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    Improving the Insulating Value of Brick with Pore Forming Agents

    Published: 2014

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    In Europe, highly cored brick with a low thermal conductivity are commonly used in masonry construction. These units use pore forming agents to further reduce the thermal conductivity of the units in addition to the coring design. Thermal performance is often expressed as thermal conductance (C value) or the reciprocal value, thermal resistance (R-value). To investigate the effect of pore forming agents on thermal performance, a series of clay brick formulations were batched, mixed, extruded, and fired in the lab. In this study, organic pore forming agents with varying particle sizes were added to a clay body. The oxidation of the organic pore forming agents during firing resulted in residual pores which reduced the thermal conductivity of the brick. The residual porosity was created by the size, volume, and the addition rate of the pore forming agent added to the body and the firing degree of the clay body. The effect of the firing temperature was also investigated. For each composition, the thermal conductivity was tested using a heat flow meter according to ASTM C518. The thermal conductivity measurements were correlated with porosity and density measurements as well as other physical properties measured according to ASTM C67-31a: Standard Test Methods for Sampling and Testing Brick and Structural Clay Tile. The effect of size of the residual pores was studied to determine how the increased porosity reduced thermal conductivity while also decreasing strength. The potential durability of the bodies with pore forming agents was also considered.


    R-value, clay brick, masonry

    Author Information:

    Shepherd, Graham
    The National Brick Research Center, Clemson Univ., Anderson, SC

    Sanders, John
    The National Brick Research Center, Clemson Univ., Anderson, SC

    Committee/Subcommittee: C07.90

    DOI: 10.1520/STP157720130135