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

centre except in super elevated and uni-directional cambered portions where it shall proceed from
the lower edge to the higher edge.
(iii)Each pass of the roller shall uniformly overlap not less than one-third of the track made in the
preceding pass.
(iv)The surface of the layer shall be carefully checked, after rolling, with a template and straight
edge and shall be within the tolerances specified, and any deficiencies corrected by reworking
and recomposing the layer.
(v)Care shall be taken not to over compact the layer.
(vi) The binder shall be heated to the temperature appropriate to the grade of bitumen approved
by the Engineer in charge and sprayed on the aggregate at the rate of IS kg15kg/10 sq. m.
(measured in terms of residual bitumen content) at a uniform rate of spray by mechanical
sprayers capable of spraying bitumen uniformly at the specified rates and temperatures.
(vii)Excessive deposits of binder caused by stopping or starting of the sprayers or through
leakage or for any other reason shall be removed and made good.
506.3.6. Spreading and rolling of coarse aggregate and application of binder for the
second layer:
(i)Immediately after the first application of the binder, the second la yer of coarse aggregates shall
be spread and rolled in accordance with the procedure detailed in Clause 506.3.5.
(ii)The second aggregate layer shall then be sprayed with binder at the rate of 15 kg/10 sq. m.
(measured in terms of residual bitumen content) in accordance with Clause 506.3.6.
506.3.7. Application of key aggregate:
(i)Immediately after the second application of binder, key aggregates shall be spread uniformly
and evenly, preferably by mechanical means, at the rate of 0.13 cu.m . /10 sqm. (ii)So as to cover
the surface completely. The key aggregate shall be clean, dry and free from dust and deleterious
matter.
(iii)If necessary, the surface shall be swept to ensure uniform application of the key aggregates.
The entire surface shall then be rolled with an 8-10 tonnes smooth wheel steel roller in
accordance with Clause 506.3.5.
(iv)While rolling is in progress, additional key aggregates, where required, shall be spread by
hand. Rolling shall continue-until the entire course is thoroughly compacted and the key
aggregates are firmly in position.
506.4. Surface Finish and Quality Control
The surface finish of construction shall conform to the requirements of Clause 902. All materials
shall comply with the requirements of the relevant provisions in Section 900 of the Specifications.
506.5. Final Surfacing
The built-up-spray-grout shall be provided with final surfacing within a maximum of forty -sight
hours. If there is to be any delay, the course shall be covered by a seal coat to the requirem ent of
Clause 513 before it is open to traffic. Where the seal coat is required as a result of the selected
method of performing this operation, then it shall be considered incidental to the work and shall
not be paid for separately.
506.6. Arrangements for Traffic
During the period of construction, arrangements for traffic shall be made in accordance with the
provisions of Clause 112 of the Ministry’s Specification for Road and Bridge Works (third revision)
1995.
506.7. Measurement for Payment
Built-up spray grout shall be measured as finished work in square meters.
506.8. Rate