J.J.BROOKS(1) and J.P. FORTH(2)

(1) Consultant

(2)School of Civil Engineering, University of Leeds


The irreversible moisture expansion of twenty different types of clay brick made from a wide range of clays has been determined. The bricks were one month old at the start of testing and measurements were made over a period of one year. No correlation was found between expansion and strength, water absorption or initial suction rate. Expansion between bed faces was greater than that between header faces, especially in the initial stages and then by a factor of two in the long term. Analysis of experimental results obtained by earlier researchers using one-day old bricks has led to the quantification of the influences of temperature and age on expansion. By standardising the firing temperature to 1050oC, brick clays can be allocated into one of six specific expansion-age categories. Appropriate relationships are presented and a prediction model developed, which satisfactorily represents previous test data and the results of the present investigation. An example is given for estimating a design value for irreversible moisture expansion using either equations or charts.