The UK construction industry is in the midst of a revolution, with companies looking for ways to reduce their carbon emissions and transition towards a more sustainable future.

For construction material companies like Tarmac a lot of the emissions come from the materials themselves. However across the construction industry as a whole, moving the materials and the use of all other construction vehicles amount to 1.1% of total global CO2 emissions.

Tarmac is committed to reducing its environmental impact and has set targets to reduce carbon emissions by 50% by 2030 and achieve net-zero emissions by 2050.

Research and investment into creating greener forms of materials, like concrete are underway and producing an emission free or net zero concrete would be a huge step for the construction industry reaching net zero. However, in the meantime there are other areas of Tarmac’s operations that can decarbonised now, and one area they identified was their construction vehicle fleet.

Tarmac’s Director of Logistics Graham Waters explains, “On the material side we move about 45 million tonnes of product across rail and road on an annual basis about 55 million kilometres.”

With important stakeholders in the industry, like National Highways announcing that by 2040 they will only accept zero emission vehicles on their projects, and the proliferation of Ultra Low Emissions Zones around the UK, action needs to be taken now to develop these green construction vehicles.

Back in 2019 Tarmac set up their Innovation Challenge, which was asking for supplier and the industry as a whole to come up with potential ways for Tarmac to decarbonise. One company who took notice was Renault Trucks, and they brought in TVS Interfleet to help create the UK’s first eMixer.

The first step Renault Truck took in the eMixers planning stage was to try and stay as close to the design of the classic diesel mixer as possible, as Renault Trucks Head of Electric Mobility Andrew Scott explains, “We have deliberately taken a diesel product and replaced the diesel drive line with an electric drive line, so that the fundamentals of the product are almost exactly the same and we make a virtue of that because the reality is that operators don’t want to introduce risk to their business that they absolutely don’t have to.”

Keeping the drive line similar in design to the diesel drive line also allows for the manufacturing of new electric construction vehicles to take place in the same factory as diesel vehicles. This helps to keep costs down and also speed up the manufacturing time of new electric vehicles.

So far the largest battery they have been able to fit into the eMixer is a 466 kilowatt battery, Andrew Scott Explains, “That gives you a total usable total installed power relay of 265 kilowatts that works through two motors into a two speed gearbox, and then using a conventional drive line. So, we tried to make it as familiar as possible.”

However when TVS Interfleet came to design the rest of the vehicle, including the mixer itself, they decided to start from scratch. The first thing they did was attach sensors to existing diesel mixers to understand the requirements they had to match.

TVS Interfleet’s Industrial Design Director Vito Ronzano explains, “The first thing we sort of did with the project was to go out and fit some data loggers onto the internal combustion engine mixers, to try and start to understand things like the mileage that the end user was actually doing per day and what loads they were carrying”

What they discovered was that an eMixer needed to be able to complete around 5 or 6 journeys between the materials plant and site each day. Another thing TVS found when looking at conventional mixers was that nothing has been changed or improved in the last 30 years.

“If you look at construction materials vehicles, if you look at our tipper trucks, if you look at our mixer trucks, they haven’t changed since the 1990s. I have Googled it, I have seen photos of all the vehicles, I have chatted with people who have been in the business for that period. And there really hasn’t been that much change.” Said Andrew Scott.

To accommodate the more limited drive range TVS looked at ways that they could reduce energy draw from the mixer. They found the speed the mixing drum turns on conventional mixers is very inefficient and the speed is set at the discretion of the driver. Vito Ronzano explains, “Normally, they fully open to when they want to spin it fast, they just fully open it to maximum RPM, and they fully close it, and they fully open it, so it sort of ends up very much to that driver’s discretion.”

The eMixer’s drum was fitted with hydraulic and pressure sensors to get a better understanding about the state of the material inside and know how much mixing it required. The drum now has speed setting that is automated for when the material is being loaded, transported and sitting on site, which keeps the concreter in an optimal state while reducing the drums energy draw.

Optimising the drums rotational speed also provides other benefits. Firstly, it improves safety, as Ben Garner Senior Manger for Logistics Development at Tarmac explains if a driver needs to also focus on the drums speed it is an additional distraction, “we want our drivers to have as, I guess, as kind of a stress free, distraction free, environment as they can possibly have. That obviously, for safety reasons. So having to control the drum spin, be aware of the drum spin and everything else while they’re driving along is ultimately a distraction.”

Secondly the automated drum rotation with sensor that can give a better understanding of the concrete’s condition could potentially allow Tarmac to guarantee the perfect condition of the concrete to their customers.

“The quality of the concrete that you’re going to deliver with an electric mixer is probably going to be higher than you would traditionally with a diesel mixer. And that’s opening up a lot of future opportunities in terms of, of traceability, of quality, and all of the challenges that come in, in the construction sector, about the integrity of the materials that are actually used for all of these projects.” Andrew Scott says.

Another part of the mixer TVS changed was the water tank. Conventional mixers have a 300 litre water tank that’s fitted high on the truck. “So we looked at the water tank and I just said ‘Well, where do we fit it? Why is it fitted high?’ It was always been like that. I said, ‘Yeah, but you know, you stick in 300 to 500 litres up at the top of the vehicle which is sloshing around constantly, what if we put it down’” said Vito Ronzano.

By moving the water tank lower the whole mixers centre of gravity is lowered making it much safer ot drive. TVS also found out that Tarmac’s mixers may have a 300 litre water tank but they only use around 100 litres a day, Vito explains how this discovery helped them improve the mixers efficiency, “We can say to Tarmac ‘look your guys that are not actually using as much water as you think, let’s look at how we can adapt that going forward and you know try and give you a bit more payload or just might your vehicle a little bit lighter’”

After years of development and design by the end of 2022 Tarmac were able for the first time to test out the eMixer on a live construction site. Based on the range limitation of an electric battery it was decided that the trial should take place in an urban setting and Taramac chose a site in Washwood Heath, Birmingham.

“We decided that with this particular truck, we didn’t need the 72 miles range, and have been able to do five or six loads based on where we’ve placed the vehicle. We don’t need to charge it fast. We can charge it slowly overnight.” Said Ben Garner.

The decision to do a full days work on one charge, then slow charge the eMixers overnight means they can use their Washwood Heat plant that is powered by 100% renewable energies.

Washwood Heath Solar Panels

While and urban setting was chosen for the trial due to the eMixers range limitation, having electrified construction equipment does provide extra benefits when doing work in a busy residential area.

The eMixer is far quieter than a diesel powered alternative, so much so that even if one drove past, you might not hear it, as Ben explains. “So earlier this year, we had our logistics conference. And while we were doing one of the speeches they actually bought the eMixer in. So when everyone went out for their tea and coffee, this mixer truck had appeared, none of them had heard it. Even though the door was open, none of them had realised this truck had driven in because it is absolutely silent.”

Not only will quieter construction vehicles benefit people who live near a construction site, it is also appreciated by those working on it and particularly those who operate the vehicle.

Andrew Scott believes that introducing more electric construction vehicles could allow new people to enter the construction industry. “If you sit on top of a diesel engine for a full shift, you come out of that vehicle tired and potentially irritated by the noise and the vibration. One of the significant things that drivers have told us is just how much more refreshed they feel at the end of the day. So we’ve talked to a number of fleet operators who are very excited by the opportunity that electric offers to attract people into the industry, and particularly women into the industry.”

Bringing the first electric mixer to the UK is an important step towards decarbonising construction sites, but there are still a few obstacles in the way of electric construction vehicles being rolled out across UK constructions sites and the biggest one is charging infrastructure.

For electric construction vehicles to complete work in more rural settings, travelling longer distances and quickly recharging throughout the day will be required. Although battery capabilities are improving all the time, for decision makers in the construction industry to feel confident about switching to electric vehicles the charging infrastructure will have to be in place, as Ben Garner explains, “If you can’t get power to a site to build your charging infrastructure, or you don’t have the space to build charging infrastructure, then you have a problem. And that is the biggest problem affecting the widespread scaling of electrification of mobility anywhere, anywhere kind of across the UK. As far as I’m aware, there’s no public HGV charging facility anywhere in the UK at the moment.”

Tarmac, Renault Trucks and TVS all believe these are challenges that can be overcome and for all those involved in the eMixer project they believe this is just the start of their journey to decarbonising construction vehicles.