Spraylock Concrete Protection helps build durable and robust bridges

Spraylock Concrete Protection’s cutting-edge technology was deployed to protect the embedded reinforcing steel of the deck of a newly constructed bridge on the N5 between Harrismith and Kestell.

DSC-Zendon, a leading provider of concrete rehabilitation services with a specific focus on bridges, was the approved applicator of the technology.

The technology was specified for this application by Aecom, which undertook the engineering design of the bridge and was later appointed to oversee the construction works.

Johann Engelbrecht, Managing Member of DSC-Zendon, says that the technology was specified because it provided a longer-lasting solution for protecting the reinforced concrete structure than other methods available on the market. “Traditionally, we would have applied a torch-on membrane on top of the surface of the bridge deck before the placement of the asphalt layer. However, this membrane degrades over time and then provides very little protection against water that penetrates the porous asphalt layer and eventually makes its way through the concrete to the reinforcing bar inside. Spraylock Concrete Protection’s technology provides permanent protection to increase the durability of the concrete over its entire lifecycle,” Engelbrecht says.

The technology has been specifically engineered to penetrate the capillaries and pores of reinforced concrete structures to protect embedded reinforcing steel. This is in addition to sealing and waterproofing the concrete capillary and pore structure to improve resistance to chemical and environmental attack.

“Our technology stabilises the pH of new concrete to maintain a high value, lowering the potential of reinforcing steel corrosion. Moreover, the colloidal silica in Spraylock Concrete Protection’s technology reacts with the available alkalis in the capillary and pore space to form more calcium silicate hydrate. By filling these spaces, our technology waterproofs concrete within the interaction zone and application area. By stabilising pH levels and preventing moisture migration from carrying chlorides within the concrete matrix, the corrosion potential is greatly reduced,” Carl White, Managing Director of Spraylock Africa, says. Spraylock Africa is the African agent for Spraylock Concrete Protection’s full range of concrete protection technologies.

The technology was applied over a 246m2 area quickly and effortlessly. Treating the bridge deck with Spraylock Concrete Protection technology was up to 50% faster than applying a torched-on membrane. This enabled the principal contractor, Raubex Construction, to proceed with the asphalt surfacing shortly after DSC-Zendon treated the concrete.

White concludes by noting that he is proud that Spraylock Africa was again able to provide a cutting-edge solution to improve the durability of reinforced concrete. “Reinforced concrete has been the most widely used construction practice globally since the 1800s. However, corrosion of reinforcing steel is the leading cause of failure of reinforced concrete structures. By reducing the corrosion potential of reinforcing steel, our technology is helping client bodies and their professional teams to build robust and durable structures that continue to add value over their entire lifecycle.”