BITUMINOUS CONCRETE

BITUMINOUS CONCRETE

  • BITUMINOUS CONCRETE( BC) IS USED FOR WEARING COURSE AND PROFILE CORRECTIVE COURSES.

  • BC IS GENERALLY LAID IN A SINGLE LAYER ON A PREVIOUSLY PREPARED BITUMINOUS BOUND SURFACE.

  • THE THICKNESS OF A SINGLE LAYER OF BC SHALL BE 30MM,40MM, AND 50MM.




MATERIALS USED IN BITUMINOUS CONCRETE:-

  • BITUMEN


HYDRATED LIME



COARSE AGGREGATE



FINE AGGRAGATE



MATERIALS

1. BITUMEN

  • THE BITUMEN SHALL BE VISCOSITY GRADED PAVING BITUMEN COMPLYING WITH INDIAN STANDARD SPECIFICATION FOR PAVING BITUMEN, IS:73.

  • THE GRADE OF BITUMEN TO BE USED WOULD DEPEND UPON THE CLIMATIC CONDITIONS AND THE TRAFFIC.


SELECTION CRITERIA BASED ON CLIMATIC CONDITIONS


2. COARSE AGGREGATES

  • THE COARSE AGGREGATE SHALL CONSIST OF CRUSHED ROCK, CRUSHED GRAVEL, OR OTHER GRAVEL OR OTHER HARD MATERIAL RETAINEDON2.36MM SIEVE.

  • IT SHALL BE CLEAN, HARD, DURABLE, AND CUBICAL IN SHAPE, FREE FROM DUST AND SOFT ORGANIC AND OTHER DELETERIOUS SUBSTANCES.

  • WHERECRUSHEDGRAVELIS PROPOSED FOR USE AS AGGREGATE NOT LESS THAN 95% BY WEIGHT OF THE CRUSHED MATERIAL RETAINED ON THE 4.75MM SIEVE SHALLHAVEAT LEAST TWO FRACTURED FACES.

PHYSICAL REQUIREMENTS FOR COARSE AGGREGATE FOR BITUMINOUS CONCRETE



  • IF THE MIN. RETAINED TENSILE TEST STRENGTH FALLS BELOW 80%, USE OF AN ANTI-STRIPPING AGENT IS RECOMMENDED TO MEET THE REQUIREMENT.

  • IMPROVE THE ADHESION OF THE BITUMEN FILM ON THE SURFACE OF THE AGGREGATES. MIXED WITH THE BINDER, THEY LOWER THE SURFACE TENSION OF THE BITUMEN.


3. FINE AGGREGATES

  • IT SHALL CONSIST OF CRUSHED OR NATURALLY OCCURRING MATERIAL, OR A COMBINATION OF THE TWO, PASSING 2.36 MM SIEVE AND RETAINED ON THE 75MICRON SIEVE.

  • THEY SHALL BE CLEAN, HARD, DURABLE, DRY, AND FREE FROM DUST AND SOFT OR FRIABLE MATTER, ORGANIC OR OTHER DELETERIOUS MATTER.

NOTES:-

  • NATURAL SAND SHALL NOT BE ALLOWED IN THE BINDER COURSE.

  • HOWEVER, NATURAL SAND UP TO 50% OF THE FINE AGGREGATES MAY BE ALLOWED IN BASE COURSES.

  • SAND EQUIVALENT VALUE >50 {IS:2720(PART 37)}

  • THE PLASTICITY INDEX OF THE FRACTION PASSING THE 0.425MM SIEVE<4 {IS:2720(PART 5)}.

3. FILLER:-

  • THE FILLER SHALL CONSIST OF FINELY DIVIDE MINERAL MATTER SUCH AS ROCK DUST, HYDRATED LIME, OR CEMENT APPROVED BY THE ENGINEER.

  • THE FILLER SHALL BE GRADED WITHIN THE LIMITS INDICATED IN THE TABLE BELOW:-

NOTES:-

  • THE FILLER SHALL BE FREE FROM ORGANIC IMPURITIES.

  • PLASTICITY INDEX NOT GREATER THAN 4

  • THE PI REQUIREMENTS SHALL NOT APPLY IF THE FILLER IS CEMENT OR LIME.

  • WHERE THE AGGREGATES FAIL TO MEET THE REQUIREMENTS OF THE WATER SENSITIVITY TEST THEN 2% BY WEIGHT OF AGGREGATES, OF HYDRATED LIME SHALL BE USED.

AGGREGATEGRADING&BINDERCONTENT

  • WHEN TESTED IN ACCORDANCE WITH THE WET GRADING METHOD, THE COMBINED GRADING OF COARSE AND FINE AGGREGATE AND FILLER SHALL FALL WITHIN THE LIMITS.

AGGREGATE GRADING & BINDER CONTENT SIEVE ANALYSIS FOR GRADING I & II



MIX DESIGN BITUMINOUS CONCRETE

  • THE BITUMEN CONTENT REQUIRED SHALL BE DETERMINED BY FOLLOWING THE MARSHALL MIX DESIGN PROCEDURE

  • THE FINES TO BITUMEN(F/B)RATIOBY WEIGHT OF TOTAL MIX SHALLRANGE FROM 0.6 TO 1.2.



REQUIREMENTS OF BITUMINOUS CONCRETE



BINDER CONTENT

  • THE BINDER CONTENT SHALL BE SELECTED TO OBTAIN 4 PERCENT AIR VOIDS IN THE MIX DESIGN.

  • WHEREMAXIMUMSIZE OF THE AGGREGATE IS MORE THAN26.5 MM, THE MODIFIED MARSHALL METHOD USING 150 MM DIAMETER SPECIMEN SHALL BE USED.

  • THIS METHOD REQUIRES MODIFIED EQUIPMENT AND PROCEDURES.

  • WHEN THE MODIFIEDMARSHALL TEST IS USED, THE SPECIFIED MINIMUM STABILITY VALUE SHALL BE MULTIPLIED BY 2.25, AND THE MINIMUM FLOW SHALL BE 3 MM.

JOB MIX FORMULA

  • THE CONTRACTOR SHALL SUBMIT THIS TO THE ENGINEER FOR APPROVAL AT LEAST 21 DAYS BEFORE THE START OF WORK:-

  • SOURCE & LOCATION MATERIAL

  • BINDER TYPE & % BY WEIGHT OF TOTAL MIX

  • COARSE AGGREGATE/FINE AGGREGATE/FILLER MATERIAL AS % BY WEIGHT OF TOTAL AGGREGATE

  • PASSING EACH SIEVE FOR MIXED AGGREGATE

  • ALL RESULTS OF THE MARSHALL TEST

  • TEST RESULT OF PHYSICAL CHARACTERISTICS

  • MIXING TEMP. & COMPACTING TEMP.

PERMISSIBLE VARIATIONS IN THE ACTUAL MIX FROM THE JOB MIX FORMULA



LAYING


WEATHER AND SEASONAL LIMITATIONS: BITUMINOUS MACADAM SHALL NOT BE LAID:

  • IN THE PRESENCE OF STANDING WATER ON THE SURFACE,

  • WHEN RAIN IS IMMINENT AND DURING RAINS, FOG, OR DUST STORMS,

  • WHEN THE BASE /BINDER COURSE IS DAMP,

  • WHEN THE AIR TEMPERATURE ON THE SURFACE ON WHICH IT IS TO BE LAID IS LESS THAN 100 C,

  • WHEN THE WIND SPEED AT ANY TEMPERATURE EXCEEDS 40 KM/H AT A 2-METER HEIGHT.

TACK COAT:-

  • IT IS A VERY THIN APPLICATION OF DILUTED BITUMEN EMULSION.

  • IT CONSISTS OF THE LOW VISCOSITY OF BITUMINOUS MATERIAL TO EXISTING BITUMINOUS, CEMENT CONCRETE, OR PRIME GRANULAR SURFACE.

  • IT IS USED TO ASSURE A BOND BETWEEN THE PAVED SURFACE AND THE NEW COURSE.



MATERIALS:-

#THE BINDER USED ARE:-

  • CATIONIC BITUMEN EMULSION (RS-1)

  • LOW VISCOSITY PAVINGBITUMEN (VG-10)

  • CUT-BACK BITUMEN (RC-70) – ONLY FOR SITES ATSUB-ZERO TEMP. OR AS DIRECTED BY AN ENGINEER



CONSTRUCTION OPERATIONS FOR TACK COAT EQUIPMENT:-

  • SELF-PROPELLED OR TOWED BITUMEN PRESSURE SPRAYER EQUIPPED FOR SPRAYING THE MATERIALUNIFORMLYAT SPECIFIED RATE& TEMPERATURE.

  • HAND SPRAYING SHALL NOT BE ALLOWED EXCEPT IN SMALL AREAS ACCESSIBLE TO THE DISTRIBUTOR.



CONSTRUCTION OPERATION FOR TACK COAT PREPARATION OF ROAD SURFACE:-

  • THE SURFACE TO BE PRIMED SHALL BE KEPT CLEAN BY A POWER OR MECHANICAL SWEEPER & MADE FREE FROM DUST.


APPLICATIONS OF BITUMINOUS PRIMER:-

# IT DEPENDS UPON THE

  • TYPE OF EQUIPMENT USED

  • SIZE OF NOZZLE

  • PRESSUREATSPRAYBARS

  • SPEED OF FORWARDING MOVEMENT

  • NO HEATING OR DILUTION OF RS1 BITUMEN EMULSION & SHALL BE PERMITTED AT SITE

# SPRAYING TEMPERATURE:-

  • BITUMINOUS EMULSION – 20-70 °C

  • CUTBACK – 50-80 °C

RATE OF APPLICATION OFTACKCOAT

QUALITY CONTROL AND TEST FREQUENCY FOR TACK COAT


MEASUREMENTS FOR PAYMENT:-

TACK COAT SHALL BE MEASURED IN TERMS OF SURFACE AREA OF APPLICATION IN SQUARE METER


MIXING & TRANSPORTATION OF MIX

MIXING, LAYING, AND ROLLING TEMPERATURES FOR BITUMINOUS CONCRETE



SPREADING:-

  • EXCEPT IN AREAS WHERE PAVER CAN NOT HAVE ACCESS, BITUMINOUS MIXTURE SHALL BE SPREAD, LEVELLED, AND TAMPED BY A SELF-PROPELLED HYDROSTATIC PAVER FINISHER PREFERABLY EQUIPPED WITH A SENSOR.



  • AS SOON AS POSSIBLE AFTER ARRIVAL AT THE SITE THE ASPHALT MIX SHALL BE SUPPLIED CONTINUOUSLY TO THE PAVER AND LAID WITHOUT DELAY.

  • THE RATE OF DELIVERY OF MATERIAL TO THE PAVER SHALL BE REGULATED TO ENABLE THE PAVER TO OPERATE CONTINUOUSLY.

  • THE TRAVEL RATE OF PAVER AND THE METHOD OF OPERATION SHALL BE ADJUSTED TOENSUREEVEN AND UNIFORM FLOW OF BITUMINOUS MATERIAL ACROSS THE SCREED, FREE FROM DRAGGING, TEARING, AND SEGREGATION

  • WHEN LAYING BITUMINOUS CONCRETE NEAR THE EXPANSION JOINT, THE MACHINE LAYING SHALL BE STOPPED ABOUT 300 MM SHORT OF THE JOINT.

  • THE REMAINDER OF THE PAVEMENT UP TO THE JOINT AND THE CORRESPONDING AREA BEYOND IT SHALL BE LAID MANUALLY.



COMPACTION:-

  • THE INITIAL OR BREAKDOWN ROLLING SHALL BE DONE WITH AN 8 TO 10 TONNES DEAD WEIGHT SMOOTH WHEEL ROLLER THE INTERMEDIATE ROLLING SHALL BE DONE WITH 8 TO 10 TONNES DEAD WEIGHT OR VIBRATORY ROLLER WITH AN AMPLITUDE OF 0.3MM TO 0.8 MM AND FREQUENCY BETWEEN 30 TO 50 HZ. OR WITH A PNEUMATIC ROLLER OF 12 TO 15 TONES, WITH A TIRE PRESSURE OF AT LEAST 0.56 MPA.

  • THE FINISHED ROLLING SHALL BE DONE WITH 6 TO 8 TONNES SMOOTH WHEEL ROLLER.

  • ROLLING SHALL CONTINUE UNTIL AT LEAST 98% OF THE LAB DENSITY OBTAINED IN THE MARSHALL MOULD MADE USING APPROVED GRADATIONANDBITUMENCONTENTISACHIEVED


NOTES:-

  • THE BC SHALL BE ROLLED IN THE LONGITUDINAL DIRECTION WITH THE ROLLER AS CLOSE TO THE PAVE AS POSSIBLE.

  • THE OVERLAP ON SUCCESSIVE PASSES SHOULD BE AT LEAST ONE-THIRD OF THE WIDTH OF THE REAR ROLL OR IN THE CASE OF PNEUMATIC WHEELED ROLLERS, AT LEAST THE NOMINAL WIDTH OF 300MM.

  • THE ROLLER SHOULD MOVE AT A SPEED OF NO MORE THAN5 KM/HOUR. THE ROLLER SHALL NOT BE PERMITTED TO STAND ON PAVEMENT, WHICH HAS NOT BEEN FULLY COMPACTED

MEASUREMENTS FOR PAYMENT:-

  • BITUMINOUS CONCRETE SHALL BE MEASURED AS FINISHED WORK EITHER IN CUBIC METRES, TONNES OR BY SQUARE METER AT A SPECIFIED THICKNESS AS INDICATED IN THE DRAWING, CONTRACT, DOCUMENTS OR AS SPECIFIED BY THE ENGINEER-IN CHARGE.

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