CONCRETE PAVEMENTS : HIGHWAYS TO...
Transcript of CONCRETE PAVEMENTS : HIGHWAYS TO...
GOOD ROADS : A FUNDAMENTAL RIGHT !
On a PIL regarding
accidental deaths due
to pot holed roads,
Hon’ble High Court of
Maharashtra observed
that this is the right
time for all concerned
to understand that
‘Right to Good Roads’
is a part of
Fundamental Rights of
Indian Citizens (20th
May, 2015)
WHICH ROAD IS A GOOD ROAD ?
Serviceability
Durability
Cost Effectiveness
Least Damage to Environment
DURABILITY AND MAINTENANCE
• Concrete highways are far more durable than other
pavement types
• Design life is normally 25-30 years but actual service life
may be more than the design life
• Do not require any major maintenance during service life
• India spends nearly 70% of the annual road sector budget
(Rs.30,000 Cr.) only on the maintenance of bituminous roads
which is a huge wastage of tax payer’s money
Marine Drive CC Road
(Mumbai)- First
Constructed in 1939
Re-constructed as CC
Road in 2012 after
more than 70 Yrs.
CONSTRUCTION AND MAINTENANCE COST
• Initial construction cost 10-15% higher than
bituminous road
• 25-35% cheaper in life cycle cost
• Almost maintenance free. Only joint resealing is
required once in 5-6 years
FUEL CONSUMPTION
• Large deflections of flexible pavement under load
due to visco-elasticity
• Very less deflections of rigid pavements
• Thus, rolling resistance of rigid pavements less
resulting in reduced fuel consumption
FUEL SAVING STUDIES
• CRRI – CMA (India – 1997) Study – 14 % Less for Heavy
Loaded Trucks
• Swedish National Road & Transport Institute (Four Axle
Trailer-2010) – 6.7 % Less
• University of Texas at Arlington for city Driving (Light
1360 kg Van – 2010) – 3 to 8.5 %
• Other Global studies show that fuel consumption of heavy
vehicles is 10-15% less on concrete highways
WHAT DOES FUEL SAVING MEAN FOR US ?
• Two lane carriageway length - 100 km
• Fuel consumption of truck @ 5 km/l = 20 Liters
• Truck traffic – 4500/day
• Annual Fuel consumption = 32850000 liters
Fuel Saving Annual Cost of
Saving @
50/L, Rs
Construction
Cost 2 Lane,
300 mm, Rs.
Pay-Back
Years
5 % 8.21 Crore
204 Crores
25 years
10 % 16.4 Crore 12.5 Years
14% 23.0 Crores 9 Years
• Total length of NH – 1,00,000 km
• Present Loss – Rs. 8210 Cr. (5% Fuel Saving)
– Rs. 16400 Cr. (10% Fuel Saving)
GREEN HOUSE GAS EMISSION OF RIGID AND FLEXIBLE
Methods CO2 Emitted (in Tonne CO2 eq)
Rigid Pavement Flexible Pavement
Embodied Energy
1246 95
During construction
6.6 84
Material Transport
46.7 40.7
Total 1299.3 219.7
• CO2 eq due to 5% Fuel Saving – 1372 T in 30 Years
TYRE BURSTING ON EXPRESSWAYS
• Sudden Release of Tyre Inflation
Pressure
• Inflation Pressure > Tyre Strength
• Temperature rise of Tyres during
Travelling
IS ROAD SURFACE FRICTION RESPONSIBLE FOR TYRE HEATING ?
• Possible External Source of Heating
• Rolling Friction:
Coefficient value - 0.01 to 0.015 (tyre-concrete)
0.01 to 0.020 (tyre-asphalt)
•Sliding / Kinetic Friction:
Coefficient value - 0.6 to 0.85 (tyre-concrete)
0.5 to 0.80 (tyre-asphalt)
• Road surface temperature:
Ambient Temperature (45°C) - 57°C (concrete)
70 °C (asphalt)
• Ambient temperature
• Thermal conductivity, W/m°C: 0.293 (rubber), 1.719 (Concrete)
FLEXING OF TYRE : TRUE CAUSE OF HEATING
• Deformation of Side Walls
• Hysterises loses in Rubber and Steel
Wire Beads leads to Heating
•Continuous built up of heat at
sustained high speed weakens the bond
of steel wire and rubber, increase
pressure and eventually tyre bursts
•Pressure increase – 1.6 psi/10°C
Flexed Tyre
Un-flexed Tyre
FACTORS INFLUENCING FLEXING
• Vehicle Speed:
Higher the speed higher the flexing & heating
Typical Maruti Swift tyre flexes per minute:
- 620 at 60kmph
- 1240 at 120 kmph
- 1550 at 150 kmph
• Tyre Pressure:
Low pressure – more flexing & heating
High pressure – less flexing & heating
• Load on Tyre:
Higher load – more flexing & heating
Lower load – more flexing & heating
LOAD-SPEED-TEMPERATURE RELATION(Yeong & Hwang, 2004, Taiwan)
Pressure = 30 psi
Load
Speed
4 KN
(Swift + 2)
6 KN
(Innova + 2)
8 KN
(Innova + 8)
40 kmph 60 °C 65 °C 70 °C
60 kmph 70 80 90
80 kmph 90 100 110
100kmph 105 120 130
120 kmph 120 135 155
Tyre Temp. : 100-110 Safe
140-150 Critically High with 80 % Probability of Bursting
160-170 Burst
CONTINUOUSLY REINFORCED CONCRETE PAVEMENT (CRCP)
• No joints & joints related
problems
• Thickness same as for JPCP
• Better riding quality
• Almost zero maintenance
• Longer life of more than 40 years
• Initial cost higher by 25 % than
JPCP
• 30 – 40 km length constructed in
Pune city
TWO LIFT CONCRETE PAVEMENT
• Two concrete layers placed wet-on-
wet within 30-60 minutes
• Top layer (50-100 mm) of good
quality concrete (M40) with good
quality aggregates
• Lower layer (200-250 mm) of lower
strength concrete (M20-M30) with
inferior quality aggregates –
marginal, recycled, C&D
• 28% saving of cement hence cheaper
• Common practice in France,
Germany, Austria, US
• IRC code under preparation
SHORT PANELED CONCRETE PAVEMENT
• Suitable for both whitetopping and
new rigid pavements
• Slab / panel size – 1m x 1m
• Dowels only at construction joints
• Lower bending and curling stresses
• 300 mm conventional thickness can
be replaced by 200-220 mm with short
panel size
• Design as per IRC:SP:76
•NICE road in Bangalore as
whitetopping
165 km long access
controlled eight lane
expressway between
Delhi & Agra, 2012
95 km long access
controlled six lane
expressway between
Mumbai & Pune, 2002
Thin White Topping, 180
mm, on Pune City Roads,
2013
Thin White Topping, 200
mm, on Bangalore Ring
Road, 2013