How to prepare existing road for asphalt works
The asphalt concreting on existing roads which asphalt is to be laid must be properly prepared. Pavement deficiencies which are likely to cause defects within the overlay should be corrected before the resurfacing commences.
These include:-
• Rutting and shoving in the surface or base
• Cracking associated with deformation from the pavement
• Pot holes and broken edges
• Bleeding, soft or elsewhere unsatisfactory patches
• Depressions greater than 25 mm due to subsidence or other causes not associated with pavement.
Areas containing rutting or shoving, cracked and deformed pavement or poor patching must be removed and replaced, usually with asphalt. (Refer Maintenance Manual for details). Broken edges should be repaired and pot holes filled up with asphalt. All loose material, vegetation etc. have to be removed before patching and tack coating.
Any small areas of fatty or bleeding surface should be burnt of (through an L.P. gas burner) or cut out and resurfaced with asphalt. Unless these areas are properly treated the excess bitumen can cause the brand new surfaces to get fatty. Where this problem is extensive it must be referred to the District Engineer for advice from the Construction Engineer as to the best method of treatment.
Depressions higher than 25 mm in an otherwise satisfactory surfaces ought to be brought towards the level of the encompassing pavement using a corrective course (for details see later).
Right before surfacing the pavement have to be swept and also a tack coat applied.
On Existing Concrete Roads
Preparation of concrete pavements for asphalt concreting on existing roads includes the next:-
• Patching of spalled areas
• Eliminating loose broken concrete and replacement with asphalt
• Cleaning loose material from joints
• Removing excess joint filler from around joints and cracks.
• Getting depressions in excess of 25 mm which has a corrective course
• Sweeping the pavement
• Tack Coating.