Substitute Raw Materials Used in UK Brick Manufacturing - 6 Year Review

Topics Covered

Introduction

Many of the drivers underpinning the development of the Resource Efficiency Roadmaps at a European level, as well as at the UK national level, have evolved from the waste reduction and recycling initiatives developed back in the late 1990s. The concept is a simple one, “why use new natural resources when there may be perfectly suitable recycled or alternative materials that can be substituted?”

In the past, barriers to use have been found in technical standards, however in the last 15 years, all these pseudo “technical” barriers have been removed. The opportunity for the use of Materials from Alternative, Recycled and Secondary Sources (MARSS) are no longer restricted, and to all intents and purposes, now treated in the same manner as any other raw material.

The brick manufacturing sector has been using recycled materials for over 100 years; Victorian Town Ash heaps, the forerunner of landfill, were traditionally used as sources of glassy materials and residual unburnt coal for inclusion into the bricks, especially in the London environs. In addition, many brickworks evolved on the sites of coal mines, utilising the “shale and clay spoil” extracted from the mine, as well as the coal, to make the bricks that were then used in the construction of the mines.

Materials from Alternative, Recycled and Secondary Sources

As a result of initiatives such as WRAP’s publication¹ on recycled materials content in construction materials, the UK brick manufacturing sector identified the need to collect and publish the annual recycled content in brick manufacturing processes. The ‘MARSS survey’² was started in 2006 and collected the previous year’s raw materials usage from UK brick manufacturers on a site-by-site basis.

MARSS are used and specifically displaced primary raw materials, typically originating from natural resources such as quarries and pits.

The 2005 – 2010 survey results² examine the trends of MARSS usage through one of the most turbulent periods in UK brick manufacturing history; a halving of production between 2005 and 2009. In spite of this, the sector is still committed to using these materials, gaining benefits above and beyond the basic environmental advantages of utilising waste or recycled materials.

Five areas of potential impact have been defined; all “push and pull” upon a given manufacturer or business sector, and could result from the use of MARSS. The “ESTEM” framework has been highlighted as a means of addressing and assessing the potential benefits to a manufacturer of utilising non- primary raw materials in their manufacturing processes.

The assessment of how the use of MARSS could impact upon the ESTEM framework offers significant opportunities and convincing justification for changes to a process, or materials within a process. The areas impacted upon can be subdivided:

• Economic (financial)
• Strategic
• Technical (product properties)
• Environmental (sustainability - natural resources, water, energy and emissions)
• Marketing

The rationale behind the use of MARSS is typically not limited to a single factor, but often a collection. Many of the materials address many, if not all of the ESTEM categories; this is not only the domain of the technical specialist.

Once the “why use them?” aspect of alternative materials is understood, “what can we use?” becomes the area of interest for the “practitioner”. The MARSS survey shows that in brick manufacturing the MARSS are grouped into 5 “types”:

1. Ash Products - e.g. residues from combustion processes
2. Hydrocarbons - e.g. residues from solid fuel processing, coal, coke, Met and Petcoke
3. Industrial Minerals - e.g. residues form mineral processing activities such as slags
4. Minerals - e.g. by-products from mineral processing/extraction such as fireclay and silts
5. Organics - e.g. products derived from biogenic sources, such as saw dust, sugars and starch.

Whilst the absolute tonnage of MARSS used in the UK brick sector has fluctuated over the past 6 years, the average content within bricks has remained relatively static at 10-13%. This indicates that MARSS, despite economic pressures, do have a valuable and long-term place as alternatives to primary raw materials, and as such, contribute both in terms of sustainability and resource efficiency within the brick manufacturing process.

Figure 1. Annual: Percentage of UK Brickworks Using MARSS, Total Raw Material Usage (‘000 tonnes) and Total Usage of MARSS (‘000 tonnes)

MARSS are often locally sourced; usage is therefore dominated by the geographical location of the resource and user. The local sourcing and usage falls clearly within the goals of sustainability, and often the impact of transporting a bulky low-value material across the UK is not warranted or cost-effective; this may have a limiting impact on the usage growth of MARSS across the sector. However, having discussed this in ‘Materials from Alternative, Recycled and Secondary Sources (MARSS) 2005 - 2010: A Review of the Use of Non- Primary Clay Raw Materials in the UK Brick Manufacturing Sector’² the location of many of the UK’s largest brickworks are in the Midlands and North of England, and hence associated with other industrial and manufacturing activities where “by-products” and wastes are generated. The key to further expanding the use of these types of materials is more of a supply issue rather than an availability one. This also requires the suitability and technical compatibility of MARSS with the existing brickworks and product ranges.

At present it is possible to manufacture very high MARSS content bricks (>70%) and achieve the technical performance and aesthetics, however the barrier has been the continuity of supply, specifically into larger production sites. Archetypal UK brickworks produce in the order of 1 million bricks per week; this requires around 3,000 tonnes of raw materials per week. If the supply chain of these MARSS by-products and waste stream materials are not readily available over a 5-10 year period, investment and migration away from primary raw materials is commercially too risky.

Table 1. Annual Usage of MARSS Group and Type 2005 – 2010

Such a conundrum is not unique to the brick sector and MARSS usage, other recycling and recovery initiatives, especially those that target high volume arisings, are always at risk of the manufacturer adopting one of the first rules in the recycling hierarchy, “reduce”. This ultimately puts the availability of these materials and the longevity of supply at risk; as reflected in the MARSS survey returns between 2005 and 20102. The ability to move from one material to another, when supply is interrupted, does highlight the flexibility of the brick manufacturing process to a wide range of MARSS.

Conclusion

MARSS do currently, and will in the future, play an important role in the resource efficiency and sustainable use of materials in the brick manufacturing sector, nevertheless it is unlikely to replace the extraction of primary clays in the foreseeable future, if at all.

Contact Details

Dr Andrew S Smith, Principal Consultant, Head of Sustainability, Ceram

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