Citi-Con’s specialist concrete repair capabilities are being harnessed by a leading agricultural company to refurbish its silos at three sites. The silos are not only being restored to their original state. Their useable lives are also being extended, a critical intervention considering the strategic nature of this infrastructure. Silos are very costly to demolish and reconstruct, which often involves specialist construction techniques to reduce build time and costs. Even so, it is not always possible to decommission this infrastructure without negatively impacting operations. This is considering the strategic role that silos play in preventing post-harvest losses by providing efficient and reliable storage capacity.
Silos require extensive concrete repairs
Considering the age of these silos, they require extensive concrete repairs. The work scope includes waterproofing the bin roofs and ceilings, as well as sealing the drip ends. Citi-Con is also sealing the ring-beam; vertical wall joints; wind inlets; and manholes.
This is in addition to comprehensive repairs to the concrete walls, each about 33,5m in height and 49m in diameter.
The process starts with thorough preparation of the concrete substrate, removing a thin layer of concrete via high pressure cleaning at 200 bar. This exposes the many vertical and horizontal cracks in the walls. A comprehensive structural investigation is then undertaken. Cracks greater than 1mm in width are addressed first. A chip hammer is used to test for honeycombing and spalling due to steel reinforcement corrosion. Compromised concrete is then marked for attention.
Thereafter, square cutting is undertaken to prepare the compromised concrete for repair. This entails cutting the edges of the cracks to about 120mm on either side and widening the bases. They are opened to about 20mm behind the reinforcement to create a shelf for the repair material to lock in.
Durable concrete silo repairs
This level of preparation is key to ensuring durable concrete silo repairs. In many instances, premature failure of concrete repairs can be attributed to poor preparation practices to save time and costs.
As part of the process, the steel reinforcement is treated with StonCor Africa’s Pro-Struct 688 Zinc Rich Primer. It was specified for this application because of its durable and corrosion resistant properties. Refer to Pro-Struct 688 Zinc Rich Primer – Pro-Struct. This a sound example of how Citi-Con is also extending the useable life of the infrastructure. Bear in mind that the biggest cause of reinforced concrete degradation and failure. In most cases, corrosion was initiated due to carbonation or chloride-ion ingress.
Thereafter, the exposed concrete is saturated with water ahead of the application of the repair mortar. For this application, StonCor Africa’s TAMMS structural mortar was specified. This is considering its high strength and increased adhesion due to its proprietary formulation. It consists of Portland cement; graded aggregates; unique fibres; and polymers, while also containing a corrosion inhibitor. Refer to Tamms Structural Mortar – Euclid Chemical.
Cracks that are less than 1mm in width are chased with V-joint/V-groove cutting discs and then reinstated with ProStruct 506 Flexicoat. This is a high quality elastomeric waterproofing membrane.
Completing concrete silo repairs
Completing the concrete silo repairs entails also treating the other repair areas with Pro-Struct 506 Flexicoat. The wall is first saturated with water using a hose. The first coat is applied horizontally from right to left and the second perpendicular, starting from the top. This ensures proper adhesion of the 2mm-thick waterproofing membrane. Refer to Pro-Struct 506 Flexicoat – Pro-Struct.
By working closely with StonCor Africa as the company’s approved applicator, Citi-Con can guarantee its workmanship to maximum available terms. Refer to https://www.stoncor.co.za/.