concrete pavements the right tool for the right job

Concrete Concrete PavementsPavements


The Right ToolThe Right Tool

for for

The Right Job.The Right Job.


The Right ToolThe Right Tool

for for

The The RightRight Job. Job.

Concrete Pavements: Concrete Pavements: The Right Tool for the The Right Tool for the RightRight Job Job

Differences between Concrete and Asphalt PavementDifferences between Concrete and Asphalt Pavement IH 610 – Four Decades of Superior Service IH 610 – Four Decades of Superior Service Forth Worth – Low Cost Concrete PavementsForth Worth – Low Cost Concrete Pavements ConclusionsConclusions

The Differences The Differences Between Concrete and Between Concrete and

AsphaltAsphaltConcrete SectionConcrete Section Asphalt SectionAsphalt Section

6” Cement Stabilized Base6” Cement Stabilized Base

SubgradeSubgrade

1” Asphalt Bond Breaker1” Asphalt Bond Breaker

8”-15” Concrete8”-15” Concrete8”-15” Concrete8”-15” Concrete

6” Lime Treated Subgrade6” Lime Treated Subgrade6” Base6” Base

SubgradeSubgrade

13” Asphalt Stabilized Base13” Asphalt Stabilized Base

4” Asphalt Surface Course 4” Asphalt Surface Course

6” Lime Treated Subgrade6” Lime Treated Subgrade

Concrete’s Concrete’s rigidrigid structure spreads the load over a larger structure spreads the load over a larger area and keeps pressures on the subgrade low.area and keeps pressures on the subgrade low.


AsphaltAsphalt

18,000 18,000

18,000 18,000

Better weight distribution means longer life for Better weight distribution means longer life for concrete pavements.concrete pavements.


AsphaltAsphalt

Better weight distribution means longer life for Better weight distribution means longer life for concrete pavements.concrete pavements.

Concrete is a long-term pavement with little Concrete is a long-term pavement with little maintenance; asphalt is a short-term pavement maintenance; asphalt is a short-term pavement that requires periodic maintenance (mill and that requires periodic maintenance (mill and overlay).overlay).


AsphaltAsphalt

Concrete Pavement AdvantagesConcrete Pavement Advantages Less rutting (less hydroplaning)Less rutting (less hydroplaning) Less maintenanceLess maintenance Less rehabilitationLess rehabilitation Better safety (Shorter stopping distance, better Better safety (Shorter stopping distance, better

light reflection, fewer work zone accidents)light reflection, fewer work zone accidents) Concrete Pavement DisadvantageConcrete Pavement Disadvantage

Higher initial costHigher initial cost


AsphaltAsphalt


AsphaltAsphalt

Concrete pavements are better suited for higher volumes and

heavier loads.

Asphalt pavements are better suited for lower volumes and

lighter loads.

Conventional Wisdom

Four Decades of Superior Four Decades of Superior ServiceService

IH 610 West Loop in HoustonIH 610 West Loop in Houston


Pavement Type:Pavement Type: Continuously Reinforced Continuously Reinforced Concrete Pavement (CRCP)Concrete Pavement (CRCP)

Project Length:Project Length: 2.4 miles 2.4 miles Construction Date:Construction Date: 1963 1963 Pavement Thickness:Pavement Thickness: 8 inches 8 inches Pavement Design:Pavement Design: 20 years, 7 million ESALs 20 years, 7 million ESALs



00

1010

2020

3030

4040

5050

19601960 19701970 19801980 19901990 20002000

Tota

l ESA

Ls (m

illio

ns)

Tota

l ESA

Ls (m

illio

ns)

Design:7 million ESALs

1963-1996 Data


18,000 lbs per axle8,000 lbs

Equivalent Single Axle Equivalent Single Axle Loads Loads (ESALs)(ESALs)

VehicleVehicle

Auto, Van, Pickup Auto, Van, Pickup

Single Units 2-axleSingle Units 2-axle

Panel Trucks Panel Trucks

Semi-tractor Trailer 3-axle Semi-tractor Trailer 3-axle

Semi-tractor Trailer 4-axleSemi-tractor Trailer 4-axle

BusesBuses

Semi-tractor Trailer 5-axleSemi-tractor Trailer 5-axle

Equivalent Single Axle Equivalent Single Axle Loads Loads (ESALs)(ESALs)

Rigid ESALs0.0040.004

0.320.321.11.1

2.02.0

2.62.6

2.72.7

3.83.8

Equivalent DamageEquivalent Damage

One 18-wheelerOne 18-wheeler 9,600 cars9,600 cars

Weight Matters!Weight Matters!

80,000 lbs. 2,000 lbs.

Maximum Truck WeightsMaximum Truck Weights

Weight Weight Limit (lbs)Limit (lbs) 58,42058,420

73,28073,280

80,00080,000

19561956 19751975

Future?Future?

CurrentCurrent

Traffic GrowthTraffic Growth

TrafficTraffic

TimeTime

Past Traffic Past Traffic PredictionPrediction

ModelsModels

Current Traffic Current Traffic PredictionPrediction

ModelsModels

Increased Pavement Increased Pavement DamageDamage

PavementPavementDamageDamage

Traffic Traffic

Damage Due to Damage Due to Past TrafficPast Traffic

Damage Due to Damage Due to Current TrafficCurrent Traffic(Increased Truck Weight)(Increased Truck Weight)44


00

1010

2020

3030

4040

5050

19601960 19701970 19801980 19901990 20002000

Tota

l ESA

Ls (m

illio

ns)

Tota

l ESA

Ls (m

illio

ns)

Design:7 million ESALs

Actual:38 million ESALs

From actual traffic counts, more than 5 times the expected life!

1963-1996 Data


Dallas:Dallas: IH 635 was built in mid-late 1960s, 8 inch IH 635 was built in mid-late 1960s, 8 inch CRCP, still in service today.CRCP, still in service today.

Dallas:Dallas: IH 45 southbound was built in late 1960s, IH 45 southbound was built in late 1960s, 15 miles of 8 inch CRCP, still in service today.15 miles of 8 inch CRCP, still in service today.

Dallas:Dallas: North Central Expressway, built in late North Central Expressway, built in late 1940s and early 1950s, in service until recent 1940s and early 1950s, in service until recent reconstruction in late 1990s.reconstruction in late 1990s.

Long Term Concrete Long Term Concrete Pavements: Pavements:

Other Texas ExamplesOther Texas Examples

City of Fort Worth City of Fort Worth Street Paving Street Paving

Low Cost Concrete Low Cost Concrete PavementPavementA Case StudyA Case Study

City of Fort Worth-1980City of Fort Worth-1980 Failing infrastructureFailing infrastructure Most of the streets were asphalt, Maintenance and Most of the streets were asphalt, Maintenance and

reconstruction dollars shrinkingreconstruction dollars shrinking Vehicle weights and frequencies were climbingVehicle weights and frequencies were climbing Asphalt section (2” mat on 6” stone base) caused Asphalt section (2” mat on 6” stone base) caused

soaring maintenance costssoaring maintenance costs

1985 1990

CURRENT PRO

1995 2000 2005

20

40

60

80

100

1985 1990 1995 2000 2005

20

40

80

60

100

City of Fort WorthCity of Fort Worth

Streets had reached a point past economical Streets had reached a point past economical maintenance and had to be rebuiltmaintenance and had to be rebuilt

Things began to change in the 1980sThings began to change in the 1980s First look on bids for Meadowbrook Road, project First look on bids for Meadowbrook Road, project

awarded to concrete despite 12% premiumawarded to concrete despite 12% premium Ederville Road alternate bid followed with a first–Ederville Road alternate bid followed with a first–

time economic analysistime economic analysis

Economic analysis procedure that compares competing alternatives over their expected life by considering all significant initial and future costs (and benefits)

Discounts all future costs and benefits to present value

Life Cycle Cost AnalysisLife Cycle Cost Analysis

Agency Costs:Agency Costs:Initial cost of pavement(s)Initial cost of pavement(s)Maintenance and operation costsMaintenance and operation costsAnticipated future rehabilitation costsAnticipated future rehabilitation costs

EngineeringEngineeringConstructionConstruction

Salvage (recycling value)Salvage (recycling value)

Life Cycle Cost AnalysisLife Cycle Cost Analysis

Ederville RoadEderville Road 8000 vehicles per day, 2.5 % trucks (45 % trucks in the design lane) 8000 vehicles per day, 2.5 % trucks (45 % trucks in the design lane) CBR = 10 (“k” value 200 pci)CBR = 10 (“k” value 200 pci) Traffic growth: 5% per yearTraffic growth: 5% per year

7” AC Pavement7” AC Pavement


Concrete SectionConcrete Section(Est Life = 35 years)(Est Life = 35 years)

Asphalt SectionAsphalt Section(Est Life = 18.7 years)(Est Life = 18.7 years)

Low Cost Concrete Low Cost Concrete PavementPavementA Case StudyA Case Study


6” PCC Pavement

Designed using Asphalt Institute MS-1 ManualDesigned using Asphalt Institute MS-1 ManualDesigned using PCA Procedure (IS 184)Designed using PCA Procedure (IS 184)

Life-Cycle Cost Life-Cycle Cost AnalysisAnalysis

Concrete5 10 15 20 25 30 35 40

Asphalt5 10 15 20 25 30 35 40

Ed

ervi

lle R

oa

d A

ss

um

pti

on

s

Chip or slurry seal

Chip or slurry seal

1.5 in.Overlay

Chip Seal

1 in.Overlay

AssumptionsAssumptions

CrackSealing

CrackSealing

CrackSealing

CrackSealing

CrackSealing

Ederville RoadEderville Road

BidsBids Concrete: Concrete: $1,178,996$1,178,996 Asphalt: Asphalt: $1,096,655$1,096,655 Difference:Difference: $ 82,341 $ 82,341

First cost differential now just $82,341 (7%) as compared with First cost differential now just $82,341 (7%) as compared with Meadowbrook Road @ 14%Meadowbrook Road @ 14%

The economic analysis showed concrete cost $60,574 The economic analysis showed concrete cost $60,574 less for the city to ownless for the city to own Staff recommended award to concrete to CouncilStaff recommended award to concrete to Council Project went AsphaltProject went Asphalt

Fort Worth Economic Fort Worth Economic Analysis Analysis AssumptionsAssumptions

First Cost Analysis Based on 2,000 lf. of Street First Cost Analysis Based on 2,000 lf. of Street 15% Engineering Costs15% Engineering Costs Asphalt Pavement Design LifeAsphalt Pavement Design Life

Light Residential / Residential (28 ft. & 30 ft. Widths) – 24 YearsLight Residential / Residential (28 ft. & 30 ft. Widths) – 24 Years Collectors / Arterials (36 ft. & 40 ft. Widths) – 18 YearsCollectors / Arterials (36 ft. & 40 ft. Widths) – 18 Years

Concrete Pavement Design LifeConcrete Pavement Design Life Light Residential / Residential (28 ft. & 30 ft. Widths) – 45 YearsLight Residential / Residential (28 ft. & 30 ft. Widths) – 45 Years Collectors / Arterials (36 ft. & 40 ft. Widths) – 35 YearsCollectors / Arterials (36 ft. & 40 ft. Widths) – 35 Years

MAINTENANCE COSTSMAINTENANCE COSTS(all based on 1984 prices)(all based on 1984 prices)

ConcreteConcrete Joint Sealing $1.00/SYJoint Sealing $1.00/SY

AsphaltAsphalt Seal CoatSeal Coat

$0.57/SY$0.57/SY 2 in. Overlay2 in. Overlay

$3.00/SY$3.00/SY Crack SealingCrack Sealing

$1.39/SY$1.39/SY

Fort Worth Economic Fort Worth Economic AnalysisAnalysis

Concrete

Asphalt

Cit

y o

f F

ort

Wo

rth

2 in.Overlay

Light Residential and Residential AssumptionsLight Residential and Residential Assumptions28 ft. & 30 ft. Widths. Analysis Period = 45 yrs.28 ft. & 30 ft. Widths. Analysis Period = 45 yrs.

JointSealing

Reconstruct

5 10 15 20 25 30 35 4540

5 10 15 20 25 30 35 4540

2 in.Overlay

Crack Seal&Seal Coat

Reconstruct(yr 48)

Reconstruct 2 in.Overlay





ASPHALT PAVEMENT ASPHALT PAVEMENT COSTSCOSTS

(28 feet wide)(28 feet wide)YearYear OperationOperation CostCost Cumulative CostCumulative Cost

00 ConstructionConstruction $127,122$127,122 $127,122$127,122

88 Crack Seal & Seal CoatCrack Seal & Seal Coat 10,00010,000 137,122137,122

1414 2” Overlay2” Overlay 16,66716,667 153,789153,789


2424 ReconstructReconstruct 127,122127,122 292,411292,411


3838 2” Overlay2” Overlay 16,66716,667 319,078319,078


4848 ReconstructReconstruct 127,122127,122 $457,700$457,700

CONCRETE PAVEMENT CONCRETE PAVEMENT COSTSCOSTS

(28 feet wide)(28 feet wide)

YearYear OperationOperation CostCost Cumulative CostCumulative Cost

00 ConstructionConstruction $153,378$153,378 153,378153,378

1515 Joint SealJoint Seal 5,5555,555 158,933158,933

3030 2” Overlay2” Overlay 16,66716,667 175,600175,600



ASPHALT PAVEMENT ASPHALT PAVEMENT COSTSCOSTS


00 ConstructionConstruction $133,387$133,387 $133,387$133,387


1414 2” Overlay2” Overlay 18,00018,000 162,187162,187




3838 2” Overlay2” Overlay 18,00018,000 336,794336,794







3030 2” Overlay2” Overlay 18,00018,000 179,275179,275



Life-Cycle Cost Life-Cycle Cost AnalysisAnalysis

Concrete5 10 15 20 25 30 35 40

Asphalt5 10 15 20 25 30 35 40

JointSealing

2 in.Overlay

Cit

y o

f F

ort

Wo

rth

Collectors and Arterials AssumptionsCollectors and Arterials Assumptions36 ft. & 40 ft. Widths . Analysis Period = 35 yrs.36 ft. & 40 ft. Widths . Analysis Period = 35 yrs.


Reconstruct

2 in.Overlay


Reconstruct 2 in.Overlay


Reconstruct

ASPHALT PAVEMENT COSTSASPHALT PAVEMENT COSTS(36 feet wide)(36 feet wide)




1212 2” Overlay2” Overlay 22,00022,000 192,964192,964



3030 2” Overlay2” Overlay 22,80022,800 385,928385,928







2020 2” Overlay2” Overlay 22,00022,000 215,663215,663



ASPHALT PAVEMENT COSTSASPHALT PAVEMENT COSTS(40 feet wide)(40 feet wide)

YearYear OperationOperation CostCost Cumulative CostCumulative Cost00 ConstructionConstruction $169,812$169,812 169,812169,812


1212 2” Overlay2” Overlay 24,66724,667 209,279209,279



3030 2” Overlay2” Overlay 24,66724,667 418,558418,558







2020 2” Overlay2” Overlay 24,66724,667 245,644245,644



SummarySummaryPavement/Street Width First Cost Maint. Cost Total CostAsphalt 28’ 48 years $127,122 $330,578 $457,700Concrete 28’ $153,378 $187,100 $340,478

Asphalt 30’ 48 years $133,387 $349,214 $482,601Concrete 30’ $155,275 $190,695 $346,970



+26,146 -143,478 -117,222

+21,888 -158,519 -135,631

+28,566 -155,085 -126,519

+42,943 -155,894 -112,961

Final Pavement Thickness Final Pavement Thickness OptionsOptions (Adopted 1986)(Adopted 1986)

ConcreteConcrete AsphaltAsphaltResidentialResidential 5-in. 5-in. 6-in. 6-in. 28’-30’ wide28’-30’ wide (now 6-in.) (now 6-in.) CollectorCollector 6-in. 6-in. None NoneType A or B, 36’-40’Type A or B, 36’-40’

ArterialsArterials 7-in. 7-in. None None

All pavements on 6” (concrete) or 8” (asphalt) cement or lime All pavements on 6” (concrete) or 8” (asphalt) cement or lime stabilized subgradestabilized subgrade

How Did the How Did the Projects Projects Change?Change?

RESIDENTIAL STREET CONSTRUCTIONRESIDENTIAL STREET CONSTRUCTIONPCC & HMAC 1984-1989PCC & HMAC 1984-1989

11

36

71 69

55

0

20

40

60

80

100

120

1984-85 1985-86 1986-87 1987-88 1988-89

Year

% of Construction

PCC

HMAC

1984-85 228,700 SY

1985-86 234,500 SY

1986-87 371,200 SY

1987-88 218,600 SY

1988-89 129,667 SY

COLLECTOR STREET CONSTRUCTIONCOLLECTOR STREET CONSTRUCTION PCC & HMAC 1983-1989 PCC & HMAC 1983-1989

30

3842

100 100 100

70

6258

0 0 00

20

40

60

80

100

120

1983-84 1984-85 1985-86 1986-87 1987-88 1988-89

Year

% of Construction

PCC

HMAC

1983-84 181,800 SY 1986-87 43,484 SY

1984-85 170,311 SY 1987-88 97,831 SY

1985-86 329,000 SY 1988-89 127,037 SY

RESIDENTIAL & COLLECTOR STREETSRESIDENTIAL & COLLECTOR STREETS1980-19891980-1989

9 9 8

27 2933

76 7479

0

20

40

60

80

100

120

1980-81 1981-82 1982-83 1983-84 1984-85 1985-86 1986-87 1987-88 1988-89

Year

% of Construction

PCC

HMAC

1980-81 375,300 SY 1984-85 399,000 SY

1981-82 247,600 SY 1985-86 563,400 SY

1982-83 320,000 SY 1986-87 469,000 SY

1983-84 522,000 SY 1987-88 262,000 SY

1988-89 247,704 SY

60

70

9194

100 100 100

0

20

40

60

80

100

120

1982-83 1983-84 1984-85 1985-86 1986-87 1987-88 *1988-89

Year

% of Construction 7” & *8”

PCC

HMAC

1982-83 245,500 SY1982-83 245,500 SY 1986-87 373,100 SY 1986-87 373,100 SY

1983-84 261,300 SY1983-84 261,300 SY 1987-88 299,300 SY 1987-88 299,300 SY

1984-85 734,200 SY1984-85 734,200 SY 1988-89 215,218 SY 1988-89 215,218 SY

1985-86 709,000 SY1985-86 709,000 SY

ARTERIAL STREET CONSTRUCTION ARTERIAL STREET CONSTRUCTION 1983-19891983-1989

TOTAL CONSTRUCTION TOTAL CONSTRUCTION 1980-19891980-1989

38

57

31

42

66 67

87 88 89

0

20

40

60

80

100

120

1980-81 1981-82 1982-83 1983-84 1984-85 1985-86 1986-87 1987-88 1988-89

Year

% of Construction

PCC

HMAC

1980-81 685,600 SY 1985-86 1,272,300 SY

1981-82 640,500 SY 1986-87 842,200 SY

1982-83 565,400 SY 1987-88 561,300 SY

1983-84 783,299 SY 1988-89 462,922 SY

1984-85 1,120600 SY

Although concrete pavements usually have Although concrete pavements usually have high initial cost, they will have the lowest high initial cost, they will have the lowest

ultimate cost over the life of the pavement.ultimate cost over the life of the pavement.

Economic Analysis:Economic Analysis:ConclusionsConclusions

Major CitiesMajor Cities

DallasDallasStarted in the 1940s by DPWStarted in the 1940s by DPWAsphalt maintenance issuesAsphalt maintenance issuesHas retained concrete “mind set”Has retained concrete “mind set”

Other cities around Dallas followed the exampleOther cities around Dallas followed the example Concrete preferred because of poor, clay soils and Concrete preferred because of poor, clay soils and

performanceperformance

Major CitiesMajor Cities HoustonHouston

Concrete dates to 1920s & WPA ProgramConcrete dates to 1920s & WPA ProgramConcrete preferred because of poor soils and Concrete preferred because of poor soils and

high water tablehigh water table Asphalt did not perform in adverse soil and Asphalt did not perform in adverse soil and

wet conditionswet conditions


Concrete Pavement can distribute the load Concrete Pavement can distribute the load better than asphalt pavement.better than asphalt pavement.

Concrete Pavement is preferred when soils Concrete Pavement is preferred when soils are poor and traffic volumes are high.are poor and traffic volumes are high.

Concrete Pavement typically has higher Concrete Pavement typically has higher initial cost and lower lifetime cost.initial cost and lower lifetime cost.


Thank You!Thank You!

concrete pavements the right tool for the right job

Documents

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asphalt pavements

asphaltconcrete pavements

right jobdifferences

subgradeconcrete pavements

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longterm pavement

shortterm pavement