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

By AZoBuild

Table of Contents

Introduction

Many of the drivers behind 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 way back in the late 1990s. The concept is whether there is any need to use new natural resources when they can be recycled or alternative materials can be substituted. Though there were restrictions previously, now there are no restrictions are are treated similar to any other raw material.

Recycled materials are being used by the brick manufacturing sector for over 100 years. The forerunner of landfill, Victorian Town Ash Heaps was conventionally used as sources of residual unburnt coal and glassy materials especially in London. Furthermore, many brickworks evolved on the coal mine sites using clay and shale extracted from the mine to make bricks that were at that time used for mine construction.

Origin of MARSS Survey

Due to initiatives like WRAP’s publication on recycled materials content in construction materials, the UK brick manufacturing sector felt the need to collect and publish the annual recycled content in brick manufacturing processes. The ‘MARSS survey’ began in 2006 and the previous year’s raw materials usage was collected from UK brick manufacturers on a site-by-site basis.

MARSS are used and specifically displaced primary raw materials that normally originate from natural resources such as quarries and pits.

The MARSS usage trends are examined through one of the most turbulent periods in UK brick manufacturing history; which is a halving of production between the years 2005 and 2009. Apart from this, the sector is committed to using these materials, obtaining advantages above and beyond the fundamental environmental benefits of using recycled or waste materials.

Areas of Potential Impact

Five areas of potential impact that could result from the use of MARSS have been defined on a specific manufacturer or business sector. The “ESTEM” framework has been highlighted as a way of addressing and examining the potential benefits to a manufacturer of utilising non-primary raw materials in their production processes.

The areas impacted upon can be subdivided into the following:

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

In brick manufacture, the MARSS is grouped into five 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.

Even though the absolute tonnage of MARSS in the UK brick sector has varied over the past six years, the average content within bricks has remained static at 10 to 13%. This shows that MARSS, other than economic pressures, has a valuable and long-term place as alternatives to primary raw materials, and contributes 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)

Sourcing of MARSS

It is important to note that MARSS are normally sourced locally, hence usage is dominated by the geographical location of the user and resource. The local sourcing and usage falls within sustainability goals and the impact of transporting a low value bulky material across the UK is not cost-effective or warranted hence may have a limited impact on the usage growth of MARSS across the sector. The key to further expanding the use of these types of materials is more related to supply than availability. It is also essential that MARSS be technically compatible with existing brickworks and product ranges.

Manufacture of very high MARSS content bricks more than 70% is possible and aesthetics and technical performance can be achieved, however continuity of supply has been a stumbling block. Archetypal UK brickworks produce in the order of 1 million bricks per week; this requires around 3,000 t of raw materials per week. In case the supply chain of these MARSS by-products and waste stream materials are not readily available over a five to ten year period, migration and investment away from primary raw materials is commercially too risky.

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

Conclusion

The MARSS survey returns between 2005 and 2010 show that the availability of these materials and the longevity of supply is at risk. The potential to move from one material to another, when supply is interrupted highlights the flexibility of the brick manufacturing process to a wide range of MARSS. MARSS will now and in the future play an essential role in the resource efficiency and sustainable use of materials in the brick manufacturing sector, nevertheless will surely not replace the extraction of primary clays in the foreseeable future.

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