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Transcript of PMB lecture
MODIFIED BITUMEN-Product, Purpose, Advantages Including Global and Indian
Scenario
Dr Sunil BoseDeputy Director
Central Road Research InstituteNew Delhi
TYPICAL PROBLEMS IN INDIA
• Severe Overloading
• Extreme variation of climatic conditions
• Premature cracking of pavements
LIMITATIONS OF CONVENTIONAL BITUMEN
• BRITTLENESS AT LOW TEMPERATURE• BECOMES SOFT IN HOT CLIMATIC CONDITIONS• HIGH TEMPERATURE SUSCEPTIBILITY• SUSCEPTIBLE TO VISCOELASTIC DEFORMATION (RUTTING)• FATIGUE FAILURE (CRACKING)
POOR ADHESION
CRRICRRI
CRACKING AT LOW TEMPERATURE
Hot Temperature Failure, Rutting
CRRICRRI
Bitumen produced by the traditional
methods of vacuum reduction and
air blowing of petroleum crude can not
meet all the requirements of increasing
severe service conditions namely :
1. Roads with high traffic intensity of
expressways & highways
2. Road locations subjected to heavy traffic
stress e.g. bus stops, intersections,
roundabouts & bridge decks.
3. Reflection cracks in bituminous overlays
over cracked concrete pavements
4. Urban roads where reduced surfacing
thickness is desired
5. Surfacing for low temperature snow
bound areas
6. Airfield surfacing where high stiffness
and thermal stability is required
A S0LUTION FOR ALL THESE PROBLEMS LIES IN USE OF POLYMER MODIFIED BITUMEN
WHAT ARE POLYMERS?
When small chemical units, called monomers, are
joined together in chains they form polymers.
When monomers such as styrene and butadiene
are reacted into chains, for example, they form
polystyrene and polybutadiene, respectively.
EFFECTS OF POLYMERS ON BITUMEN PROPERTIES
Reduced temperature
Susceptibility resulting in :
Increased stiffness at high
Road temperatures
(reducing permanent deformation)
Reduced stiffness at low road
Temperatures
(reduced cracking)
Classification of Polymer Modifiers
There are mainly two types of polymers used for development of Polymer Modified Bitumen (PMB)
Thermoplastic:
Plastomers: e.g low density Polyethylene (LDPE)
Ethylene Vinyl Acetate (EVA)
Elastomers: Ethylene Butyl Acrylate (EBA).
Styrene Butadiene Rubber (SBR)
Styrene Butadiene Styrene (SBS)
Polyisoprene, chloroprene
Polybutadiene, Ethylene Ter Polymer
Natural Rubber,
Waste Tyre Rubber
Thermosets :
Epoxy Resins
Properties Improved by Rubber/Polymer
A sufficient increase in viscosity, prevents
plastic deformation.
An increase in flexibility and elasticity of
binder at low temperatures to delay the crack
formation (mainly due to fatigue failure) and
loss of chipping.
High thermostability, improved homogeneity and
aging resistance, thus helping to reduce the
hardening of the binder during mixing, laying and
pavement service life.
Development of PMB
• Melting Behaviour of Polymers LDPE - 114 ° C EVA - 90 ° C Ethylene Ter Polymer - 60 ° C • Degradation Behaviour Above 250 ° C
Basic Blending Plant
~15-20 HP
~100RPM
Temperature of Asphalt 160 °C.
Ability to add polymers
Polymer’s Interaction with Bitumen
Polymer Dispersed in Bitumen
CRRICRRI
Polymer’s Interaction with Bitumen
Bitumen Dispersed in Polymer
Polymer’s Interaction with Bitumen
Polymer Network in Bitumen
CRRICRRI
Polymer’s Interaction with Bitumen
Polymer Network Grafted to Bitumen
CRRICRRI
PRODUCT (MODIFIED BITUMEN)
Be compatible with bitumen
Resist degradation of bitumen at mixing temperature
Be capable of being processed by conventional mixing and laying
machinery
Produce coating viscosity at application temperature
Maintain premium properties during storage, application
and in service
Be cost-effective on a life- cycle-cost basis.
Advantages of PMB
- Lower susceptibility to daily and seasonal
temperature variations
- Higher resistance to deformation at elevated
pavement temperature
- Better age resistance properties
- Higher fatigue life of mixes
- Better adhesion between aggregates
and binder
- Prevention of cracking and reflective
cracking
- Overall improved performance in
extreme
climatic conditions and under heavy traffic
conditions.
Extreme climatic conditions require different grades of bitumen similar to
different grades of engine oil in vehicles
CRRICRRI
With Polymer Modification, use the same bitumen for areas with extreme climatic
conditions
CRRICRRI
APPLICATIONS OF POLYMER AND RUBBER MODIFIED BITUMEN
Stress Absorbing Membranes (SAM)
Stress Absorbing Membranes Interlayer
(SAMI)
Renewal courses as a part of maintenance
High traffic loads, e.g., Highways and
Airfield Pavements
Flexural Fatigue Test
Apply Cyclic load till failure
37.6mmX37.6 mm X200 mmsizeMix Beam
Measured Strain0
2
4
6
8
1 0
1 2
0 1 2 3 4 5 6 7 8 9 1 0 1 1
100 Cycles/Minute
FLEXURAL – FATIGUE LIFE RESULTS
Beam Size- 200 mm x 37. 6 mm x 37.6 mm (Temp
25 °C )
SAMPLE CYCLES SAMPLE CYCLES
TO FAILURE TO FAILURE
A 80/100 4500 A+2 % LDPE 4080
B 60/70 11500 A+5 % LDPE 4800
A+2 % SBS 48802 A+10% LDPE 750
A+5% SBS 91000 A+2 % PE+2% EVA 10840
A+10% SBS 63800 A+2% PE+5% EVA 14750
A+2% EVA 4900 B+2 % PPW 8800
A+5% EVA 8800 B+1% HTPB 46500
A+10% EVA 10100 B+2% HTPB 16500
Global scenario
Modifiers as an individual or as a group
of materials have made successful path
into the road and other construction
industries in advanced countries.
Elastomer modified binders
(SBS, SBR, SIS) 75%
Plastomer modified binders
(EVA, LDPE, EMA, EBA) 15%
Rubber and other miscellaneous
modified bituminous binders 10%
APPLICATIONS AND TYPE OF MODIFIERS
USED IN DIFFERENTCOUNTRIES
INDIAN SCENARIO
LABORATORY RESEARCH
In India, the Flexible Pavements Division
of CRRI initiated laboratory research on
polymer modified bitumen in 1980. Since
then number of polymer/rubber modifiers
were investigated for their feasibility of
using for hot mix as well as cold mix
paving applications.
These modifiers are :
LDPE
EVA
SBS
GILSONITE
NATURAL RUBBER
POLYBUTADIENE RUBBER
ETHYLENE TER POLYMER
SYNTHETIC RUBBER
PLASTIC WASTE
SEALOFLEX
STARFLEX
CRUMB/TYRE RUBBER
CHEMICALLY TREATED CRUMB
RUBBER
Field Trials : Field trials using PMB products patented by CRRI
were carried out in different climatic regions of
India. A list of such trials is given below :
R-54 Ministry of Surface Transport
Research Scheme
• Test Tracks were laid on NH-2 on
Kanpur Varanasi with Bitumen
Modified with LDPE, EVA, SBS
and
Crumb Rubber
PMB Test Tracks using SBS and
EVA were laid on :
NH-3 near Bombay
SH-45 Km. 308.8 to 309.0 Joshimath
Badrinath Road
Manali Kulu Road
Hindustan Tibet Road near Shimla
Chemically Treated Crumb Rubber- Test Tracks were laid on NH-1 near Ambala
- Ring Road Opposite Rajghat near Delhi
Natural Rubber Modified Bitumen- M.C. Road Trivandrum
ETHYLENE TERPOLYMER Jaipur Agra Road near Jaipur
Goa Airfield
PERFORMANCE OF TRIAL SECTIONS
• Periodic performance evaluation of test
section laid with PMB/CRMB upto five
years after construction proved their better
performance over conventional surfacing.
• Maintenance period of 12 years on a
National Highway with a heavy traffic, two
renewal coats will be enough instead of
three as required under the existing
specification.
• The use of SAMI of modified bitumen in
between old surface having extensive
cracks and renewal coats, extends life of
renewal by 2-3 years.
• The cost of periodic maintenance may be
reduced by 20-30 Percent.
PMB Road after 7 years
CRRI
Extensive potholes on the existing surface
prior to laying
Hump formation due to bleedingon the existing surface
Ravelling on the surface before laying the test section
Cracking on the existing surface before laying of test section
View of the test section in 2003
Surface condition of test section in 2006
Crumb Rubber Modifier for Use in Modified Bitumen
CONSTRUCTION OF A PMB SECTION IN PROGRESS
Laying in progress
View of Ahmedabad
Vadodara
Expressway
CRMB SECTION ON NH-8
EXTENSION OF LIFE BY USE OF PMB/CRMB
SPECIFICATION COST(Rs)/m2
LIFE(Years)
EXTRA LIFE(Years)*
25 mm Thick SDBC – 60/70 70 3-4 -125 mm Thick BC – 60/70* 80 4 –5 --25 mm Thick BC – 80/100* 74 4 –5 --25 mm Thick BC – 60/70 96 5-6 +1SAM-CRMB 28 4-5 --SAMI+25 mm Thick BC – 80/100 102 6-7 +2SAMI+25 mm Thick BC – 60/70 108 6-7 +2SAMI+40 mm Thick BC – 80/100 110 7-8 +3SAMI+40 mm Thick BC – 60/70 116 7-8 +3SAMI+25 mm Thick BC (CRMB) 116 7-8 +325 mm Thick BC (EVA+LDPE) 90 7-8 +325 mm Thick SDBC (SBS) 88 7-8 +325 mm Thick SDBC (EVA+LDPE) 84 6-7 +225 mm Thick BC (CRMB) 84 6-7 +3
* with reference to 25 mm thick BC of conventional bitumen, cost 1999