Unisa Campus

The University of South Africa is the largest distance-learning institution on the continent. Its principal Pretoria campus is a landmark of mid-century modernist architecture, built as a dramatic terraced concrete structure stepping down the slope of Muckleneuk ridge.

Large exposed-concrete institutional buildings of this era present a characteristic set of problems. Decades of weathering drive carbonation into the concrete, which depassivates the reinforcing steel and allows corrosion to begin; as the steel corrodes it expands, spalling the surrounding concrete and opening fresh paths for water. Treating the symptom without arresting that mechanism achieves very little, so effective work means repairing the concrete substrate properly first and waterproofing over sound material. Terraced and stepped structures also generate an unusual concentration of horizontal-to-vertical junctions and level changes — precisely the details where water finds its way in, and where the quality of the detailing matters more than the choice of product.