The completion of the new Sol Plaatje University library and resource centre in September 2017 will reinforce Murray & Dickson Construction Group’s standing as a specialist contractor associated with complex building projects.
This will be the second structure that the building division of the leading South African construction group has completed on behalf of the institution of higher learning. The division’s sound work on the main administration block earlier led to it also being entrusted with delivering the central showpiece of the development node in the larger Kimberley central business district.
It is immediately noticeable by its concrete façade that seamlessly blends in with the roof of the structure and appears as if floating 2,4 metres (m) off the ground.
This three-dimensional concrete envelope is functionally, structurally and technically separated from the inner core of the building. The void created between the external envelope and floor plates along the perimeter of the building acts as a thermal duvet between the non-insulated external shell and its habitable building, while facilitating all vertical movement, houses the services and allows natural light to all floors.
Renell Samuel, Murray & Dickson Construction Group’s building construction director, says the 220 millimetre (mm)-thick walls were climb-formed, while supported eccentrically off slender steel columns. As the wall progressed, it was tied to the floor slabs by steel struts which resist the overturning nature of the design.
“The professional team, including structural engineer, Aurecon, spent up to six months preparing to construct this cast in-situ “liquid-stone” facade, with significant focus placed on limiting the influence of concrete shrinkage on such a large, continuous in-situ concrete element,” Samuel says.
Specialist supplier, Lafarge, helped design a concrete mix with the necessary low-shrinkage properties. The design also incorporated 600 mm-wide shrinkage pour strips that would run the full vertical height of three sides of the building and remain open for 90 days afterwards. This enabled unrestrained movement of up to 50% of the expected shrinkage movement in the walls. In addition, Murray & Dickson Construction Group followed a stringent concrete-curing regime, which further limited the effects of drying shrinkage.
This high-slump concrete mix with a smaller-sized aggregate would have to be carefully vibrated in-and-around the closely-spaced reinforcement and other embedded cast-in elements.
By becoming involved early during the design phases of the facade, Murray & Dickson Construction Group was able to share critical insights on shuttering, staging technology and construction sequencing. The building division also helped optimise the programme and align costs to the client’s budget.
Joining Murray & Dickson Construction Group on this project was specialist supplier, Uni-Span, as well as Kimberley-based emerging contractor, OIK, which was tasked with the extensive and challenging steel fixing and shuttering activities.
OIK also worked alongside its mentor, Murray & Dickson Construction, to construct the two striking internal in-situ concrete A- frames that required an intricate construction sequence, starting with building of the large temporary support columns. Ultimately, the A-frames were jacked upwards by 400 ton jacks to remove temporary shim plates, and then deflated to allow the A-frame to span free, followed by demolition of the two temporary concrete columns. Tolerances were achieved within a few millimetres of the engineer’s design on this aspect of the work programme.
Samuel is especially proud of the extensive skills and training undertaken under his watch on this construction site, considering the dearth of specialist building skills in Kimberley.
“We also outperformed in other important areas, such as Black Economic Empowerment; as well as spending on local sub-contractors and labour, especially youth and women,” he says.
He concludes that he is very proud of Murray & Dickson Construction Group’s performance on this contract that has also ensured its ongoing involvement at Sol Plaatje University and elsewhere in the Northern Cape city!