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3.6 Other Countries (Spain, Portugal,Switzerland, Italy)

Due to travel and time constraints theUS TECH Study Tour could not visitall of the countries in Europe that arebuilding concrete pavements. Thecountries of Spain, Portugal,Switzerland and Italy, among others,have built concrete pavements tovarying degrees. A representativefrom each of these countries graciouslyagreed to make a presentation to theStudy Tour in Dusseldorf, Germany.In addition, a representative ofCEMBUREAU, a cement industryassociation which represents 19countries, gave a presentation on theuse of cement and concrete pavementsin Europe. A summary of only the keypoints of their brief presentationsfollows.

l Spain

Early Concrete Pavements. The firstconcrete pavement in Spain was builtin 1915. A few concrete pavementswere built thereafter until the 1960’swhen a few dowelled JPCP pavementswere constructed. The first was asection of dowelled JPCP near Madridin 1963 having a 25-cm (9.8 in) slabthickness, a sand base and 5 and 6 m(16.4 and 19.7 ft) joint spacing. Thispavement gave good performance formany years until it was widened andoverlaid in 1981. (1)

In 1968 the first freeway JPCP wasconstructed near the 1963 project withdoweled joints spaced at 6 m (19.7 ft),a 25-cm (9.8 in) slab thickness, a 15-cm(5.9-in) CTB and a 10-cm (3.9-in) sandcement subbase. The shoulders wereAC. All joints were sealed with

neoprene compression seals. Thetraffic level is now about 5000 trucksper day in each direction and the ADTis 80,000. This section is still in goodcondition, having carried over 30million trucks in each direction with nosignificant structural distress.

California JPCP Design. In 1971,extensive construction began usingslipform pavers and the “California”JPCP undowelled pavement wasadopted by the toll roads. Over 700km (440 miles) of two-lane one-direction freeways of this pavementhad been constructed up to 1985,mostly by toll roads. These pavementswere generally 25 cm (9.8 in) thick, hadskewed joints, and 15 cm (5.9 in) ofCTB. A nonplastic granular materialwas placed under this layer in areas ofpoor subgrade. No subdrainage pipeswere placed. AC shoulders had agranular base. Heavy traffic on thesepavements resulted in pumping andfaulting, followed by cracking whichhas caused considerable roughness.

Design modifications made in the late1970’s included thicker slabs,trapezoidal sections (24 to 28 cm (9.4 to11.0 in)), reduction of joint spacing (3.7-4.6-4.0-4.3 m (12.1-15.1-13.1-14.1 ft)),lean concrete base, cement-stabilizedgranular base for the AC shoulder, andslotted longitudinal pipe forsubdrainage. This pavement designhas performed well and faulting is notsignificant.

Current Design Catalog. For heavytruck highways (800 trucks per day inthe design lane), due to the availabilityof automatic dowel inserters, and toprovide more reliability againstfaulting, the conclusion has been

i

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reached that dowels must be used.This is now standard practice in Spain.Contractors are now equipped withautomatic dowel insertion equipment.The cross-section is trapezoidal and thethickness depends on the truck trafficand subgrade support. A designcatalog is available that specifies thefollowing slab thicknesses:

First Year TrapezoidalTrucks per lane Slabper day Thickness

> 2,000 26-30 cm(10.2118 in)

< 2,000 23-27 cm(9.1-10.6 in)

A 15-cm (6in) base, usually leanconcrete, is specified for either case. Ifthe subgrade CBR exceeds 20 percentno granular subbase is required. If thesubgrade CBR is between 10 and 20percent, a 20-cm (7.9 in) granularsubbase layer is required. If thesubgrade CBR is less than 10 percentthe soil is unacceptable and must bereplaced. (1)

Dowels (2.5cm (l-in) diameter) in aplastic tube are clustered in each wheelpath (18 dowels spaced over two trafficlanes with six dowels in the outerwheel path spaced every 30 cm (11.8in)). Transverse joint spacing is 5 m(16.4 ft), perpendicular to thecenterline, and sealed in wet areas butnot sealed in dry areas. Longitudinaljoints are sealed in all pavements andinclude tie bars. (1)

Concrete for Slab and Base. Concretecontaining crushed limestone as thecoarse aggregate has proven to yieldlow shrinkage and good flexuralstrength, and facilitates joint sawing.The requirement that at least 30percent of the fine aggregate becomposed of siliceous particles hasresulted in pavements without frictionproblems associated with texture wear.Concrete must attain a flexural strengthat 28 days of 4.5 MPa (640 psi) in third-point loading. Lower-strength concretecan be used but the slab thicknessmust be increased. Blended cementscontaining flyash are used in theconcrete (38 percent) and lean concretebase (50 percent). A large costreduction was obtained by thegovernment for these blended cements.The water/cement ratio is between 0.44and 0.50, slump is between 2 and 4 cm(0.8 and 1.6 in), and plasticizers areused in drier mixes.

The lean concrete or cement-treatedbases must have a minimumcompressive strength of 8 MPa (1143psi) at seven days; or alternatively notless than 12 MPa (1714 psi) at 90 daysfor slower-strength-gaining mixtures.To prevent reflection cracks from thebase to the slab, a plastic sheet is laidon top of the base.

Curing Compounds. The hightemperatures and low relativehumidity in Spain have made itnecessary to use high-quality curingcompounds based on organic resinsolutions.

Joint Sawing. The extremetemperature gradients prevalent duringconstruction produce high curlingstresses. It is necessary to saw the

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longitudinal joint at the same time asthe transverse ones instead of delayingits cutting which is the usual practice.All of the joints need to be cut thesame day the concrete is placed.

More than 800 km (500 miles) of two-lane, on-direction freeways have beenconstructed with this general design.These pavements are performing verywell in Spain.

CRCP Design. CRCP was constructedon one long section in northern Spainin 1975. This section has carried veryheavy traffic (ADTT exceeding 5,000).Two traffic lanes are 7.5 m (24.6 ft)wide, 22 cm (8.7 in) thick, with a 16-cm(6.3-in) CTB, and a 22-cm (8.7-in)granular subbase. The amount ofreinforcement was 0.85 percent. Onetest section had 0.73 percent with nochange in the pattern of cracking. Thesteel was placed on chairs. Theperformance of the CRCP has beenexcellent and has required very littlemaintenance work Recently, otherCRC pavements have been constructed.The design catalog allows a thicknessreduction of 4 cm (1.6 in) fromJPCP. ( 1 )

Surface Texture. Many surfacetexturing techniques have been used inSpain, ranging from burlap to tining.Longitudinal texturing produced by acombination of brush and combachieves both a microtexture (with thebrush) and a macrotexture (with thecomb), whose initial grooves are about1.5 mm (0.06 in) deep. However, inthe latest construction project a lessrough texture is sought: 0.7 to 1 mm(0.03 to 0.04 in). Measurements offriction and rolling noise taken after

several years of operationdemonstrated that these procedureshave given excellent results. (1)

Roller-Compacted Concrete. Thismaterial is defined as a homogenousmixture of aggregate, water andcement which is laid in similar fashionto CTB, although its cement content issimilar to that of regular concretepavements. Over 4 million squaremeters (4.78 million square yards) ofroller-compacted concrete pavementhave been constructed in Spain since1970 on low- and high-volume roads,widening, and overlays.

Roller-compacted concrete requires nospecialized equipment and enables theroad to be immediately opened totraffic after compaction. This isparticularly beneficial for overlays.Surface unevenness problems requirean 8- to 10-cm (3.1- to 3.9-in) ACoverlay for higher-speed pavements.The RCC ranges from 22 to 25 cm (8.7to 9.8 in) and the soil cement base is 20cm (7.9 in) thick Lighter roads requirethinner layers.

Joints are now provided at 7- to 10-m(23- to 33-ft) intervals to try to reducereflection cracking through the AClayer. One section recently constructednear Madrid had a joint spacing of 2.5to 3.5 m (8.2 to 11.5 ft). After twoyears and over 1 million trucks, only0.5 percent of the cracks have reflectedthrough. (1)

Traffic. Truck traffic in Spain onfreeways ranges from 1000 to over 5000ADTT in one direction. The legal axleload limit in Spain is among thehighest in the world: 13 t (28,600pounds) for a single axle and 21 t

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(46,300 pounds) for a tandem axle. Themost recent weigh-in-motion data haveshown 4 percent of axles above thelegal limit, with some loadings of 20 t(44,000 pounds) on a single axle and30 t (66,000 pounds) on tandem axles.

Spain Reference

1. Jofre, C., “Spanish Practice andExperience With ConcretePavements,” paper presented tothe US TECH Study Tour inJune, 1992.

l Portugal

Concrete pavements were constructedin Portugal during three time periods:

J 1935-1945, when 70 km (43 miles) ofheavily trafficked routes wereconstructed with concrete. These areare all still in service.

J 1945-1965, when some concretepavements were constructed onmilitary bases. In 1965 the firstprestressed pavement in the world wasconstructed at Beja NATO airfield.

J 1965 on, when construction of thenational network of highways began.Because of increased axle loads andincreased traffic, concrete pavementsare very competitive with asphaltpavements. The design life used inPortugal is 30 to 40 years. From 1986to 1992 about 130 km (80 miles) ofconcrete pavements (mostly JPCP)were constructed. This was 10 percentof the total highway mileageconstructed, and included the firstJRCP and CRCP. Concrete pavingblocks are also used in Portugal.

It is expected that about 20 percent ofthe major highways will be constructedof concrete.

The current JPCP design used inPortugal is a 23-cm (9.1 in) slab with 15cm (5.9 in) of CTB. The current JRCPdesign is a 20-cm (7.9 in) slab and a 15cm (5.9-in) CTB. The longitudinalreinforcement is 0.06 percent area.

’ Italy

The past (that brought about thepresent): Ancient Rome was the centerof an extensive 80,000 km (50,000 mi)network of roads that crossed manycountries. The first link to the southwas the ancient Via Appia (or AppianWay) that radiates out from the centerof Rome. Construction of the ViaAppia began in 312 B.C., and it is stillbeing used today after 2,000 years, asshown in Figure 3.20. The Via Appiahas been called the “most famous roadever built in any age or any clime.“(3)

“The prestige of the Via Appia hascontinued to grow with eachsucceeding century because of theexcellence and durability of itsconstruction.” (3)

Grooves from ancient wheels wereobserved on some of the stones. Theoriginal surfacing layers are gone, andthe existing surfacing consists of fairlylarge stones imbedded in thefoundation. This pavement is up to10.7 m (35 ft) wide with curbs on bothsides.

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Figure 3.20 Via Appia Roman road, built 312 B.C., south of Rome (note that the truckis parked off the main road).

“In the most advanced stage of itsimprovement, Via Appia was built byfirst excavating a trench in the naturalsoil down to a solid foundation. Theearth was tamped with beetles andcovered with a light bedding of sandor mortar upon which were laid fourmain courses:

(1) The ‘statumen’ layer of large, flatstones 25 to 60 cm (10 to 24 in) inthickness;

(2) Next the ‘rudus’ course of smallerstones mixed with lime, some 23 cm (9in) thick;

(3) The ‘nucleus’ layer, about 30 cm (12in) thick, consisting of small gravel andcoarse sand mixed with hot lime; and

(4) On this fresh mortar was placed the‘summa crusta,’ or wearing surface, offlint-like lava, about 15 cm (6 in) deep.

The total thickness of the four coursesdescribed above varied from 0.9 to1.5 m (3 to 5 ft). The massive solidityof this thick roman cross-section wasstandard practice for more than 2,000years until superseded by Macadam’slight wearing surface in the nineteenthcentury.” (3)

Although these roads were builtprimarily for military purposes, it ishard to imagine the long-term thinkingthat went into building such incrediblythick and durable pavements to carrythe traffic that existed at the time.

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Some interesting axle weights:

J Maximum Roman axle load for slowfreight wagons: 0.7 t (1,436 pounds) (3)

J Recommended wagon axle load byTelford in 1819 (England):!’ 1.8 t (4,000pounds) (3)

J Current legal axle load in USA 9.1 t(20,000 pounds)

J Current legal axle load in someEuropean countries: 13 t (28,652pounds)

One historian stated that “As early asthe eulogy of Appius Claudius thebuilding of the Via Appia was put onthe same plane as military victories orpolitical deeds.” Another historianstated, “The Roman engineers had aclear idea of the true value of the roadand of false economy in materials andlabor, and their technique has not beenexcelled until quite recent years.”

These ancient Roman roads that werebuilt over many parts of Europe musthave had an influence on modern dayEuropeans as to the value of making asubstantial investment in a qualityhighway infrastructure that willprovide service for long time periodswithout disruption.

The present: JPCP without dowelsand JRCP were built in Italy from 1950to 1975. One heavily trafficked JRCPwas observed in Rome by a Study Tourmember, a four-lane highway (themodern Via Appia) constructed in 1950(42 years old). The pavement has a 20-cm (7.9-in) thick slab, 12 m (39 ft) jointspacing, and was observed to be in faircondition with joint spalling and some

deteriorated transverse cracks. Somejoints had been repaired with concrete.The concrete is very dark because itcontains a dark igneous rockExpansion joints had been cut in thepavement which allowed nearby cracksand joints to open up and deteriorate.

Traffic. On Italian highways, trucksare typically 25 to 30 percent of ADT.Axle load distributions from the weigh-in-motion scale on the Al freeway nearRome for singles and tandems aregiven in Figure 3.21. The measuredmaximum single axle load is 14 t(30,900 pounds), the tandem axle limitis 29 t (63,900 pounds), and the tripleaxle limit is 39 t (86,000 pounds).

The Autostrade toll road company hasrecently developed a design calledPolyfunctional Composite Pavements(PCP). (1) This design consists of thefollowing:

J 4 cm (1.6 in) porous asphalt surfaceJ 22 cm (8.7 in) CRCP (12.8 m (39 ft)wide with two longitudinal joints)J 20 cm (7.9 in) CTBJ 20 cm (7.9 in) granular layer

PCP Al Project. Two major PCPprojects were constructed in 1988 onthe Al and the Al2 near Rome, both ofwhich have very heavy truck traffic(approximately 5,000 trucks in onedirection). The crack spacing in theCRCP was reported to be 1.2 to 2.5 m(3.9 to 8.2 ft). This section has threelanes in one direction and the CRCPslab is 12.8 m (42 ft) wide with twolongitudinal joints. One key aspect isthat the two longitudinal joints arespaced so as not to be in the wheelpaths of trucks, so that truck wheelsusually produce interior loads.

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15.4 tons = 34 kips. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

0.1 1-2 2-3 34 a, 7-9 a9 ~1010.1111-1212-131314 0.3 3-s 53 7.9 01, l,.13 ,a-,5 ,,,7 ,749 I%?, 21-P zM5 25-27 214

Single Axle Load, metric tons Tandem Axle Load, metric tons

Figure 3.21 Italian axle load distributions measured near Rome on freeway system.

Also, the CRCP continues on 1.8 m (5.9ft) beyond the painted edge stripe toeliminate any edge loading. At thispoint, a porous concrete base begins toprovide for drainage. This pavementhas a 2.5 percent cross-slope. Nocracks or any other distress wereobserved after four years of service.The porous asphalt surfacing providesa very quiet ride. There is a noticeabledifference (about 3-4 dB) between thissurface and a conventional AC surfacethat exists on the next section of theAl.

Concrete properties measured on theAl CRCP project are as follows: (2)

J Mean compressive strength at 28days: 56.5 MPa (8072 psi)

J Water/cement ratio: 0.42

This design has the followingadvantages: (1)

J Eliminates hydroplaning,J Eliminates tire spray,J Good friction resistance,J Low emission of tire/pavement

noise,J Smooth ride,J Waterproofing of cracks in CRCP,J Resistance to fatigue due to interior

loadings, andJ Easier maintenance (surface replaced

at seven years)J Mean flexural strength at 28 days:

8.3 MPa (1186 psi)

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It is expected that about every sevenyears the porous AC will need to bemilled off and replaced due to cloggingfrom fines or other problems. The totalstructural design life is 40 years.

Cost Comparison. A cost comparisonof the PCP versus the conventionalsemi-rigid pavement that has an ACsurface over lean concrete or CTB wasgiven as follows, where R equals theratio of the cost of the PCP divided bythe cost of the semi-rigid pavement:

r

Item R

Construction 1.30Maintenance 0.30User costs 0.55Total life-cycle costs 0.87

Italy References

1. Camomilla, G. and A.Marchionna, “P.C.P.Polyfunctional CompositePavements,” Technical Report,Autostrade Central Maintenanceand Research Division, Rome,Italy, 1991.

2. Marchionna, A., et al., “CementConcrete Characteristics forRoad Pavements, PracticalExperience with thePolyfunctional CompositePavement,” Proceedings: 6thInternational Symposium onConcrete Roads, Madrid, Spain,1990.

3. Rose, A. C., “Public Roads of thePast - 3500 B.C. to 1800 A.D.,”AASHTO, Washington, D.C.,USA, 1952.

l Switzerland

Switzerland has a 70-year tradition inbuilding concrete pavements. Severalexisting concrete pavements wereshown to the Study Tour. A designcatalog is available that was developedusing the AASHTO design procedureand varying the subgrade and trafficlevel. A manual for concrete pavementdesign and construction practices dated1992 will soon be available. It wasreported that concrete pavementsrequire about 20 percent less electricalenergy for lighting than AC pavementsdue to the lighter surface. JPCP, CRCPand prestressed pavements have beenconstructed in Switzerland.

Example Project. The main runway atBasal airport was built in 1956 and wasrehabilitated in 1986. Slabs werereplaced during the night and openedto traffic at 5 A.M. with about 4.5hours of curing time. The central keelsection (24 m ((79 ft) wide by 2600 m(8530 ft) long) was completely replacedover a three-week period. Thisrequired only one week of completeclosure for all traffic and then nightwork for two weeks where someheavier aircraft were restricted fromusing the runway during the day.

Concrete Durability. The key aspectof the Switzerland presentation wastheir quality control program toachieve high durability. Since 1965,highways in Switzerland have beendeiced using large amounts of chemicaldeicing salts. This has increased the

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durability requirements for concretepavement. Existing pavements at thattime suddenly developed damage fromscaling as well as concentrateddisintegration of the concrete pastestructure.

The durability of the concrete wasimproved by increasing the quantity ofair voids, graded according to size anduniform distribution in the cementpaste. The measurement of the totalcontent of air voids of the freshconcrete was not sufficient for theevaluation of frost and salt durability.They believe that only an appropriatetesting method applied to the hardenedconcrete can give valid information. (1)

The total air content should never beless than 4.5 percent of total mixvolume. However, during placing,consolidating and finishing of concretethe total pore fraction, poredistribution, and pore size in thehardened concrete may be affected.Therefore, rapid and practicalprocedures were developed to examinethese in the hardened concrete forconstruction projects. The microscopiccontrol of concrete is carried out onthin sections made from a concrete corespecimen impregnated with a specialfluorescent dye and examined underthe microscope in transmittedultraviolet light. The complete qualitycontrol process is as follows:

J Laboratory tests are conducted afew months before the project begins.Several concrete mixes are prepared todevelop a mix design of highdurability. The aggregates aresubmitted to quality control: grainshape, repartition, porosity, cracks,content of mica and impurities are

checked. Attention is paid to the bondquality between aggregates and cementpaste. The suitability of the selectedair-entrainment agent is checked andthe proper dosage determined. The airvoid system, size, quantity anddistribution in the cement paste aremeasured. (1)

J Trial run tests take place two orthree weeks before construction toevaluate the batching, mixing plant andplacement equipment to test thesuitability of the mix design from thelaboratory under in situ workingconditions. The concrete is mixed,hauled and placed in two or three trialslabs that are constructed on site.Several test cores are obtained as soonas possible and tested in the laboratory.These results are compared to thoseobtained from the previous laboratoryresults and any adjustments needed aremade to the mix or constructionprocess. (1)

J During the first few days ofconstruction, cores are taken from thepavement and tested in the laboratory.A microscopic analysis is againconducted to ensure the hardenedconcrete maintains the proper air voidsystem. These results are availablewithin 36 hours after the concrete isplaced. If the air void system isinadequate, a rapid-cycle freeze-thawtest is conducted on one of the cores(Dobrolubov-Romer method). (2)

If the air void system is inadequate, thesurface of the concrete is impregnatedwith an agent (3). These qualitycontrol procedures have led to theelimination of frost-salt durabilityproblems in concrete pavements inSwitzerland.

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Switzerland References

1. Wilk, W. and G. Dobrolubov,“Microscopic Quality Control ofConcrete during Construction,”Bulletin of Betonstrassen AG,Concrete Roads Ltd., Wildegg,Switzerland, July/ September1981.

2. Dobrolubov, G. and B. Romer,“Guidelines for determining andtesting the frost as well as frost-salt resistance of cement-concrete,” Bulletin ofBetonstrassen AG, ConcreteRoads Ltd., Wildegg,Switzeriand, June 1985.

3. Wilk, W., “The development ofquantitative and qualitativemicroscopic control of concretequality and durability,” paperpresented at the 6thInternational Conference onCement Microscopy, March 26-29, 1984, Albuquerque, NewMexico, USA.

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4 ACRONYMS, DEFINITIONS,AND TECHNICAL TERMS

AASHTOAmerican Association of StateTransportation Officials444 North Capitol Street, N.W.Suite 225Washington, D.C. 20001Phone (282) 624-5800

ACPAAmerican Concrete PavementAssociation3800 North Wilke Road, Suite 490Arlington Heights, Illinois 60004Phone (708) 3945577

F H W AFederal Highway Administration400 Seventh Street, SW.Washington, D.C. 20590Phone (202) 366-0660

P C APortland Cement Association5420 Old Orchard RoadSkokie, Illinois 6007-1083Phone (708)966-6200

SHRPStrategic Highway Research Program818 Connecticut Avenue, N.W.Suite 400Washington, D.C. 20006Phone (282) 3343774

TRBTransportation Research Board2101 Constitution Avenue, N.W.Washington, D.C. 20418Phone (202) 3342989

Definitions/Technical Terms

PCC - Portland cement concreteAC - Hot-mixed asphalt concreteRAP - recycled asphalt concrete (usedin recycled concrete)LCB - lean concrete baseCTB - cement-treated baseJPCP - jointed plain concretepavements (with or without dowels)JRCP - jointed reinforced concretepavementsCRCP - continuously reinforcedconcrete pavementsdB(A) - noise emission level in decibelsUS TECH - U.S. Tour of EuropeanConcrete HighwaysNCHRP - National CooperativeHighway Research Program (USA)LCPC - Laboratoire Central des Pontset Chaussees - Central Laboratory ofBridges and Roads in FranceCEMBUREAU - European cementassociationBAST - Bundesanstalt furStrassenwesen (Federal HighwayResearch Center in Germany)ISTEA - Intermodal SurfaceTransportation and Efficiency Act of1991 (USA highway legislation)R & D - research and development

Common SI (modern metric)conversion units used in this report:

t - metric ton (1 t = 2204.62 pounds)MPa - megaPascal (1 MPa = 145 psi)