Mapei South Africa Pty (Ltd) is currently supplying admixtures to Grinaker LTA Mining and Contracting for use at Nchwaneng mine near Black Rock – a project that involves the construction of a new screening and conveying system being constructed for a manganese mine in the Northern Cape.

Mapei devised mix designs for a variety of concrete applications in the construction of the screening and conveyor system. These include conventional and pumped concrete to be used in the construction of the system's vibrators, and pumped concrete to be used for the infrastructure, as well as specialised concrete to be used for slip formed concrete applications.

“The biggest challenge that we faced in this project was the extreme temperature differential that the environment is subject to.”

Mapei developed a retarder dosage system whereby mix designs were based on a set temperature scale. In hot conditions the company added retarder to negate the rapid setting of the concrete. In a similar manner, retarder was removed from the mix in cool conditions. In this way Mapei is able to control the set rate of the concrete in various applications.

The only OPC cement available in the region is a rapid setting variety which complicates the application. To overcome this challenge Mapei used Mapetard SD 2000, a liquid retardant that demonstrates low slump loss characteristics. “Mapetard SD 2000 is the ideal product for applications like these, as the product retains concrete workability.” says Offenberg.