Sika’s high-quality construction chemicals help reinforce Pioneer Foods’ Malmesbury Mill Silo complex

Sika prides itself on providing a wide range of high-quality construction chemicals for a variety of industries and applications, from construction to residential. Covering all aspects of construction – from basement to roof, and everything in between – Sika’s construction solutions are innovatively designed to deliver high performance with minimal environmental impact and at affordable prices.

Our products were recently selected to be used in a large-scale repair project, seeing the complete restoration of Pioneer Foods’ Malmesbury Mill. Find out more below.

The silo is around 77 years old, already having outlived its original life expectancy
Sika prides itself on providing a wide range of high-quality construction chemicals for a variety of industries and applications, from construction to residential

The project’s background & context

Pioneer Foods is one of South Africa’s largest producers and distributors of various well-known food and beverage brands and products. Operating predominantly within South Africa, while exporting to more than 80 countries across the globe, Pioneer Foods provides wholesale, retail, and informal trade customers with consistently high-quality products. Pioneer Foods (Pty) Ltd is part of Pioneer Food Group (Pty) Ltd which is a wholly owned subsidiary of Simba (Pty) Ltd and ultimately a wholly owned subsidiary of PepsiCo Inc.

Sitting within its Essential Foods division, the Grains business unit prides itself on supplying foods of exceptional quality that are safe, nutritious, and trusted by millions of consumers every day.

So, when Pioneer Foods detected large vertical cracks in the grain silos of its Malmesbury Mill silo complex in 2018, it appointed LNW Consulting Engineers and Project Managers to investigate and determine the structural integrity and remaining lifecycle of the silo complex. Once the investigation was completed, LNW were directed to refurbish the silos to ensure the high standards Pioneer Foods promises its customers.

Assessing the damage & the best way forward

The silo is around 77 years old, already having outlived its original life expectancy. To determine the cause of the structural distress and the best possible way to extend the silo’s life for another 20 years, LNW conducted a root cause analysis. Making use of the latest state-of-the-art infrared and high-resolution scanning equipment, LNW collected evidence of the typical distress patterns to complete a thorough structural analysis.

Pioneer Foods grain silo complex
Sika’s premium construction solutions meant that this project was the first of its kind. There has been no such repair of a multiple silo complex of this nature in South Africa

The insights gained from this investigation indicated ring tension failure of the horizontal reinforcing with large areas of fatigue within the concrete walls. This information enabled the engineers to design and develop a complete silo rehabilitation repair methodology. The decision was to repair the entire silo complex, utilising external structural reinforcement methods such as horizontal carbon fibre composite strapping, along with various types of mortars, epoxies and protective coatings.

After assessing the original diagnostic survey and rehabilitation proposals, as well as trialling various product options, the team decided that Sika’s innovative products were the best-performing solutions for this project. LNW was appointed as the Consulting Engineers and Project Managers, and Sika products were specified in the tender. REDEC Industrial and Engineering Solutions, a specialised contractor, was appointed as the successful repair contractor. 

Ensuring minimal environmental impact

As the work was to be done in an operational grain silo storage facility, it was crucial to select products that posed no risk of food contamination nor any other health and safety risks to the applicators. The silo storage levels had to be constantly monitored as repair work took place, and silos needing internal work had to be emptied. As the silos are situated next to Malmesbury Mill, innovative preparation techniques had to be adopted to minimise dust pollution.

A pioneering approach backed by extensive experience

Leveraging all the data and technical information collected, FEM models were constructed in Ansys software to determine the typical structural behaviour, as well as high stress zones at which operational loading cycles cause structural stress and fatigue.

LNW has a team of engineers and technical specialists that have a long-standing record in concrete rehabilitation, with specific experience in concrete silos, reservoirs, cooling towers and chimney stacks. The team is led by Structural Engineer Johan van Vuuren, who boasts almost 40 years of experience in rehabilitating steel and concrete structures. Combined with the latest technology, this experience guided the team in deciding the best possible materials and way forward.

Specially designed scaffolding enabled the installation of the external repairs, with the erection of the scaffolding ensuring that REDEC was able to stick to the project timelines. Internal work was done via skilled rope access.

Utilising Sika’s innovative construction chemicals & technology

The concrete repair method:

Because all the repairs were vertically orientated, the repair method had to make use of either trowel-applied mortars, or a letterbox shutter and pour system. After consulting Sika South Africa directly, it was decided that SikaTop® Armatec®-110 EpoCem® would be used as the primary rebar protective coating for the concrete repairs, protecting the steel reinforcement and inhibiting corrosion.

SikaTop® Armatec®-110 EpoCem® and Sika MonoTop®-610 were used as bonding primers for the concrete substrate. 

Sika MonoTop®-615HB was utilised as an R4 high build repair and re-profiling mortar due to its unique Ferrogard corrosion inhibitor and excellent lightweight properties. This product allowed for easy application and compaction, enabling a quicker application rate. Sika MonoTop®-615HB stands out as a one-component, polymer-modified, low-shrinkage structural repair mortar.

Due to the age of the structure and its low concrete compressive strength, there was a large amount of cracking, which had to be reamed open, stitched and repaired. Some of the minor cracks were saw cut and sealed with the Sikaflex® PRO-3, an I-Cure polyurethane sealant with high mechanical and chemical resistance.

Concrete repairs had to be carried out on the spalled concrete areas of the silo and, in some cases, badly corroded rebar had to be removed and replaced.

Specially designed scaffolding enabled the installation of the external repairs, with the erection of the scaffolding ensuring that REDEC was able to stick to the project timelines

Protective coatings:

Due to the current state and surface imperfections of the concrete, Sikalastic®-152 was chosen as a cementitious, flexible, fibre-reinforced mortar for waterproofing and concrete protection, and was applied on the entire external surface as a protective coating.

The Sikalastic®-152 was trowel applied in 2 coats of +- 1.5mm thickness per coat. The first coat was applied horizontally, and the second coat vertically.

The Sikagard®-550 W Elastic and Sikagard®-550 W Primer were chosen as the most ideal protective coating systems for the external concrete soffits, due to their excellent crack-bridging properties even at low temperatures.

For minor cracks, the Sika® Primer-3 N, an epoxy primer for porous substrates, and the Sikaflex® PRO-3 I-Cure were utilised.

The Sikadur-Combiflex® SG-20 P, a high-performance movement joint and crack sealing bandage system, was applied over all expansion joints to seal and waterproof. This Sika product uses the Sikadur-31DW structural epoxy as its adhesive for enhanced performance.

For crack repairs on the concrete roof slab floors, Sikadur®-43 ZA was used. This solvent-free, three-component repair and filling mortar was applied prior to application of the modified structural steel, which was fortified with the new SikaCem®-810 additive.

A crucial project successfully completed through careful planning

The silos that were repaired are critical to the safe storage and functioning of the Malmesbury Mill. Due to the time constrains and much higher costs, a complete demolition and rebuild was not possible. Fortunately, through careful planning by Pioneer Foods and LNW, the project proceeded with very little loss of productivity.

This project also took place during the COVID pandemic, which introduced many complications and risks. Pioneer Foods and LNW went above and beyond to keep the rehabilitation project alive, assisting the contractor along the way.

A quick turnaround time enabled by creative solutions

Time was a critical component of this project, which is why the client and LNW assisted with the ongoing demands, while keeping the mill functional throughout. The unique scaffolding solution was created to provide a safe working platform for the entire external face of the silos, and the products selected allowed for ease of installation, leading to further timesaving.

Not only was the project completed in record time, but the high-quality protective coatings utilised, such as the Sikalastic®-152 and Sikagard®-550 W elastic, will further enhance the longevity of the concrete repairs.

A ground-breaking project that exceeded expectations

The innovative approach taken alongside Sika’s premium construction solutions meant that this project was the first of its kind. There has been no such repair of a multiple silo complex of this nature in South Africa.

The highly durable, high-performing Sika products utilised in the refurbishment of the Malmesbury silos will ensure a longer service life, meeting and exceeding the required 20 years. This unique project required innovative product technology, complicated logistical planning, and good collaboration amongst the project team. As the mill was operational throughout the project, inventive, effective, and safe solutions were essential.

Sika was honoured to be a part of such a challenging yet rewarding project. Not only did we have the chance to showcase our innovative product technology, but we were also able to contribute to ensuring the safety and longevity of a crucial, life-sustaining project.

SIKA SOUTH AFRICA CORPORATE PROFILE

Sika is a specialty chemicals company with a leading position in the development and production of systems and products for bonding, sealing, damping, reinforcing, and protecting in the building sector and motor vehicle industry. Sika has subsidiaries in 101 countries around the world and manufactures in over 300 factories. Its 25,000 employees generated annual sales of CHF 9.24 billion in 2021.

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