A range of paving designed specifically to meet The Department
of the Environment, Transport and the Regions ‘Guidance on the Use
of Tactile Paving Surfaces’.
Design considerations
Complementary products
British
Standard kerb and British Standard paving – all developments may
require tactile paving to conform to Building Regulations Approved
Document M.
Standards
Tactile paving products comply with the performance levels in
European Standard BS EN 1339.
Composition and manufacture
Tactile paving is hydraulically pressed in special moulds
incorporating pre-formed profiles.
Performance
Strength
Hard wearing under typical pedestrian usage.
Specification clauses
For further information, please refer to Charcon Technical Services.
Hazard warning paving
For use in identifying any potential hazard to pedestrians and
warning them to proceed with care.
Blister paving
For use in identifying a crossing place for the visually
impaired. Guidelines exist concerning the use, layout and colour of
blister paving.
Guidance paving
For use in identifying a safe route for pedestrians to travel,
avoiding obstacles and hazards.
Platform edge warning (offset blister)
Denotes the proximity of a railway platform edge. It can be used
on either surface or underground rail systems.
Platform edge warning (lozenge)
Used at street level to denote the existence of a platform edge
for light transport systems (e.g. monorails and trams).
Cycleway paving
Used at the beginning of a shared pedestrian/cycle route to
denote the path that each should follow.
Installation and maintenance
The following guidelines are applicable for both concrete flag
paving and natural stone flags. If further assistance is required,
please contact the Technical Helpline 01335 372222
Design standards
All installations should be detailed and constructed in
accordance with the relevant British Standard. This is BS 7533:
Part 4 for installation. For structural design, please refer to
either BS 7533 Part 12 or the Interpave Design Guide.
Laying
Select site category:
- Heavy duty applications of more than 60 commercial vehicles per
day (over 1.5T unladen)
- Medium duty applications of 60 or less commercial
vehicles.
- Medium-light duty applications – 5 or less commercial vehicles
per day.
- Light duty applications – no commercial vehicles.
Select laying method
- Flags laid rigidly for all categories
- Flags laid rigidly for category 4 only
- Flags laid flexibly for categories 2,3,4.
Laying method
- Flags laid rigidly for all categories
For this category, a hydraulically bound road base should be
used and should be designed in accordance with the relevant
standard (see above).
The back of the flag and the top surface of the roadbase should
be primed with a slurry of the material that will be used in the
joints. This is to ensure a good bond.
The laying course material should be a modified mortar as
specified in BS 7533: Part 4 and spread to give a depth of 30 mm
after compaction. Cement sand mortars are not suitable for use in
this method.
The flags should be laid with a 6-10 mm joint.
A minimum of 12 hours after laying, the flags should be
thoroughly wetted and the jointing material, as specified in BS
7533: Part 4 in slurry form, is spread over the entire surface. The
material should be moved towards the open joints.
Once the joints are full, the flags should be wetted again and a
squeegee used to remove excess mortar.
The area should not open be open to traffic until the bed and
joints have reached sufficient strength.
Guidance should be sought from the mortar suppliers.
The flags should be compacted down using a paviors maul.
- Flags laid rigidly for category 4 only
The laying course should consist of a workable mix of 1:3 cement
sand mortar, thickness between 15 and 25mm after compaction.
The flags should be laid with a 6-10mm joint.
These should be filled within 2-3mm of the surface of the flag
with a 1:4 cement sand mortar and pointed work as proceeds.
The flags should be compacted down using a paviors maul.
- Flags laid flexibly for categories 2,3,4
The laying course should be fine aggregate to BS EN 12620 Gf 85
0/04 (mp).
The thickness of the laying course after compaction should be 25
mm.
This can be done by either:
- Screeding the material to give the required depth after
compaction. (A small trial area may be required to determine the
amount of surcharge). The top 10 mm should then be loosened with a
rake.
- 25 mm of laying course material should be screeded out and
compacted. Then a further 10 mm of loose material screeded out on
top.
The flags should be laid with a 2-5 mm joint that is filled with
kiln dried silica sand to BS EN 12620 Gf85 0/04 (mp).
Note: the gradings for the laying course
material and joint filling material may be found in BS 7533: Part
4.
The flags should be compacted using a vibrating plate compactor
in accordance with BS 7533: Part 4.
Top up the joints with kiln dried silica sand as necessary and
during early life.
After laying light coloured paving on site, care should be taken to
protect from dirt and detritus while the remaining construction
works are completed.
Successful installations
The key factors in designing successful paving installations are
(in summary):
Anticipation of applied loads
In particular, the ability of flag paving to support loads is
dependent on specification of the correct thickness for sub-base
and bedding and for the flags themselves.
Pre-planned drainage
Drainage method should be considered before installation, with
adequate falls to dished or linear drainage systems for quick
removal of surface water.
Appropriate sub-grade
Well-compacted to appropriate thickness, with all sub-grade
drainage completed and, where necessary, measures taken to
stabilise soft ground.
Well-prepared sub-base
Systematically layered and properly compacted to a close-textured
surface using materials appropriate for the paving type
concerned.
Correct bedding and laying
Bedding materials must be protected from adverse weather prior to
laying. Paving should be laid with correctly spaced jointing.
Bedding layer damage and creep can be minimised by working up
slopes and/or away from edge restraints.
Stable edge restraints
Required to provide sufficient lateral support for the paving
during laying and long-term.
Careful detailing
At edges, around access points (e.g. manhole covers, drain inlets),
adjacent to kerb crossings and around obstructions.
Installation planning
Edge restraints
Suitable kerbing or edge restraints are required. Most proprietary
kerbing, channelling or edging systems are suitable, including the
following Charcon systems:
These should be bedded in concrete and haunched in accordance
with BS 7533: Part 6.
Sub-grade
If ground is soft/poor quality, consider laying a geotextile
membrane (eg. Terram) or capping layer to help support
sub-base.
Sub-base
Material: (for most cases) granular sub-base type 1 (in
accordance with clause 803*).
Alternatives: cement-bound material 1-3 (in accordance with
appropriate clauses*).
- Compacted depth: 100 mm min.
- A binding layer of fine material may be required for an
open-textured sub-base.
* Clauses refer to Specification for Highway
Works.
Preparation (all flags)
Sub-grade
Clear top-soil: complete sub-grade drainage.
Excavate and back-fill soft spots: compact well throughout.
Protect sub-grade from adverse weather.
Lay geotextile fabric or capping layer (if specified/required).
Sub-base
Prepare in accordance with the Specification for Highway
Works.
Lay and compact in layers to a close-textured finish.
Open-textured sub-bases may require a binding layer of finer
material.
General principles
Lay paving immediately on prepared bedding, do not leave bedding
exposed to weather and/or overnight.
To avoid bedding layer damage and creep, lay paving units up slopes
and/or away from edge restraints.
Stand on previously laid paving when placing next row.
Maintenance
Maintenance requirements are minimal under normal service
conditions.
Basic cleaning
If necessary, surfaces may be washed with brush and water or
using high pressure hoses. If the latter, care should be taken not
to blast away sand in joints.
Note: Do NOT use high pressure jets or suction cleaners for at
least 3 months to allow normal detritus build up (considerably
longer for paved areas under cover). Alternatively, joint sealants
may be considered.
Stain removal
If surfaces become contaminated with (e.g.) oil, chewing gum,
efflorescence, the use of proprietary chemical cleaners may be
necessary.
Charcon can supply on request:
- Advice on stain-removal techniques.
- Suitable products.
- Referrals to specialist cleaning companies as appropriate.
Note:
Advice and recommendations are subject to the circumstances of
specific problems. Removal of stains cannot therefore be
guaranteed.
Certain cleaning products may be subject to statutory
regulations for safe handling and usage (including COSHH and CDM
regulations).