Aspects of freezing process in porous material-water system Part 2. Freezing and properties of frozen porous materials

In Part 1 of this series it has been shown that ice is a strong material and adheres well with hydrophilic materials. In this part of the series the strengths of ice-infiltrated porous, both unconsolidated and consolidated, materials have been reviewed. Ice-infiltrated porous materials are much stronger than the original materials. The contribution of ice to strengths of frozen materials is higher than is expected from strengths of bulk ice itself. The disruptive pressure needed to cause damage during freezing of porous materials has also to be much higher; this fact seems not to have been considered in often-quoted mechanisms of frost attack. Ice infiltrates porous bodies in the form of dendrites and in the process encapsulates still unfrozen water in many places. During further cooling unfrozen water develops high hydrostatic pressure capable of causing damage. Different proposed mechanisms of frost damage have been examined against the above background. (C) 1999 Elsevier Science Ltd. All rights reserved.