A detailed seven-year study has been made of the moisture expansion of clay products, with special emphasis on bricks and the consequent damage to brickwork. Methods have been developed for measuring the expansion of bricks and brickwork under varying conditions of exposure. These methods are described, and the results are briefly discussed with reference to the influence of various factors on the rates and magnitude of expansion. Finally, the possible causes and kinetics of expansion are considered and estimates made of the likely maximum expansion of brickwork. Results have shown that bricks expand on leaving the kiln, and expansion of brickwork in buildings can reach more than 2 in. per 100 ft.

Tasmania is shown to possess exceptionally good supplies of limestone and dolomite, well distributed through the State. These include high-grade PreCambrian and Ordovician and low-grade Permian, Tertiary, and Pleistocene to Recent varieties. All are described in some detail with particular reference to composition and relative purity and, after a discussion of the present lime industry, Tasmania's requirements of limestone and of lime in its various forms are considered. Finally, the manner in which the lime industry in the State should be expanded to meet these demands, with the emphasis on the Ordovician Gordon River Limestone, is indicated.

It has been found that clay bricks start to expand permanently as soon as they are exposed to the atmosphere after leaving the kiln. This expansion is sufficient to account for much of the cracking of brickwork structures previously considered to be due to other causes. Measurements of expansion have been made on some 500 bricks representing the raw materials and types used in Melbourne and Sydney, following their exposure to air both in an air-conditioned laboratory and out of doors, to cycles of soaking and drying, and to saturated steam at 200 deg.C. The expansion of and damage to brickwork in experimental brick walls and many actual buildings has also been investigated . The raw material, temperature of firing, and possibly the method of manufacture all affect the rate and extent of expansion, and the influence of each and the causes of expansion are discussed. From the expansions of individual bricks and experimental brick walls the extent to which brickwork may be expected to expand in practice has been estimated for the various types and varieties of brick examined. These expansions have been discussed in relation to the movement and damage ill actual buildings. To prevent damage through expansion it is recommended that (i) only well-built bricks be used, (ii) all bricks be allowed to stand as long as possible before use, (iii) lime-rich mortars be used instead of strong cement mortars, and (iv) efficient movement joints be provided at sufficiently frequent intervals to take up expansion of the bricks.