Highway Research Record

II. PAVEMENT ENGINEERING AND PAVING MATERIALS
2. FLEXIBLE PAVEMENT
ON GOING PROJECTS
Demonstration of Microsurfacing Technology Using Natural Rubber Latex Modified Emulsion and Imported Machine Available with Assam PWD

Date of Start: January 2004
Central Road Research Institute, New Delhi (R, I)

Present Status & Progress

Three locations with different values of deflection (2 mm, 1.5 mm and 1.0 mm), traffic (5500 CVD), distress (30% and 50%) etc. were identified at NH-37 near Guwahati for construction of experimental test sections and demonstration of microsurfacing technology. Two specifications of ISSA Grading II and Grading-III using natural rubber latex as binder have been laid at km 177 of NH-37 near Shonapur and km 136 and km 137 of NH-37 near Guwahati Airport. An emulsion containing 3% natural rubber latex having compatibility to Guwahati Aggregates was prepared. Mixes were designed for grading II & III of ISSA. First demonstration stretch using microsurfacing technology was laid in March 2004 using grading III and 10% natural rubber latex as binder on a pavement having a deflection of 2.0 mm. Two observations on the stretch laid in March 2005 have been undertaken. Performance of pavement under test section is found satisfactory. It appeared from surface condition that road shall be in good serviceability for at least one more year. Development of hairlines cracks have been observed at the time of second observations. Recently, demonstration of grading II at km 136 and 137 of NH-37 near Guwahati Airport in which microsurfacing using 12 % natural rubber latex modified emulsion has been laid near Airport followed by knowledge dissemination workshop for Engineers of North East States were organized in March 2005.

Findings/Conclusions
(i) Microsurfacing is fast and environment friendly technology.
(ii) Microsurfacing technology can be used for preventive as well as periodic maintenance of pavements.
(iii) Microsurfacing technology can be used for deficient pavement conditions. Deflection of pavement should not exceed 1 mm for periodic maintenance. Preventive maintenance can be undertaken on a deficient pavement with 2mm deflection to      improve serviceability.
(iv) Natural rubber latex can be used as modifier for manufacture of microsurfacing emulsions for cost effective road       maintenance.
(v) In case, surface has extensive deep cracks, either a scratch coat of microsurfacing is needed or two layers of microsurfacing      may be used. In North Eastern States, like Assam, demonstration project showed that cost of single layer treatment is      about Rs.60/m2, using 8 Kg/m2 aggregate quantity, which is 80-100% economical than 25 mm thick BC/SDBC surface.

Limitations
(i) Since performance monitoring is in progress, final conclusions may be drawn after completion of two more observations.
(ii) Experimental studies and performance monitoring of microsurfacing treatments at few more locations is needed.

Recommendations
NHAI may sponsor further studies for usage of technology for maintenance of NHDP corridor, since technology is fast, environment friendly and highly economical.