Pore properties as indicators of breakdown mechanisms in experimentally weathered limestones

The results are reported of four experimental weathering tests – freeze – thaw, wetting and drying, slake durability and salt weathering – on five different types of limestone. Effective porosity, mercury intrusion porosimetry and scanning electron microscopy were used to evaluate changes in pore properties, while weight loss and fracture density were used to assess deterioration severity. A primary aim was to observe modifications in porosity due to weathering and to draw inferences about the internal rock deterioration mechanisms taking place. It is concluded that the five limestones not only show a wide range of resistance to weathering in general but considerable difference in resistance to particular weathering processes. Consequently, when assessing durability it is essential to consider rock properties in the context of the weathering process to which the rock is subject. The type of deterioration indicator used is also important in interpretation of durability. A variety of pore modification mechanisms operate, including changes in pore connectivity, pore infilling, and the introduction of additional void space. There are indications that changes to the internal pore structure of rocks due to weathering may be a precursor to more substantial macrodeterioration. Copyright © 2001 John Wiley & Sons, Ltd.

[1]  N. Brook,et al.  The Measurement and Estimation of Basic Rock Strength , 1993 .

[2]  J. Franklin,et al.  The slake-durability test , 1972 .

[3]  J. Ozouf,et al.  Experimental frost shattering , 1982 .

[4]  Philip G. Meredith,et al.  4 – THE THEORY OF SUBCRITICAL CRACK GROWTH WITH APPLICATIONS TO MINERALS AND ROCKS , 1987 .

[5]  Dawn T. Nicholson,et al.  Physical deterioration of sedimentary rocks subjected to experimental freeze–thaw weathering , 2000 .

[6]  E. W. Washburn.  Note on a Method of Determining the Distribution of Pore Sizes in a Porous Material. , 1921, Proceedings of the National Academy of Sciences of the United States of America.

[7]  Cristobal Viedma,et al.  Salt crystallization in porous construction materials I Estimation of crystallization pressure , 1997 .

[8]  K. Pye,et al.  Tafoni on coastal slopes, South Devon, U.K. , 1994 .

[9]  R. Fort,et al.  Pore size distribution and the durability of a porous limestone , 1997, Quarterly Journal of Engineering Geology.

[10]  Robert J. Allison,et al.  A non‐destructive method of determining rock strength , 1988 .

[11]  A. Goudie,et al.  Experimental salt weathering of limestones in relation to rock properties , 1999 .

[12]  R. Allison.  Developments in a non‐destructive method of determining rock strength , 1990 .

[13]  R. B. G. Williams,et al.  Weathering of sandstone by alunogen and alum salts , 1998, Quarterly Journal of Engineering Geology.

[14]  N. Matsuoka,et al.  Mechanisms of rock breakdown by frost action: An experimental approach , 1990 .

[15]  C. Lovell,et al.  Measurements of pore size distributions in cements, aggregates and soils , 1981 .

[16]  D. Pollard,et al.  Progress in understanding jointing over the past century , 1988 .

[17]  E. T. Brown.  Rock characterization, testing & monitoring: ISRM suggested methods , 1981 .

[18]  A. Goudie,et al.  The relations between modulus of elasticity and temperature in the context of the experimental simulation of rock weathering by fire , 1992 .

[19]  Robert J. Allison,et al.  The effects of fire on rock weathering: some further considerations of laboratory experimental simulation , 1999 .

[20]  F. Homand-Etienne,et al.  Laboratory velocities and attenuation of P-waves in limestones during freeze-thaw cycles , 1994 .

[21]  W. R. Dearman,et al.  The engineering petrography of a weathered granite in Cornwall, England , 1978, Quarterly Journal of Engineering Geology.

[22]  R. Kranz.  Microcracks in rocks: a review , 1983 .

[23]  Giorgio Accardo,et al.  Artificial weathering of Carrara marble: relationships between the induced varlations of some physical properties , 1981 .

[24]  A. Goudie,et al.  Further experimental investigation of rock weathering by salt and other mechanical processes , 1974 .