Sika Strengthens Tweeespruit Brdige

When the ageing deck of the Tweespruit Bridge was identified as needing structural strengthening, Sika’s internationally renowned Carbodur Plates were specified. Consulting engineers, Mott Mac Donald PDNA, and contractor, Bridge Jointing & Rehabilitation, were awarded the contracts for this South African National Roads Agency Limited (SANRAL) project.

Situated on the N8 between Tweespruit and Ladybrand in the Free State, it was crucial that minimal interruption to traffic was caused during the project. These pultruded carbon fibre reinforced polymer (CFRP) laminates were bonded onto the bridge as external reinforcement, using a Sikadur epoxy resin adhesive. Surface preparation on the bridge entailed grinding away the weak surface paste where the Sika Carbodur M914 Plates were to be placed.

In order to prepare and clean the Sika Carbodur Plates prior to installation, they were wiped with Sika Colma Cleaner. These lightweight, easily transported laminates are simple to install, especially overhead and are supplied in rolls of unlimited lengths thereby eliminating the need for joints. Sika Carbodur Plates are high strength, non-corrosive and provide outstanding fatigue resistance and durability. Supplied in numerous combinations of high strength and modulus of elasticity, they are suitable for strengthening in a wide variety of situations for load increase, structural damage, change in structural systems, specification changes and for design or construction defects.

The prepared areas were then coated with a thin layer of Sikadur-30 (1-2mm, 48 kits), a thixotropic, structural, two-part adhesive, based on a combination of epoxy resins and special filler. This easy-to-mix and apply, high strength adhesive requires no primer, provides high creep resistance and hardens without shrinkage. Besides bonding Sika Carbodur plates to concrete, it provides very good adhesion to masonry, steel, cast iron, aluminium and timber. Additonal Sikadur-30 was then applied to the plates and bedded done onto the prepared surface, ensuring that all undulations in the plate where taken out and the plate was firmly in place.

The entire application of Sika Carbodur M914 Plates (410m) was carried out with no interruptions to traffic along the N8 or across the bridge and, due to the ease of installation, the project was completed in less than two weeks. As Sika Carbodur Plates are used worldwide in a multitude of applications, including rectifying earthquake damage, SANRAL is assured of the longevity of the Tweespruit Bridge.