Concrete Block Permeable Pavements (CBPPs)
provide a structural pavement whilst allowing water to
pass straight into the pavement construction for temporary
storage and dispersal into the ground or for collection.
They are one of the main techniques for Sustainable Drainage
Systems (SUDS) which have grown in popularity in the UK
and many other countries over the last 20 years and now
form part of the drainage regulations.
CONTEXT AND REGULATORY BACKGROUND
With growing urbanisation, the increase in hard landscaping,
roads, driveways, parking areas and indeed roof areas,
has dramatically reduced the capacity for natural, sustainable
drainage. This urbanisation, coupled with recent changes
in rainfall pattern, means continuing growth in the volume
of surface water run-off that we have to handle.
Both Sustainable Drainage Systems (SUDS)
and Concrete Block Permeable Pavements (CBPP) – one
of the most important SUDS techniques – seem to be
encouraged by government at every opportunity today. But
their use is still by no means as widespread as it should
be, suggesting the need for more rigorous implementation
by all involved in the development process. This document
examines each of the stages in development control to highlight
the clear requirements for SUDS – and hence CBPP.
Concrete Block Permeable Pavements (CBPPs)
provide a structural pavement while allowing rainwater
to infiltrate into the pavement construction for temporary
storage prior to infiltration to the ground, reuse or release
to a water course or other drainage system.
CBPPs are suitable for a wide variety of residential,
commercial and industrial applications. They are particularly
popular for car parks, residential roads and cycleways
but are also capable of substantially heavier duty uses.
CBPPs also optimise land use by combining two functions
in one construction: parking or other paving combined with
the handling of surface water from the pavement itself
as well as from adjacent roofs and impervious pavements.
They are one of the main techniques for Sustainable Drainage
Systems (SUDS) which now form part of the drainage regulations.
The SUDS approach usually involves combining and linking
a number of different techniques as a ‘management
train’ but CBPPs can be used in isolation, particularly
where full infiltration to the ground is intended.
Concrete block paving has been used widely
in the UK for over 30 years on diverse project types ranging
from footpaths to container terminals. One of the most
exciting recent developments is the use of this technology
for permeable pavements, offering major environmental benefits
acknowledged by planning guidance, regulations and environmental
regulators.
However, the potential cost advantages of concrete block
permeable pavements (CBPP) are less well understood and
to address this Interpave has commissioned Scott Wilson
to carry out independent, comparative cost research of
various pavement types including CBPP used in different
applications and ground conditions.
Concrete block paving meets today’s ‘Modern
Methods of Construction’ requirements for fully engineered,
prefabricated products and the increasing use of efficient,
fully mechanised site processes adds to this. In Germany
and some other countries, machine laying has been the norm
for many years and is used on even the smallest jobs. Here
in the UK, the proportion installed mechanically is growing
rapidly, particularly as more forward-thinking contractors
invest in readily-available equipment. Opposite are just
three recent examples of machine laid concrete block paving
projects.
Machine laying principles
Basically, a hydraulically operated clamping system is
used to lift a ‘cluster’ of concrete paving
blocks, about 1 square metre in area and already in the
required laying pattern. Clamps can be fitted to a variety
of site equipment or form an integral part of a dedicated
machine designed for good site manoeuvrability. While the
machine does all the work, there is sometimes an operative
guiding the cluster into place, as well as the machine
driver.
