A major structural rehabilitation and strengthening project at the PPC Hercules Plant has been successfully completed, restoring the structural integrity and long-term performance of a critical cement storage facility while allowing the plant to remain fully operational throughout the construction period.
The PPC Duo-Cell Silo Strengthening and Repair Project, valued at approximately R26 million, was delivered by specialist civil engineering contractor Smart Civils & PT Systems as a turnkey project with consulting engineers Jones & Wagener. The project was carried out between July 2025 and December 2025.
The project required advanced structural rehabilitation techniques and careful coordination to ensure repairs could be executed safely within an active industrial environment.
Structural Assessment and Intervention
In June 2024, vertical cracking was identified along the external wall of one of the plant’s reinforced concrete duo-cell silos. The cracks resulted in the leakage of cement fines and the ingress of water, indicating structural deficiencies in the silo shell.
A detailed structural assessment was subsequently undertaken by PPC to evaluate the extent of cracking and to determine the condition of the reinforced concrete wall. PPC, with the assistance of consulting engineers, developed a recommended repair and strengthening strategy. PPC then issued a tender to a list of pre-qualified suppliers. After an extensive tender evaluation process, Smart Civil Construction was awarded the tender.
“Once the cracking was identified, 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 Grant Harli, lead engineer on this project from Jones & Wagener.
Based on the findings, a rehabilitation methodology was developed combining 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.
Rehabilitation Methodology
As the main contractor, Smart Civils was responsible for executing the rehabilitation works in accordance with the engineering design and technical specifications while coordinating specialist suppliers and subcontractors.
The 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 (PT) cables around the silo wall. The external strengthening system comprised of 176 rings of specialised UV protected strand, each anchored at 180 degrees 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,” says Grant Harli.
Following completion of the structural repairs, 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.
Materials and repair systems were supplied in collaboration with Sika South Africa.
Working Within a Live Industrial Environment
Executing the works within a fully operational cement plant presented significant logistical and safety challenges. Continuous truck movements required careful management of site access and construction activities. Segregated truck routes were implemented using signage 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.
Sporadic power outages and load-shedding also affected site operations. To maintain continuity, Smart Civils deployed a generator system to provide reliable power during outages.
Safety and Logistics Management
Access to elevated work areas relied on a shared Alimak elevator, used by both the main contractor and subcontractors. Controlled time allocations were introduced to manage personnel and material movement.
All scaffolding was erected by certified personnel in accordance with approved designs, with formal handover certificates issued before use. Routine inspections were conducted throughout the project, and fall-arrest systems were mandatory for all work-at-height activities.
The project was completed with a strong emphasis on safety, achieving zero safety incidents over its duration.
Successful Project Delivery
There were some operational and environmental challenges during the project, and the project was successfully implemented with effective workaround plans to counter the challenges.
“Strong collaboration between the PPC team, the supplier, and the consulting engineers kept the project on time and within budget. Due to the risks of working at heights, PPC ensured that dedicated safety personnel were deployed on the project.” says Bevin Munsamy the PPC Project Manager.
An effective execution of the project was achieved without hindering day-to-day Plant operations.
“The innovative strengthening measures implemented have restored the structural integrity of the silo and enhanced its durability, ensuring reliable performance well into the future,” says Clinton Barnes the Smart Civils & PT Systems site manager
The project highlights Smart Civils’ expertise in delivering complex structural rehabilitation projects within active industrial environments through a combination of advanced engineering solutions, careful construction planning and rigorous safety management.
