JSE-listed construction materials company PPC has completed the R26-million major structural rehabilitation of one of the reinforced concrete duo-cell silos at its Hercules plant, in Tshwane, Gauteng.

The project restored the structural integrity and long-term performance of a critical cement storage facility. The plant remained fully operational throughout the construction period.

The project required advanced structural rehabilitation techniques and careful coordination to ensure repairs could be executed safely within an active industrial environment, PPC says.

The project, completed by specialist civil engineering contractor Smart Civils & PT Systems and consulting engineers Jones & Wagener, was carried out between July and December 2025.

Before the rehabilitation project, vertical cracks in the silo had resulted in the leakage of cement fines and the ingress of water, which indicated structural deficiencies in the silo shell.

PPC conducted a detailed structural assessment to evaluate the extent of cracking and to determine the condition of the reinforced concrete wall. With the assistance of consulting engineers, it then developed a recommended repair and strengthening strategy.

“The priority was to understand the structural behaviour of the wall and implement a repair methodology that would not only address the defects but also enhance the long-term performance of the structure,” explains Jones & Wagener project lead engineer Grant Harli.

The rehabilitation methodology that was developed combined crack injection, localised concrete repairs, external strengthening through post-tensioning and the application of protective coating systems to restore the structure and mitigate future deterioration.

Works began with detailed inspection and mapping of cracks and concrete defects across the external faces of the silo. Structural cracks were treated through pressure injection techniques, restoring continuity within the concrete matrix and preventing further leakage of cement fines.

Localised concrete repairs were undertaken in areas where deterioration or surface defects were identified, reinstating the structural and durability performance of the concrete.

A key component of the strengthening strategy involved the installation and stressing of external post-tension cables around the silo wall, Harli says.

The external strengthening system comprised of 176 rings of specialised UV protected strand, each anchored at 180° using Dywidag’s ME Anchor. A total of 352 Dywidag anchors were installed.

Each ring required four jacks to be operated simultaneously at each anchorage point to limit the lateral movement of the cables during stressing and ensure an even distribution of load.

“The installation of the external post-tensioning system provided additional circumferential restraint to the structure, effectively improving the load-carrying capacity and enhancing the overall structural performance of the silo wall,” he says.

Further, a primer and specialised protective coating system was applied to the external concrete surfaces to improve resistance to environmental exposure and extend the structure’s service life.

The rehabilitation programme was completed with the installation of a waterproofing system on the silo roof, PPC says.

“The strengthening measures have restored the structural integrity of the silo and enhanced its durability, thereby ensuring reliable performance into the future,” says Smart Civils & PT Systems site manager Clinton Barnes.

CONTINUOUS OPERATIONS
The project was executed within a fully operational cement plant and continuous truck movements required careful management of site access and construction activities.

Segregated truck routes were implemented using signs and physical barricades, while structural bracing and anchoring systems were installed to protect scaffolding from potential vehicle impact.

Weather conditions, including periodic thunderstorms and heavy rainfall, occasionally suspended work-at-height activities. Weather allowances and daily forecast monitoring were incorporated into the construction programme to minimise delays, PPC says.

Additionally, sporadic power outages also affected site operations and Smart Civils deployed a generator system to provide reliable power during outages.

The project was completed with a strong emphasis on safety, including strict working at heights safety measures, which resulted in zero safety incidents during its execution.

The project was successfully implemented with effective workaround plans to counter operational and environmental challenges.

“Strong collaboration between the PPC team, the supplier, and the consulting engineers kept the project on time and within budget. Owing to the risks of working at heights, PPC ensured that dedicated safety personnel were deployed on the project,” says PPC project manager Bevin Munsamy.