Sika refurbishes Serepta Bridge

(continued from the December 2017 Issue of ADM)

…in Bellville South, Cape Town. When Sujean Property Investments acquired 120 000m2 of land surrounding the old disused railway bridge, they were required to completely refurbish the bridge prior to re-developing the area into a modern industrial Mega Park.

Exeo Kholeka was contracted for the project that commenced in February 2017. Prior to filling internal voids and cracks in the bridge walls, Sikadur-AP (160 litres) was used to close all surface cracks. An all-purpose, two-component epoxy paste adhesive, Sikadur-AP provides excellent adhesion on a wide variety of materials, and is ideally suited for vertical and overhead applications. With a convenient 1:1 mixing ratio, it is easy to apply on either dry or damp surfaces and provides high abrasion resistance.

To treat spalling on the bridge, SikaTop Armatec-110 EpoCem (30 kits) was applied. As a cementitious, epoxy resin compensated, three-component coating material with corrosion inhibitor, SikaTop Armatec-110 EpoCem meets the requirement of EN 1504-7 and is certified for application under dynamic load conditions. Numerous advantages provided by this product include extended open times for repair mortars, excellent adhesion to concrete and steel and good resistance to water and chloride penetration.

Thick layer concrete was repaired using Sika MonoTop-615 HB (50 bags), a high build, cementitious, polymer-modified, one-component repair and reprofiling mortar, containing silica fume and Ferrogard corrosion inhibitor. With excellent workability characteristics as well as excellent thixotropic behaviour, Sika MonoTop-615 HB is especially suited for vertical or overhead applications and provides good resistance to water and chloride penetration.

Prior to waterproofing the bridge, injection specialist, Dampmen was sub-contracted to inject Sikadur-52 ZA (600 litres), a two-part, solvent-free, low viscosity injection liquid, via ports into the bridge structure. Sikadur-52 ZA not only forms an effective barrier against water infiltration and corrosion-promoting media, but also structurally bonds concrete sections together. The product is suitable for use on dry or damp surfaces, even in low temperatures and hardens without shrinkage. Some cracks in the bridge were so large that SikaGrout-212, a one-component, ready to mix, free-flowing, shrinkage-compensated expansive grout, was used prior to injecting Sikadur-52 ZA.

The sub-contractor then coated the entire bridge with Sikalastic-152 (300 kits), a two-component, fibre-reinforced mortar based on cement modified with special alkali-resistant polymers containing fine particle size, selected aggregates and adequate additives. Sikalastic-152 provides flexible waterproofing and concrete protection all in one product.

To cover all their bases and ensure absolute structural integrity of the bridge, engineers specified Sika Carbodur S512 plates to be bonded onto the interior vertical walls using Sikadur-30, a thixotropic, structural two-part adhesive based on a combination of epoxy resins and special filler. Extensive Testing and Approvals of Sika Carbodur plates are available from many countries worldwide. Dampmen attached approximately fifty, 4.2 metre lengths of Sika Carbodur S512 plates to the walls.

Sika Carbodur plates are pultruded carbon fibre reinforced polymer (CFRP) laminates designed for strengthening concrete, timber, masonry, steel and reinforced polymer structures. They are used to improve, increase or repair the performance and resistance of structures for increased load carrying capacity, damage to structural elements, improvement of serviceability and durability, change of the structural system, resistance to possible events such as earthquakes, and to repair design or construction defects. The high strength laminates are non-corroding, provide excellent durability and fatigue resistance and are supplied in lightweight rolls that are easily transported and installed.

The combination of all these renowned Sika products together with the Sika Carbodur system will significantly increase the longevity of the old Serepta Bridge.

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