Specification Part 3 - Road & Bridge Works - Urban Administration ...

(2) Spraying the chips with a light application of creosote, diesel oil or kerosene at ambient
temperature. This spraying can be done in a concrete mixer or on a belt conveying the chips from
stockpile to gritting lorries.
510.3. Construction operations
510.3.1. Weather and seasonal limitations: Clause 501.5.1 shall apply.
TABLE 500-21.
GRADING REQUIREMENTS FOR CHIPS FOR SURFACE DRESSING
IS
Designation
mm
Sieve
Cumulative per cent by weight of total aggregate passing
for the following nominal sizes (mm)
19 13 10 6
26.5 100 - - -
19.0 85-100 100 - -
13.2 0-40 85-100 100 -
9.5 0-7 0-40 85-100 100
6.3 - 0-7 0-35 85-100
4.75 - - 0-10 -
3.35 - - - 0-35
2.36 0-2 0-2 0-2 0-10
0.60 - - - 0-2
0.075 0-1.5 0-1.5 0-1.5 0-1.5
Minimum 65%
by weight
of aggregate
Passing 19 mm,
retained 13.2mm
Passing 13.2 mm,
retained 9.5 mm
Passing 9.5
mm, retained
6.3 mm
Passing 6.3
mm, retained
3.35 mm
510.3.2. Preparation of base:
(i)The base on which the surface dressing is to be laid shall be prepared, shaped and conditioned
to the specified lines, grade and cross section in accordance with Clause 501 or as directed by
the Engineer in charge.
(ii)Prime coat, where needed, shall be provided as per Clause 502 or as directed by the Engineer
in charge.
(iii)Where the existing surface shows signs of fatting up, the excess bitumen shall be removed by
burning off, or manually, as specified in the Contract or directed by the Engineer in charge.
(iv)The bituminous surface to be dressed shall be thoroughly cleaned either by using a
mechanical broom and / or compressed air, or any other approved equipment / method as
specified in the Contract or by the Engineer in charge.
(v)The prepared surface shall be dust free, clean and dry, (except in the case of cationic emulsion
where the surface shall be damp).
510.3.3. Application of binder:
(1) Apply the binder (at specified temperature) as per rate of speared of binder or as designed
with an appropriate bitumen distributor bitumen distributor fitted with a spray bar. Binder shall be
sprayed/ distributed uniformly over the prepared base, with self propelled or towed sprayer,
capable of supplying the binder at specified rate to provide a uniformly unbroken spread of
binder.
(2)The application temperature for the grade of binder used shall be as given in Table 500-22 and
the rate of spray as given in 510.2.3.
510.3.4. Application of stone chips: