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 an d adheres well with hydrophilic materials. In this part of the series the s trengths of ice-infiltrated porous, both unconsolidated and consolidated, m aterials have been reviewed. Ice-infiltrated porous materials are much stro nger than the original materials. The contribution of ice to strengths of f rozen materials is higher than is expected from strengths of bulk ice itsel f. 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 con sidered in often-quoted mechanisms of frost attack. Ice infiltrates porous bodies in the form of dendrites and in the process encapsulates still unfro zen water in many places. During further cooling unfrozen water develops hi gh hydrostatic pressure capable of causing damage. Different proposed mecha nisms of frost damage have been examined against the above background. (C) 1999 Elsevier Science Ltd. All rights reserved.