ICAO SEMINAR ON ICAO SEMINAR ON AIRFIELD PAVEMENT AIRFIELD PAVEMENT MAINTENANCE AND MAINTENANCE AND SHORT COURSE ON SHORT COURSE ON

AIRCRAFT /PAVEMENT AIRCRAFT /PAVEMENT INTERACTIONINTERACTION

SANTA CRUZ DE LA SANTA CRUZ DE LA SIERRA, BOLIVIA SIERRA, BOLIVIA

22 TO 27 JULY 200222 TO 27 JULY 2002

EXPERIENCE ON AIRFIELDEXPERIENCE ON AIRFIELD

PAVEMENT MAINTENANCE PAVEMENT MAINTENANCE IN AFRICAIN AFRICA

V P. PERICLESV P. PERICLES Coordinator Airport Development Coordinator Airport Development

in Haitiin HaitiProject HAI/98/901 Project HAI/98/901

Office National de l’Aviation Civile Office National de l’Aviation Civile (OFNAC)(OFNAC)

OVERVIEW OF AERODROME OVERVIEW OF AERODROME MAINTENANCE IN AFRICAMAINTENANCE IN AFRICA

Organization of maintenance services.Organization of maintenance services.Management of maintenance.Management of maintenance.Priority given to maintenance services.Priority given to maintenance services.Maintenance programming /planning.Maintenance programming /planning.Maintenance methodology .Maintenance methodology .Maintenance technology.Maintenance technology.Maintenance practices.Maintenance practices.Aerodrome maintenance and safety Aerodrome maintenance and safety RelationsRelations with and assistance from with and assistance from international organizationsinternational organizationsPersonnel training.Personnel training.

AERODROME MAINTENANCE AERODROME MAINTENANCE IN AFRICAIN AFRICA

Historical BackgroundHistorical Background• First workshop on this subject – Dakar, First workshop on this subject – Dakar,

Sénégal, 8-12/03/1982Sénégal, 8-12/03/1982• Second workshop on this subject – Second workshop on this subject –

Dakar, Sénégal, 8-12/02/1988.Dakar, Sénégal, 8-12/02/1988.• Third workshop on this subject – Dakar, Third workshop on this subject – Dakar,

Sénégal, 6-12/02/1992 Sénégal, 6-12/02/1992 • Fourth workshop on this subject – Fourth workshop on this subject –

Dakar, Sénégal, 5-8/12/1995.Dakar, Sénégal, 5-8/12/1995.

ParticipationParticipation All African States, including States, All African States, including States, accreditedaccredited to the Cairo, Nairobi and Paris to the Cairo, Nairobi and Paris Offices were invited. Also invited, were Offices were invited. Also invited, were international organizations concerned international organizations concerned such as: IATA, ASECNA, IFALPA, AACC such as: IATA, ASECNA, IFALPA, AACC (ACI) and the FAA. Total participants: (ACI) and the FAA. Total participants: 51,66, 70 and 81, respectively, in the 51,66, 70 and 81, respectively, in the first, second, third and the fourth first, second, third and the fourth workshop.workshop.Indication of increased interest in the Indication of increased interest in the subject.subject.

JUSTIFICATION FOR JUSTIFICATION FOR ADEQUATE MAINTENANCEADEQUATE MAINTENANCE Continued expansion / construction of Airports Continued expansion / construction of Airports in Africa.in Africa.Need for higher level and quality of service.Need for higher level and quality of service.Increased investments made at these Airports.Increased investments made at these Airports.Availability of best procedures, methods and Availability of best procedures, methods and equipment to ensure serviceability, safety and equipment to ensure serviceability, safety and achievement of substantial savings.achievement of substantial savings.Accomplishment of a high degree of operating Accomplishment of a high degree of operating reliability to assist in the safe and efficient reliability to assist in the safe and efficient movement during landing, take-off and taxiing movement during landing, take-off and taxiing maneuvers.maneuvers.Need to ensure the establishment of effective Need to ensure the establishment of effective maintenance programme maintenance programme

ORGANIZATION AND PROGRAMMED ORGANIZATION AND PROGRAMMED MAINTENANCE IN AFRICAMAINTENANCE IN AFRICA

At the majority of the more than 170 Aerodromes At the majority of the more than 170 Aerodromes in AFI, it exits some form of maintenance in AFI, it exits some form of maintenance organization.organization.The programs observed (up to 1998) varies in The programs observed (up to 1998) varies in scope, size and effectiveness.scope, size and effectiveness.In certain cases, these programs consist of In certain cases, these programs consist of sporadic unscheduled and unrecorded sporadic unscheduled and unrecorded inspections and evaluation of the airport facilities.inspections and evaluation of the airport facilities.There were also cases of well conceived There were also cases of well conceived comprehensive programmes with adequate comprehensive programmes with adequate planning, scheduling and well distributed planning, scheduling and well distributed responsibilities.responsibilities.

New and more sophisticated equipments and New and more sophisticated equipments and maintenance toolsmaintenance tools

Engineers had been trained and assigned to Engineers had been trained and assigned to airports in the AFI Region the number is airports in the AFI Region the number is below the need. In other States, services below the need. In other States, services were totally lacking, thus creating a vacuum were totally lacking, thus creating a vacuum which constituted then, permanent, serious which constituted then, permanent, serious concern for safety.concern for safety.

MAINTENANCE PRACTICESMAINTENANCE PRACTICESGENERAL GENERAL

BASICBASIC: Maintenance of all structures had : Maintenance of all structures had been considered vital in order to been considered vital in order to

prolong their economic service life, prolong their economic service life, maintain their standard of appearance maintain their standard of appearance and ensure their capacity to operate and ensure their capacity to operate properly throughout their expected life properly throughout their expected life span.span.African states agreed that lack of proper African states agreed that lack of proper maintenance leads, inexorably, to maintenance leads, inexorably, to problems causing undesirable problems causing undesirable expenses, even disasters.expenses, even disasters.

This common concern of states in the This common concern of states in the AFI Region is not always translated into AFI Region is not always translated into practice.practice.

Some positive measures are in force Some positive measures are in force today at the majority of international today at the majority of international airports in Africa, but not with the airports in Africa, but not with the desirable consistency and periodicity.desirable consistency and periodicity.

MAINTENANCE PRACTICESMAINTENANCE PRACTICESPRACTICES MOST OFTEN OBSERVED AT PRACTICES MOST OFTEN OBSERVED AT

AFRICAN AERODROMESAFRICAN AERODROMES

Pavement repairs, cleaning and scalingPavement repairs, cleaning and scalingRemoval of foreign objects (fob) from maneuvering Removal of foreign objects (fob) from maneuvering areas.areas.Routine checks of pavement joints for repairs.Routine checks of pavement joints for repairs.Cleaning of drainage system.Cleaning of drainage system.Repair of lighting aids.Repair of lighting aids.Repainting of deteriorated pavement markings.Repainting of deteriorated pavement markings.

Control of vegetation growth.Control of vegetation growth.

Routine repairs of airport buildings.Routine repairs of airport buildings.

Inspection and correction of defective Inspection and correction of defective sewage system.sewage system.

Repairs of vehicles, with priority to Repairs of vehicles, with priority to emergency vehicles.emergency vehicles.

Routine checks of equipments (COM, Routine checks of equipments (COM, MET, ATS …)MET, ATS …)

MAINTENANCE PERSONNELMAINTENANCE PERSONNELPROGRESS HAS BEEN ACHIEVED IN AFRICA PROGRESS HAS BEEN ACHIEVED IN AFRICA

(1998) IN THIS FIELD(1998) IN THIS FIELD

A Section or Department responsible for A Section or Department responsible for maintenance has been created at most maintenance has been created at most aerodromesaerodromes

It comprises a senior engineer who heads a It comprises a senior engineer who heads a group of engineers and techniciansgroup of engineers and technicians

The number of personnel is often related to the The number of personnel is often related to the size and activities at the airport.size and activities at the airport.

There continues to have shortage of trained There continues to have shortage of trained technicians, primarily in the pavement, electrical technicians, primarily in the pavement, electrical and mechanical engineering fields.and mechanical engineering fields.

Lately, the introduction of larger aircraft at Lately, the introduction of larger aircraft at many aerodromes in Africa and the advent of many aerodromes in Africa and the advent of new technology (CNS, ATM), implies new technology (CNS, ATM), implies additional heavier burden on maintenance additional heavier burden on maintenance units. Thus, a need for more specialized units. Thus, a need for more specialized equipments for maintenance and better equipments for maintenance and better organization. organization.

SOLVING THE PERSONNEL SOLVING THE PERSONNEL PROBLEMPROBLEM

Different approaches by States in training and retention of Different approaches by States in training and retention of personnel.personnel.Trained personnel are lost to other employees due to lack Trained personnel are lost to other employees due to lack of incentives and/ or competitivity, also careerof incentives and/ or competitivity, also career prospects.prospects.Need to reverse current trend?Need to reverse current trend?a) intensification of traininga) intensification of trainingb) creation of incentives.b) creation of incentives.c) competitive salaries, career prospects to retain c) competitive salaries, career prospects to retain personnel.personnel.d) funds derived from aviation and assistance (UNDP, d) funds derived from aviation and assistance (UNDP, bilateral arrangements) should be used to finance bilateral arrangements) should be used to finance personnel training and recycling. Participation at this personnel training and recycling. Participation at this meeting is just but one example of wise investment in meeting is just but one example of wise investment in human resources.human resources.

PAVEMENT MAINTENANCE PAVEMENT MAINTENANCE MANAGEMENT SYSTEMMANAGEMENT SYSTEM

Importance of preventive Vs corrective maintenance.Importance of preventive Vs corrective maintenance.Periodical pavement evaluation for maintenance Periodical pavement evaluation for maintenance purpose.purpose.Evaluation and identification of the pavement surface Evaluation and identification of the pavement surface distress.distress.Evaluation of the hydroplaning risks of the pavement.Evaluation of the hydroplaning risks of the pavement.Runway roughness evaluation.Runway roughness evaluation.Collecting and reporting of pavement deterioration.Collecting and reporting of pavement deterioration.Monitoring of evolution of identified deficiencies.Monitoring of evolution of identified deficiencies.Planning/programming of corrective intervention.Planning/programming of corrective intervention.Financing.Financing.

STATES USING SUCH STATES USING SUCH SYSTEM (1998 DATA)SYSTEM (1998 DATA)

South Africa– Integrated Airport Pavement South Africa– Integrated Airport Pavement Management Systems (IAPMS). Management Systems (IAPMS).ASECNA States (16) Similar to JFK, la Guardia ASECNA States (16) Similar to JFK, la Guardia and Newark Intl and Newark Intl Ghana- Computer Assisted Management (CAM).Ghana- Computer Assisted Management (CAM).Morroco/Tunisia- use a monitoring Morroco/Tunisia- use a monitoring system/condition surveysystem/condition survey ResultsResults: Reduce frequency of large scale and : Reduce frequency of large scale and costly intervention.costly intervention.

Note: the IAPMS is a self contained software Note: the IAPMS is a self contained software package designed to run on an 1986 class package designed to run on an 1986 class desktop computer.desktop computer.

It assists the engineer or planner to It assists the engineer or planner to make the kinds of rational predictions of make the kinds of rational predictions of future pavement conditions and performance future pavement conditions and performance that are essential for accurate budget that are essential for accurate budget forecasting and sound management. The net forecasting and sound management. The net effect is the preservation of infrastructure effect is the preservation of infrastructure through improved pavement performance and through improved pavement performance and reduced maintenance and rehabilitation cost.reduced maintenance and rehabilitation cost.

MAINTENANCE PRACTICESMAINTENANCE PRACTICES

Preventive maintenancePreventive maintenance

Routine maintenanceRoutine maintenance

Major maintenanceMajor maintenance

LandscapingLandscaping

Environment (protection)Environment (protection)

Pavement maintenancePavement maintenance

General*General*

Flexible pavementFlexible pavement

Rigid pavementRigid pavement

Unpaved surfaces*Unpaved surfaces*

FLEXIBLE PAVEMENTFLEXIBLE PAVEMENT

Preventive measuresPreventive measures

*Programming / scheduling*Programming / scheduling

-.Routine evaluation-.Routine evaluation

-.Technical evaluation-.Technical evaluation

-.Planned intervention-.Planned intervention

Corrective measuresCorrective measures

-.Short term-.Short term

-.-.Long term, resurfacing (overlay)Long term, resurfacing (overlay)

-.-.ReconstructionReconstruction

RIGID PAVEMENTRIGID PAVEMENT(Practices/observation)(Practices/observation)

General surface texture conditionGeneral surface texture condition

Structural conditionStructural condition

Pavement sealant and faults in jointsPavement sealant and faults in joints

Growth of plants and fungus on pavement Growth of plants and fungus on pavement and in jointsand in joints

NON CONVENTIONAL NON CONVENTIONAL /RECYCLED MATERIALS/RECYCLED MATERIALS

Fly AshFly Ash

Lime cement fly ashLime cement fly ash

Fibrous concreteFibrous concrete

Sulfur asphaltSulfur asphalt

ShellsShells

Silica sand asphaltSilica sand asphalt

FLY ASH ( MAY 1969 )FLY ASH ( MAY 1969 )

Mixtures of fly ash from several Electrical Power Mixtures of fly ash from several Electrical Power Plants have been used for the construction of Plants have been used for the construction of several runways repairs and construction at JFK several runways repairs and construction at JFK and Newark Airports.and Newark Airports.

The Ashes came from the Central Heating The Ashes came from the Central Heating Plants of Ravenswood and Astoria of Con Plants of Ravenswood and Astoria of Con Edison and from the Hudson and Mecer Central Edison and from the Hudson and Mecer Central of the Electricity and Gas Public services of New of the Electricity and Gas Public services of New Jersey. Jersey.

The decision to use fly ash for these runway The decision to use fly ash for these runway pavements had been taken by the Port Authority pavements had been taken by the Port Authority of New York and New Jersey ( PONYANJ ) of New York and New Jersey ( PONYANJ ) after three years of thorough experimental trials.after three years of thorough experimental trials.Condition that led to the decisions to use ash as Condition that led to the decisions to use ash as a good, cheap material:a good, cheap material:

- Sand is available in large quantity in - Sand is available in large quantity in

NewarkNewark..- Lab experiments were conducted with - Lab experiments were conducted with

several additives /mixtures (sand + ash, sand + several additives /mixtures (sand + ash, sand + ash +coke, sand +ash +sodium carbon with ash +coke, sand +ash +sodium carbon with mixed results)mixed results)

the adopted formula with respected weight was:the adopted formula with respected weight was:

Fly ash 12 – 14 %Fly ash 12 – 14 %

Coke 2.8 – 3.0 %Coke 2.8 – 3.0 %

Portland cement 0,7 – 0.9 %Portland cement 0,7 – 0.9 %

Sand 80 – 84.5 %Sand 80 – 84.5 %

Finally a small quantity of Portland cement was Finally a small quantity of Portland cement was added to the above mixtures, and in each case a added to the above mixtures, and in each case a good strength was achieved after a reasonable good strength was achieved after a reasonable duration of the solidificationduration of the solidification . In addition the cost . In addition the cost was not too highwas not too high

Called LCF (Lime Cement Fly ash) this material offered Called LCF (Lime Cement Fly ash) this material offered a strength of 56 to 100 bars in about 90 days at a a strength of 56 to 100 bars in about 90 days at a temperature from 18 to 21 degrees Celsius. As temperature from 18 to 21 degrees Celsius. As necessary, 30 % of aggregates can replace sand. In necessary, 30 % of aggregates can replace sand. In which case a strength of 105 bars can be achieved.which case a strength of 105 bars can be achieved.The characteristics of the LCF (expansion , module of The characteristics of the LCF (expansion , module of elasticity sensibility to freeze temperature elasticity sensibility to freeze temperature freeze/defreeze) were determined with precision in the freeze/defreeze) were determined with precision in the laboratory.laboratory.Experiments were conducted at Newark airport. Half Experiments were conducted at Newark airport. Half millions us dollars were spent to demonstrate that the millions us dollars were spent to demonstrate that the LCF was, by far, superior to the other formula.LCF was, by far, superior to the other formula.Three contacts for a total of 20 millions USD were Three contacts for a total of 20 millions USD were awarded for Newark. This program was to be repeated awarded for Newark. This program was to be repeated for JFK Airport.for JFK Airport.

As regards the cost

the sand for the Central Heating plants had to be

Humidifed with 16 to 18% of water to avoid spilling of five particles by the wind. Transport to the site costs 2 to 3 dollars/ton. The greasy coke delivered on site costs 6 to 18 $/ton and the cement 20 to 22 $/ton. The mixture operation costs 1 to 1.5 $/ton

Total cost for the runway was found to be half that of the highway and less than one third of the concrete of good strength. These costs do not include the sand which was available on the site.

The judicious use of fly ash for runway pavement permitted significant savings to the Port Authority as well as to the electrical power plants for several years

Sulfur asphalt (1973)

Saving from the use of abatement sulfur may help offset cost of pollution control (?)Sulfur valuable natural resource1973 abatement sulfur production was a small, 3.5 million tones (3.2 x 109 kg) or 15% of elemental sulfur produced by the West.In 1975 the production of abatement sulfur exceeded 16.0 millions tones. No exact figure is available to us todayIt can be assumed that since a large quantity of sulfur

is awaiting development of the technology that could create a useful outlet.Estimate prepared by the U.S Federal Power Commission (FPC) indicated that abatement sulfur supply to reach 43 millions tones in the early, 2000. Figure to be verifiedThe use of elemental sulfur in sand asphalt-sulfur pavements is still foreseen in Africa (ASECNA, South Africa) as having one of the least potential for the use of this element. (Illinois Institute of Technology)Shell Canada has developed material using elemental sulfur in asphaltic hot-mixes that permits greater flexibility in mix designs in the utilizations of either sands of minerals aggregates. Shell uses the term “Thermopave” to their sand asphaltic binder sulfur pavement

Other studies, US Bureau of Mines, Sulfur Institute, Texas Transportation Institute (TTI)Final consideration is still dependant on availability of sulfur and cheap aggregates. All conditions considered, the potential for using sulfur asphalt mixture in pavement construction remains high (to be confirmed).

UNPAVED SURFACESUNPAVED SURFACES

Maintenance generally conducted Maintenance generally conducted

Under contract with nearby public or private Under contract with nearby public or private companies including nearby farmers. companies including nearby farmers.

Monitoring by authorized personnel (CAA) Monitoring by authorized personnel (CAA) to ensure compliance with air traffic safety.to ensure compliance with air traffic safety.

Visual and / or mechanical inspection Visual and / or mechanical inspection Typical distress looked for:Typical distress looked for:

FLEXIBLE PAVEMENTFLEXIBLE PAVEMENTCracking of the surfaces (Alligator cracks, random Cracking of the surfaces (Alligator cracks, random cracks, longitudinal cracking due to failure of underlying cracks, longitudinal cracking due to failure of underlying pavement layers.pavement layers.Surface wear.Surface wear.Loose materials (identification of their provenance)Loose materials (identification of their provenance)Subgrade failure.Subgrade failure.Deformation of surface Deformation of surface Channelisation of trafficChannelisation of trafficLocalized failure due to overloading conditions.Localized failure due to overloading conditions.Pumping.Pumping.

Vegetation growth on the surfacesVegetation growth on the surfaces..

Deterioration attributed to jet fuel Deterioration attributed to jet fuel spillage and other contaminants (oil, spillage and other contaminants (oil, rubber deposits dirt or leakage from rubber deposits dirt or leakage from cargo containers).cargo containers).

Erosion of pavement edges and Erosion of pavement edges and shoulders shoulders

Surface erosion caused by wind.Surface erosion caused by wind.

Erosion due to poor drainage system.Erosion due to poor drainage system.

IN SUMMARYIN SUMMARYFINDINGS 1995FINDINGS 1995

Maintenance levels below required standardsMaintenance levels below required standardsExpensive facilities, specially pavement, being run down Expensive facilities, specially pavement, being run down fast due to lack of preventive maintenance.fast due to lack of preventive maintenance.Civil aviation sector being wrongly construed to be a Civil aviation sector being wrongly construed to be a drain to the economy of the country.drain to the economy of the country.Civil aviation considered in some countries as a source Civil aviation considered in some countries as a source of founds.of founds.Quality of services at the airports sometimes below Quality of services at the airports sometimes below minimum level.minimum level.Civil aviation staff demotivated leading to loss of qualified Civil aviation staff demotivated leading to loss of qualified staff (to private sector) staff (to private sector)

ALLOCATION OF FUNDS BY CAA ALLOCATION OF FUNDS BY CAA IN AFRICAIN AFRICA

In general, allocation of funds for aerodrome maintenance In general, allocation of funds for aerodrome maintenance in AFI region is reduced to a minimum.in AFI region is reduced to a minimum.Survey conducted in 1995 indicates that from the fifty three Survey conducted in 1995 indicates that from the fifty three (53) African States, thirty seven (37) are known to make (53) African States, thirty seven (37) are known to make provisions for maintenance.provisions for maintenance. Among the States, nineteen (19) are from the Western and Among the States, nineteen (19) are from the Western and Central African Office.Central African Office. In most of the thirty seven (37) States, the allocation is In most of the thirty seven (37) States, the allocation is apparentlyapparently not sufficient.not sufficient.In five States, no funds are specifically reserved for In five States, no funds are specifically reserved for maintenance works.maintenance works.The service is provided but sporadically performed at times The service is provided but sporadically performed at times not until the affected areas constitute a threat to safety.not until the affected areas constitute a threat to safety.

PAVEMENT MAINTENANCE IN PAVEMENT MAINTENANCE IN AFRICA AFRICA THE FUTURETHE FUTURE

The problem is not how to design and build new The problem is not how to design and build new pavement system for larger, heavier, greater frequency pavement system for larger, heavier, greater frequency and magnitude of loading modern aircraft.and magnitude of loading modern aircraft.The dilemma is how to upgrade and provide remedial The dilemma is how to upgrade and provide remedial measures for existing pavement systems to meet current measures for existing pavement systems to meet current and future traffic demands.and future traffic demands.Other dilemma, the required systematic team effort Other dilemma, the required systematic team effort (Airport Authorities,(Airport Authorities, the users and decision makers ) is the users and decision makers ) is complex and not successfully implemented in Africacomplex and not successfully implemented in Africa

THE FUTURETHE FUTURE

WHAT IS REQUIRED?WHAT IS REQUIRED?a) Establishment of a well organized and thought pavement a) Establishment of a well organized and thought pavement maintenance plan fully supported by the CAA and government maintenance plan fully supported by the CAA and government authorities (coordination)authorities (coordination)b) To ensure that the higher authorities do not consider civil b) To ensure that the higher authorities do not consider civil aviation as a drain to the economy of the country.aviation as a drain to the economy of the country.c) Achievement the above (b) and remembering that civil c) Achievement the above (b) and remembering that civil aviation development projects are not popular with the aviation development projects are not popular with the providers of the material resources.providers of the material resources.d) Provision of incentives to ensure that civil aviation staff are d) Provision of incentives to ensure that civil aviation staff are not demoralized, leading to brain drain not demoralized, leading to brain drain Implementation of the use of appropriate new technology Implementation of the use of appropriate new technology Planning ahead for the resources: financial, personnel, tools Planning ahead for the resources: financial, personnel, tools and equipments.and equipments.

UNPAVED RUNWAYS UNPAVED RUNWAYS IN AFRICAIN AFRICA

1- Stabilized lateritic1- Stabilized lateritic soilssoils

2- Temperate soils2- Temperate soils

3- Grass Runways3- Grass Runways

4- Turf 4- Turf

UNPAVED SURFACESUNPAVED SURFACES

ProblemsProblems-.Irregularities of the surface-.Irregularities of the surface-.Presence of foreign objects, rocks etc...-.Presence of foreign objects, rocks etc...-. Pot holes-. Pot holes-.Mud and erosion after heavy rain-.Mud and erosion after heavy rain-.Vegetation growth on surfaces-.Vegetation growth on surfaces-. Loss of bearing strength-. Loss of bearing strength

Causing accidents due toCausing accidents due to-.Loss of control of aircraft by pilots.-.Loss of control of aircraft by pilots.-.excessive tire wear.-.excessive tire wear.-.Aquaplaning and loss of control over slippery -.Aquaplaning and loss of control over slippery

surface.surface.

Note: The ICAO ADREP contains data giving Note: The ICAO ADREP contains data giving number of accidents which occurred on unpaved number of accidents which occurred on unpaved surfaces.surfaces.

LATERITIC SOILSLATERITIC SOILS

Reddish brown silty clay and coarse to medium fine send Reddish brown silty clay and coarse to medium fine send with trace of medium to fine gravels.with trace of medium to fine gravels.It contains iron and aluminum oxydes. These soils are It contains iron and aluminum oxydes. These soils are subjected to heat. Characteristics which are most subjected to heat. Characteristics which are most intriguing and may explain why lateritic soils can be intriguing and may explain why lateritic soils can be found only in the tropics.found only in the tropics.Laterite available mainly in Central, Eastern and Laterite available mainly in Central, Eastern and Southern Africa.Southern Africa.Lateritic soils used as sub-base material for construction Lateritic soils used as sub-base material for construction of roads and runway / taxiway pavements.of roads and runway / taxiway pavements.

Limited studies are available on these soils: Ghana Limited studies are available on these soils: Ghana Building and Road Research Institute, Study by Samuel Building and Road Research Institute, Study by Samuel A. Ola of Ahmadu BelloA. Ola of Ahmadu Bello

University, Zaria, Nigeria ( A S C E Proc. Paper 10534, University, Zaria, Nigeria ( A S C E Proc. Paper 10534, May 1974 ) and the study by G.A. Liantaud, Ingénieur en May 1974 ) and the study by G.A. Liantaud, Ingénieur en chef du Service Outre–Mer du C.E.B.T.P. France.chef du Service Outre–Mer du C.E.B.T.P. France.It has been demonstrated that less than 50% of the It has been demonstrated that less than 50% of the cement requirement for a temperature zone soil is cement requirement for a temperature zone soil is required for efficient stabilization of a lateritic soil. This required for efficient stabilization of a lateritic soil. This result demonstrates the need for determining the result demonstrates the need for determining the appropriate cement requirements for lateritic soils like appropriate cement requirements for lateritic soils like those presented by the PCA for temperate zone soils, those presented by the PCA for temperate zone soils, (Refer to ASCE Proc.10534 by Samuel A. Ola )(Refer to ASCE Proc.10534 by Samuel A. Ola )