These precast Concrete Block Pavers (CBP) were laid 48 years ago in Chatsworth, Durban and according to Concrete Manufacturers Association (CMA) president, Taco Voogt, they look good for at least another half century. When they reach the 50 year mark they will have provided twice the length of service expected from a good tarmac road.
What is more, the roads have been essentially maintenance-free, unlike their asphalt equivalent installed in Chatsworth around the same time. The little upkeep that has taken place was not the result of surface failure, but was due to the installation and repair of water pipes and electric cables which run under the roads. Moreover, pockets of heaving clay were subsequently encountered, a condition in which tarmac cracks and breaks up. In the case of Chatsworth’s CBP roads, the pavers were simply lifted and relaid after the clay had been replaced with sabunga (compacted stone and sand).
The project was initiated and controlled by Derek Hall, Pr.Eng. who says it was the first of its kind in Africa south of the equator.
Derek discovered concrete block paving technology during a business trip to Germany in 1964 when he was general manager of Hume Rhodesia Co. He visited the headquarters of the S.F.Roadstone Co in Bremen and negotiated the African rights to manufacture the S.F. block paver south of the equator.
Shortly after Hall’s return, the annual brick road tender was issued by Durban Municipality, and Hall placed a provisional order for an S.F. Roadstone CBP machine. He then tendered against a clay brick manufacturer and won the paving award for Chatsworth.
This led to the installation of a CBP plant in Chatsworth by German fitters, and the production of S .F. pavers to a minimum strength of 5 000psi (±35MPa) – the prevailing German standard – commenced. Strict control of aggregate grading and mix design, personally handled by Hall, meant that the quality and crushingstrength of the pavers was very high. On completion of the contract in 1967 the machinery was relocated to Hume Pipe Co in Pinetown.
Voogt adds that good bedding material and sub-base engineering also played a substantial role.
“This project proves quite emphatically what the CMA has been promoting for the past 30 years, namely that CBP is an ideal surface material for suburban and township roads. Besides offering exceptional maintenance-free performance, CBP is also labour intensive, creates employment and skills the unemployed, and therefore is ideally suited to the Government’s Expanded Public Works Programme (EPWP),” advises Voogt.