A.Bremner1, J.P.Forth1, J.J.Brooks1, P.R.Bingel2


An indication of the presence of cryptoflorescence in clay masonry has been found in the unusually high level of moisture expansion measured in some 13-stack unrestrained clay masonry single-leaf walls. This expansion, which greatly exceeds that which would be expected from the unbonded brick expansion, is referred to as an enlarged expansion.

Considering the unbonded brick properties; clay type, soluble salt level and range, water absorption, compressive strength and irreversible moisture expansion characteristics, it is possible to assess the potential for enlarged expansions caused by cryptoflorescence, in clay masonry. The benefit of using these properties for an assessment is that the majority are readily available from the brick manufacturers.

The paper discusses the background to the choice of these properties to assess cryptoflorescence in clay masonry. Results are presented of tests on single-leaf clay masonry test panels constructed from a wide ranger of brick units, which showed that an enlarged expansion occurred in all of the test panels constructed with units based on the chosen properties.

Key words: Cryptoflorescence Efflorescence Expansion Bricks Movement