Physical deterioration of sedimentary rocks subjected to experimental freeze--thaw weathering

Ten types of sedimentary rock were subjected to repeated cycles of freezing and thawing. In addition to monitoring sample weight loss throughout testing, a detailed graphic record was made of deterioration mode and its relationship to pre-existing rock flaws. Results suggestthat the presence or absence of rock flaws alone does not control deterioration mode, but rather that it is the coupled relationship between these flaws, and rock strength and textural properties which exerts greatest influence. While some pre-existing flaws such as syndepositional deformation structures do not appear to influence breakdown, others such as incipient fractures, cavities and minor lithological boundaries frequently coincide with concentrations of deterioration. Acharacteristic mode of deterioration which is independent of pre-existing flaws tends to develop in sandstones, indicating the influence,in this case, of rock texture. Particularly strong rocks such as crystalline limestone and metasediment tend to fracture preferentially along distinct linear weaknesses such as mineral veins, stylolites andincipient fractures. Particularly weak rocks, such as low-density chalk, break down in a random fashion without regard to pre-existing flaws. In addition to providing some insight into the role of pre-existing flaws in rock deterioration, this work also has practical implications for (i) the study of landform development due to weathering, and (ii) the selection of representative rock samples in durability testing for building stone. [ABSTRACT FROM AUTHOR]