CONCRETE BLOCK PAVING MORE COST-EFFECTIVE THAN PREMIX ASPHALT IN MANY APPLICATIONS:
Article Date: 13 November 2007
 An independent survey conducted on behalf of the Concrete Manufacturers Association (CMA) shows that concrete block paving (CBP) is, in most instances, a more cost-effective surfacing option for driveways, car parks, residential streets and township roads than premix asphalt paving (PAP). The results of the survey have been published by the CMA in an updated leaflet, first published in 2003.
The survey, conducted in Gauteng during June, also found CBP to be more cost-effective for light and heavy duty industrial yards as well as for bus terminals and through-roads in urban areas.
Comparisons are outlined and illustrated on the basis of three qualities of sub-grade materials (CBR3, CBR7 and CBR15) as well as three application scenarios comprising:
• Multi-dwelling driveways, car parks and residential streets up to 3 000m²
• Urban road developments in townships, estates and light duty industrial areas up to
5 000m²
• Heavy duty areas, where applications might include bus terminals and through-roads in urban areas up to 10 000m² .
The classification of subgrade and earthwork layers beneath the paving are based on UTG 2 and the table is reproduced in the leaflet for ease of reference.
CMA director, John Cairns, says it is crucial that any cost comparison of CBP and PAP road surfacing be approached as a total road costing exercise in which all cost elements are taken into account.
“Simply making a direct comparison between the two surfacing materials in isolation presents a distorted picture. It should be noted that unlike PAP, CBP forms an actual structural layer which means it requires less substrative material. However, besides the type of surfacing material, final costs are also influenced by the design, size and intricacy of the specific project,” says Cairns.
The leaflet compares all attendant costs and draws the conclusion that, in most cases, CBP is the less expensive alternative, both in the initial road laying phase, and subsequently, over a 10 year life cycle.
Cairns says that CBP is also structurally superior, requiring little or no maintenance over the 10 year life cycle.
“Asphalt surfaces, by contrast, generally require overlaying after seven to 15 years, based on
UTG 3. As the PAP layer makes up approximately 27% to 37% of the total pavement cost, any secondary overlaying costs as well as maintenance costs should be added to the initial budget for a more accurate costing exercise,” says Cairns.
He notes that CBP is more resistant to wear from applied loads and its interlocking action facilitates far better load distribution. It is usually the preferred material when pavement surfaces are subjected to:
• Heavy industrial loads
• Stop/start traffic
• Turning and slewing wheels
• Spillage of petro-chemicals or other contaminants
• Cushion or solid tyre wheels
Safety features, specific to CBP, include:
• High skid resistance
• High luminance
• Rapid shedding of rainwater
• Low traffic noise levels
• Drainage channels easily accommodated
“The fact that CBP offers greater aesthetic versatility through numerous colour and texture options, provides specifiers with an added incentive to use it.
“Concrete blocks are also much more user-friendly when service work must be done beneath the paved surface. Paving blocks can be lifted and re-laid without leaving any unsightly scars or incurring further material costs. Any blocks not re-used after service work can be used on other paving projects. Moreover, extensions are easily facilitated because new blocks will match the existing paving, and finishing off work, for instance around trees, etc., may be done with a header course which is both attractive and practical.
“One of the great benefits of CBP surfaces in an African or developing country context is that they offer job creation opportunities. Unskilled people can be trained to lay concrete blocks with a high level of workmanship. Township roads can be built by local communities who then take ownership of and pride in their newly improved environments. An added bonus is the money earned in the laying of CBP roads has a multiplier effect, being circulated several times within the same community,” observes Cairns.
Anyone interested in obtaining the leaflet should contact Pam Zukor at the CMA on
Tel: (011) 805 6742 or email main.cma@gmail.com . Alternatively, it can be downloaded from the CMA’s website, www.cma.org.za.
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