As SAMI Bitumen Technologies’ Hamidreza Sahebzamani, Kanjana Yindee and Sebastien Chatard write, the company is helping to inspire and influence greener outcomes for transport projects Australia-wide.
In the dynamic field of road construction, where escalating demands, increasing traffic loads, and extreme environmental conditions intersect, the combination of innovation and sustainability is no longer a luxury, but a priority.
As the globe struggles with the intensifying threats of global warming and the imperative to limit carbon emissions, the road construction industry faces a dual challenge: to revolutionise its practices while responsibly using limited resources.
Innovative products and construction methodologies that can withstand heavy loads and harsh climates, yet minimise environmental impact, are crucial for sustainable development. Using green materials, recycling existing road surfaces, reducing pavement thickness, increasing the longevity of road lifespan, and energy-efficient construction techniques are examples of sustainable innovations that not only preserve the environment, but also ensure resilience and cost-effectiveness.
Prioritising sustainability and innovation in road construction not only aligns with global environmental targets, but also delivers tangible benefits by creating infrastructure that can endure the test of time and adapt to future demands.
SAMI Bitumen Technologies, established in 1978, has been a pioneer in the Australian roads industry, meeting the market demand for advanced bitumen technology. The company prides itself on providing a reliable and consistent full range of high-quality bituminous products for the construction of critical infrastructure, suitable for projects such as highways, bridges, runways, and local roads.
SAMI’s commitment to sustainability is ingrained in its operations, as it continually strives to develop environmentally friendly solutions that contribute to the long-term durability of Australia’s road network.
SAMI’s R&D sustainability initiatives are built on three key pillars. The first is encouraging the use of cold technologies in pavement construction and maintenance.
The second is the development of high-performance binders that enable roads to last longer with reduced thickness. The third and final pillar is advancing low-carbon emission products.
Pillar one
The utilisation of cold technologies has the potential to greatly reduce the carbon footprint associated with pavement construction and maintenance. As part of SAMI’s development strategies, there is a focus on the development and promotion of new, specialised high-performance emulsions. These emulsions play a vital role in enhancing the performance of pavement materials, while also contributing to sustainable and environmentally friendly construction practices. By embracing these innovative technologies and advancements in emulsion formulations, SAMI aims to further minimise the environmental impact of the construction industry while delivering high-quality and durable pavement solutions.
Australia boasts one of the largest road networks per capita globally, spanning over 870,000 kilometres. Approximately 40 per cent of this network is paved using various bituminous products. These road surfaces typically involve essential applications such as prime coats, initial seals, SAMI seals, and spray seals. However, it is unfortunate that a significant quantity of cutback products are still utilised.
Surprisingly, the road industry in Australia consumes a high amount, approximately 12,000 tonnes, of kerosene and 15,000 tonnes of diesel each year in the production process, excluding the fuels themselves.
Australia remains one of the largest consumers of cutback products globally, despite being one of the pioneering countries to adopt bitumen emulsion approximately 100 years ago. Regardless of the underlying reasons, the current outcome is undesirable, emphasising the need for a change in mindset. This significant quantity could be greatly reduced by replacing cutbacks with bitumen emulsions, resulting in an annual decrease of approximately 12,300 tonnes of CO2e emissions, according to the AfPA (Australian Flexible Pavement Association) LCA (Life Cycle Analysis) calculator.
Bitumen emulsions play a crucial role in various aspects of flexible or composite pavement construction, maintenance, and preservation. From the base layers, where emulsions (ETB) can be used to treat base courses, to surface layers where structural cold wearing courses known as grave emulsions can be applied, they offer a wide range of benefits.
Emulsions serve as penetrating prime coats, primer seals, and tack coats with high shear strength. They can be sprayed as fog seals, rejuvenating/enrichment seals, or scrub seals to extend the lifespan of aged surfaces and effectively seal them to prevent water penetration.
The use of bitumen emulsion in the world has always been growing due to the expansion of road construction and maintenance activities, as well as its substitution for cutback products and conventional hot applications. According to the key figures from IBEF (International Federation of Bitumen Emulsion) in 2022, the global consumption of bitumen emulsion amounted to 10 million tonnes, accounting for eight per cent of the total global bitumen consumption.
SAMI Bitumen Technologies has been a pioneer in bitumen emulsion innovations and production for nearly half a century. SAMI offers a range of unique products tailored for various applications.
Two well-known emulsion primes from SAMI are SAMIprime K2 and K2P, which are commonly used as prime coats for granular, stabilised, and concrete base layers. SAMIBioPrime is a fast-penetrating prime coat formulated with 100 per cent petroleum solvent-free ingredients, aiming to achieve a carbon-neutral product.
SAMIfloat is a polymer-modified cationic high float emulsion, specifically designed for exceptional performance in cold seasons and suboptimal aggregate conditions during spray sealing applications.
SAMIflex covers a range of high-performance polymer-modified emulsions suitable for spray sealing and Stress Alleviating Membrane Interlayers. These examples exemplify SAMI’s commitment to research, development, and promotion of bitumen emulsion within the industry, bridging the gap between Australia and global standards.
SAMIfilla EC is a specially formulated, highly polymer-modified emulsion with a thixotropic effect, capable of filling cracks without the need for heating.
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Pillar two
The development of high-performance binders is a critical aspect of constructing sustainable and long-lasting roads, summarised in the strategic approach in this pillar. The logic behind this strategy is straightforward yet reflective: the most sustainable road is the one that lasts the longest. It is counterproductive to build roads with minimal carbon footprints if they degrade quickly and require frequent repairs or replacements. Therefore, the durability and longevity of the pavements are of utmost importance when considering the sustainability of road infrastructure.
Furthermore, the smoothness of a road plays a significant role in environmental sustainability. A smooth road surface reduces the rolling resistance experienced by vehicles, which in turn reduces fuel consumption and associated carbon emissions. Studies have shown that driving on rough, uneven roads leads to significantly higher carbon emissions from vehicles when compared to driving on smooth roads. As such, ensuring that a road is as smooth as possible is an essential consideration in sustainable road design and construction.
In response to the demand for more sustainable and durable road materials, SAMI has introduced a product known as I-Brid. This highly modified binder represents a significant innovation in road construction materials. It is a hybrid binder that incorporates a mix of additives from various sources, fitted to enhance the pavement’s performance. I-Brid’s unique formulation delivers superior resistance to rutting, which is the permanent deformation of the road surface under the stress of traffic loads, particularly in hot weather.
Additionally, the binder exhibits excellent fatigue resistance, meaning that it can withstand repeated loading from traffic without cracking prematurely. The importance of such a property cannot be overstated, as roads that resist fatigue maintain their integrity for longer periods, reducing the need for maintenance and the resources associated with it.
Moisture sensitivity and fuel resistance are other critical properties addressed by the I-Brid binder. By resisting the damaging effects of water and fuel spillages, the road’s lifespan is extended, and its performance remains consistent regardless of exposure to these elements.
Another important aspect of sustainability in pavement construction involves minimising the use of raw materials. One highly effective method to achieve this is by reducing the thickness of pavements. This approach has been recognised as a significant arm in the pursuit of sustainability. France has long been utilising high-modulus asphalt with EME2 binders, a durable and long-lasting pavement structure.
Through the promotion of EME2 and the development of the I-Brid binder, SAMI is contributing to the construction of roads, airports, ports, and racetracks that not only have a reduced environmental impact during their construction phase, but also promote sustainability through their enhanced durability, longevity, and reduced maintenance requirements.
This innovative material answers the pressing need for infrastructural solutions that are both environmentally responsible and economically viable, ensuring that the roads that are built today can serve the needs of tomorrow without compromising the planet’s health.
Pillar three
The third pillar of SAMI’s sustainability initiative emphasises the adoption of low-carbon emission products, a step that reflects a critical awareness of environmental responsibility within the industry. Central to this endeavour is the introduction of SAMIGreen, a groundbreaking product line that incorporates partially biogenic additives. The development of SAMIGreen is the result of extensive research dedicated to identifying a biogenic source that maintains the binder’s performance both in short and long-term ageing.
Hitting a balance between environmental sustainability and product efficacy, SAMIGreen binders represent a significant innovation. These binders can be formulated into various grades of Polymer Modified Bitumen (PMB) suitable for diverse applications in asphalt and spray seal projects. Furthermore, they have been smoothly emulsified to craft low-carbon polymer-modified emulsions.
A remarkable feature of SAMIGreen is its technical profile, which mirrors that of traditional binders while cutting the carbon footprint by more than 50 per cent. This substantial reduction illustrates SAMI’s commitment to cutting-edge, eco-friendly products. The whole-life embodied carbon of the pavement is considered when designing SAMIGreen. This means that by using SAMIGreen, the quality and technical performance of the road will not be compromised, and the road will remain as long-lasting as it should be.
Hybrid modifications of bitumen are a relatively new concept in bitumen modification, where two or more different additives with different natures are used as modifiers in bitumen. This allows the sector to take advantage of the different benefits offered by each additive while limiting their disadvantages.
One popular method of hybrid modification is the simultaneous use of crumb rubber and elastomeric additives. This approach helps maintain the desired technical properties while reducing the need for elastomeric additives, which typically have a carbon footprint of over 5000 kilograms of CO2e per tonne of product.
By increasing the use of crumb rubber, which is produced from waste end-of-life tyres, SAMI aligns with the principles of the circular economy. Furthermore, crumb rubber has a significantly lower carbon footprint compared to elastomeric additives and even pure bitumen in the Australian context, with emissions of 376 kilograms CO2e per tonne for crumb rubber versus 425 kilograms CO2e per tonne for bitumen.
Crumbflex is a hybrid polymer-modified binder developed by SAMI, which incorporates both elastomeric additives and crumb rubber simultaneously. This binder can be produced in various grades of modification, offering the same technical properties as traditional PMBs but with approximately 10 per cent less carbon footprint.
By combining Crumbflex with SAMIGreen products, the company can maximise the advantages of low-carbon footprint products while ensuring the preservation of desired technical properties. The unique engineering composition of elastomeric additives, crumb rubber, and biogenic additives has resulted in a polymer modified binder with an impressive 70 per cent reduction in carbon footprint.
Innovation is at the heart of SAMI’s success story. Over the years, the company has invested heavily in research and development, pushing the boundaries of bitumen technology to provide cutting-edge solutions to its customers.
The company’s forward-thinking approach enables it to adapt to the ever-evolving needs of the road industry, delivering innovative products that enhance the safety and efficiency of road construction and maintenance.
This article was originally published in the November edition of our magazine. To read the magazine, click here.