Addressing maintenance backlogs is a pressing concern. IMIESA speaks to Tosas representatives Werner Tessendorf, business development manager, and Hannes Lambert, technical manager, about adding value to the industry.
South Africa’s roads infrastructure network is a vital socio-economic conduit and, given budget constraints, innovative solutions are needed to extend their life. One such innovation from Tosas is Ralumac® microsurfacing. The company has acquired the sole licence to produce this revolutionary cold asphalt formulation locally and is forging ahead on a series of roads contracts backed by a new slurry truck fleet.
In South Africa, Ralumac was first introduced during the early 1980s, but the brand subsequently exited the market in 2001. Tosas’ reintroduction of Ralumac now ensures positive traction for this cost-effective product, well known worldwide as a high-performance, versatile road maintenance solution when applied in microsurfacing, overlays and rut filling applications on deformed surfaces, highways and freeways.
Ralumac can be used with reinforced synthetic fibres that improve fatigue properties and surface texture. Pigmented binders can also be used for cycle lanes and pedestrian walkways.
“From a costing perspective, Ralumac’s life expectancy usually exceeds seven years and it’s an excellent option for maintenance interventions,” Lambert explains. “The product improves undulations, profile and skid resistance, and provides excellent cohesion. Once applied, the bond is irreversible, and no tack coat is required.”
With fast-acting Ralumac, pedestrian walkways can be opened within 10 to 15 minutes and vehicular traffic can resume within 30 minutes within ambient temperatures of 25°C and rising. By comparison, conventional, slow-setting slurries can take up to four hours under the same climatic conditions.
Slurry trucks are equipped with special mixers and spreader boxes that allow for continuous agitation to prevent premature breaking. As the specialised machine moves forward, it spreads the microsurfacing material across the width of the traffic lane in a single pass.
The specially engineered rut fill boxes are designed to place the largest aggregates in the deepest part of the rut to give strength and maximum stability in the deformed wheel path. The break rate can be controlled and slowed down by the use of chemical additives to assist with hand work or in very hot climates. Variable-width spreader boxes mounted on skids assist with road surface undulations and automatically compensate for width variations.
“Another advantage of Ralumac is that it promotes an element of labour-intensive construction, since a work crew of around 10 is normally required,” says Lambert.
Ralumac has been used successfully during night work due to its ability to meet a broad range of temperature and weather conditions. The product can also be used on airfield landing strips due to the dense-graded mix and improved skid-resistant surface without the risk of loose aggregate that can damage small aircraft props. Another advantage is that microsurfacing can restore the surface profile by eliminating areas where hydroplaning occurs. It will create a new, stable surface that is resistant to rutting or shoving in summer and to cracking during cold winter months.
Experiences in durability
Tosas has an exceptional track record for product durability. A prime example is a bitumen rubber grid seal applied in Ruimsig, Roodespoort, as an alternative to regravelling in the late 1990s. More than 25 years later, a recent site visit to this area has confirmed that this very thin layer has remained intact, without an interim treatment application and with limited damage.
“That was a very basic formulation, but it demonstrates our ability to think outside the box,” says Lambert. “A more recent example is an ultra-thin friction course (UTFC) paving contract on a section of the N5, which shows how we can find equally lasting solutions for more advanced applications.”
Blended at Tosas’ Wadeville facility, the company’s new AR2 (crumb rubber technology trademarked as NCRT™) asphalt forms a core component of the final mix design and is being transported in specialised haulers to a Much Asphalt plant in Bloemfontein. Here, the UTFC is blended and transported a further 340 km away to be paved on the N5 near Harrismith, made possible by the warm-mix capabilities of the NCRT. So far, more than 2 000 t of UTFC has been paved successfully on
Traditionally, a bitumen rubber plant would have to be established and installed with a header-tank system in order to get a consistent feed of binder to the asphalt plant. NCRT makes it possible to blend off-site with no specialised header systems.
Alongside its product focus, Tosas is developing its qualifying small enterprise (QSE) programme to support the growth of new entrants in the paving industry. Recent developments include the signing of an agreement with Thandabantu Materials and Applications, which will become one of Tosas’ dedicated supply partners.
“As a leading industry player and Level 2 BBBEE company, Tosas is committed to driving transformation and we are excited about expanding our QSE pool,” Tessendorf explains. A spokesperson for Thandabantu says that the agreement enables the company to help address the three main social challenges facing South Africa, namely alleviating poverty, inequality and high unemployment, through construction work that will flow from this agreement.
Alongside its mainstream Sanral projects, Tosas is targeting growth in the provincial market, where it believes Ralumac has a major role to play in “repairing more kilometres with less money”.
Currently, Tosas is working on key projects for TRAC and the Western Cape Provincial Government. Cross-border work is also ongoing in Botswana, Mozambique, Namibia
“We have a good order book for the winter period; however, there’s a concern within the roadbuilding industry about delays in the awarding of Sanral projects for the upcoming summer period. There’s also very limited activity at provincial level, with the exception of the Western Cape,” Tessendorf continues. “This situation needs to be urgently addressed by National Treasury, the Department of Transport and Sanral to ensure the longer-term sustainability of the roads construction industry.”
Another concern is the rise in community protests and disruptions on roads projects, which has huge cost implications in terms of construction delays and the ensuing penalties for contractors. Together with the industry, Tosas is engaging with public sector stakeholders to find more equitable procurement solutions.
“One of our strengths has always been our ability to invest and adapt to cost-sensitive industry requirements, so we and the larger Raubex Group to which we belong are confident that we can win and deliver on new work over what is expected to be a very challenging two- to three-year period ahead. We will continue to do our part to drive industry transformation, while selecting technologies like Ralumac that are cost-competitive and promote job creation,” Tessendorf concludes.