nac pavements

3/29/2015 Construction Project Management, NAC, Hyd

PAVEMENT MATERIAL CHARACTERIZATION

- A. Ramesh M.TECH, MITE (Ph.d)

Sr. Asst. Prof, CED,

VNR VJIET, HYD


OVERVIEW

• Introduction on Pavements

• Materials used in Pavements

• Tests on Subgrade soil

• Test on Road Aggregates

• Test on Bitumen Materials

• Failures in Materials

• Closing Remarks


TYPES OF PAVEMENTS

•Un Surfaced

–Earthen roads

–Gravel roads

•Surfaced

–Bituminous Road

–Cement Concrete Road

•Un Conventional

–Block Pavement


• Flexible Pavements

–Earthen Roads

–Gravel Roads

–Bituminous Roads

• Rigid Pavements

–Reinforced Concrete

–Plane Concrete Roads

FURTHER CLASSIFICATION OF PAVEMENTS


GRAVEL ROADS


BITUMINOUS PAVEMENT


COMPONENTS OF FLEXIBLE PAVEMENT


LOAD DISPERSION IN

FLEXIBLE PAVEMENTS

Base

Black Topping

450

Sub Grade300mm

Sub Base

450

LOAD DISPERSION IN FLEXIBLE

PAVEMENTS

Base

Black Topping

450

Sub Grade300mm

Sub Base

450

Base

Black Topping

450

Sub Grade300mm Sub Grade300mm

Sub Base

450

450

LOAD DISPERSION IN FLEXIBLE

PAVEMENTS


RIGID PAVEMENT


REINFORCED CEMENT CONCRETE PAVEMENT DETAILS


BLOCK PAVEMENTS


PAVEMENT MATERIALS

Different materials are used in different types

of pavements

• Soil

• Aggregates (natural, artificial)

• Bitumen, Tar, Emulsion, Cutbacks

• Modified bituminous binders (PMB & CRMB)

• Bituminous mixes


• Cement

• Cement concrete (plain, reinforced, pre-

stressed)

• Stabilized materials

• Recycled materials

• Geo-textiles/ geo membranes

PAVEMENT MATERIALS CONTD..


• Characterization of materials

• To obtain necessary inputs for design ofnew structure (pavement)

• To obtain inputs regarding the conditionof the materials in an existing pavement

• To ensure proper quality duringconstruction

STUDY OF PAVEMENT MATERIALS


Pavement material properties are

evaluated by

• Conducting laboratory experiments on

representative samples

• By field evaluation

STUDY OF PAVEMENT MATERIALS


•Loads

•Climatic conditions

•Weathering action

PARAMETERS FOR MATERIAL CHARACTERIZATION


MATERIAL PROPERTIES

• The material properties to be consideredshould be relevant to the design approachadopted

• The properties should also reflect theperformance of the pavement structure

• Stress-strain relationship

• Ability of the material to recover after

release of load


MATERIAL BEHAVIOUR (STRESS-STRAIN RELATIONSHIP)


California Bearing Ratio Test

Strength of unbound Materials- Subgrade, subbase,

base course material

Examples: Native/borrow soil in subgrade; WBM or

WMM/GSB in subbase/ base course layers

Sample is to be prepared and tested as per standard

procedure.

TEST ON SOIL SUBGRADE


CALIFORNIA BEARING RATIO (CBR)


CBR Apparatus

CBR Test: Started around 1927 period, USA

Apparatus: CBR with accessories

Adopted standard Procedure-sample

preparation, testing and reporting the result

Definition: CBR value- load required to cause

depth of penetration measured at 2.5 and 5.0

mm compared with standard material ( >0 to

more than 100 % is possible)

More the value, higher is the strength

Less – poorer is the soil

Size: passing 20 mm


TEST ON ROAD AGGREGATE

• Aggregate Crushing Value

• Aggregate Impact Value

• Abrasion Test

• Sp. Gravity & Water Absorption

• Soundness

• Shape Test

– Flakiness Index

– Elongation Index

– Angularity Test


* Uniformly graded

- Few points of contact

- Poor interlock (shape dependent)

- High permeability

* Well graded

- Good interlock

- Low permeability

* Gap graded

- Only limited sizes- Good interlock- Low permeability

TYPES OF GRADATIONS


DIFFERENT GRADATIONS


•Dense or well-graded gradation - near maximum density.

•Gap graded gradation - contains only a small percentage

of aggregate particles in the mid-size range.

curve is flat in the mid-size range.

mixes - prone to segregation during placement.

•Open graded gradation - contains only a small percentage

of aggregate particles in the small range. -results in more air

voids because there are not enough small particles to fill in

the voids between the larger particles.

-curve is flat and near-zero in the small-size range.


•Uniformly graded gradation - contains most

of the particles in a very narrow size range.

-all the particles are the same size.

-curve is steep and only occupies the narrow

size range specified


AGGREGATE PROPERTIES AND TESTS

Property Explanation Test

Strength Resistance to Crushing Crushing Test

Hardness Resistance to Abrasion Los Angeles

Abrasion Test

Toughness Resistance to Impact Impact Test

Shape Better workability, Interlocking

and Strength

Shape Tests

Soundness Resistance to weathering Soundness Test

Specific Gravity Measure of strength and

presence of voids

Specific Gravity

Test


AGGREGATE CRUSHING TEST

• Internal Dia 11.5 Cm and Height 18 Cm (Measuring)

• 25 Times Tamping – Three Layers

• Testing – 15.2 Cm Internal Dia

• 40 Tons in 10 Mins (4 Tons/Min)

• Passing 2.36mm Sieve


ABRASION TEST • Internal Dia 700mm, and Length

500mm

• Abrasive Charges of Cast Iron with48mm Dia weighing 390 - 445 gms

• Quantity of Aggregates 5 – 10 Kg(Depending upon the size ofaggregates taken)

• Cylinder Speed 30 – 33 Rpm

• No. of Revolutions 500 – 1000(Depending upon the size of theaggregates taken)

• Passing 1.7mm sieve


• Metal hammer ofweight 13.5 to 14Kg is arranged todrop with a free fallof 38.0 cm byvertical guides andthe test specimen issubjected to 15number of blows.

• The crushedaggregate is allowedto pass through 2.36mm IS sieve.

• Aggregates to beused for wearingcourse, the impactvalue shouldn'texceed 30 percent.

IMPACT TEST


SPECIFIC GRAVITY AND WATER ABSORPTIONTESTING

Water Absorption and Bulk Specific Gravity

• 2 – 3 Kg Aggregate Sample, Wire Mesh Container

• 24 Hours (20 cm dia X 2o cm hieght)

• 100 – 1100C

• Percentage Water Absorption (Continuity of Voids)

• Bulk Specific Gravity of Aggregates

= (Dry Wt of Aggregates)/(Vol. Of Aggregates)

= (Dry Wt of Aggregates)/(Vol. Of Displaced Water)

= (Dry Wt of Aggregates)/(Wt of Displaced Water/ G of Water)

= (Dry Wt of Aggregates)/(Wt of Displaced Water)


SOUNDNESS TEST

• Soundness test is intended to study the resistance ofaggregates to weathering action, by conductingaccelerated

• weathering test cycles. The Porous aggregates subjectedto freezing and thawing are likely to disintegrate

• prematurely. To ascertain the durability of suchaggregates, they are subjected to an accelerated soundness

• saturated solution of either sodium sulphate ormagnesium sulphate for 16 - 18 hours and then dried inoven at

• 105 – 110oC to a constant weight. After five cycles, theloss in weight of aggregates is determined by sieving


Particle Shape and Surface Texture

• Important for compaction, deformation resistance,

workability, binder requirement of bituminous mixes and

workability in PCC

Angular RoundedFlaky

ElongatedFlaky & Elongated

SHAPE OF AGGREGATES


AGGREGATE SHAPE TEST

Elongation Index: Percentage weight particles

by total weight of aggregates whose greatest

dimension is 1.8 times the mean dimension

Flakiness Index: Percentage weight particles by

total weight of aggregates whose least dimension

is 0.6 times the mean dimension


50

T

O 4

0

27 mm

THICKNESS GAUGE

63

T

O 5

0


LENGTH GAUGE

50 TO 40

81 mm


TESTS FOR AGGREGATES WITH

IS CODES


Bituminous surfacing

Aggregate Impact Value : 50%[IS:2386-Part:4]

Los Angeles Abrasion value : 40% [IS:2386-Part:4]

Flakiness and Elongation Index: 35% [IS:2386-Part:1]

Water Absorption : 2%[IS:2386-Part:3]

Stripping Value : 15 % [IS: 6241-1971]

Soundness Value : 12% [Sodium Sulphate][IS:2386-Part:5]

: 18 % [magnesium Sulphate]

SPECIFICATION OF VARIOUS LAYERS OF RURAL ROADS


BITUMINOUS MATERIALS

Bitumen is a viscous liquid, semi-solid or solid

material ; colour varying from black to dark

brown; having adhesive properties; consisting

essentially of hydro carbons derived from

distillation of petroleum crude.

Adequate viscosity at the time of mixing and

compaction

Low temperature susceptibility

Good affinity with aggregates


Consistency Tests

Composition Tests

Specific Gravity Test

Flash and Fire Point Test

TEST ONBITUMINOUS MATERIALS


CONSISTENCY TESTS

Penetration Test ( IS 1203 – 1978 )

Viscosity Test ( IS 1206 – 1978 )

Softening Point Test ( IS 1205 – 1978 )

Ductility Test ( IS 1208 – 1978 )


PENETRATION TEST

• Test at 25O C

• Needle assembly 100 gm

• Readings in 1/10th of mm

• Load application 5 seconds

• Determination of Grade of Bitumen

0

After 5 sec

35


SOFTENING TEST

Ring and Ball, water bath, stirrer etc

Def: - temp. at which bitumen

changes its state from semi-solid

to semi-liquid.

Procedure: Heat the bitumen up to

100 C and pour this in two

standard rings and cool in

atmosphere for 30 minutes and

then place the balls and soak in

water bath 5 C for 15 minutes.

Normally value: >50 C.


DUCTILITY TESTDistance in cm

Temperature 27oC

Rate of pulling 50 + 2.5 mm

per min

To whether the binder has ductileproperty or not.

Def: It is the distance at which thethin film formed, when astandard sample of bitumen in abriquette mould trenched at theconstant rate of pulling, breaks.Units cm.

Procedure: Heat the bitumen up

to 100 C and pour it in a

briquette mould Cool it for 30 -

45 minute in air and in water

bath at 27 C for 85-95 minutes.

Normal value: 50 cm


LOSS ON HEATING

• When the bitumen is heated it loses the volatility and

gets hardened. About 50gm of the sample is weighed.

• It is then heated to a temperature of 1630C for 5hours

in a specified oven designed for this test. The sample

specimen is weighed again after the heating period and

loss in weight is expressed as percentage by weight of

the original sample.

• Bitumen used in pavement mixes should not indicate

more than 1% loss in weight, but for bitumen having

penetration values 150-200 up to 2% loss in weight is

allowed.


WATER CONTENT TEST

• It is desirable that the bitumen contains minimumwater content to prevent foaming of the bitumenwhen it is heated above the boiling point of water.

• The water in a bitumen is determined by mixingknown weight of specimen in a pure petroleumdistillate free from water, heating and distilling of thewater.

• The weight of the water condensed and collected isexpressed as percentage by weight of the originalsample.

• The allowable maximum water content should not bemore than 0.2% by weight.


CUTBACK BITUMEN

• To reduce the viscosity of Bitumen

some solvents are used resulting in

cutbacks. The solvents are of volatile

nature and materials normally used are

• Naphtha

• Kerosene

• Diesel Oil

• Furnace Oil


CUTBACK BITUMEN TYPES

Type Bitumen

Grade

Type of

Solvent

Amount of solvent by

percentage volume of

cutback bitumen

Rapid

Curing

( RC )

80/100 Naphtha 15 - 45

Medium

Curing

( MC )

80/100 Kerosene 15 – 45

Slow

Curing

( SC )

80/100Heavy

Distillate0 - 50


BITUMEN EMULSION

• Finely Divided Suspended in Aqueous MediumStabilised by One or More Suitable Materials(60% Bitumen and 40% Water)

• Rapid, Medium and Slow Setting

• Cationic and Anionic Emulsions

• Viscosity Requirements: Table no. 4.12, Pg. No.80, IRC:SP:20-2002


Application of single coat of low viscosity bitumen

on a porous granular surface

PRIME COAT


Purpose of Tack Coat:

To ensure a bond

between the new

construction and

the old surface

TACK COAT

Use of Cutback: It should be restricted for sites at subzero temperatures or for emergency applications


TACK COAT

• Single coat low viscosity bituminous binder

• Materials

• Emulsions → (IS – 8887: 2004)

• Cutback → (IS – 217) (in sub-zerotemperature)


WRONG PRACTICE OF TACK COAT


MODIFIED BITUMEN (IRC SP 53 - 2002)

Polymer/Crumb Rubber Modified Bitumen

Advantages

• Low Temperature Susceptibility

• Improved Resistance to Deformation

• Improved Age

• Higher Fatigue Life

• Prevention of Cracking


The penetration test determines the hardness or

softness of bitumen by measuring the depth in tenths

of a millimeter to which a standard loaded needle will

penetrate vertically in five seconds. The sample at 250 C

The bitumen grade is specified in terms of

penetration value. 80 –100 or 80/100 grade bitumen

means that the penetration value of the bitumen is in

the range 80 to 100 at standard test conditions.

Different grades are 30/40, 40/50, 50/60, 80/100

Some Properties of Bitumen

Grade


Flash & Fire Point

The flash point of a material is the lowest

temperature at which the vapour of a substance

momentarily takes fire in the form of a flash under

specified conditions of test.

The fire point is the lowest temperature at which the

material gets ignited and burns under specified

conditions of test.

The minimum specified flash point is 1750 C

Properties…..


Viscosity

Viscosity is defined

as inverse of fluidity and it

is measure of resistance

to flow.

Properties…..

Viscosity is measured by determining the time taken

by 50 ml of the material to flow from a cup through

a specified orifice under standard test conditions and

specified temperature.


Specific Gravity

The specific gravity is defined as the ratio of the

mass of a given volume of the substance to the mass

of an equal volume of water, the temperature of both

being 270C.

Generally the specific gravity of pure bitumen is in

the range of 1.01 to 1.03

Properties…..


Penetration test…. for testing hardness or softness

Ductility test…. for adhesiveness & elasticity

Viscosity test…. for measuring resistance to flow

Float test…. to define the consistency

Specific gravity test…. for knowing mass / weight

Softening point test…. temperature at which it softens

(350 to 750)

VARIOUS TESTS ON BITUMEN


Flash point test…. lowest temperature at which

takes fire momentarily

Fire point test…. lowest temperature at which it

ignites and burns

Solubility test…. for testing impurities

Spot test…. for determine over heated or

cracked bitumen

Water content test…. to know the water content

Bitumen content test…. to know the bitumen content

Various tests on bitumen……..


IS SPECIFICATIONS FOR BITUMEN TEST


FAILURES IN PAVEMENT

• Major are two in category

– Fatigue

• Fatigue cracking - series of interconnecting cracks onthe pavement surface caused by repeated trafficloading

• Fatigue occurs at places of bituminous layer

– Rutting

– It is called permanent deformation because it represents an accumulation of small amounts of unrecoverable deformations

– under the channelized repeated wheel loads


FATIGUE


Fatigue cracking


RUTTING

Rutting in wheel paths


Reflection cracking at PCC Joints


• Subgrade - Core Cutter Method or Sand Replacement Method

• Overlays - Benkelman Beam Deflection

» In combination with roughness (5th towed wheel bump Integrator)

FIELD EVALUATION


SAND REPLACEMENT


BITUMEN EXTRACTION


FIFTH TOWED WHEEL BUMP INTEGRATOR


Road work is under progress under PMGSY


Strengthening of rural infrastructure through construction of roads under PMGSY


Connectivity with urban areas through road constructed under PMGSY


CLOSING REMARKS

All roads need maintenance

Several types of maintenance works

Timely maintenance measures avoids severe damage

and saves lot of money

Quality control measures during selection of pavement

materials and construction always lessen the

maintenance


QUESTIONS AND DISCUSSION

nac pavements

Documents

hydbituminous pavement

hydrigid pavement

hyd block pavements

bitumen materials failures

base course material

hydmaterial properties

hydcementcement concrete

subgrade wbm