SAMI Bitumen Technologies’ SAMIfloat polymer modified emulsion has once again surpassed expectations, this time assisting in road rehabilitation works in a popular coastal municipality. Representatives from SAMI, Colas and Central Coast Council explain.
Central Coast Council in New South Wales is home to some of the state’s most iconic beachfronts and scenery, making it a highly frequented area by locals and tourists alike.
With many essential links and arterial roads – all exposed to coastal weather fronts – Central Coast Council is required to regularly maintain connections while reducing disruptions to traffic.
Just one of the challenges has been road surface flushing and bleeding on a number of roads located within the municipality. As such, Central Coast Council has been on the lookout for innovative solutions to support the delivery of taxpayer-led transport services.
A chance encounter at an industry event gave the council its first exposure to SAMI Bitumen Technologies products, with one product in particular standing out.
SAMIfloat, a polymer modified cationic high float emulsion, designed to have a viscous structure (thixotropic) that prevents the flow of residual binder.
With a higher softening point and elastic recovery, SAMIfloat can withstand higher traffic loads and harsher weather conditions. Due to the gelly nature of the residue, SAMIfloat’s structure prevents bleeding or flushing at high temperatures and reduces aggregate loss at low temperatures.
Shortly after the industry event, SAMI began discussions with Matt Nazemi, Team Leader, Geotechnical and Pavements – Central Coast Council, to learn more about the municipality’s needs and challenges.
As Nazemi explains, a mixture of geographical and climate factors makes the long-term performance and application of conventional bitumen untenable.
“In the Central Coast we have many rural roads and highways that have dense tree cover and therefore shade, which makes curing more difficult, especially in the colder seasons,” he says.
“That’s why we identified SAMIfloat as a product of interest. Because its water based, we wouldn’t need to use cutters, oil or wait for its evaporation. Using environmentally friendly SAMIfloat creates a durable seal that resists bitumen excessive flow in hot days and aggregates embedment. Therefore, it reduces the risk of foamed bitumen stabilised base layers’ softening and flushing at the surface by eliminating cutter oil and reducing curing time.
“A new seal design incorporating SAMIfloat, developed by the Central Coast Council’s Geotechnical and Pavement Team and in collaboration with COLAS resulted in a satisfactory project delivery.”
Hamidreza Sahebzamani, Research & Development, and Technical Support Manager – SAMI Bitumen Technologies, says close consultation with clients helps the company to determine the best course of action for application and long-term performance.
“The initial direct discussion between SAMI, as the main supplier, and the client, gives us the opportunity to hear their problems and focus so that we can customise a solution and provide appropriate technical support,” he says.
Application time
Tumbi Umbi, a coastal township situated within the Central Coast Council, was identified as an ideal suburb to apply SAMIfloat.
The first of two applications took place late in 2024, at Palm Valley Road.
COLAS, the contractor engaged for the works, was tasked with sealing over foam bitumen stabilised pavements where traditional spray seals had failed due to flushing (where the hot binder had reacted negatively with the pavement, causing failures).
Andrew Carter-Meggatt, East Coast Regional Spray Seal Manager – COLAS, was appointed as the lead applicator.
“As SAMIfloat is cold, not hot, it doesn’t tend to activate the binder that’s in the road base; one of the reasons why it was so ideal for this three-to-four kilometre stretch of road,” he says.
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SAMIfloat can be sprayed at lower temperatures, reducing energy consumption and making the process safer for both workers and the environment. Roads treated with SAMIfloat also tend to have increased longevity, requiring less frequent repairs and reduced resource use over time.
“Central Coast Council is committed to implementing more sustainable solutions for its road network,” Carter-Meggatt says. “Moving forward, using SAMIfloat is a greener way for them to be more environmentally friendly.”
Nazemi says he and his team take pride in embracing sustainable and efficient products and processes where possible.
“Central Coast Council is always seeking sustainability and innovation within our pavement rehabilitation programs, which provide an opportunity to reduce potential defects in our network,” he says.
Second works
The success of the initial project paved the way for a second, which took place at Hansons Road, also within the suburb of Tumbi Umbi.
These works consisted of a reseal project over an existing pavement – a first for the team using the SAMIfloat product, which comprised a single coat application with 14-millimetre aggregate.
“We took the job on as an opportunity, knowing that it would present a challenge,” Carter-Meggatt says. “We’d never done anything like that with this product before.
“Traditionally, emulsions are placed in a double-coat seal treatment, just because you want to lock down that larger aggregate size. We went with a single coat, and it worked perfectly well, with no signs of stripping. SAMIfloat grabs hold of the aggregate quite well, and it’s got great stone retention.”
Proving to be effective in cold weather and high traffic, SAMIfloat’s performance characteristics were supported by consistent collaboration of all parties, which contributed to the success of both projects.
“From beginning to end, the collaboration was fantastic. Every party was open to listening and learning from other’s experiences and benefitting from that shared knowledge,” Nazemi says.
“There was great teamwork, with all parties on site, monitoring the construction stages. That filled us with confidence that we’d get the outcome we were after.”
For SAMI, the successful works mark the beginning of what could be a long-term partnership with Central Coast Council, as Sahebzamani explains.
“I’m thrilled and very happy that this connection has started,” he says. “I’m also happy for the whole industry, as this is yet another SAMI product that can contribute to the commitment of using more sustainable solutions, that also incorporate safety factors for people and the environment.
“At the end of the day, these projects with SAMIfloat have delivered whole-of-life savings in terms of cost and carbon emissions, while providing better roads for taxpayers as well.”
This article was originally published in the October edition of our magazine. To read the magazine, click here.
