ASPHALT, ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS

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ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS
Bituminous Concrete layer

ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS

What is Asphalt Concrete ?:➤

➤Basically Asphalt Concrete is Just Aggregate Coated With Asphalt Cement.. and Then Compacted.
There Are Three Basic Elements To The Compacted Mix.
➱1-Aggregate Particles,
➱2-Asphalt Cement,
➱3-Air Voids,
What is meant by bituminous concrete?
What is the difference between bituminous concrete and asphalt?
What is BM and BC?

INTRODUCTION ➤

➤Asphalt is a Mixture of Bitumen of Tar with aggregate,
➤Bitumen Is an Extract of Petroleum Crude,
➤Crude Oil is formed by decomposition of dead marine microorganism in the absence air or oxygen,
➤Bitumen is waste collected during the distillation of petroleum crude,

ACTIVITIES IN ASPHALT WORK ➤

➤Dense Bituminous Macadam( DBM) Or Bituminous Macadam(BM),
➤Bituminous Concrete(BC) OR Semi Dense Bituminous Concrete(SDBC),
➤Prime Coat – SS 1
➤Tack Coat -RS 1

What is DBM and BC?

What is DBM and BC in road construction?
What is BC layer in road construction?

MATERIALS IN ASPHALT CONRETE ➤

➤Aggregate ,
➤Bitumen,
➤Mineral filler (Lime/Cement/Rock Dust),
➤Anti striping Agent,
ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS
Asphalt Concrete materials

MATERIALS PROPERTIES(AS PER BELOW TABLES)

ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS
ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS

ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS

ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS

ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS

ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS

PAVING OPERATION ➤

CHECKS BEFORE PAVING(PRE-PAVING ACTIVITY)➱

➤Check The Trucks Are Adequate,
➤Check The Production capacity and Paving Capacity is Matching,
➤Check The Rollers Are Adequate,
➤Check The string line,Thermometer, other tools are ready,
➤Check the screed Of the Paver is Heated As much as Required, (Maximum up to mix Temperature),
➤Check The screed is Blocked to required loose thickness,
➤Check The Cold Joints are cleaned and applied with tack coat,
➤Check The Cleaning Should Be done Properly Before Applying tack coat, The Surface Should be Free From loose particles, Dust, Or any other Deleterious Material,
➤Paver Level Sensor To be Set For Required Level Given Of String Wire Or Average Beams,
ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS

CHECKS DURING PAVING ➱

➤Tack Coat Should be Applied Uniformly With rate of  Spray of 2.5 to 3 kg per 10 Square meter area,
➤Total Area Should Be covered With Tack Coat,
➤Start The Unloading Of Truck into the paver, After checking The Temperature Of Mix,
➤Loose Thickness Should Be Checked With Thickness Gauge Regularly in some Interval of Time,and Length,
➤Check The Camber with line rope , taper.
➤If any Segregated area is Found spread the fines with shovels prior to rolling,
➤Check for Rolling Should Be done As per Rolling pattern,
ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS

SURFACE FINISH ➤

➤The tolerance in level should be in between +/- 6 mm,
➤The Core Density should be 92 % of Lab GMM.
➤Road Unevenness index shall be less than 2000 mm per kilometre for road works,
➤The Mix Binder Content shall be +/- .3% of  Designed OBC,
➤Surface Regularity DBM, BC shall be +/- 6 mm , +/- 3 mm,

TRANSVERSE JOINT MATCHING➤

➤The Joint Should be rolled parallel to the joint,
➤These joints to be Rolled without vibrations,
ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS

LONGITUDINAL JOINTS MATCHING➤

➤Compact The joint during breakdown Rolling,
➤If two pavers are Working in echelon ,then the roller in the second lane shall roll the joint,
ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS

PLANT OPERATIONS➤

CHECKS DURING PRODUCTION➤

➤Feed The aggregate to plant to get design mix,
➤Maintain The Bitumen Temperature as 150 degree Celsius,
➤Maintain the aggregate Temperature as 160 to 170 degree Celsius,
➤Ensure The Mix temperature should be Between 140 to 150 degree Celsius,
➤Clean the Vehicles Neatly,
➤Load The mix to Trucks and Cover with Tarpaulins and Hauled to site,
➤ Check The temperature at plant,site and record it,

ROLLING PATTERN➤

The Rolling process should start 12 to 15 inches from the lower unsupported edge as the un-compacted edge provides the initial confinement during the first pass,thus minimizing lateral movement of the mix. 
Succeeding pass should move to the edge once the central portion of the spread is compacted to some degree because the mix will support the roller and allow the edge to be compacted without lateral movement, 

ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS



ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS



ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS


REQUIRED MACHINES➤

Following some important machines are required for Laying of Asphalt concrete , Bituminous Concrete Layer ,

1➮Paver machine

ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS
Paver machine



2➮Tendem Rollers

ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS
Tendem Roller



3➮Pneumatic Tyre Rollers


PNEUMATIC TYRE ROLLER➤

What is pneumatic tyre roller ?

➤The Pneumatic tire roller(PTR) is tire mounted roller having smooth tire surface,
➤It’s Weight can be adjusted according to the requirement(Generally 16 to 18 mt for bituminous layers rolling is used),➤It is used for Compaction and kneading action,
➤Longitudinal movement of the mix doesn’t take place unless the dia. is very less,
➤Horizontal forces is minimized with the use of larger diameter.
➤The movement of mix under the tire tends to be lateral,
➤The humps created during breakdown are of no significance and can be cleared in subsequent pass,
➤Under normal conditions, when the roller is on top of a firm mat it has no horizontal thrust as the tire flattens on the bottom which permits an 100 % vertical force,

ASPHALT,ASPHALT CONCRETE, BITUMINOUS CONCRETE LAYERS
PTR


CONDITIONS FOR PNEUMATIC TIRE ROLLERS TO BE EFFECTIVE➤

➤The most effective pressure is the highest pressure that can be used without over stressing the mix,
➤Pressure for a normal Highway work when the tire is hot 90 psi and 70-75 psi when tires are cold,
➤Nine -Wheel roller is used commonly ,
➤Weight per wheel should not exceed 2000 to 3000 pounds,
➤Rim diameter for tire -20 inches,
➤Tire width – 9 or 11 inches,
➤While compacting water should not be used on the tires,

SUMMARY TABLE OF INFLUENCES OF COMPACTION➤

ITEMS EFFECTS CORRECTIONS
AGGREGATE
➮Smooth Surfaced

➮Rough Surfaced
➮Unsound

➮Absorptive 

➮Low inter-particle friction

➮High inter-particle friction
➮Breaks under steel-wheeled rollers
➮Dries-Mix difficult to compact

➮Use light rollers,Low mix Temperature,
➮Use Heavy Rollers
➮Use Sound Aggregates, Use pneumatic rollers,
➮Increase asphalt in mix
ASPHALT
Viscosity 
➮High

➮Low

➮Particles Movement Restricted
➮Particles moves easily during compaction
➮Use heavy rollers, Increase temperature,
➮Use light rollers
QUALITY
➮High

➮Low

➮Unstable and plastic under roller
➮Reduce Lubrication – difficult compaction 
➮Decrease asphalt in mix

➮Increase asphalt in mix,Use heavy rollers

MIX
➮Excess Coarse aggregate

➮Over-sanded

➮Too much filler

➮Too light filler

➮Harsh mix – difficult to compact
➮Too workable – difficult to compact
➮Stiffens Mix-difficult to compact
➮Low cohesion – mix may come apart
➮Reduce coarse aggregate,Use heavy rollers
➮Reduce sand in mix,Use light rollers,
➮Reduce filler in mix,Use heavy rollers
➮Increase filler in mix
MIX TEMPERATURE
➮High

➮Low

➮Difficult to compact-mix lacks cohesion
➮Difficult to compact-mix to stiff
➮Decrease mixing temperature
➮Increase mixing temperature
COURSE THICKNESS
➮Thick lifts

➮Thin lifts

➮Hold heat – more time to compact
➮Lose heat – Less time to compact
➮Roll normally

➮Roll before mix cools, Increase mix temperature

WEATHER CONDITIONS
➮Low air temperature
➮Low surface temperature
➮Wind
➮Cools mix rapidly
➮Cools mix rapidly
➮Cools mix-crusts surface 
➮Roll before mix cools
➮Increase mix temperature
➮Increase lift thickness



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