Mobile ‘hot-mix-in-a-bag’ oven trailer combo for labour-intensive road repairs
05 March 2019 | Web Article Number: ME201913521
NATIONAL Asphalt has developed a ‘Hot-Mix-in-a-Bag’ solution that it says optimises labour in construction without compromising cost, quality and productivity.
The company is collaborating with Siyeza Consulting, one of the Gauteng Department of Roads and Transport’s (GDR&T’s) newly appointed consulting engineering firms working on the Tswelopele programme, exploring ways to boost service delivery on road repairs by maintenance contractors in Tshwane.
According to the company, this intervention will help ensure key GDR&T contractor/service delivery objectives and targets are met. These include optimum budget expenditure, local labour enhancement, accredited contractor training, skills transfer and mentorship to underpin quality delivery of all road maintenance services to the department.
Gerald Gundu of Siyeza Consulting Engineers said many of these contractors are focused on pothole repair work, edge breaks and minor patchwork, and there was a need to find a viable asphalt solution.
“The objectives of Tswelopele include increasing the capacity, equity ownership, sustainability and quality of the technical and business practices of targeted learner contractors. As part of contractor development, Siyeza Consulting Engineers asked National Asphalt to demonstrate its products and technologies which these contractors could use,” Gundu said.
An aspect of the Tswelopele initiative is to create labour-intensive techniques for road repair and maintenance. This is aimed at employment creation and upskilling small contractors who would start at a Construction Industry Development Board (CIDB) level 1 and complete the Incubator Programme with a CIDB level 4 status after three years.
The asphalt solution proposed by National Asphalt is LT40 – or ‘Hot-Mix-in-a-Bag’ – which offers contractors ease of use of a quality continuously graded low temperature asphalt but with results that compare with traditional Hot Mix Asphalt (HMA).
“National Asphalt LT40 has zero waste materials, cuts down on time spent in queues at HMA plants, or product loss arising from bad weather,” said Pascal Garrioch of National Asphalt. “It also improves contractors’ productivity, allowing them to proceed directly to site with all the tools necessary to begin work without delay.”
“Heating of material on site using the mobile oven trailer means quality asphalt material is readily available and on hand 24/7,” Garrioch added.
Conventional HMA needs to be applied at around 150°C and must be laid within a few hours of manufacture. National Asphalt’s LT40 can be applied at between 80°C and 100°C and can be reheated for ongoing use without compromising any physical or technical properties or benefits of the asphalt mix.
Garrioch said the product was perfect for edge-breaks, minor patching, pothole repairs and the reinstatement of trenches with the application process carried out in the same way as traditional HMA repair.
“LT40 is supplied in 25 kg bags and is heated to between 100 to 110⁰ C in a specialised oven which is supplied on a custom-built trailer. Once at the right temperature, the product is shovelled onto a wheelbarrow and taken to the repair site where it is placed in the prepared area, spread, levelled and compacted accordingly,” Garrioch said.
Contained in sealed plastic bags, LT40 has a shelf life of up to 12 months, allowing contractors to purchase and store the product for use at their convenience.
“The mobile hot-mix-in-a-bag oven trailer is the latest innovative alternative technology for maximising labour-intensive construction methods with improved quality in the maintenance and repair of paved roads,” said Gundu.
He said the construction method was being assessed for suitability to labour-intensive projects, along with suitable funding models that could facilitate its uptake by learner contractors and small to medium enterprises.