In this introductory article to our annual feature on Exterior Flooring we take another look at whether to use concrete block or clay brick paving, and will examine how well permeable paving is taking off in South Africa – given that in the UK and Europe is it almost a compulsory requirement for public areas.
We try to find out how artificial grass is performing in the marketplace. Decking is an important consideration in outdoor living, and for this we have produced a secondary article in this issue. Enjoy!
Clay brick or concrete block paving can be used in almost any exterior project, and they are particularly useful in residential and hospitality applications, where they look great on driveways and will provide many years of service.
They can also be used to great effect as paths, or patios, or mixed with other paving types to create unique features, and are a viable alternative to the more traditional asphalt or macadam surfacing for estate roads.
They are even in great demand for use in areas of exceptional loads, such as container terminals, airport taxi-ways, docks and many industrial applications including car parks and freight yards.
Also, the design possibilities enabled by the use of these relatively small paving units are limited only by one’s imagination. Whatever your design, it can probably be construed in brick or block paving.
The bricks and blocks are available in a range of thicknesses, from 40mm to 100mm. There are even 120mm units for exceptional applications, but for domestic use the 50mm or 60mm units are the most suitable. Units 80mm thick are usually employed on road construction or where there will be regular vehicle overrun, while the 100mm thick units are for heavy-duty pavements.
Concrete block paving (CBP)
Amongst the concrete blocks there is an enormous variety of shapes, sizes, colours and textures now available, with all the major concrete paving manufacturers producing their own versions of the standard rectangular block, and also special shapes such as faux cobblestones and an ever- increasing array of textured blocks.
Modern technology allows CBP to be available in a variety of colours achieved by a pigmenting process during manufacture, but some may be prone to fading, so take the advice (or the guarantee!) of the supplier before you commit to coloured CBP.
Concrete Block Paving (CBP) has been used to pave public roads in South Africa for close to half a century. The first public roads to be surfaced with CBP were in Chatsworth, Durban, almost 50 years ago. These roads have been essentially maintenance-free and have provided double the service life of a good asphalt surface. Moreover, the roads are still in very good condition and may well last another 50 years.
Taco Voogt, Technical Director of the Concrete Manufacturers Association (CMA), is on record as saying, “Sustainability is key to CBP’s growing acceptance as an alternative paving medium to asphalt. Most local governments are under severe budget constraints and in many cases are unable to maintain their existing road networks, which are largely paved with asphalt.”
“CBP is essentially maintenance-free provided it is laid in compliance with best practice standards. What’s more, the initial capital outlay on CBP roads is only marginally greater than the asphalt equivalent. Therefore it makes sense for all new urban road projects to be surfaced with CBP. The saving on maintenance would be huge and would very quickly offset any higher capital spend.”
Laying roads with concrete block paving is labour-intensive and offers the unskilled and unemployed an opportunity of acquiring a marketable skill and earning income. Over the years thousands have benefited from CBP projects. The income earned has a multiplier effect, stimulating economic activity in other sectors of local communities, and it imbues residents with a new-found pride in their communities and this is reflected in cleaner streets and better-maintained houses.
“Another advantage of CBP is that the individual paving blocks can be lifted – for instance for the laying of water pipes and underground cabling – and then replaced with no visible sign of disturbance, unlike tar surfaces which must be broken and then patched.”
When using CBP for road surfaces, it is also very easy to construct pavements and cycle paths adjacent to the roads at very little extra capital cost. Proper pavements and kerbing have an uplifting effect on communities, enhancing pride of ownership among residents in surrounding properties.
Permeable paving is a range of sustainable materials and techniques for pavements with a base and sub-base that allow the movement of stormwater through the surface. In addition to reducing runoff, this effectively traps suspended solids and filters pollutants from the water.
Application examples include roads for housing estates, pedestrian areas, shopping mall exteriors, paths, lawns and areas that are subject to light vehicular traffic, such as car parking lots, cycle paths, service or emergency access lanes, road and airport shoulders, and residential sidewalks and driveways.
Permeable paving is the domain of CBP, and it has developed into the provision of a sustainable urban drainage system (SUDS), which prevents runoff and flooding from paved areas and collects and filters stormwater for later use.
This system is now so prevalent in the UK that its use by municipalities is almost compulsory! The main benefits are lower construction costs; low and simple routine maintenance; the ability to harvest and re-use rainwater; and preventing the effects of storm flood water and also pollution – because discharge water can be cleaned.
Although permeable paving (and SUDS) has been ‘flavour of the month’ for some years now in the UK, it cannot be said that it has really caught on in South Africa, except in the Cape area where, due to the tenacity and expertise of one consulting engineer and a major CBP manufacturer in the Cape, over 43 permeable paving projects in the Western Cape have been completed to date.
To get a feel for the current situation on permeable paving, FLOORS in Africa contacted Peter Wium for his opinion. Eighteen months ago Peter started his own consultancy with a heavy involvement in permeable paving, after 25 years with De Villiers Sheard – which is where his experience with the concept first developed. Now he is one of the few dedicated specialists on this type of paving in the country.
Although he still gets involved in consulting on traditional civil engineering projects, he is now most concerned with sustainable stormwater systems including technical design and working as a consultant for a proprietary UK system in South Africa. He also handles stormwater master planning for larger areas, catchments and specific sites, and assists consultants with the design of systems and gaining approval of permeable paving projects from authorities, as well as promoting awareness of the benefits of permeable paving in the industry.
Peter says permeable paving is only one of the options of dealing with stormwater at source, which is the SUDS goal, but developers and authorities are seeing it as a very viable and efficient alternative, borne out by the increasing demand for it.
The City of Cape Town has a very proactive Catchment Management Department which recently introduced a Management of Urban Stormwater Impacts Policy (May 2009), which embraces the SUDS philosophy and sets out targets for attenuation and treatment of stormwater runoff, with which all new or upgrading developments under the City’s jurisdiction need to comply.
“They have endorsed permeable paving as a control option that completely satisfies the Policy. This has had a direct positive impact on the demand for permeable paving,” says Peter. “I must add that the current severe winter has tested those installations thoroughly and all have functioned with aplomb.”
“It is interesting to note that the City has always been quite happy to approve permeable paving on private projects but was reluctant to use it themselves in their own infrastructure. This was largely due to administrative reasons, budgets and maintenance programming,” says Peter.
“However, they have recently installed a permeable paving option on one of their IRT Bus Depots in the centre of Cape Town. The deciding reason was that they could tie up the maintenance side of the installation by ensuring it was included in the management contract of the future operator.”
“Since then we have installed permeable paving at a number of the City’s Park-and-Ride facilities, all associated with the IRT Bus system, and I am currently assisting the City in drawing up a Maintenance Manual for use at these facilities and hopefully at other projects where they will install permeable paving,” Peter concludes.
Most of the major brick manufacturers produce their own ranges of clay paving bricks. These are generally available as rectangular bricks, although there is now a good choice of size variations, from 60x60mm ‘cobbles’, 150x150mm ‘setts’ and 300x300mm squares.
The most usual size is 100-105 x 200-215 x 60mm; this means that, with some bricks, there are less than 50 bricks per square metre, and not all clays are interchangeable. However, unlike concrete blocks, most clays are manufactured with two presentable faces, allowing them to be inverted to replace stained paving.
There are many different laying patterns that can be achieved using clay block paving, of which the most common is the herringbone pattern; this is the strongest of the block paving bonds as it offers the most interlock, therefore making it a good choice for driveways and road surfacing.
A herringbone pattern can be created by setting the blocks at either 45º degrees or 90º to the perpendicular. Other popular types of pattern include stretcher bond and basketweave, with the latter being better suited to paved areas that will only receive light foot traffic, due to its weaker bond.
Peter Kidger, Corobrik Director of Marketing, is also on record as saying that clay pavers offer a high-quality authentic solution with little maintenance costs, the variety of colourfast hues and sizes allowing creativity in promenade, pathway and patio design.
“It has been very rewarding to see the increasing application of clay pavers in a wide variety of applications from residential through commercial and municipal projects such as the large-scale paving done by all major municipalities which are ongoing,” he says.
Elevating the aesthetics of urban spaces in an unobtrusive manner is what clay paving does. The ranges of earthy tones from pale buff hues to rich, dark burgundy and bright, strong shades offer a palette to suit all design needs. Colour alone is not the only factor. The wide selection of patterns and the combinations of different size and shapes of pavers that complement other finishes are also a major consideration.
Kidger also points out that landscape architects have the bonus of creating a skid-resistant outdoor surface that is durable and long-lasting. This is of particular importance in harsh weather conditions or exposed areas such as beachfront promenades where sea spray conditions are particularly harsh.
“Adding to their sustainability profile, clay pavers are easily recycled and for dealing with underground services for repairs or maintenance can be ‘unzipped’ to gain access and then ‘rezipped’ using the same bricks without leaving a scar”, he concludes.
Although wood has always been the preferred material for both residential and commercial decking installations, the upkeep was often a deterrent in terms of cost and the labour required, but the latest advances in wood sealing products ensure that maintenance is kept simple and cost-effective.
The old varnish type sealants are no longer used, thus peeling and flaking of deck sealants is a thing of the past and limited sanding of decks is required, but unless the wood is treated in this manner it will be difficult and costly to maintain and will have a much reduced service life.
However, wooden decks seem to be under a great deal of pressure with the advances made by alternative decking materials. (See the separate article on Exterior Decking in this issue).
Car Park Decking
Decking for car park and similar applications bring with them their own challenges, and although there are steel and other materials that can provide their own answers, the favourite subfloors are inevitably power-floated concrete.
The surface finishes then become the main concern, because these have a need to be hardwearing; resistant to oils and chemicals; have the ability to accommodate a variety of different vehicle movements; be easy to keep clean; require minimal maintenance; produce no slip hazards; and remain looking good.
The provision of a trouble-free car park decking surface is a specialist application, and there are several companies with proprietary systems and installation techniques to meet these requirements, including the provision of solvent free, flexible, polyurethane coating systems and other epoxy solutions, and it is wise to incorporate a specialist into the design team before planning any car park project, above or underground.
Although artificial grass is obviously a man-made product, it can be said that it is far more eco-friendly than the real thing! The manufacturing processes may use energy and involve transportation, but once it is laid artificial grass needs no water, no fertilizer, no mowing, no weeding, provides more leisure time, and works well in areas where grass would not survive.
Constructed out of durable, tufted polyethylene yarn, artificial grass feels and performs like a normal grass surface, without all the hassles of its upkeep, and it considerably enhances the exterior of any building. In addition, it is in wide use overseas for sports venues and for landscaping although, in relation to the latter, local landscapers that FLOORS in Africa spoke to were not enamoured of this development.
On the sporting front, artificial grass systems are a realistic alternative to natural fields, requiring minimal maintenance and providing a premium surface for all forms of athletic use.
Most manufacturers seem to tailor the product to the specific sport, engineer it to meet the requirements of the players and to withstand even the strongest environmental elements in providing a level sporting field over time.
In landscaping, whether it is a large-scale project or the back garden of the family home, these ‘grasses’ provide a lush, vibrant, green and healthy lawn every day of the year.
Most turf field systems are composed of mixed polymers, which make up the turf grass, and also infill components – usually sand and crumbed rubber – which fill the grass to add shock absorbency.
The turf grass is usually a mixture of polyethylene, polypropylene and polyurethane, though some can use materials like nylon or polyester as well, but these man-made materials raise a problem of their own.
Most artificial turf will last 10-15 years, but what happens then? OK, it has paid for itself time and again and it makes sense to replace it with a new application – but does this mean the old synthetic lawn now finishes up in a landfill, and negates the advantages of having had it installed?
While the plastic in turf field systems can usually be recycled on its own, it is difficult for recyclers to separate the plastics from the sand and rubber infill. However, companies in the USA are claiming a breakthrough, which means that perfect and total reclamation should be available soon – well before you have a need for it!
Deciding what exterior materials you want for your home can required a lot of thought, but the end result – which upgrades your living standard and well as adding value to your biggest asset – is well worthwhile, and the South African flooring industry is well ahead in bringing you the latest technology and trends to your doorstep.