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

Contractor is unable to complete a required length with a single continuous length of geogrid, a joint
may be made with the approval of the Engineer. Geogrid reinforcement shall be placed to lay flat and
pulled tight prior to backfilling . After a layer of geogrid has been placed , suitable means, such as pins
shall be used to hold geogrid in position until the subsequent soil layer can be placed. Under no
circumstances shall a track type vehicle be allowed on the geogrid before at least 150mm of soil has
been placed.
706.5 Measurement for Payment
Geogrid will be measured by square metre of roadway placement as shown in the plans with no
allowance for overlapping at transverse and longitudinal joints.
706.6 Rate
The Contract unit rate will be for geogrid for subbase or base. The rate is full compensation for the work
performed and furnishing, preparing, hauling, and placing materials including all labour, material,
freight, tools, equipment, and incidentals to complete the work to these Specifications.
707 GEOSYNTHETICS OVER EXISTING BITUMENOUS SURFACE
707.1 Scope
This work shall consist of laying geosynthetic materials over existing bituminous surface, including
preparation of surface and joining, stitching or overlapping of geosynthetic fabric etc., as part of
highway pavement strengthening in layers as shown on drawings or as directed by the Engineer.
707.2 Paving Fabrics
707.2.1 Description: This work shall consist of furnishing and placing as asphalt/ bitumen
overlay textile (paving fabric) beneath a pavement overlay or between pavement layers to provide a
water resistant membrane and crack retarding layer.
707.2.2 Material Requirements
The paving fabric will be a nonwoven heat set material consisting of at least 85 per cent by weight of
polyolefins, polyesters or polyamides. The paving fabric shall be resistant to chemical attack, rot and
mildew and shall have no tears or defects which will adversely alter its physical properties. The fabric
shall be specifically designed for pavement applications and be heat bonded only on one side to reduce
bleed-through of tack coat during installation. The fabric shall meet the physical requirements given in
Table 700-7. Heavy duty paving fabrics should be used in areas experiencing unusually high impact
forces or heavy loads such as airport runways and taxiways.
Table 700-7. Physical Requirements for Paving Fabrics
Property Units Standard
Requirements
Tensile Strength
Kg
36.3
Test Method
ASTM D 4632
Elongation
%
50
ASTM D 4632
Asphalt Retention
Kg/10 sq.m.
10
Texas DOT 3099
Melting Point
°C
150
ASTM D 276
Surface Texture
-
Heat bonded on
One side only
Visual Inspection
Notes: 1. Certification of conformance from paving fabric manufacturer shall be required.
2. All numerical values represent minimum average roll values (average of test results from any
sampled roll in a lot shall meet or exceed the minimum values) in weaker principal direction.
Lot shall be sampled according to ASTM D 4354, “Practice for Sampling of Geosynthetics for
Testing”.
3. Conformance of paving fabrics to specification property requirements shall be determined as
per ASTM 4579. “Practice for Determining the Specification Conformance of Geosynthetics”.