Debunked: The Myths and Truths about Bitumen Emulsion on Haul Roads
Use of bitumen emulsions on haul roads is not a new concept to the mining industry. Its benefits include significant reductions in wheel generated dust, lower ongoing road maintenance costs, fuel savings, faster bounce back after adverse weather and improved truck tyre life.
Despite these benefits, several misconceptions about bitumen emulsions have developed over the years. Some of these beliefs relate to the cost of emulsion solutions, how hard it is to use and the negative impacts it has on the environment.
In this blog, we set the record straight and explain in detail why certain perceptions about bitumen emulsions are simply untrue.
First - here’s a quick definition of what a bitumen emulsion is:
A bituminous emulsion is a two-phase mixture of fine bitumen droplets and emulsifiers, dispersed in water. The binding and sealing properties, robustness and re-workability of bitumen makes this a reliable dust control solution, particularly for treating and maintaining haul roads. The solution can be established into the wearing course layer of a road or used as a spray on treatment. Bitumen emulsions are specifically formulated to minimise wheel generated dust, as well as bind, seal and suppress fugitive dust.
Now let’s explore and debunk the 10 most common myths.
Myth # 1 - Bitumen emulsion is expensive to use on haul roads
The word “bitumen” is synonymous with the concept of building a road and the business of building roads is a costly one. However, the cost of purchasing and using bitumen emulsion compared to purchasing and using standard bitumen is significantly less than you may think.
Standard bitumen is extremely viscous and has to be heated to incredibly high temperatures in order to be used when laying roads. As a consequence, it has to be classified and handled as a Dangerous Product during transport. This of course drives up transportation costs.
On the other hand, bitumen emulsion does not need to be heated in order to be used. It’s also much thinner and easier to handle compared to standard bitumen, making it cheaper to transport as it doesn’t have to be classified as a Dangerous Product.
Furthermore, when bitumen emulsion is established into roads, construction costs are lower overall. Specialised paving machines which can withstand heated bitumen are not required due to the fact that the emulsion is cool in temperature.
Myth # 2 - Using bitumen emulsion holds up road establishment projects
The benefits of incorporating bitumen emulsion into a haul road are best realised when it is spread into the wearing course layer of the road during the establishment phase. Once the road has been established, the emulsion will work to provide a surface seal that significantly reduces wheel-generated dust and the ingress of water into the road-base.
However, if a mining operator does not want to hold up production by taking this additional step, a “spray only” application can be just as effective. The bitumen emulsion solution is simply applied onto the surface of the road via a series of light dilutions using a water cart.
The repeated application of the emulsion and penetration properties of the formulation will lead to progressive build up of a bitumen sealed surface that binds surface materials together and prevents water ingress. This spray-on approach can be incorporated into the regular grading program.
Roads can be trafficked immediately after the road has been established or the spray on application is completed. Heavy traffic actually aids compaction and improves running surface conditions.
Myth # 3 - Bitumen emulsions can’t be applied to mine roads inhouse, an external supplier needs to be hired to manage the process entirely on-site.
This myth is somewhat debunked by the point made above. If establishing the emulsion into the haul road network seems too time consuming or labour intensive, the alternative is to use the spray on approach.
Whilst your mine can opt to engage an external supplier to manage the process for you completely on-site, reputable bitumen emulsion suppliers are willing to supply mines with the necessary products along with comprehensive training on how it works and how to store it correctly.
Suppliers can also work with and train water cart operators in the correct dosage of bitumen emulsions based products and assist with the development of an application schedule to ensure high levels of dust control are achieved.
Myth # 4 - Once applied, the bitumen emulsion can’t be reused on other roads
Another key argument against incorporating bitumen emulsion into roads is that the benefits of doing so are only realised once - the investment doesn’t get a second or third life.
However, bitumen emulsion is not a permanent formulation. It can actually be moved - either at the end of life of the mine or recycled into another section of the road network if needed for continued operations.
The wearing course layer containing the emulsion can be removed with a front-end loader and transported to the location of a different road. It is rolled into place during establishment and incorporated with a small amount of additional emulsion to complete the wearing course layer.
Myth # 5 - It doesn’t make sense to use a dust control product which minimises water usage when a mine has access to free unlimited water
One of the biggest sources of water consumption in mining operations is for dust control on haul roads. Mine operators often have the mindset that the water they use is ‘free’ because it is usually pulled from underground water tables available to access within the mine lease.
But how long will this water last? And just because a mine has access to a water table, should they not be looking for more sustainable ways to use that water, particularly as their use of this water impacts on surrounding creeks and rivers?
Mines are facing increasing pressure by the public to reduce water consumption, especially in regional communities where there are farmers who are struggling to get by in times of drought and have water access limitations imposed on them.
Utilising a bitumen emulsion (such as Dust-A-Side’s DAS Product) either in the wearing course layer of roads or as a spray on treatment can achieve upwards of a 90+% reduction in water usage for dust control purposes.
Not only is precious water saved when a mine forgoes its reliance on constantly watering roads, but safety conditions are improved as well as the roads aren’t always saturated which helps to prevent uncontrolled vehicle movements.
Myth # 6 - Bitumen emulsions can have negative environmental impacts
There has been some debate in the industry as to whether there are any environmental risks associated with using bitumen emulsions, due to the fact that bitumen is an oil based product.
In truth, bitumen emulsion is actually an environmentally friendly formulation. Since bitumen emulsions are largely water based, and often highly diluted, they have minimal impact on the environment. When the bitumen breaks, bonds and cures with the road material in-situ, the end result is a manageable, inert solid that won’t leach into sub-soils, regardless of the weather.
As mentioned above, bitumen emulsion is not considered Dangerous Goods. In particular, Dust-A-Side’s emulsion formulation doesn't contain cutters (solvents) like some cutback bitumens. Our emulsion only contains environmentally friendly emulsifiers.
Myth # 7 - Bitumen emulsion ruins (or shortens the life of) water carts
Water cart contractors often push back on recommending the use of bitumen emulsions based on the theory that the emulsion will damage the tanks on the carts. But it really comes down to taking care of the equipment properly.
If a water cart is left with bitumen emulsion residue in it without being flushed out correctly, then an internal buildup can occur in the tank and lead to blockages. However if the correct maintenance procedures are followed, water carts used to spray bitumen emulsion will operate successfully for many years. Proper maintenance would include full flush spray cycles after main applications. If not used everyday, carts should always be stored with spray bars/nozzles having been cleaned first so they do not become blocked.
Myth # 8 - Bitumen emulsion is mainly suitable for haul roads and not service roads
There is a perception in the mining industry that bitumen emulsion is only really suitable for use on haul roads. But in actuality, because of its versatility and low lifetime cost to apply, it is appropriate to also use on service roads.
On lighter traffic service roads, the cycle time between spray on treatments is much longer — further reducing the cost of maintaining safe, dust-free roads. This makes bitumen emulsion the ideal lowest cost treatment for any semi-permanent or life of mine road across the life of the asset.
Myth # 9 - Bitumen emulsion makes roads more slippery when wet
There’s a misinformed perception that haul roads treated with bitumen emulsion are more slippery than non-treated roads when it rains. Yet the reality is all roads are slippery when wet and operators must drive to conditions just like on normal public roads.
Roads treated with spray on bitumen emulsions require much less frequent watering for dust control, which means less potential for slippery conditions. And roads with bitumen emulsion incorporated into the wearing course layer are not more slippery than non-treated roads under the same conditions. In fact, the bound, stabilised pavement provided by the emulsions eliminates uncontrolled movements that would otherwise occur on an untreated road.
Myth # 10 - Bitumen emulsion is suitable for use in all circumstances
There is simply no one-size-fits-all approach in regards to road stabilisation and dust suppression on mine roads. There are an endless litany of variables that have to be taken into consideration. For example - the wearing course layer material being used on the road, the expected longevity of the road, commercial considerations as well as traffic types/volumes.
All of these factors need to be thought about when determining the best road binder or dust suppression product to use on your road.
Emulsion/water and emulsion/material compatibility testing is essential to ensure that you achieve the results you desire whenever using bitumen emulsions. Expert suppliers have the capability to carry out such testing and recommend the right solution for your individual mine road network.