Quality Assurance Handbook for Rural Roads Volume-I - pmgsy

501. PREPARATION OF SURFACE
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Quality Assurance Handbook for Rural Roads
This Subsection deals with preparing an existing granular or black-topped surface prior to laying a
bituminous course.
A. Methodology
1. Preparing an existing granular surface
(i) All loose and extraneous materials should be removed and surface cleaned where a granular
profile corrective course is to be provided prior to laying a bituminous course; the existing
granular surface after cleaning should be slightly watered and the granular course laid.
(ii) The surface of all granular layers on which a bituminous course is to be laid should be
cleaned of all loose material and dust by air jet or wire brushes or other approved means
and should be correct to line, level and camber within the tolerances specified for base course.
(iii) Where a profile corrective course of bituminous material is to be laid, the granular surface
after removal of all loose material and dust should be primed with a suitable bituminous
primer as per ‘Sub-section’ 502.
2. Scarifying an existing bituminous surface
(i) Where an existing bituminous layer is required to be removed, it should be done by hand
picking without causing undue disturbance to the underlying layers. Any underlying material
which may have been disturbed should be removed and fresh base material supplemented,
if necessary and compacted.
(ii) The compacted granular surface, finished to line, level and cross-slope should be primed as
per specified procedure.
3. Preparing an existing bituminous surface
The surface shall be cleaned and any pot holes and cracks repaired before laying bituminous
treatment.
(a) Pothole and Patch Repairs
(i) The existing bituminous surface should be inspected and all pothole and patch areas made
free of any loose, defective material. The edges of all potholes shall be cut / trimmed with
hand tools vertically to form rectangular shape and shall be thoroughly cleaned with wire
brush, compressed air or other approved means. All dust and loose materials should be
removed from site. Layers below the level of bituminous construction should be replaced
using material of equivalent specification to the original construction and degree of
compaction. The area of bituminous construction should be primed and/or tacked with an
emulsion (meeting requirements of IS:8887) depending on whether the lower area is granular
or bituminous in nature. The sides of the excavated position should be painted with tack
coat material using a hand brush/sprayer.
(ii) The bituminous patching material should be either a hot mix or a cold mix, adopting the
respective specification. The bituminous mixture, prepared in a plant of suitable capacity
should be placed in layers of not more than 100 mm (loose) and compacted in layers with
roller/plate compactor/hand roller/rammer to the desired compaction standard.