Quality Assurance Handbook for Rural Roads Volume-I - pmgsy

(ii) Aggregate Grading:
107
Quality Assurance Handbook for Rural Roads
The combined coarse and fine aggregates shall conform to one of the gradings given in
Table 509.1
TABLE 509.1 AGGREGATE GRADATION FOR MIX SEAL SURFACING
IS sieve designation (mm) Cumulative percent by weight passing
Type A Type B
13.2 — 100
(b) Binder
11.2 100 88 -100
5.6 52 -88 31 -52
2.8 14 -38 5 -25
0.090 0 -5 0 -5
Requirements specified in Sub-section 508.1 shall apply.
2. Horizontal Alignment
Surface levels, surface regularity and quality control tests and frequencies shall be exercised as
per the requirement given in Sub-section 508.1
C. Do’s and Don’ts
(i) Follow do’s and don’ts given under Sub-section 508.1
(ii) Generally, Mix Seal Surfacing should not be placed directly over WBM base.
510. SEAL COAT
The seal coat shall be any of the three types mentioned below:
Type A : Liquid seal coat comprising of an application of layer of bituminous binder followed by a
cover of stone chips.
Type B : Premixed seal coat comprising of a thin application of fine aggregate premixed with
bituminous binder.
Type C : Premixed seal coat comprising of an application of 6.7 mm size stone chips premixed with
bituminous binder.
A. Methodology
Apply seal coat immediately after laying the bituminous course. The surface should be clean and
free of dust and extraneous material before application of the seal coat.
1. Type A Seal coat with bitumen:
(i) Apply heated bitumen with a temperature between 150 0 C and 163 0 C uniformly with the
help of a bitumen sprayer.