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CE-415-Lecture 4

Lecturer Ms RabiyaSemester 6

7 Feb 11 10 Jun 11

I saw the angel in themarble and carved until Iset him free.Michelangelo

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oa cons ruc on anConstruction equipmentConstruction of road

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Roman & Greek roads

HISTORY OF ROADSHISTORY OF ROADS

The oldest road was constructed from Knossues to Leben

Stone slab

Longitudinaldrain

Limeconcrete

throungh Crete in 2000 BC.

The Romans built Britain's first proper roads. After the Romansleft they were allowed to decay because people forgot how torebuild and repair them.

Laid well above the ground levelStraight, cambered and composed of multiple layers, wellcompacted Lime as a stabilization agentWidth was 5.5 m

Trsa uet's work

Broken stone ,25 mmEdge stone

Longitudinaldrain

Chamber

building his roads in trenches, so that they could be accessed from the sides, which undermineddrainage principle.Random use of large stones result in differential settlementsintroduced a system of continuous maintenance, where a roadman was allocated a section of roadto be kept up to a standard

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HISTORY OF ROADSHISTORY OF ROADS

Modern tarred roads were the result of the work of two Scottishengineers, Thomas Telford and John Loudon McAdam. Telford designed the system of raising the foundation of the road in thecenter to act as a drain for water.

Thomas Telford born 1757 im roved the method of buildinroads with broken stones by analyzing stone size/thickness , road traffic, road alignment and gradient slopes. Eventually his

design became the norm for all roads everywhere.

broken stones laid in symmetrical, tight patterns and covered with small stones to create a hard surface. McAdam's design,called "macadam roads," provided the greatest advancement inroad construction.

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HISTORY OF ROADSHISTORY OF ROADS broken stone,60 mmGravel/broken stone ,20mm

John Loudon McAdamUse of angular aggregates strong interlockingWell graded material used CompactionIdea of impermeable ,durable binder

broken stone,20 mm

broken stone, 75mm

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Crawler Bulldozer HoeRotary Tiller Disc harrows

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Truck mountedTruck propelled Self propelled

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Core cutter Sand cone

Nuclear guage

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Hydraulic Sweeping Machine

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Constant rate/volume/pressure

Suitable distribution mechanism

Smooth surface finish, blemish free

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Pulverization stabilization purposes degree of pulv.Mixing in place method or stationary plant - manualBinder spraying spray rate & pattern

Check for double overlap (d) Check for triple overlap

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Rolling & compaction Normal camber, R start from outer edge towards central lineSuper elevated stretch, R start from inner to outer edgeGrade/cross slopeIn situ densities

Curing time for concrete /bitumen , no loading allowLimitations extreme weather is not suitable

Foggy, rainy, windy, low temperatureConstruction technique / practices matters

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Cut/fillo Cleaning & grubbing -150mm , vegetation & existing

structureso Excavation for road & draino m an men cons ruc on orrow p so Replacement of weak soils replaced by quality soil/higher

CBR underlying weak layers not disturbed / replaced soilcompacted

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Invo ve eart wor vo ume, a ancing cuts i s, p anning economicamaterial hauls

End area determination : subdivision of areas into geometric figuresrectangular, triangular, trapezoidal etc, precision =+/- 0.5%

Average end area : precision =+/- 1.0%

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Conversion factor from compacted to bank cubic yards =0.9

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Information

materialsAve haul distance

Type of equipmentconsidered

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on ro s unwan e proper es o su gra e, excess vecompressibility, permeability, frost susceptibility, settlement,volume change and so on.

Mechanical soil stabil. : soils of diff. plasticity indicesor aggregates of desired gradation ,mixed with existingmateria .

Stabil. With cement additives & chemicals:

using lime, concrete or ash to convert poorer soils into astrong impermeable medium.

suspended in a finely divided condition in an aqueous mediumand stabilised by suitable materialChemicals like: phosphoric acid, calcium chloride , sodiumchloride etc

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Thermal stabilization

Geotextiles : to provide drainage, reinforcement insurface dressing, erosion control & prevent crack

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In a batch plant (Figure) , the aggregates are heated and sorted (by screening) into different sizes. They are thenrecombined (batched) in a pugmill in precise proportions(by weight) according to a mix design. A measured quantityof asphalt cement is added and mixed with the aggregate.

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In a drum plant (Figure ), a cold feed

system of individual bins and precisefeeders proportion the aggregates. Thecombined aggregates, along with asphaltcement are continuously fed into a drumdryer where the aggregates are dried and mixed with the asphalt. The resultantmixture is conveyed to a holding silowhere it is then loaded into haulingvehicles.

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Heavy duty fourbin feeder unit

Inclined Sliner beltconveyer

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Truck Mounted Concrete Batching Mixing Plant

Concrete Batching Mixing Plant with Radial

Scrapper