Infinite Engineers Projects

Working closely with multidisciplinary consultant, Chiefton Consulting & Services, Infinite Consulting Engineers designed a quick, efficient and cost-effective way of constructing the suspended slabs for a large low-cost housing development in Polokwane.

This 17,000m² development consists of 11 double- and triple-story apartment blocks. Together, they provide an additional 500 30m² one- and 40m² two-bedroom units in Polokwane. The development was successfully completed on behalf of the Polokwane Housing Association, a division of the Polokwane Municipality.

Initially, the professional team intended to construct the suspended floor slabs using a traditional rib-and-block system. However, due to tight production schedules, Infinite Consulting Engineers was approached to design a solution that was based on hollow-core slabs. This is considering that they provide a faster and more cost-effective method of constructing suspended slabs.

Hollow-core slabs are manufactured in a controlled factory environment and then installed on site by a specialist sub-contractor. This approach eliminates the risk of potential errors to keep projects on schedule.

Once the hollow-core slabs have been grouted in place, work can also commence above and below the suspended slab almost immediately to help further accelerate a construction project. With other methods of suspended slab construction, work can only commence with the brick work at the next level once the in-situ concrete has reached a compressive strength of 17MPa. This is also when the propping that restricts trades from working below the slab can be removed.

Cost savings were also realised by eliminating the need for raw materials and extensive propping associated with rib-and-block systems. An accurate installation the first time round meant that there was also no wastage due to having to redo inaccurate work. Potential mistakes would have also compromised the overall quality of the final structures.

Moreover, hollow-core slabs provide a safer solution for constructing suspended slabs. The hollow-core slabs are manufactured at ground level at the factory and installed by a skilled and experienced team.

Notably, Infinite Consulting Engineers' quality design was swiftly approved by the National Home Builders Registration Council.

The company then also supervised the installation of about 15,000m² of hollow-core slabs, a task that was successfully undertaken by Coreslab, while working alongside principal contractor, Motheo Construction.

Coreslab installed a total of 3,000 hollow-core slabs, each mainly 5,500mm in length and 150mm in thickness, for this project. This is in addition to the more than 90 precast-concrete steps that it also manufactured with a special reveal and installed for this development.

Coreslab worked according to a very strict production schedule, and careful planning was critical to the success of this project. The professional team also had to make up for lost time due to unforeseen circumstances that delayed the start of the project.

An optimal installation rate on this project was about 350m² a day, and it took about two days for the factory to manufacture the more than 800m² of hollow-core slabs required to complete a single floor. To avoid delays, there was also constant interaction between the factory, the heart of the operation, and the installation team, which can easily place up to 400m² a day by installing one slab every six minutes in a single shift.

The hollow-core slabs were dispatched to site on a just-in-time basis and then lifted directly from Coreslab's truck trailers using a mobile crane. This also freed up available space to provide a clean and clear worksite.

After the hollow-core slabs were installed on the first three blocks, an optimal production process had been established, and progress continued unhindered. Located close to the construction site, Coreslab's team was also on permanent standby to quickly troubleshoot unforeseen challenges.

While less labor-intensive than rib-and-block and in-situ floor construction, many jobs were created on other aspects of this sizable project. This was an important consideration that also helped to tip the balance in favor of using hollow-core slabs for this project.

Infinite Consulting Engineers is proud of the role that it played in helping to alleviate an acute shortage of quality housing in the province.