Nagpur: The Central Road Research Institute (CRRI), New Delhi, has suggested four rehabilitation options for VIP Road, where the cement road constructed some years ago under Phase-II of the Rs324 crore project has developed cracks.
TOI had highlighted the horizontal and vertical cracks on VIP Road between Traffic Park Square and Alankar Square. NMC has withheld part payment of Rs40 lakh to the agency that constructed the VIP Road stretch.
In a letter to NMC’s public works department, head and principal scientist (rigid pavement division, CRRI) Dr Rakesh Kumar has offered four rehab options. One option asks NMC to provide an ‘edge sub-surface drain’ adjacent to concrete pavement slab on each carriageway of the road. This provision may drastically minimize the rate of increase in cracking, crack width and overall deterioration of the pavement, by providing quick drainage to water infiltrating through cracks or by any other means. Other options include reconstruction of pavement using concrete 120mm paver blocks.
A senior official from NMC’s PWD department said though the CRRI offered four options, the civic body will adopt the first one. Under this method, hot bituminous mix overlay with glass fibre grid technology will be used to fill the widening cracks.
As per CRRI’s suggestion, a hot bituminous mix overlay with saw cut and seal on top of the joints with glass fibre grids as an asphalt interlayer. It has also suggested four steps to carry out repair over road cracks of this particular stretch, he said.
The CRRI rehab options suggest NMC should first clean and seal the wide cracks with a good hot bituminous mix of proven performance, which is similar to one generally used in the geographical region of Nagpur. The filled bituminous mix shall be properly compacted and levelled, it reads.
The CRRI, however, pointed out the pavement slab distresses are almost absent in VIP Road like joint breaks, corner breaks etc.
After proper sealing and compacting the wide cracks, a layer of tack coat would be provided on the pavement slab. Over the tack coat, a high quality glass fibre grid as an asphalt interlayer will be used. This is used to delay the propagation of reflective cracks while acting as SAMI (Stress Absorbing Membrane Interlayer). The final step will include the tack coat applied geo-composite being overlaid with a 35mm thick high quality hot bituminous mix. The CRRI, however, suggested NMC to ensure a proper transverse slope is provided to drain out rain water.
INFOBOX
ERROR AND TRIAL METHOD
* Hot bituminous mix overlay with glass fibre grid technology will be used to repair the cracks on VIP Road
* Cracks will be cleaned, sealed with hot bituminous mix
* A layer of tack coat (3-4mm) will be provided on the pavement slab
* Over the tack coat, a high quality glass fibre grid as an asphalt interlayer will be used. Again glass fibre will be overlaid with a tack coat
* Tack coat applied geo-composite will be overlaid with 35mm thick high quality hot bituminous mix of SDCA/DAC with PMB
* Proper transverse slope will be provided to drain out rain water