A super-tough custom-made concrete paving block was developed specifically to support the heavy axle load of hundreds of buses using the new Rea Vaya bus rapid transit (BRT) depot at Dobsonville in Soweto. Technicrete engineers developed the Armorflexpaver from a block normally specified for flood and erosion control.
The new Armorflex paver is a modification of the standard 115mm-thick Armorflexblock – eliminating the drainage slots which allow for vegetation to grow through it in its normal erosion and flood-control role, and made of a stronger, especially hard-wearing concrete mix to handle continuous, heavy-load bus traffic.
A key feature in Armorflex paving is that during the laying process, the blocks are linked together by a tensioned wire restraining system which prevents ‘rutting’ – the creation of track indentation by the repeated procession of heavily laden vehicles along the same route. The entire paved surface is enclosed by barrier kerbing.
“Even on some hard paved surfaces, you eventually get a middle-mannetjie building up when vehicles are continually following the same route,” says Taco Voogt, Technicrete commercial product manager. “This cannot happen with Armorflex, due to the steel wire restraining system.”
He adds that an additional cost advantage was gained in the Dobsonville project because less earthwork construction was required than would have been necessary for conventional paving.
This is the first time that the modified Armorflex paver has been used in South Africa. With its success at the Dobsonville BRT depot, it could become a stock ultra-heavy duty paving item at Technicrete plants.
Kevern Ramborosa, a director of Hlanganani Engineering and Project Managers, which designed the depot, says, “Factors which we had to consider when deciding on the type of paved surface we needed included the very heavy axle loads of the articulated buses, their turning movements, and possible chemical attack from oils and diesel fuel. We turned to Armorflex, although it had never been used for this type of application before.”
Ramborosa says the client, the Johannesburg Development Agency (JDA), supported the recommended though unusual paving application. “And throughout the process, Technicrete experts were on hand to assist with design checks as well as on-site training,” he adds.