By

P.Ramu Assistant Professor

Dept of Civil Engineering

VNR VJIET

1 VNR PROTOCOL FOR LABORATORIES

VNR Lab Protocol – Transportation Engg. Lab

Need of Lab Protocol

Why we want to conduct ,what experiments to be

conducted.

What safety measures to be taken while conducting the

experiments.

Laboratory maintenance.

2

Agenda

What is the Role of Highway Engineering in INDIA?

Types of Pavements?

Importance of Flexible Pavement.

What is the Role of Materials in Construction?

Need of Conducting different types of material tests.

Safety Measures

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Role of Highway

In terms of road network, India is the second largest country in the

world (next to USA) having a stretch of 33, 13,739 km.

National Highways having stretch of 65,569 km (2%), respectively.

Surprisingly, the government statistics say that 40% of the road traffic runs

on the 2% stretch of National Highway road network.

Thus, a great care and attention is given to develop the National Highways

to International Standards.

The road network is the backbone of a nation and speaks about the degree

of development of a Country.

Hence, a lot of care has been taken by the Government and NHAI to

substantially improve the road network.

Keeping in view the fact that on an average about 75,000 people fall prey

to road accidents.

4

Classification of Pavements

Flexible Pavements.

Earthen Roads.

Gravel Roads.

Bituminous Roads.

Rigid Pavements.

Reinforced Concrete.

Plain Concrete Roads.

Pavement Blocks

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Importance of Flexible Pavement

6

A bituminous road is that which is constructed by using Bitumen. It is also called

flexible pavement.

because it changes its shape according to nature of load and sub base.

A road or pavement is a structure consisting of super imposed layers of processed

materials above the natural soil subgrade.

whose primary function is to distribute the applied vehicle loads to be sub grade.

The pavement structure should be able to provide a surface of acceptable riding

quality, adequate skid resistance, favorable light reflecting characteristics, and low

noise pollution.

Importance of Flexible Pavement 7

The flexible pavement layers reflect the deformation of the lower layers on to the

surface of the layer.

Thus if the lower layer of the pavement or soil subgrade is undulated, the flexible

pavement surface also gets undulated.

Load Distribution of Pavement 8

Role of Materials in Construction

9

While designing a structure, engineer assumes certain value of strength for each of

material being used therein.

When the structure is being constructed, it is the bounden duty of the field

engineers to get the same validated by regular testing of material.

The quality of materials used in any infrastructure does play a vital role with regard

to its ultimate strength and durability in the long run.

The most important Highway materials are Soil, Road aggregates, Bitumen and

Bituminous Materials, concrete (cement, sand, water) etc.

Road Aggregate Properties & Tests 10

Property Explanation Test

Strength Resistance to Crushing Crushing Test

Hardness Resistance to Abrasion Los Angeles

Abrasion Test

Toughness Resistance to Impact Impact Test

Good Shape Better workability, Interlocking

and Strength

Shape Tests

Specific Gravity Measure of strength and

presence of voids

Specific Gravity

Test

Angularity

number

Workability( level of

roundness)

Angularity test

Road Aggregates

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These have to bear the stresses due to the wheel loads and hence they should

posse’s sufficient strength to resist crushing.

They should be hard enough to resist wear due to abrasive action of traffic.

The aggregates in the pavement are also subjected to impact hence toughness is

another desirable property of aggregates.

The stones used should be durable and resist disintegration due to action of

weather, this property is called soundness.

Aggregates may have rounded cubical angular flaky or elongated shape of particles.

The flaky or elongated particles will have less strength and durability hence too

flaky and elongated particles should be avoided.

C.A should be hard, strong, dense, durable, clean, and free from clays or loamy

admixtures or quarry reuse or vegetable matter.

Tests on Road Aggregates

Aggregate Crushing Value

Aggregate Impact Value

Abrasion Test

Sp. Gravity & Water Absorption

Shape Test

Flakiness Index

Elongation Index

Angularity number

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Aggregate Crushing Test

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Dry material passing 12.5 mm-10 mm retaining

Internal Dia 11.5 Cm and Height 18 Cm (Measuring)

25 Times Tamping – 3 Layers in measure as well as cylinder

Preparation of sample in

15.2 Cm Internal Dia

40 Tons in 10 Mins (4 Tons/Min)

Passing 2.36mm Sieve

Conclusion The principal mechanical properties required in stones are

a) Satisfactory resistance to crushing under

ROLLER during construction.

The application of heavy wheel loads on the pavement during its service life.

b) adequate resistance to surface abrasion under traffic.

The aggregate crushing value gives a relative measure of the

resistance of an aggregate crushing under gradually applied

compressive load .

The aggregate crushing value for C.C roads - ≤ 30%

The aggregate crushing value for wearing surfaces - ≤45%

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Conclusion

A low aggregate crushing value indicates higher resistance to

getting crushed under the application of specified load or

Higher Crushing Strength.

With aggregate crushing value 30 or higher’ the result may be

anomalous and in such cases the ten percent fines value

should be determined instead.

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Abrasion Test

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Abrasion Test

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Internal Dia 700mm, and Length 500mm

Abrasive Charges of Cast Iron with 48mm Dia weighing 390 - 445 gms

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

Cylinder Speed 30 – 33 Rpm

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

Passing 1.7mm sieve

Conclusion

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The aggregate used in surface course of the highway pavements

are subjected to wearing due to movement of traffic.

When vehicles move on the road, the soil particles present

between the pneumatic tyres and road surface cause abrasion of

road aggregates.

The steel reamed wheels of animal driven vehicles also cause

considerable abrasion of the road surface.

The principle of Los Angeles abrasion test is to produce abrasive

action by use of standard steel balls which when mixed with

aggregates and rotated in a drum for specific number of

revolutions also causes impact on aggregates.

Bituminous concrete surface course - ≤30%

cement concrete surface course - ≤35%

Impact Test

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Metal hammer of weight 13.5 to 14 Kg is arranged to drop with a free fall of 38.0

cm by vertical guides and the test specimen is subjected to 15 number of blows.

The crushed aggregate is allowed to pass through 2.36 mm IS sieve.

Aggregates to be used for wearing course, the impact value shouldn't exceed 30

percent.

Cup -25 times , measure – 25 times three layers

12.5- 10 mm retained material

The aggregate impact value is a measure of

resistance to sudden impact or shock,

which may differ from its resistance to gradually applied compressive load.

Specific Gravity & Water Absorption Test

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Material larger than 10 mm – wire mesh test

Smaller than 10 mm- pycnometer test

Take about greater than 2 kg of material.

Clean it with water to remove any fines.

Place in basket, then entire set up in water, move up and down 25 times to remove

any entrapped air.

Keep the agg. for a period of 24 hrs in water then find their weights along with

mesh.

Place the aggregates on cloth clean the surface and surface dry, then find weight

Find its oven dry weight 100 to 110 deg c for 24 hrs.

Find SSD weight

Find weight in water

Specific Gravity & Water Absorption Test

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Conclusion

The specific gravity of an aggregate is considered to be a measure of strength or quality of the material.

The specific gravity of aggregates normally used in road construction ranges from about 2.5 to 3.0 with an average of about 2.68.

Stones having low specific gravity are generally weaker than those with higher specific gravity values.

Though high specific gravity is considered as an indication of high strength, it is not possible to judge the suitability of a sample road aggregate without finding the mechanical properties such as aggregate crushing, impact and abrasion values.

Water absorption shall not be more than 0.6 per unit by weight.

Generally the water absorption not more than 2%.

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Shape Tests 23

The shape tests give only a rough idea of the relative shapes of aggregates.

Flaky and elongated particles should be avoided in pavement construction,

particularly in surface course.

If such particles are present in appreciable proportions, the strength of pavement

layer would be adversely affected due to possibility of breaking under loads.

Important for compaction, deformation resistance, workability, binder requirement

of bituminous mixes and workability in PCC.

Shape Tests 24

Flakiness Index: Percentage weight particles by total weight of aggregates

whose least dimension is 0.6 times the mean dimension.

Elongation Index: Percentage weight particles by total weight of aggregates

whose greatest dimension is 1.8 times the mean dimension

Thickness Gauge

Length Gauge

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Angularity Test Contd., 26

Angularity Test Contd., 27

The coarse aggregate angularity (CAA) test is a method of determining the

angularity of coarse aggregate.

Coarse aggregate angularity is important to ensure adequate aggregate interlock

and prevent excessive HMA deformation under load (rutting).

This test is used to help ensure that the resulting HMA mixture will be resistant

to deformation under repeated loads.

Specifying a minimum percentage of coarse aggregate angularity can also be

used to obtain improved durability for aggregates used in surface treatments

and to obtain increased friction and texture for aggregates used in pavement

surface courses.

Tests For Aggregates With IS Codes

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SPECIFICATION OF VARIOUS LAYERS OF RURAL

ROADS

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]

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