WHO’S WHO IN CEMENT & CONCRETE
Flooring refurbishment at the SAAO The Southern African Large Telescope is the largest single optical telescope in the southern hemisphere
Flooring refurbishment operations in progress
A section of the restored floor
T
he Southern African Large Telescope (SALT) is the largest single optical telescope in the southern hemisphere. It is situated at the South African Astronomical Observatory (SAAO) field station, near Sutherland in the Northern Cape. Funded by a consortium of local and international partners, SALT has been in full scientific operation since 2011 – Africa’s giant eye in the sky. Even as SALT scientists look up, what lies beneath their feet is as important. The SAAO needed a complete floor refurbishment in the 120 m2 instrument room and appointed Eyethu Alpha as the main contractor. Botwei Projects, a Sika-approved applicator, was then appointed by Eyethu Alpha as a specialist contractor for the Sikafloor systems. The refurbishment process started with the floor preparation, which was done using the cup grinding method. This exposed the problem areas of the floor, which determined the repair process and product requirements. All cracks in the floor were exposed and cleaned,
and thereafter, gravity fed with Sikadur-52 ZA epoxy resin. Used to fill and seal voids and cracks in structures such as bridges and other civil engineering buildings, Sikadur-52 ZA is a two-part, low-viscosity, multipurpose epoxy resin, which has excellent penetration and high bond strength. Following a good cleaning and a wipe with an oil-free solvent, the floors were then primed using Sikafloor-161. Thereafter, an inspection was conducted to locate any pinholes, which were subsequently closed with Sikadur-31 DW epoxy. This is a two-part, epoxy-based, moisture-tolerant structural adhesive that bonds most construction materials, has high mechanical strengths, and can also be used for minor concrete repairs, joint filling and crack sealing. It has been specially formulated to meet the requirements for use in contact with drinking water.
Self-smoothing epoxy floor screed A final 2 mm thick layer of Sikafloor-263 SL epoxy floor screed was then applied. This
self-smoothing epoxy solution is for concrete and cement screed with medium to heavy traffic. It is highly durable and applied by a Sika-approved specialist applicator. After curing, the existing floor joints were cut, reemed and then primed with Sika Primer-3N. This is a solvent-based primer designed for use prior to other Sika products, on porous substrates such as concrete. It is also easy to apply, has a short flash-off time and is water-repellent. The joints were then sealed using Sikaflex PRO-3, a high-performance polyurethane sealant designed for floor joints and various other civil engineering applications. It is a single-component, moisture-curing, elastic sealant with high mechanical and chemical resistance. It cures without bubbles and is solvent-free. Eyethu Alpha and Botwei Projects successfully refurbished the floor, and the project was completed in December 2021. Together with Sika products, these contractors reached for the stars to provide a result that was simply a beautiful floor, but out of this world.
IMIESA May 2022
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