They replaced kerosene and all other additives with water, which leaves behind only clean bitumen on the road once the water evaporates afterwards. This increased the strength and durability of the chipseals.
The crew also added polymer, a type of rubber that further increased the strength and durability of the chipseals, saved ratepayer money when used instead of expensive asphalt.
The environmental benefits are plentiful, halving Council’s chipsealing carbon emissions.
There are practical benefits for the chipseal crew too, as this new approach enhances their safety on the job, says Renier.
“Cutback bitumen was volatile and needed heating past 160 degrees celsius to be used, so severe burns would result if people got into contact with it. Emulsions can be used at a much safer 80 degrees celsius.”
Two years on, the roading crew has switched over completely to this way of working.
“We don’t apply any cutbacks on our roading network anymore. Waka Kotahi has only recently followed suit, so we are well ahead of the pack on this.”
Find out more about bitumen emulsion on the Road Science website.