The development of unfired clay building materials for sustainable building construction

    Student thesis: Doctoral Thesis


    Currently there is a growing pressure on energy efficiency for new buildings in the UK and worldwide. This has arisen partly due to the increasing awareness of the public for sustainable building construction. In addition, there is pressure on building materials manufacturers, due to new government regulations and legislations that are targeting energy usage and carbon dioxide emissions in new buildings. This research work reports on unfired clay building materials (unfired clay bricks) technology for sustainable building construction. The technology aims at the reduction of the high energy input, especially that arising from firing clay bricks in kilns. The research has investigated the use of lime or Portland cement as an activator to an industrial by-product (Ground Granulated Blastfurnace Slag-GGBS) to stabilise Lower Oxford Clay (LOC). Portland cement was used in the formulation of the unfired clay brick tests specimens predominantly as a control. The development of an unfired clay brick in this current work is considered by the researcher as a significant scientific breakthrough for the building industry. Another breakthrough is the fact that only about 1.5% lime was used for GGBS activation. This is a very low level of usage of lime that is not comparable to, or sufficient for, most road construction applications, where far less strength values are needed and where 3-8% lime is required for effective soil stabilisation. Hence, the final pricing of the unfired clay brick is expected to be relatively low. Industrial scale brick specimens were produced during two separate industrial trials. The first trial was at Hanson Brick Company Ltd, Bedfordshire, UK, while the second was carried out at PD Edenhall Ltd, Bridgend, South Wales, UK. The results clearly demonstrate that all key parameters such as compressive strength, thermal properties and durability were within the acceptable engineering standards for clay masonry units. From the environmental and sustainability analysis results, the unfired clay material has shown energy-efficiency and suggests a formidable economical alternative to the firing of clay building components. This study is one of the earliest attempts to compare fired and unfired clay technology, and also to combine energy use and CO2 emission for unfired clay bricks relative to those bricks used in mainstream construction. This is an attempt to come up with one parameter rating. The overall results suggest that the spinoff from this technology is an invaluable resource for civil engineers and other built environment professionals who need quick access to up-to-date and accurate information about the qualities of various building and construction materials.
    Date of AwardJun 2010
    Original languageEnglish


    • Sustainable buildings - Design and construction
    • Buildings - Environmental aspects

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