A Sustainable Solution

CONCRETE ROADS

BACKGROUND

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East Africa has a history of relatively poor roads infrastructure : Poor road conditions Road congestion Transport economic challenges

Superficially, East Africa appears to be doing well. Annual economic growth rates are averaging around 6%, and trade and foreign investment are rising. This economic growth isnt matched infrastructure development.

This is evident in the deterioration of both urban and rural roads

Better road networks will lead to

Increased economic activity Linking economic trade between countries Better efficiencies

Governments across the region are investing in expanded roads infrastructure program to address the current backlog and shortage

Current road building method have significant challenges:

High cost of bitumen Roads constructed have short lifespan High cost of maintenance

BACKGROUND CONTD

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Governments / Road Agencies should consider Concrete paved roads

Concrete roads will offer: Availability of materials (All materials will be proudly East African) Low cost of maintenance (Virtually no costs in the first 25 years) Road drivability Environmentally sustainable

Usage of concrete roads will help curb unemployment through job creation at construction phase

Opportunity is Knocking

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The Shift

ASPHALT

CONCRETE

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OVERVIEW

History of paved roads

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First record of stone paving 4000 BC By 2000 BC pavement paving started.

377 Km Appian Way, built in 312 BC, still carries traffic between Rome and Italys South-Eastern Port of Brindisi Concrete pavers first manufactured in Netherlands 1924

Widely used since

Concrete roads Global experience

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Concrete roads have been in existence for the past 100 years

Oldest roads in USA & Australia - still exist even today with little maintenance required.

Concrete roads have an excellent track record as a cost effective investment.

Rigid concrete roads outperform asphalt roads with economic and safety benefits and has less impact on the environment.

Concrete roads are visible in Sub-Sahara South Africa Kenya Zambia

Statistics on pavement elements

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Paved roads present the world over

Use of paved roads worldwide {in millions of square meters per annum}

Economic activity

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More Paved Roadways = STRONGER ECONOMY

Kenya

South Africa

CONCRETE ROADS BENEFITS VS. ASPHALT

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Concrete pavement spreads the load

Performance and Durability Aspects

Concrete is rigid Loads are distributed over relatively large areas Stresses on the subgrade/subbase are relatively low Thus, concrete pavements do not necessarily

require exceptionally strong foundation support

UNIFORMITY >> STRENGTH

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Concrete is always rigid Asphalt stiffness changes with the temperature At hot temperature asphalt becomes very soft. It may even be weaker

than the unbound aggregate layer underneath it Creep of asphalt layers High stresses transmitted to granular layers leading to structural rutting

Performance and Durability Aspects Concrete pavement is more Durable

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Performance and Durability Aspects Concrete pavement is more Safer

A study by the University of Illinois entitled, Safety Considerations of Rutting and Washboarding Asphalt Road Surfaces demonstrates that overall stopping distances on concrete surfaces are shorter than for asphalt surfaces, especially when asphalt is wet and rutted

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Aspect Concrete Pavement Asphalt Pavement Riding comfort index Results of the study concluded in 1999,

showed that asphalt ride quality falls below concrete after a very short period of road life

Profile ride index (smoothness)

Results of the study indicate that the concrete pavement maintained much of its original smoothness, while the asphalt section showed increased deterioration

Quiet ride In a five year study the concrete pavements roadside noise level was on average 2-4 decibels higher than the asphalt pavement. To put this into perspective, normal conversation registers at 60 to 70 decibels and a human whisper registers at 20 decibels

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Performance and Durability Aspects Concrete pavement is more User Friendly

Source: (Leif Wathne, P.E., ACPA.) Introduction to Concrete Pavements (Part II)

Economic Aspects Concrete pavement Lasts Longer

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Pavement types perform differently over time.

Equivalent designs are not always achievable.

LCCA compares the total discounted cost of each design over a specific analysis period to minimize the financial burden of the roadway on taxpayers.

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Economic Aspects Concrete pavement costs less

City of Milwaukee LCCA Example

Concrete vs Asphalt bids

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Initial Costs Milwaukee Area Costs

Concrete pavement bid prices from City of Milwaukee projects in the WisDOT letting.

Hot Mix Asphalt (HMA) bid prices from recent City of Milwaukee projects

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Life Cycle Cost Analysis Present Worth Worksheet

Project: City of Milwaukee - Reconstruct Analysis Period: 60 Years Discount Rate: 3%

Roadway Scenario: Length = 2000 LF Pavement Width = 32 LF Roadway SY = 7111 SY Excavation Width = 41 LF 4.5-Inch HMA = 1840 Ton

Concrete Alternative #1: PCC Pavement Design 7-Inch Concrete over Existing

Concrete Alternative #2: PCC Pavement Design 7-Inch Concrete over 3-Inch CABC

HMA Alternative #1: Asphalt Pavement Design 4.5-Inch HMA over 6-Inch CABC

HMA Alternative #2: Asphalt Pavement Design 5.5-Inch HMA over 8-Inch CABC

Present Worth Costs:

Concrete Alternative #1 Concrete Alternative #2 HMA Alternative #1 HMA Alternative #2

7-Inch Concrete over Existing 7-Inch Concrete over 3-Inch CABC 4.5-Inch HMA over 6-Inch CABC 5.5-Inch HMA over 8-Inch CABC Initial Pavement Costs $127,856 $155,656 $139,923 $181,938 Maintenance Costs $938 $938 $3,917 $3,917 Rehabilitation Costs $2,015 $2,015 $73,797 $73,797 Reconstruction Costs $0 $0 $0 $0 Operation Costs *** *** *** *** User Costs *** *** *** *** Agency Costs *** *** *** *** Remaining Service Life $0 $0 $0 $0 Total Facility Present Worth Cost $130,808 $158,608 $217,637 $259,652 Present Worth LF Roadway Cost $65 $79 $109 $130

100% 121% 166% 198%

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Life Cycle Costs could be lowered 45 -98 percent utilizing concrete pavements!!!!

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City of Milwaukee conclusion:

Ghassan Khorban, Commissioner of Public Works

Concrete, thanks to its

natural light color,

reflects much more and

absorbs less heat than

asphalt.

Using concrete

pavements contribute

to reduce Heat island

effects in urban areas.

Concrete reflects the light

while asphalt absorbs it.

Using concrete

pavements permits to

reduce light energy

consumption and the cost

of lightning equipment by

almost 30%.

Environmental Aspects Concrete pavement Reflects Light

Source: http://www.pavements4life.com/QDs/Environment_1HeatIsland.asp 22

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APPLICATIONS - CONCRETE ROADS

Types of Concrete Roads

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Depending on the level of reinforcement, the rigid pavements can be categorized into three basic types:

Jointed unreinforced concrete pavements (JUCP) Jointed reinforced concrete pavements (JRCP) Continuously reinforced concrete pavements (CRCP)

There are two common concrete surface finishes;

Transverse Textured Concrete Surface (TTCS) Exposed Aggregate Concrete Surface (EACS) formerly known as whisper concrete.

Exposed Aggregate Concrete Surface

Transverse Textured Concrete Surface

Concrete roads application

Complete Concrete Road

Appropriate pavement for heavily trafficked roads

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Composite Roads Combining Asphalt and Concrete Areas subjected to heavy loading and common to

start-stop traffic. Applies to new roads and road repairs alike

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Intersections/ Traffic Circles Climbing/ Slow Lanes

Overlays Inlays

Concrete roads application

PROS AND CONS CONCRETE VS ASPHALT - SUMMARISED

Concrete Asphalt

Pros Cons Pros Cons Quick construction

Sustainable construction

Reduced lighting costs.

Lower whole-life cost

Easy maintenance

Heavy truck fuel saving

Re-usable & recyclable

A quiet ride (EACS)

Use local materials

Can employ labour based construction

Possibility of cracking

Initial construction costs might be high

Technically challenging

Lower initial construction cost

Easy to install

Availability of expertise

Need to seal every 3-5 years

Development of potholes.

Rutting

Higher whole-life cost

Deteriorates quickly

Environmentally unfriendly

Shortage of materials

Involves importation of binder material

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Concrete Can Cost Less Initially!!

Since 2008, concrete pavement has had a lower INITIAL cost than comparably designed asphalt pavement in many areas of the US

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The Initial Cost Myth

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