JOINT SEALANTS
CSL 316 Self Levelling Silicone Joint Sealant for Roads, Bridges and Infrastructure
CSL 316 is a single component self levelling silicone joint sealant manufactured by CSL Silicones and distributed exclusively across Sub-Saharan Africa by Technical Solutions Supplies. It seals horizontal concrete expansion joints on roads, bridges, airport aprons and taxiways, harbour and port infrastructure, industrial floors and logistics yards. It flows into the joint without tooling, bonds to concrete without primer in most applications, and cures at ambient temperature and humidity.
Furthermore, it meets ASTM C920 Type M Grade P Class 50 and SANRAL specifications for South African road infrastructure projects. One correctly installed application delivers more than 20 years of waterproof joint performance where polyurethane sealants require replacement every five to seven years in the same conditions.
Why Polyurethane Joint Sealants Keep Failing on South African Infrastructure
Polyurethane joint sealants dominate the South African construction market because they cost less at point of purchase and bond to most substrates. For decades this made them the default specification on roads, bridges, airports and industrial floors across the country. The performance record in South Africa’s specific conditions tells a different story.
South Africa has some of the highest UV radiation levels in the world. Polyurethane is a carbon based organic polymer that degrades under UV radiation through photo-oxidation. The sealant yellows, loses flexibility, chalks and cracks under sustained UV exposure. This process begins within three years in high UV environments. Once a joint sealant cracks it stops functioning as a seal. Water enters the joint, reaches the subgrade and begins the erosion cycle that generates pothole formation and pavement deterioration.
South Africa’s thermal cycling compounds the UV degradation. Daily temperature swings on the highveld between overnight lows and afternoon highs regularly exceed 20 degrees Celsius. This drives constant joint movement that pushes standard Class 25 polyurethane sealants beyond their movement capability, causing cohesive failure in the sealant body.
The consequential costs of failed joint sealants are never just the cost of the sealant itself. Water ingress through failed road joints damages subgrade layers and accelerates pothole formation. On bridges, water through failed deck joints reaches reinforcing steel and initiates the corrosion cycle that drives expensive structural repair.
CSL 316 addresses both failure mechanisms directly. Silicone does not photodegrade under UV radiation. Class 50 movement capability handles double the movement range of standard Class 25 polyurethane. One application lasts 20 or more years where polyurethane requires three or four replacement cycles over the same period.
Key Performance Properties
ASTM C920 Class 50 movement capability accommodates plus or minus 50% movement of the joint width. This is double the Class 25 rating of standard polyurethane sealants and handles the full thermal and dynamic movement range generated by South African highway, bridge and airport pavement joints.
Permanent UV stability means CSL 316 does not yellow, chalk, crack or lose flexibility under any UV exposure. The silicon oxygen polymer backbone is not affected by UV radiation. A silicone joint sealant installed on a South African highway does not begin the photo-oxidation degradation cycle that causes polyurethane sealants to fail within three to five years.
Self levelling flow fills horizontal joints completely without tooling. The sealant flows under gravity across the joint width, bonds to the full joint face area and produces a smooth flush surface. This eliminates the void formation and partial bonding that results from applying non-sag sealants to horizontal joints.
Chemical resistance to jet fuel, aviation fuels, oils, hydraulic fluids and mild chemicals makes CSL 316 the appropriate specification for airport apron and taxiway joints, industrial floor joints in chemical and petrochemical facilities, and harbour pavement joints in port operations environments.
No primer required on most clean, dry concrete applications, saving time and material costs on large joint sealant programmes across South Africa’s road and infrastructure network.
Service life exceeds 20 years in exposed outdoor infrastructure in Southern African conditions. Polyurethane sealants in the same conditions deliver five to seven years before UV degradation and movement fatigue require replacement. Over a 20 year asset life the lifecycle cost advantage of silicone is substantial when all replacement, mobilisation and traffic management costs factor into the calculation.
Where CSL 316 Is Used
SANRAL roads and highways carry thousands of linear metres of concrete expansion joints across the national road network. CSL 316 meets SANRAL and COTO specifications and accommodates the movement ranges that South African highway joints generate under thermal cycling and heavy freight loading.
Bridge deck joints face continuous dynamic loading from vehicle traffic, the full range of thermal movement generated by the bridge structure, and exposure to rain, salt and contamination from road drainage. CSL 316’s Class 50 movement rating and permanent flexibility handle the full demands of bridge deck joint applications.
Airport aprons and taxiways face jet fuel spillage, aircraft loading and the constant thermal stress of tarmac surfaces in full sun. CSL 316 resists jet fuel and aviation chemicals that would degrade polyurethane sealants, and its 20 year plus service life reduces maintenance intervention on operational surfaces where every shutdown carries a significant cost.
Harbour and port infrastructure combines salt water exposure, heavy container handling equipment traffic, chemical contamination from cargo operations and continuous wetting and drying cycles. CSL 316’s silicone chemistry resists chloride attack and does not hydrolyse in the marine environment.
Industrial floors and logistics yards carry forklift and heavy vehicle traffic that generates constant dynamic loading on joints. CSL 316’s ultra high elongation and low modulus mean it recovers from that loading repeatedly without fatigue failure across its full service life.
Water infrastructure including reservoirs, canals and water treatment facilities requires joint sealants that maintain waterproof integrity under continuous water contact and structural movement. CSL 316 does not absorb water or degrade under continuous water immersion.
Application Summary
Substrate: concrete, steel and most construction substrates, clean dry and free of contamination and old sealant residue. Joint width: 10mm to 50mm, depth to width ratio of 1 to 2. Backer rod: closed cell polyethylene foam backer rod required to control depth and prevent three sided adhesion. Application method: self levelling, flows without tooling in horizontal applications. System: single component, no mixing required. Cure: moisture cure RTV at ambient temperature and humidity. Movement capability: ASTM C920 Class 50, plus or minus 50% movement. Chemical resistance: jet fuel, oils and mild chemicals. Standards: ASTM C920 Type M Grade P Class 50, ASTM D5893, COTO, SANRAL approved. Service life: 20 or more years in exposed outdoor conditions.
CSL 316 vs Conventional Joint Sealants
Standard polyurethane sealants carry a Class 25 movement rating, degrade under UV radiation within three to five years in South African conditions, and require replacement every five to seven years on exposed infrastructure.
CSL 316 carries a Class 50 movement rating, provides permanent UV stability, resists jet fuel and chemical exposure, and delivers a service life exceeding 20 years in the same conditions.
For full technical specifications and application guidelines, download the Technical Data Sheet below or contact Technical Solutions Supplies directly.
Phone: 031 002 7376 Email: sales@tssupplies.co.za
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