The Clay Life Cycle - Production Process

The manufacture of clay building products is constantly improving. The clay brick and tile industry is continually monitoring its energy usage which forms a significant part of total production costs. Much work has already been done to decrease energy consumption and consequently CO2 emissions in line with government guidelines. Firing gives our products their exceptional performance, long life and durability and is an indispensable part of the production process.

Some products are designed to be energy efficient in use and there has been a significant increase in thermal performance qualities of products over the past few years. Our objective is to continue this trend in order to deliver efficient products that are manufactured with careful energy usage, controlled emissions and minimal waste.

Production Process - Short description

After extraction from quarries, the clay raw material is laid out in order to obtain a homogeneous mixture.

Several stages are involved in preparing the clay. It is stockpiled , then crushed to attain the required grain size and then stockpiled again for several days or even months.

Before processing, the moisture content is controlled and it may be necessary to add water to obtain the right consistency for forming. Materials such as sawdust or residue of paper industry can be added to increase the porosity of the final product.

For bricks, the clay is extruded or moulded to obtain the shape required and then cut to size. In roof tile making, the clay can undergo a two-stage process, the second of which may occur after extrusion, depending on the roof tile being manufactured. For example, for interlocking tiles, the extruded clay is pressed between two moulds.

The formed clay is dried in order to reduce its moisture content and then loaded into kilns for firing. When this is completed and the products have cooled, they are packed ready for dispatch. Throughout all stages of production, the process is subject to rigourous quality control.

Example of Production of extruded bricks and handmade bricks

Example of production of pressed roofing tiles

The Clay Life Cycle

Clay bricks and tiles form the basis of the European building tradition. They are the link between our architectural heritage and our future. When thinking about sustainable aspects of clay building materials, one has to consider all life cycle stages:
• Quarrying and Reserves

• Production Process

• Design and Construction

• Building in Use

• Demolition and Recycling

The Clay Life Cycle - Demolition and recycling

The last phase in a product’s life cycle can become the first, if demolition is followed by recycling and re-use. Despite the potential long life of clay brick buildings (well in excess of a 100 years), they are sometimes demolished well before the end of their useful life. The text below examines the options for re-using ceramic building materials.

A research project carried out by TBE in the late 1990s concluded that the following are possible uses for recycled clay building materials:

• Reclaim as bricks and tiles
• Filling and stabilizing material for infrastructure works
• Aggregates for in-situ and precast concrete and mortars
• Aggregates for calcium silicate bricks
• Tennis sand
• Plant substrates
• Other options

Building & demolition waste is used extensively throughout Europe for roadworks and for use as aggregate. This is facilitated by fast developing recycling technology that allows precise extraction of various materials from mixed demolition waste. Separating out ceramic matter provides an opportunity to recycle and re-use a very sustainable building material.

Demolition and recycling - European Policy

The European Commission is formulating a strategy for the reduction and recycling of waste. There are no barriers for the use of granulated ceramic material. But unfortunately, it is often mixed with contaminated demolition waste. If this is purely brick masonry it is not a problem when converted to landfill, as generally contact between ceramic material and ground or surface water causes no toxic side effects. After all, bricks and tiles in service are frequently exposed to ground and surface water and do not normally pose a threat.

For a more sustainable construction, ceramic building products should be incorporated into flexible buildings with long design lives in order to ward off the spectre of demolition for as long as possible. Ceramic products are certainly very durable and will stand the test of time to prove they are truly sustainable.