Long-Life Concrete Pavements In Long-Life Concrete Pavements In The WorldThe World

Submitted to : Assoc.Prof. Mustafa Submitted to : Assoc.Prof. Mustafa SAHMARAN SAHMARAN

Prepared BY : Prepared BY : Hazhar HayderHazhar Hayder Samadar SalimSamadar Salim

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This Search is about LLCP in these Countries:

CanadaGermanyAustriaBelgiumNetherlandsUnited Kingdom

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The motivation for an international scan of long-life

concrete pavement technology:

1 - Safety

2 - Mitigation of congestion

Aging highway system

Heavier truck loads

High maintenance costs

Congestion

Work Zone Safety

Noise

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BackgroundWhy long life?––Reduce future maintenance and rehabilitation requirements

–– Minimize traffic disruptions

–– Reduce user costs

–– Increase safety (fewer work zones)

–– Reduce life-cycle costs

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Solution 30--60 year service lives Includes minor maintenance and rehabilitation

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LLCP require:

less frequent repair RehabilitationReconstruction

and therefore contribute to

Improving Highway safetyMitigating congestion

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Scope of the scan include the following:

• Materials evaluation and specification procedures for both virgin and recycled materials

• Design methods of long-life concrete pavements

• Construction practices

• Maintenance practices

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Issues of Interest

•Materials (cement, coarse & fine aggregates, admixtures, and supplementary cementations materials)

•Concrete mixture design

•Pavement thickness design (including geometrics, spacing, and location of joints)

•Specifications

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Issues of Interest cont.• Construction procedures

• Maintenance procedures

• Rapid construction and rehabilitation techniques

• Performance of jointed plain JPCP, jointed reinforced JRCP, and continuously reinforced concrete pavements CRCP.

• Life-cycle costs

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Pavement Selection Strategies

Long-life concrete pavements:

In every country , "concrete pavement" is considered synonymous with "long life.“ These countries expect concrete pavements to be strong and durable, provide service lives of 25, 30, or more years before rehabilitation or replacement.

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Technology Changes

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Public and environment: The public is expressing concerns about environmental issues such as noise, congestion and safety.

Environmental issues, especially noise, are becoming major concerns to the driving public.

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Public and environment:

In all these countries , there is a heavy emphasis on traffic safety, noise mitigation, congestion relief, and use of recycled materials.

In UK , political forces have driven the decision to reduce noise, (all highway pavements must have asphaltic surfaces).

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Scan Objectives Identify techniques used in other countries, and Implementable in US, for achieving longer-life concrete pavements

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Pavement type selection factors

1. Life-cycle costs2. Functional class3. Truck traffic levels 4. Initial cost5. Environmental issues

Pavements optimized for a performance period in excess of 40 years,

An extended time to first rehabilitation and minimal interventions for M & R activities.

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Design catalogs used in

Austria, Belgium &Germany

Design lives of 30 years

typically used up to 50 years

service expected

Truck loadings are

heavier than in US,

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Note : Maximum concrete slab thicknesses are a common

feature of the design catalog.1919

Catalog designs (updated regularly) based on :

1.Theoretical & lab studies

2.Field experiments

3.Performance observations

Pavement DesignPavement Design

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Pavement DesignPavement Design In Netherlands & United Kingdom

Mechanistic-empirical design software is used for project-level design works The maximum slab thicknesses appear to be thinner than those designed in US for similar traffic levels and in many cases heavier trucks.

Full-width, full-depth concrete emergency lanes constructed for future capacity needsWidened slabs used to reduce concrete stress and deflection (as in US) and extending pavement life.

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Fewer tie bars used in longitudinal joints (about half the number used in US).

Smaller dowel bars (25 mm diameter) used

JCP and CRCP built to same thickness (as in US)

CRCP used for long life in Belgium - technology adopted from the US

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Sealed and unsealed joints

both perform well

Bases: dense HMA and CTB;

5 mm thick Geotextile used to

separate CTB and PCC in Germany

Foundations are drainable, stable,

protect against frost, and allow

recycling of materials

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Concrete

HMA

Unbound Base

Type 5

Concrete

HMA Layer

CTB

Type 6

Portion of Austria’s design catalog page showing concrete pavement layerthicknesses for different traffic loading levels. Motorways are in the S class.

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1970 -1977 PCC t = 20 cm Steel =

0.85%1977 -1991 PCC t = 20 cm Steel =

0.67%1992 -1995 PCC t = 23 cm Steel =

0.72%Since 1995 PCC t = 23 cm Steel =

0.76%

Catalog DesignsCatalog DesignsEX: Class B1EX: Class B1

Design life Design life 30 years30 years

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Emergency LaneTop lift w/ exposed aggregate

Bottom lift w/ recycled aggregates

10 in.

Concrete (combined graded)HMAC or CTB (with AC/geotextile)

Thick frost protection layerSubgrade

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Lower-alkali cements and blended cements used to mitigate ASR

SCMs typically not considered in mixture proportions

Attention to aggregate quality and gradation … specially for top layer in two-lift construction

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Construction and MaterialsConstruction and Materials

Recycled concrete and recycled asphalt pavement used (or mandated) in lower layer in two-course construction

Some countries use tie bars coated only in middle third

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Construction and MaterialsConstruction and Materials Coated dowel bars used

Intelligent compaction control used in Austria

Small-plate proof testing of granular layers used in some countries

Roughness measured with four-meter straightedge; excellent smoothness achieved

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ConcreteConcrete Freeze-thaw resistant Flexural strength (28-

days)Bottom lift 800 psi Top lift 1,000 psi

Compressive strength (28days)Bottom lift 5,000 psiTop lift 6,000 psi

Well graded aggregates – 4 bins

Two plants Bottom lift concreteTop lift concrete

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Max. agg. size typically used in Europe is (20 mm).

Aggregates

In Netherlands, where primarily single-lift construction is done, (32 mm) is the maximum aggregate size.

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Aggregate BinsAggregate Bins

16 to 32 mm 8 to 16 mm 4 to 8 mm 0 to 4 mm

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Interlayer's

In Germany: using (5mm-thick) Geotextile interlayer as a bond breaker between concrete pavement and cement-treated base is a recent requirement.

German engineers indicated that the mortar is presumed to saturate the Geotextile during construction, adding just enough stiffness to provide support while still acting as a bond breaker.

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Geotextile Interlayer's

The required concrete thickness for cement-treated base alternative was increased from (26 - 27 cm) when the design was changed from one with a bonded base to one with a base separated from the slab by a Geotextile.

In the other countries , the typical interlayer between a concrete slab and a cement-treated base is a layer of hot-mix asphalt concrete.

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Recycled materials (including concrete and masonry from demolition) have been used in the base layers in various countries.

Austria requires the use of Recycled Concrete and Recycled Asphalt Pavement (RAP) in the lower layer of two-course concrete (and for base). Recycled asphalt is allowed up to a maximum of 30 % of the coarse aggregate in these mixtures.

Recycling

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Recycling Concept for ConcreteRecycling Concept for Concrete

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Compaction control

In Austria : Intelligent compaction control is used.

The European countries are strict about control of compaction of all layers.

In some countries load testing of granular layers to check compaction is conducted with a small plate.

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350 kg/m3 = 590 lb/cy

400 kg/m3 = 674 lb/cy , 450 kg/m3 = 758 lb/cy

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Top Lift Concrete Placement Fresh to fresh on bottom lift concrete

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Placing of the top lift concrete

Tie-bar placed by hand (right behind first paver)

Dowels - placed automatically

Densely compacted bottom lift – No sinkage

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Two-lift paving

Two-lift construction is the placement of two wet-on-wet layers or bonding wet to dry layers of concrete, instead of the homogenous single layer commonly placed in concrete paving. 

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The bottom layer ( thick & lower quality) (lower durability or strength), locally available aggregate or recycled aggregate (such as recycled asphalt, concrete rubble, or local aggregate). The top layer (thin & consists of high-quality aggregate designed to provide better resistance to freeze-thaw damage, reduced noise, or improved friction.

The high-quality surface also increases friction and reduces noise.

Goals of Two-Lift Paving

•Improved Surface Durability

•Improved Safety (friction)

•Reduced Tire/Pavement Noise

•Improved Environment by Recycling

•Improved Pavement Performance

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Low-noise exposed aggregate surfacing: The solution to concrete pavement noise popular in some European countries is exposed aggregate surfacing, in which exceptionally high-quality, durable aggregates are used in the top course of the concrete slab, and a process of set retardation and abrasion is used to produce an exposed aggregate surface with good low-noise properties. Exposed aggregate is also touted as yielding other benefits, including good friction and durability. However, favorable noise levels may also be achieved by specific pavement texturing techniques.

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Exposed Aggregate Surface

Step 1 - Curing compound + retarder - water-repellent coefficient > 90 % (first 24 h)

Step 2 - Curing compound (applied after brushing)

- water-repellent coefficient > 85 %

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Minimal Minimal surface surface finishing - finishing - longitudinal longitudinal smoothersmoother

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BrushinBrushing g

MachineMachine

Exposed aggregate surface 8 or 11 mm max size

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Cement and concrete testing. Workability is evaluated using a compaction test, similar to the ASTM Vibe test.

Ontario and Austria check the air content in hardened concrete.

In the European countries : alkali-silica reaction (ASR) is controlled, if detected by preconstruction testing, using blended cements or cements with low alkali content.

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Pavement testing

Countries do not perform quality control testing for noise. Texture measurements are made, both for end-product and pavement management system-based data collection.

Only in Germany and Canada MIT-SCAN equipment used for detecting dowel bar misalignment for both quality control and quality assurance purposes.

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Pavement testing

In EU countries A 4-m straightedge is typically used to measure roughness . Belgium also uses APL (length profile analyzer) to measure pavement profile. The smoothness of pavements was excellent in all countries .

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MaintenanceMaintenance Typically, very little maintenance done on

concrete pavements

Little if any joint resealing done

One widely used maintenance technique is a thin asphalt overlay to correct rutting caused by studded tires or to mitigate tire-pavement noise.

Ontario is field-testing precast slab techniques (similar to US) for rapid repair

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MaintenanceMaintenanceOnly in Canada is

diamond grinding used to improve smoothness on bare concrete pavements (Diamond grind whole surface and perform full-depth repairs on 1.5% of surface area at 25 years)

In UK, concrete pavements overlaid with asphalt to reduce noise.

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Precast slabs for rapid repair

Canada is evaluating the use of U.S developed precast concrete technology for rapid repair.

Also panels were used for individual slab & multi slab replacement.

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Overall HighlightsOverall Highlights Standard designs

Frost-free foundation & good base (HMAC/CTB)

Standard materialsHigher strength concrete than in USBlended cements more common, less SCMsUp to 4 bins for concrete aggregateExposed aggregate surface – lower noise

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Overall HighlightsOverall Highlights Good construction practices

Good ride, even though no ride specs

They use straight-edge testingLow paste surface (only 1 to 2 mm –

brushed off)Joint sawing with very little raveling

Very careful approach to introducing new features/techniques

Design, materials and construction features need to be well integrated

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