Why sustainability is a concrete matter.

As with the majority of the construction industry, concrete production is in a state of flux as it tries to balance growing project demands with the need for a more sustainable approach to building. However, James Bullock, managing director of ConSpare, says that by taking a holistic approach to reducing carbon emissions associated with production, concrete batch plants can not only be more sustainable, but save on cost as well…

With global construction output expected to grow by 42% by 2030 according to the Institute of Civil Engineers, concrete usage is only going to increase. Our comprehensive database puts the number of batching plants in the UK at approximately 2,000, with these plants currently contributing 1.5% of the nation’s carbon footprint per year.

The importance of concrete batch plants

The concrete industry is undertaking a wide range of solutions to reduce its environmental impact, but often the concrete batching plant itself is overlooked. What measures can be undertaken at a batching plant level to complement other carbon reduction initiatives?

Producing concrete through concrete batch plants has always been a resource intensive process. It requires large volumes of raw materials, particularly high CO₂ cement, is powered by electricity, and consumes large amounts of steel components such as wear parts and spare parts.

The challenge today is finding ways in which this long-running approach to concrete batching plant operation can be improved to provide reductions in both carbon emissions and cost.

Challenges in the process and maintaining the process

The concrete production process has five distinct stages; storage, conveying, batching, mixing, and discharging (Fig 1). Breaking the activities of a typical concrete batch plant down into these processes allows producers to find the problems which are creating inefficiencies, which can then be assessed and their impact on production analysed.

Although an initial problem may seem small at batch level, for example, a little extra cement added to each batch to ensure strength requirements are met, or mixers taking a few extra seconds to homogenise the mix, the additional cost and carbon emissions start to add-up very quickly.

When you combine this with the linear process of concrete production, any problems start to have knock-on effects across other elements of the process and can create bottlenecks. This cumulative effect ensures great rewards can be found when tackling problems within the batch plant and production process.

When you consider that a concrete batch plant often has an operational life of up to 30 years, plant maintenance decisions, however small, will have an important impact over time, in terms of both carbon emissions and whole-life maintenance costs.

Even the highest performance concrete batching plant will reduce in efficiency over time, and proactive maintenance investments and maintenance interventions provide a perfect platform to implement further improvements. 

If the concrete industry can draw on the theory of marginal gains – making small, seemingly insignificant changes to processes that compound over time into wholesale improvements – this has the ability to make a big impact on improving plant uptime and Overall Equipment Effectiveness (OEE) while simultaneously delivering carbon reduction.

By constantly making small improvements, our combined journey to net zero is accelerated – especially when these changes have the potential to be scaled up throughout the wider industry.

Finding solutions within the batching plant and process

Across the concrete batch plant and the five stages of the production process, there are three key areas in which efficiencies can be made in terms of both carbon and cost; reducing raw material usage and waste, reducing power usage, and reducing maintenance interventions.

There are multiple solutions depending on the problems or requirements of the plant. By its very nature, the production process is full of bottlenecks, and it is these that are often hidden producers of waste.

For example, the practice of over-cementing is a significant contributor to CO₂ emissions associated with the concrete production process. However, by switching from the ‘averaging’ method of measuring moisture in materials to Hydronix, one of the leading readymix producers was able to drastically reduce the requirement to over-cement at one of their plants, with an average reduction of 26kg of cement per cubic metre of concrete - equivalent to 1,413 tonnes of cement per year. This would save £185,000 and 1,030 tonnes of CO₂ from cement reduction per year.

Alternatively, power usage is also an area where small improvements can lead to impressive savings in both cost and carbon emissions. In 2010, ConSpare replaced an energy intensive rotating pan mixer with a Teka TPZ1500 planetary mixer at a leading roof tile manufacturer. This resulted in 68,000 kWh of power saved per year, equating to 23.8 tonnes of CO₂ per year and £40,800 per year.

Maintenance interventions are a third critical area where efficiencies can be made, bringing about significant reductions in downtime and spare parts. A renowned manufacturer of building materials in Scotland was using cast steel blades in their pan mixer, which required replacement after three months due to the abrasive nature of the aggregates used. When replaced with Hawiflex polyurethane blades, these lasted three times longer, saving 342kg of CO₂ per year and reducing component purchasing costs by 52%.

Therefore, by looking at the plant through the lens of carbon, targeted investment decisions can be made to ensure that concrete plant operators achieve maximum benefit, with process improvement and smart maintenance techniques used to reduce the emissions associated with production.

An obvious choice

It is not often that an industry has the obvious choice. From a business standpoint, all too often compromises must be made to achieve a set of aims. In this instance, however, reducing carbon from the concrete production process can realistically be achieved at the same time as reducing cost.

By providing the most effective equipment and smart maintenance solutions we can reduce material wastage, energy usage, and minimise spare part consumption at plant level. 

Long-term economic growth cannot come at the cost of the planet. It is imperative that the concrete production industry finds a sustainable way forward through evidence-based solutions that are proven to reduce environmental impact and preserve our planet for future generations. 

We believe the industry will work together as a coalition of change-makers to focus on the things that matter and drive as much carbon as possible out of the concrete production process as quickly as we can, however we can.