Highway Research Record

Investigation and Suggestion for Rectification of Cracked Slabs of National Highway - 4 (km 515 to km 592)

Duration: July 2004 February 2005
Central Road Research Institute, New Delhi (R, I)

Present Status and Progress
The project has been completed


Belgaum-Maharashtra Border Road Project consists of rehabilitation and strengthening of existing 2 lane road and widening to 4/6 lane divided carriageway from km 515 to km 592 section of NH-4 in Karnataka. The project road is to be constructed and maintained on BOT/Annuity scheme. For widening the existing road, a new 2 lane rigid pavement has been constructed. Some concrete slabs of the rigid pavement have cracked.
The general information about the project like structural design of the pavement, concrete mix design, material properties, laboratory test results of compressive and flexural strength of concrete, etc was collected from the records maintained by the contractor at site. A condition survey of the whole pavement stretch was carried out to know the type, severity, amount, and location of the distress. Cores were taken from the cracked slabs to get the information about the extent of deterioration from the top and the soundness of slabs. Cores were also taken from the sound portion of some slabs to check the compressive strength of the concrete. Cores taken from the cracked portions were examined and relevant information regarding width, depth, and possible cause of crack was recorded. Investigations on cores sample, survey of concrete pavement, and discussions held with the engineers at site led to the following causes of cracking.
(i) Delayed Joint Cutting
(ii) Construction on Gradients
(iii) Settlement of Subgrade
(iv) Plastic Shrinkage Cracks

Repairing Methodology Suggested
For the type of the cracks observed in slabs, following repairing techniques would be adopted depending upon the amount, extent, width and depth of the cracks in different slabs.
(i) Crack Grooving and Sealing with Suitable Epoxy Resin
(ii) Crack Stitching and Sealing
(iii) Full Depth Repairs
(iv) Slab replacement in heavily cracked panels

Performance study of repaired concrete slabs repaired with different techniques needs to be done so that the guidelines could be developed for economical and long lasting repairing techniques.