SEMINAR ON EFFECT OF AIR VOIDS ON HOT GRADED DENSE

BITUMINOUS MIX DESIGN

Made By:►Avinash Bhosale►Ketan Palwe ►Dipak Mengane►Priyanka Patekar►Bhawana Tejale

GUIDED BY :

► Mr. A . D . Kale

Karamveer Kakasaheb Wagh Polytechnic, Nashik

Index

Introduction Introduction about road pavements Definitions of technical terms Materials and test standards Mix design Effect of Air Voids on mix design Occurrence of Air Voids Conclusion Reference

Introduction

In order for a pavement to have adequate film

thickness, there must be sufficient space between

aggregate particles in the compacted pavement.

Thus it is necessary to have a sufficient quantity

of air voids.

A structure having several layers bound together and placed on top of the soil sub grade so that is provides a smooth riding surface for the vehicles.

Road Pavement

Component of Road Pavement.

Wearing Course (B.C.) Bituminous Base Course (D.B.M.) Non Bituminous Base Course (W.M.M.) Sub-base course (G.S.B.) Sub-grade.

Technical Terms

Specific gravity Sp. Gravity of bitumen Bulk Sp. Gravity of combined aggregate Apparent specific gravity of combined aggregate Max. specific gravity of paving mix Effective specific gravity of aggregate

Bulk Sp. Gr. Of compacted mix Maximum Percentage paving mix Percentage paving mix Percentage of voids Voids Filled by Bitumen Voids in Mineral Aggregates

Materials

Bitumen :- Viscosity Grade 30 Coarse Aggregates :- Hard material retained on

the 2.36mm sieve. Fine Aggregates :- Passing fro the 2.36mm sieve

and retained on the 75 micron sieve. Filler :- Rock dust, hydrated lime or cement

Test standards

Specific gravity Flakiness and elongation Ductility Softening Viscosity

Mix design

BY USING MARSHALL METHOD General Preparation of test specimenTest procedure Interpretation of test data

MIX DESIGN CRITERIASuitable according to Indian climatic condition.

Standard mix design criteriaSuitable according to United States climatic condition.

AIR VOIDS The total volume of small pockets of air between the coated

aggregate particles throughout a compacted paving mixture, expressed as percent of the bulk volume of the compacted paving mixtures.

Air voids occurrence LOW VOIDS :

Typically mix problem Mix design problemPoor quality control

Redesign or adjust Removal or replace High binder content

HIGH VOIDS : Typically a compaction problem Change roller, rolling pattern , temperature

EFFECT OF AIR VOIDS ON MIX DESIGN

If air voids are too high: Increased binder aging Reduce fatigue life Moisture damage Decrease durability

If air voids are too low :Plastic flowRutting and shoving under

trafficflushing and bleeding

Conclusion

We designed the mix according to the narrow range of bitumen content is up to 3.8 to 4.7 %

4% of bitumen is good which keeps air voids between 3-6%

This mix retain stability up to 91.08%

References

Asphalt manual series – 2 MORTH – Ministry of roads ,transportation and

highway department IRC – Indian road congress Codes of Indian standards Science direct . Com ASCE.com / library