CMA REPRINTS MANUAL ON DRAINAGE OF CONCRETE BLOCK PAVING:

The Concrete Manufacturers Association (CMA) has reprinted its concrete block paving (CBP) manual ‘Drainage of Concrete Block Paving’ on conventional paving installations.

 Aimed at architects, landscape architects, engineers and contractors, the six-sided manual provides diagrammatic illustrations on surface and bedding layer drainage.

CMA director, John Cairns, says good surface and subsoil drainage are essential for satisfactory CBP performance.

“Drainage should form part of the design, specification and construction phases, and factors such as rainfall, water levels and soil conditions, must be taken into account at the outset.

“Tests conducted by Dr Brian Shackel of the University of New South Wales in Australia have shown that between  30% to 35% of rainfall will penetrate newly laid, untrafficked and unsealed block pavements. Therefore the drainage of bedding sand is crucial, particularly in instances where stabilised bases are used or in areas close to kerbs, edge beams and manhole inlets. This aspect is often neglected and leads to a build-up or  ‘boxing’ of water and the progressive failure of CBP,” notes Cairns.

Cairns advises that the permeability of joints can be reduced by up to 50% with the application of a water-based Acrylic sealer.

“Similarly, infiltration can be inhibited by adding 10% of lime or 6% of bentonite to the jointing sand. And a bituminous seal should be considered for all unbound base material before bedding sand is placed.”

The manual provides a bedding sand grading with nominal sieve sizes ranging from 9.52mm to 0.075mm and various surface drainage diagrams depicting drainage and gutter applications, are included. There is also an illustration of a manhole inlet, where special attention must be paid to compaction and the possible stabilisation of backfill.

Bedding layer diagrams include: sand-bed drainage details on steep slopes; and three drainage pit drawings. Diagrams of CBP on a concrete slab and flownet drains are also covered.

The manual includes a list of CMA paving block producer members, associate members and contractor members. Copies are obtainable at no charge from Pam on 011 805 6742 or on main.cma@gmail.com .

DATE                    March, 2009

ISSUED BY           David Beer Communication Consultants

FOR                      Concrete Manufacturers Association                                                        

ENQUIRIES           John Cairns (011) 805 6742

                             David Beer (011) 478 0239 or 082 880 6726.  Email: bigsky@ibi.co.za