The Sappi (the South African Pulp and Paper Industries Limited) Ngodwana Paper Mill, situated 50km from Mbombela in Mpumalanga, recently underwent a major concrete rehabilitation. Ngodwana is one of the oldest and largest paper mills in the country.
Ngodwana Mill not only complies with responsible and sustainable forestation practices and is FSC (Forest Stewardship Council) accredited, it is also uniquely designed to minimise fresh water usage, a significant factor considering the current drought conditions in South Africa.
Sappi required a highly durable solution that would be able to withstand an adverse operational environment at the paper mill, which led to DPA Specialist Consulting Engineers specifying Sika’s specialised products to cover all aspects of the necessary concrete repairs.
Sikacrete-214, a free-flowing, high strength micro concrete with a maximum aggregate size of 9mm was used to repair all the floor areas. The product provides excellent adhesion and rapid strength development with high resistance to freeze/thaw cycling. It is also economical, easy to mix, shrinkage compensated and vapour permeable.
The plant has been in operation since 1966 and in 2013 entered the Dissolving Wood Pulp (DWP) market using a process known as the kraft or sulphate process. For this reason, consultants specified sulphate-resistant Sika MonoTop-412 S, a one-component, fibre-reinforced, low shrinkage, structural repair mortar that meets the requirement of Class-R4 of EN 1504-3. The specialised product was applied to all areas subjected to high sulphate attack as it is suitable for preserving or restoring passivity and has been is tested for application under live dynamic loading.
Severe time and budget constraints, combined with adverse working conditions, made the project challenging. Sika’s products enabled the rehabilitation project to be significantly expedited and will also extend the operational future of the historic Ngodwana Mill.
For more information, contact Sika on +27 (31) 792 6500 or via www.sika.co.za.