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SAMI: Up to the challenge

SAMI Bitumen Technologies recently conducted trials of the SAMIfloat emulsion in Glen Innes, New South Wales.

SAMI Bitumen Technologies’ SAMIfloat emulsion spray sealing solution has been put to the test. Roads & Infrastructure learns how the product performed and what’s to come.

Ever since its inception in 1978, SAMI Bitumen Technologies has been recognised as one of the industry’s leaders when it comes to research and development.

SAMI Bitumen Technologies is responsible for the creation and introduction of many products that are now considered and used as standard domestically. This includes polymer modified binders, emulsions and polymer modified emulsions.

For years, hot modified cutback binders were the method of choice for Australia’s spray sealing industry.

However, a shift towards sustainable road construction, as well as safer and easier to use products, encouraged SAMI Bitumen Technologies to develop an alternative and SAMIfloat was born. 

The Glen Innes trial aimed to understand the spray-ability, setting time and residue behaviour of the emulsion product.
The Glen Innes trial aimed to understand the spray-ability, setting time and residue behaviour of the emulsion product.

Developed in early 2022, SAMIfloat is a polymer cationic high-float (thixotropic) sprayed sealing emulsion. High Float emulsions are designed to have a gel structure that prevents the flow of residual binder.

It represents the company’s commitment to producing innovative products, particularly when it comes to sprayed sealing.

SAMI Bitumen Technologies National R&D and Laboratory Manager Kanjana Yindee says that unlike conventional bitumen emulsions, SAMIfloat leaves more than just the residual, after the water evaporates.

“SAMIfloat creates a gel structure in the residue that permits a thicker binder coating on the aggregate particles,” Yindee explains. “SAMIfloat residue is resistant to flow at high temperatures while not being affected as much by low ambient temperatures.”

The SAMIfloat concept has been further developed to create a ‘high float emulsion’ that is more suited to Australian conditions. 

“Australia’s climate has warmed, and the duration, frequency and intensity of extreme heat events have increased across large parts of Australia [Bureau of Meteorology 2016],” Yindee says. “As a result, spray seal binders from conventional emulsion typically used in the past may not function and be suitable.

“Colas Canada (a subsidiary of the Colas family) uses high float emulsions to construct graded seals as standard practice. The Colas Canada team has long experiences and technical skills with the use of anionic high float emulsion. We worked very closely with them to engage their expertise for the development of this new binder.”

The high float emulsion provides increased resilience for the residual binder at colder temperatures, while also enhancing the performance of the binder in warmer temperatures. This is thanks to the gel structure of the residue, which can also enable greater stone retention as well as reduced delays when opening the road to traffic following construction. 


 

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The trial 

SAMI Bitumen Technologies recently put the SAMIfloat through its paces at a trial in Glen Innes, New South Wales.

Andrew Meggatt, Colas Northern New South Wales Operations Supervisor, oversaw the trial that examined the performance of the product in Australian conditions.

“The main objective of the trial was to implement a new product that hadn’t been sprayed before in Australia, which could deliver the same results as the products the client had used previously,” Meggatt says.

“We also wanted to implement a graded seal that was more environmentally friendly by reducing our greenhouse gas emissions. This was achieved by reducing the volume of cutters required, to make the material more flexible, which meant not having to burn excessive fuel to heat the material to be sprayed evenly across the pavement.”

Meggatt says the Glen Innes region presented an ideal location for these trials, due to the variety of weather conditions.

“The region experiences weather on two very different ends of the spectrum. In summer, the temperature exceeds 30 degrees Celsius, with road temperatures reaching close to 50 degrees Celsius. In winter, it’s often freezing,” he says.

“These fluctuations in temperature can place immense strain on the pavement wearing courses. The Glen Innes Severn Council Shire, which has seen our business complete close to 100 kilometres of traditional graded seal, was eager to discover what else would work best for their unsealed road network.”

According to Meggatt, SAMIfloat performed better than expected. 

Expectations were that the high application rate and road gradient would result in the emulsion flowing to the lowest point when applied. This would have resulted in a lack of emulsion to maintain aggregate adhesion, but Meggatt says the emulsion barely ran off, instead adhering quickly with the aggregate.

“The emulsion trial was sprayed in conjunction with a traditional cutback modified binder graded seal to compare its performance under the same weather and traffic conditions. The emulsion has performed better under the weather and traffic conditions, there is minimal flushing of binder and there is a slight increase in stone retention,” Meggatt says.

SAMIfloat was developed as a viable alternative to hot modified cutback binders.
SAMIfloat was developed as a viable alternative to hot modified cutback binders.

Despite his previous experience with emulsions in the industry, even Meggatt was surprised by the trial results.

“Traditionally emulsion seals have not been as effective as traditional hot binder seals, due to more time required for their cohesion development and having to limit their exposure to traffic early post placement,” he says. 

“However, this emulsion was opened to vehicle movements within 10 minutes of application. It also received some rain during the night, which didn’t affect the seal.”

SAMI Bitumen Technologies will now conduct further trials, including applications such as single spray sealing with uncoated dusty aggregate.

“If it works very well with graded seal and single chip seal, we would love for this product to become the preferred alternative for new and resealing projects in Australia,” Yindee says. 

This article was originally published in the February edition of our magazine. To read the magazine, click here.

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