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- Buyers' Guide
Events such as World of Asphalt (USA, various locations) offer a wealth of technology with initials like GPS and RFID, mostly designed for industrialised country conditions where recycling of pavement is normal and high-tech levelling and measuring via satellite is the norm.
But the commonest road contract for blacktopping in Africa remains the 10-20km stretch, often just single-track upgrading of a bush-road base. For this it’s often second-hand semi-continuous plant that’s best; far better to spend the money on upgrading the base.
For such small contractors wishing to expand into the booming road surfacing business the 3Ss rule is the best – Supplies, Scheduling and Supervision. Safety comes in at an equal third.
A good sealed road requires properly planned arrangement of sand, with its equivalent dry weight calculated (otherwise you’ll spend a fortune in driving off the moisture). The binder used is likely to be bitumen, with a ‘penetration grade’ which will affect the workability of the hot mix, and the durability of the finished road; consult your supplier on this. The filler incorporated will be dependent on what’s available locally, including stone dust and re-used by-products of the hot-mix process. Make sure you’ve got enough bottled fuel to get you through this day and next, too. And you’ll need a water bowser, especially when it comes to the final roll.
This is absolutely crucial; spend more time on this than anything else. Most of the equipment will likely be hired, so make sure it’s only in the right place at the right time. Not a day longer. And that goes for operators, too. The ideal is for a ‘rolling’ programme to be carried out, with the sub-base preparation team working a day or so ahead of the asphalt plant operators. With an all-important inspection from your own trusted staff in between. Fail to do that and you’ll lose all of your profit, and more, ripping up and recycling that nice clean pavement.
Supervision and Safety
These go hand-in-hand, which is why our total of S’s adds up to three above. Every single step, every movement of plant and materials both on and off the site, needs to be accurately planned before the first grader pass is made. Check every delivery for volume, quality and, in the case of aggregates, moisture content too.
Ensure all oil, water and LPG tanks are full and that’s there’s no holdup on the supply delivery line. Make sure every employee and casual operative knows what to do and when. And remember that hot asphalt of whatever composition is a dangerous commodity at 1500C or more which needs to be handled carefully in any volume, especially when a wide stretch is being laid. Never allow the gas burner of whatever type to be misused. And be particularly careful at the finish of all edges laid as this is where the inspector’s eye will fall first.