stresses if the length of

cement concrete slabs:

L= 5 m, 10 m, 20 m,

Solution

Compared with other stresses, the frictional stress is relatively low. It affects the edge and interior of the

slab. It is considered in winter tensile and in summer compressive stress.


Stresses of Rigid Pavement / CombinationDuring Summer: The critical combinations for interior and edge during mid day exists when the slab tends to warp downward.

At this moment tensile stresses develop at the bottom fibre which are additive to the tensile stresses due to the loading.

σ(total) = σ(Load) + σ(warping) - σ(friction).

During Winter: The critical combinations for interior and edge exists when the slab contracts and the slab warps downward

during the midnight. σ(total) = σ(Load) + σ(warping) +σ(friction).

Since the Δt during winter lower than in summer, the combination during summer is the worst in our country

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Design and construction of pavement joints

Although the existing of joints in the rigid pavement can be considered sometimes as a

reason of distresses in the pavement, their construction in the rigid slab is very

necessary. Through joints, thermal stresses can be minimized. This means while the joints

carry stresses induced by expansion, contraction and warping of the slab, the slab resists all stresses caused by wheel loading.


Design and Construction of Pavement Joints

Joints can be divided according to their locations into two types:

• Transverse Joints: are perpendicular to the centerline of the roadway (at right angle to the traffic direction) .

• Longitudinal Joints: are parallel to the centerline (the same direction of traffic)

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Design and construction of pavement joints

Joints can be divided according to their functions into three types:

- Expansion Joints- Contraction Joints- Construction Joints


Design and construction of pavement joints/ Expansion Joints

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Jointed plain concrete pavement (JPCP) or unreinforced concrete pavement (URC)



Jointed reinforced concrete pavement (JRCP) or jointed reinforced concrete (JRC) pavement

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Design and construction of pavement joints/ Contraction Joints

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Design and construction of pavement joints/ Contraction Joints


Aggregate interlock joints are formed during construction by sawing

1/4−1/3 of the way through the pavement to create a plane of weakness. A

crack then propagates through the remaining thickness of the pavement as

the concrete contracts. This crack has a rough surface because it propagates

around the aggregates through the green cement paste, and as long as

it remains narrow the joint can transfer load from one slab to another

through bearing stress of the aggregate particles against each other across

the crack. Load transfer is compromised if the joint opens too widely or if

the aggregates wear away. The quality and erosion resistance of the material

supporting the slab at the joint also affect load transfer.

Design and construction of pavement joints/ Contraction Joints/ Aggregate interlock

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Design and construction of pavement joints/ Longitudinal Joints and Construction Joints


Reinforcement of Rigid Pavement

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Time

Tens

ile S

tres

s

Tem

pera

ture

Relationship between temperature variation of (concrete direct after laying due to hydration and tensile stress) and time



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Design of rigid pavement


Design of rigid pavementModulus of Subgrade Reaction

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Design of rigid pavementPCC Elastic Modulus


Design of rigid pavementPCC Modulus of Rupture

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Design of rigid pavementPCC Modulus of Rupture S’C or (fT)

fT

fC

fT = 0.79 (fC ) 0.5

Third Point Loading


Design of rigid pavementLoad Transfer coefficient J

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Design of rigid pavementLoad Transfer coefficient J

.


Design of rigid pavementDrainage Coefficient Cd

.

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Example



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Design of rigid pavement / Example

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Design of rigid pavement / Example


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11-13. week rigid pavement [وضع...

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