Working with paving is fun, and can even be addictive. When I’m out on my bike I often take note of the road surface when I’m held up in traffic, and sometimes I stop on the hard shoulder to take note of the condition of the paving while my travel companions are giving me that ‘what are you doing?’ look.
One day your turn comes to take part in the construction of a race track, so, all excited to read the specifications laid down by the motoring world, you suddenly find yourself faced with a pleasant surprise – there are no rules, it all depends on what the customer wants, a track with more or less grip.
What is grip?
Grip is a common term used in competitive racing circles that refers to nothing more than the ability of the rubber tyre to grip the asphalt, a property that depends on the characteristics of both materials, how clean they are and, most of all, their respective temperatures.
How do you measure grip?
Accustomed as you are to working to ‘office’ specifications, you look up how to measure grip, or traction, and you find that is that it is something that depends on the opinion of drivers and the racing world in general. Some companies and brand names, like Toyota Racing, have their own grip measuring devices. So, accustomed as you are to a highly standardised environment with its corresponding tests and ranges, you find you are obliged to ‘tailor’ the surface to what the track owner and users want.
The best way around this is to first of all consider what type of grip the customer wants – low or high – then prepare a number of laboratory formulations and put them through real-life tests carried out by the customer and test drivers. This is the interesting part of the process, as the paving technician has to translate what they say into a type of paving formulation, the most important factor being that the ‘opinions of the test drivers’ are correctly interpreted in terms of the theoretical formula and manufacturing of the end product.
How should the grip be?
The grip, of course, must be constant throughout the circuit. And then there are other variables to consider, such as the life span of the tyres, and, for example, if it rains, the surface must drain and dry out quickly so that the race can be restarted, as the commercial interests of the television stations are also a key factor.
It can also be the case that, once everything has been finished, the grip is found not to be sufficient, and the customer wants more, so we have to carry out a follow-up treatment with micro-milling, micro-grooving, or by increasing the friction using pressurised water to generate a different type of fine milling. If the customer wanted less grip, we would have to employ techniques to smooth the surface, or lay another layer on top.
Many circuits also have post-season campaigns to tailor the surface with micro-milling or by repositioning the established surface.
On a final note, the most challenging scenarios from a job execution perspective are tilted oval circuits. As you can see in the photo, not only do we have to adapt to extend the asphalt surface using pavers and compactors on the incline, but the incline itself is also curved.
In conclusion, a fascinating world, not only at the races, where anything can happen, but also in the construction of the circuits themselves, with which we could fill volumes.