Heavy clay changes

Clay Technology magazine
,
16 Apr 2010
bricks

Dr Denzil Spencer, former Technical Director of Ibstock, Leicestershire, UK, summarises the impact of technology changes on the market and the prospects for heavy clay products.

Since 1990, there has been a major change to the ownership and structure of the major UK brick producers. In 1990, all 12 major brick companies were owned by British organisations and they accounted for over 85% of all bricks produced in the UK. These businesses, together with some smaller operations, have been absorbed into three large companies all owned by overseas multinational construction materials groups. They account for 90% of UK brick production.

Industry employment and turnover

There has been a dramatic decline of employees in the industry, falling from 24,000 in the mid 1980s to around 7,500 prior to the latest recession.

Industry turnover has declined by a lower percentage, only 27% during 1995-2008. While employee numbers fell by 65% in the same period. The difference represents improved productivity from capital investment, an increased proportion of higher value refractory products and synergy savings as mergers rationalised facilities.

Energy and emissions

The industry contributes 0.6% of the carbon emissions of UK-based industries covered by Phase 2 of the European Union Emissions Trading Scheme. This compares with 0.75% for glass, four per cent for cement and 7.7% for iron and steel. The longevity of clay-based construction products reduces the environmental impact over their lifecycle.

However, carbon footprints of all products will become increasingly important and the industry needs to continue its investment and management programmes to progressively lower emissions. To date, the energy consumption reduction targets set by the UK Climate Change Agreement have been achieved, however, research is required to identify new processes for the recovery of waste heat.

Clay pipes

The market for land drainage clay pipes virtually disappeared in the 1970s when the UK Government subsidy was withdrawn, and plastic pipe has replaced clay for underground telecommunication cables.

The market for clay pipes is virtually limited to sewage and effluent disposal. Plastic dominates the small diameter pipe market and concrete, the very large diameters. Clay remains the preferred product for mid range diameter pipes for use in industrial and roadway applications. Consequently, UK production of clay pipes has declined from circa 500,000t/pa in the late 1970s to around 100,000t/pa.

Roof tiles

During the 20th century, clay roof tiles gradually lost their share of the pitched roof market in the UK to concrete products, and, by the 1970s, concrete accounted for 80% of all pitched roof areas with clay at five per cent. Clay could not compete on cost and the concrete sector developed larger format, fully interlocking tiles which enabled lower pitch and reduced building and installation costs.

The companies that have retained a presence in this sector have invested in technology to produce plain, fully overlapping tiles and some profiled format tiles to save on manufacturing costs. Following investment, a small increase, from five to eight per cent, in market share has been achieved.

In mainland Europe, clay roof tiles dominate the market and the concrete share appears to continue to decline.

Refractories

The refractories sector differs from the others in that the products are of higher value, technically specialised and compete in an international market. Clay-based products constitute about 10% of refractories made in the UK, compared with over 50% in the late 1970s. They have become obsolete in certain applications due to process changes and have been replaced by higher quality and more cost effective products such as high alumina.The iron and steel industry accounts for roughly 75% of all refractory consumption. Advances in steelmaking processes and improved refractory products, particularly basic, high alumina and specialised ceramics, led to a reduction in total shaped products manufacture from 800,000t in the late 1970s to 400,000t by 1990.

Since 1990, the total tonnage of shaped products produced has reduced further to around 100,000t. The decline results from:
•    UK Steel production falling by ~50%.
•    Some of the refractory operations becoming part of multinational organisations, with a global spread of manufacturing facilities.
•    Further improvements in refractory properties and process control, leading to reduced refractory consumption.
•    Importation of low priced products.
•    Businesses exiting the sector or reducing investment in capital intensive process plants.

Bricks

The market for brick has remained more resilient than the other sectors. There are three main application product qualities
– facings, commons and engineers. Vast quantities of common bricks were produced post-1945 for re-building and for internal walls until this application was lost to concrete in the 1960s, and commons now account for about 12% of the market. Engineering bricks, which are supplied solely to a technical specification, account for nine per cent of the market.

Trends in the demand for UK produced brick are shown in the image, above right. Clay brick is the preferred material for cladding houses – a sector which consumes around 70% of the product. The decline in demand for facing bricks over the past five years results from –
•    The change in mix of dwelling types, with a fall in the proportion of detached houses. These typically have 8,000 bricks/unit. The number of flats, which on average have 2,000 bricks/unit, has risen to over 50%.
•    Imports of bricks accounted for nearly 10% of the total UK facing brick market by the end of 2007. Volumes have markedly dropped in the latest recession and the proportion of the market held by imports decreased to 6.5% during the second half of 2009.
•    The current slump in house building. Brick demand fell during the recession by 42% to bottom out at 1.4bln. Two million new homes are required over the next decade, and there is a need to replace a significant proportion of the existing housing stock. Further support for a recovery in the brick market comes from the Government target for new social housing of 45,000 units per anum by 2011, compared with a current level of 24,000 units.

Technological trends

One reason for the decline in employee numbers is investment in highly automated, large capacity extruded and soft mud factories.

Modern kilns typically have a capacity of around 200,000t/pa of fired product (60-100 million British Standard size bricks). This compares with 50,000-100,000t/pa capacity for kilns built in the early 1970s for which the unit energy consumption was about double. Robotic handling of bricks was introduced in the mid 1990s to bring greater reliability and flexibility. The investments have also led to a widening aesthetic character.

Challenges

Changes in building design are already providing opportunities for a broader range of clay products, including rain screen cladding tiles, brick slips for pre-assembled panels and re-cladding existing buildings, with a wider range of brick sizes and shapes to provide architects with greater design opportunities.

The most interesting potential development for the UK is the use of solid external walls constructed from large clay blocks with high insulating properties. Thin bed mortar joints and high density clay blocks are being used for internal walls to provide a high level of sound insulation. Such building systems are well established and proven in mainland Europe.

Future success will depend on the quality, ability, enthusiasm and commitment of people within the industry. Investment in education and training at all management and supervisory levels will be essential to ensure the skills are available to progress the necessary product and process innovation.