Three Rivers success

A striking illustration of how precast concrete panel flooring can radically trim costs by speeding construction time is the Three Rivers apartment block project in Vereeniging, where clever application of the system turned a design that was initially considered uneconomical and un-saleable into a commercial success.

The original design, providing for an in-situ frame and in-situ floor at the lower level, with a transfer slab supporting the upper three floors, turned out to be not economically viable. Seeking a solution, the developer, Belrex, approached concrete floor panel manufacturer Echo Floors, whose engineers came up with an alternative construction formula, making extensive use of precast slabs on a load-bearing masonry structure.

The result: Three Rivers was completed more quickly and at significantly less cost than the original design – it was judged an economic success.

All walls at the lower level were 220mm slabs with a series of 550x440mm solid brick columns down the entire length of the building. A 150mm deep continuous composite slab was installed to support the high imposed-loads from the upper floors. This, with the introduction of 220mm walls and columns at the ground floor level, provided the lateral stability required for the upper floors.

The ground floor was divided into a series of single garages. At the upper levels the walkway piers were moved in line with the columns below and inverted steel “T” sections were placed from the pier to the unit to support the walkway slabs. A series of lintels and reinforced brick beams were used over openings in the load-bearing masonry.

The upper floors were a simpler configuration of units which are wall above wall. The loads of the upper walls are transferred to the bottom slab, and in some areas to the 220mm walls below. The column foundations provided were specifically designed to accommodate the transferred loads.