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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
3
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
5
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
11
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
12
Aggregate Crushing Test
13
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%
14
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.
15
Abrasion Test
16
Abrasion Test
17
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
18
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
19
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
20
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
21
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%.
22
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
25
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
28
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]
29
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