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Modified Bitumen in India - Must Know

1. Specifications Following publications govern the property of ModifiedBitumen in India;

a. IRC SP: 53(2002) or Indian Roads Congress Special Publication 53;Guidelines on Use of Polymer and Rubber Modified Bitumen in Road

Construction

b. IS 15462 : 2004; Indian Standard on Polymer and Rubber ModifiedBitumen- Specifications

c. Ministry of Shipping Road Transport and Highways- Clause 5212. Type of Modified Bitumen These are divided as follows:

a. Rubber Modifiedi. Natural Rubber Modified Bitumen (NRMB)

ii. Crumb Rubber Modified Bitumen (CRMB)b. Polymer Modified

i. Modified with Elastomeric Polymers PMB (E)ii. Modified with Plastomeric Polymers PMB (P)

3. Relative Performance CRMB, NRMB, PMB(P) and PMB(E) having the samesoftening point are not equivalent in performance and the cost. They maydiffer in following attributes:

a. Elastic Recovery, Fatigue resistance, life of pavementb. Creep and rut resistancec. Susceptibility to low temperatures and high rainfalld. Suitability for extreme temperaturese. Suitability for subzero temperaturef. Suitability for very heavy/intense traffic

4. Suffix. It denotes the following:a. NRMB and PMB - Penetration valueb. CRMB Softening Pointc. Suffix in PMB(E) 40, PMB(P) 40, NRMB 40 denotes their penetration

value whereas in CRMB 60, it denotes the softening point.

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5. High Shear Device An essential part of a processing plant for modifiedbitumen. As per the note in Clause 3 of IS 15462 2004:

Homogeneity is very important for the desired performance of polymer

and rubber modified bitumen. Hence these should be prepared at refinery

or by appropriate industrial process and plant having high shear device. The

use of high shear mixer is essential.

6. Refinery Modification of Bitumen does NOT require a refinery. Modifiedbitumen produced by a vender in a refinery, if not processed using a high

shear device, violates the provisions of IS 15462 2004 and therefore

cannot be permitted for use as binder.

7. Central Plant Processing of modified bitumen requires a central plant andan established process using high shear device, curing of the material and

functional laboratory to test the material for penetration, elastic recovery

and softening point, before dispatch to the client.

8. Transportation Modified Bitumen can be transported in bulk tankers or indrums. The bulk tankers must have the following:

a. Good functional insulation so that the drop in temperature is notmore than 10deg C in 24hours.

b. Unloading pumpc. Heating arrangementd. Circulation mechanism

9. Storage at HMP Modified Bitumen must be stored separately in a cleanstorage having the following:

a. Good functional insulationb. Indirect heating arrangementc. Circulation Mechanismd. Agitation mechanism

10.Temperatures Temperature regime of modified bitumen and its mixes is 15to 20deg C higher as compared to straight grade bitumen. These have been

specified in section 521 of the MOSRT&H specifications.