A REVIEW OF BITUMINOUS PAVING MIXES

Presented by,

NISCHAY.N B.E(CIVIL)., M.Tech., IGBC-AP.

The bituminous paving mixes have evolved in 1960 as specified in MORTH Specification.

A critical review of commonly used bituminous paving mixes has attempted based on

Mix selection based on function and location within flexible pavement.

Capabilities of present day hot mix asphalt plants.

PROVIDE STRUCTURAL STRENGTH FACILITATE SUBSURFACE DRAINAGE PROVIDING SURFACE FRICTION

ESPECIALLY WHEN WET

TYPICAL C/S OF PAVEMENT IDEAL C/S OF PAVEMENT

PERMEABLE ASPHALT TREATED BASE CONNECTED TO PAVEMENT EDGE DRAIN

REDUCE SPLASH AND SPRAY .

REDUCE TYRE-PAVEMENT NOISE.

ENHANCE VISIBILITY OF PAVEMENT MARKINGS, AND

REDUCE NIGHTTIME SURFACE GLARE IN WET WEATHER.

OGFC REPORTEDLY PROVIDES THE FOLLOWING ADVANTAGES:

PREMATURE OGFC RELATED DISTRESS ON A HIGHWAY

A VIEW OF RUTTING ON PAVEMENT

FOLLWING BITUMINOUS PAVING MIXES SPECIFIED IN THE MORTH SPECIFICATION

BITUMINOUS MACADAM (BM)

DENSE BITUMINOUS MACADAM (DBM)

SEMI-DENSE BITUMINOUS CONCRETE (SDBC)

BITUMINOUS CONCRETE (BC)

FLEXIBLE PAVEMENT WITH BM AS A BASE COURSE OR PCC

FLEXIBLE PAVEMENT WITH BM AS A BASE/ BINDER COURSE

BM AND DBM SHOULD BE COMPARED BY CONSIDERING FOLLOWING FACTORS:

PERMEABILITY

STRUCTURAL STRENGTH

USE OF PCC

COST CONSIDERATIONS

TRAFFIC CONDITIONS

PERMEABILITY:BM IS A HIGH PERMEABLE MIX WHEN COMPARED TO DBM

OPEN SURFACE TEXTURE OF BM GRADING1 AND GRADING2 RESPECTIVELY

Mix Type Bitumen content,

%

Air Voids, % Permeability,

cm/sec

BM

Grading1(Coarse)

3.25 13.6 3.4

BM Grading1

(Fine)

3.25 8.9 0.4

BM

Grading2(Coarse)

3.4 15.4 3.6

BM Grading2

(Fine)

3.4 8.3 0.6

ROAD FAILURE IN OKLAHOMA,US RESULTING FROM SATURATED BINDER COURSE

STRIPPED BINDER COURSE IN NH48 IN INDIA

STRUCTURAL STRENGTH:DBM IS FAR SUPERIOR THAN BM IN TERMS OF STRUCTURAL STRENGTH , MIX DESIGN CRITERIA, AND MIX PRODUCTION CONTROL.

USES AS A PCC: BM IS A GOOD MATERIAL FOR PCC BECAUSE IT RESISTS REFLECTION CRACKING.

COST CONSIDERATIONS:ACCORDING TO THE CURRENT PREVAILING SCHEDULE, THE

COST OF BM LAYER IS Rs.3,465/Cu.m WHERE OF DBM IS Rs.4,193/Cu.m. THAT IS BM IS CHEAPER THAN DBM.

TRAFFIC CONDITIONS:ACCORDING TO SOME HIGHWAY ENGINEERS, BM IS

INTENDED FOR LOW TRAFFIC ROADS ONLY.

DBM IS SPECIFIED FOR USE AS A BASE COURSE AND/OR BINDER COURSE.

TWO GRADATIONS ARE SPECIFIED IN MORTH SPECIFICATIONS:GRADING1 HAS A NMAS OF 37.5mm GRADING 2 HAS A NMAS OF 25mm

GRADING 1 OF DBM IS HIGH PERMEABLE ,IT SHOULD BE SEALED BEFORE RAINY SEASON, OTHERWISE IT WILL PENETRATE AND DAMAGE WMM .

DBM GRADING 2 OF WITH 25mm NMAS IS SUITED FOR A BASE COURSE.

IT IS NEITHER DENSE GRADED NOR OPEN GRADED,CONTAIN THE SO CALLED PESSIUM VOID WHEN CONSTRUCTED.

THE REGION BETWEEN B AND C IS PESSIUM VOID RANGE, IT REPRESENTS OPPOSITE OF OPTIMUM.THE OBJECTIVE IS TO STAY OUT PESSIUM VOID RANGES

THERE IS A NEED TO SELECT A BINDER COURSE AND TWO WEARING COURSE. BC GRADING 1 WITH NMAS OF 19mm IS SUITABLE FOR A BINDER COURSE. BC GRADING 2 WITH NMAS OF 13mm IS SUTABLE FOR A WEARING COURSE ON HEAVY TRAFFIC ROADS.

THERE IS A NEED TO ADD A THIRD BC GRADATION WITH NMAS OF 9.5mm.

BC GRADING 1&2 NEED TO BE REVISING TO MAKE IT MORE RUT RESISTANT

NCAT TEST TRACK IN AUBURN UNIVERSITY WHERE TRUCKS WITH LOADED TRAILERS APPLYING TRAFFIC USING SPECIFIED BC COURSES

Grading Proposed DBM Base course Grading 1

Proposed DBM Base course Grading 2

Proposed BC Binder Course

Proposed BC wearing course

Grading 1

Proposed BC wearing course

Grading 2

Lift thickness 75-100mm 75-100mm 50-75mm 30-50mm 25-40mm

NAS 37.5mm 25mm 19mm 12.5mm 9.5mm

Sieve size, mm Per cent passing45 100 - - - -

37.5 90-100 100 - - -

26.5 63-93 90-100 100 - -

19 - 71-95 90-100 100 -

13.2 55-75 56-80 66-86 90-100 100

9.5 - - 55-75 70-88 90-100

4.75 38-54 38-54 35-55 53-71 55-75

2.36 28-42 28-42 28-44 38-54 40-55

1.18 - - 20-34 24-38 29-44

0.6 - - 15-27 17-29 21-330.3 7-21 7-21 10-20 12-22 14-250.15 - - 5-13 7-15 7-150.075 4-7 4-7 4-7 4-7 4-7

Bitumen Content

4.0-5.5 4.0-5.5 4.0-5.5 5.0-7.0 5.2-7.5

IT IS NOT NECESSARY TO USE ALL THREE COURSES IN A NEW FLEXIBLE PAVEMENT UNLESS THE TRAFFIC IS VERY HIGH. FOLLOWING ARE THE COMBINATIONS OF BITUMINOUS PAVING MIXES:

WMM + DBM BASE COURSE + BC BINDER COURSE + BC WEARING COURSE.

WMM + BC BINDER COURSE + BC WEARING COURSES.

WMM + BC WEARING COURSE ONLY.

FOR ENSURING LONG TERM PERFORMING PAVEMENTS, FOCUS SHOULD SHIFT TO DENSE GRADED RATHER THAN OPEN GRADED BITUMINOUS MIXES.

THE STUDY RECOMMENDS IN TOTAL 5 NUMBERS OF BITUMINOUS MIXES:

37.5mm NMAS,DBM BASE COURSE GRADING1

25mm NMAS,DBM BASE COURSE GRADING2

19mm NMAS BC BINDER COURSE

12.5mmNMAS BC WEARING COURSE GRADING1

9.5mm NMASBC WEARING COURSE GRADING 2

REASERCH IS GOING ON FOR THE USE OF LARGE NMAS IN DBM AND CORRECTIONS MUST BE MADE AFTER ITS COMPLETION ON THE NMAS OF EACH COURSE IF RESULTS ARE POSITIVE.

BITUMINOUS MACADAM IS HIGHLY PERMEABLE AND NOW IT IS SUBSTITUTED BY DBM

USE OF THICK WEARING COURSE IS RECOMMENDED FOR TROPICAL COUNTRY ONLY.

BM USED AS PCC IS DISCOURAGED AND NOT ALLOWED NOW A DAYS.

i. JURNAL OF INDIAN ROAD CONGRESS (vol. 69-2, jul-sep-2008)ii. www.Oklhoma.comiii. Bureau of Indian standard IS 73: 2006, jul-2009

?QUESTIONS

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