Starmac - CRMB is a Crumb Rubber based Modified Bitumen produced by mixing crumb rubber and other additives which are compatible with bitumen.
Starmac - CRMB, which is Crumb Rubber Modified Bitumen, is prepared in a centrally located state-of-the-art plant equipped with special high shear mixing facility, the first of its kind in South India. Starmac - CRMB has been specially designed after extensive research to meet the requirements of high traffic intensity, increasing axle loads, and varying climatic conditions of our country.
Starmac - CRMB is the ideal binder to overcome the concurrent problems of raveling, rutting, un-dulations, cracking, bleeding, shoving and pot-holing of bituminous pavement.
Bituminous mix, prepared with STARMAC has a higher stifness modulus, enhanced fatigue life, better resistance to creep & higher indirect tensile strength and quite suitable as renewal course and overlay materials on surface which are badly cracked and subjected to heavy traffic.
| CHARACTERISTICS | GRADE | METHOD OF TEST | ||
| Starmac 50 | Starmac 55 | Starmac 60 | IS No. | |
| Peneration at 25 Cm 0.1 mm, 100 g, 5s | <70 | <60 | <50 | 1203 |
| Softening point (R&B), 0C, Min | 50 | 55 | 60 | 1205 |
| Flash point, COC, 0C, Min | 220 | 220 | 220 | 1209 |
| Elastic recovery of half thread in ductilometer at 150 C, percent Min |
50 | 50 | 50 | Appen.1 of IRC:SP:53-2002/ Annex.A of IS 15462:2004 |
| Separation, difference in softening point (R&B), C, Max |
4 | 4 | 4 | Appen.1 of IRC:SP:53-2002/ Annex.B of IS 15462:2004 |
| Viscosity at 1500 C, Poise | 1-3 | 2-6 | 3-9 | 1206(PART 2) |
| Thin film oven test and tests on residue | ||||
| Loss in mass, percent, Max | 1.0 | 1.0 | 1.0 | 9382 |
| Increase in softening point 0C, Max | 7 | 6 | 5 | 1205 |
| Reduction in penetration at 250 C Max | 40 | 40 | 40 | 1203 |
| Elastic recovery of half thread at 250 C Min | 35 | 35 | 35 | Appen.1 of IRC:SP:53-2002 / Annex.A of IS 15462:2004 |
Starmac-CRMB is recommended for roads with heavy intense traffic and also for extreme climatic conditions.
Starmac - CRMB performs better than normal bitumen in high rainfall areas and in situations where the aggregates are prone to stripping. Due to its better creep resistance properties, Starmac - CRMB can also be used at busy intersections, bridge decks, and round-abouts for increased life of surfacing. Starmac - CRMB also finds useful applications in porous asphalts.
The selection of the grade of Starmac - CRMB will be based on traffic intensity and climate conditions as given below:
Starmac - CRMB is produced in a state of the art central plant with a high shear machine as per the guidelines laid down by IRC: SP: 53 and Indian Standard IS: 15462 specifications for Polymer & Rubber Modified Bitumen. Starmac - CRMB is available in bulk as well as packed drums.
Minimum Pavement Temperature C |
Minimum Atmospheric Temperature, 0C | |||
| <35 | 35-45 | >45 | ||
| <-10 | STARMAC 50* | STARMAC 55 | STARMAC 55 | |
| 10 to -10 | STARMAC 50 | STARMAC 55 | STARMAC 60 | |
| > 10 | STARMAC 55 | STARMAC 55 | STARMAC 60 | |
Temperature of mixing and rolling shall be slightly higher than conventional bituminous mixes.
The Broad range of temperature at different stage is as follows:
| Stage of work | Indicated temperature 0C |
| Binder at mixing | 165-185 |
| Mix at mixing plant | 140-160 |
| Mix at laying site | 130-150 |
| Rolling at laying site | 115-135 |