CPD Specifier May 2015 issue September 2014 | Page 43
Outdoor Engineering
Fit for Purpose - the key issues
for grass reinforcement
With increased demand for grass paving to driveways, access roads and commercial
and domestic parking, there are important considerations that building specifiers and
installers should make
Today’s wide choice of grass paving
systems means that specifiers need to be
more informed when selecting a product.
Without an industry standard - making
that choice is difficult. Grass Concrete,
experts in permeable paving, highlight a few
considerations.
WEIGHT LOAD IMPACT
In most instances ground reinforcement failure,
stems from either an inability to accept weight
load or an issue of water logging Both cause
loss of grass and weakened support; with, in
some cases, both of these problems being
evident.
With a long established history of installations,
Grasscrete is uniquely placed to work closely
with engineers and architects to recommend
appropriate systems, where areas can be
effectively maintained with plastic, or the more
vulnerable areas with concrete alternatives.
How do you choose something that
will stand the test of time and achieve
sustainability?
For example, a car park in daily use: will the
grass cover and the structure stand up to that
sort of regime?
If the application is to slopes:
will it function as an armouring layer and will it
offer grip?
These are challenging questions that should be
asked to ensure a correct specification.
FIT FOR PURPOSE
With more than 40 years industry
experience, Grass Concrete guides clients to
choose the most appropriate system to meet
their need.
Whether that is insitu concrete, pre-cast
concrete or plastic systems, they will advise
where there is an appropriate use of a particular
system.
Grass Concrete is being increasingly
approached by clients looking to replace failed
areas of cellular plastic pavers, re-emphasising
the need of specifiers to consider fit for purpose
systems - which is key to maintaining the
reputation of the grass paving industry.
When considering a design there are a few
golden rules to consider:
l Think about the potential for unplanned
heavy use such as refuse and skip vehicles.
l For fire applications think about the need to
support the modern CARP 18 tonne emergency
fire vehicles on the fire access roads as part of
building regulations.
GRASS CONCRETE LTD
GROUND CONDITIONS
Subterranean conditions are critical to
performance. Most circumstances will see a
sub-base depth of 150mm as being sufficient
This should, however, be proportionally
increased where CBR values of 4 per cent or
less are encountered. Care should be taken in
specifying the type of sub-base, DOT Type 3
materials may suggest high rates of percolation
while Type 1 material less so. However they
provide a greater consistency both in grading
and in availability.
For watercourses Grasscrete recommend the
installation of a geo-textile of appropriate flow
rating below the paving layer.
Given the demands for Sustainable Urban
Drainage, grass reinforced systems can
permeate at up to 90 per cent the rate of natural
grass, a safe lag time can be achieved. Lag time
is beneficial in the prevention of flooding and
can be extended by introducing an underlying
drainage blanket across the full extent of
the paved area. Grasscrete can and does
combine with proprietary forms of sub-ground
attenuation.
For permeable paving solutions talk to the 40
year experts.
TEL: 01924 379443
WWW.GRASSCRETE.COM
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READER ENQUIRY NO: 55