Experimental sandstone weathering using different wetting and drying moisture amplitudes

Abstract

Wetting and drying is an acknowledged yet still poorly understood rock weathering process. Previous experiments documented in the literature measure physical changes or mass loss in relation to moisture oscillations but only one study directly compares different moisture amplitudes by using different modes of moisture application. In this experimental study, four sets of sandstone tablets are subjected to 48 h wetting and drying cycles at set moisture content fluctuations of 29, 42, 56 and 63% respectively. A common moisture application, full immersion, is used for all four sets. Mass loss after 52 cycles averaged 0·27%, some three times more than that of the control samples. Average porosity of the samples increased, while water absorption capacities and the saturation coefficients of the samples decreased. No discernable difference in mass loss or change in physical properties was found between the different sample sets. When compared with previous studies, results suggest that the effect of moisture application type may be more of a controlling factor on the weathering effect than actual moisture content achieved. A need to move towards a more standardized approach in wetting and drying experimental studies is emphasized.

Weathering of basalt and sandstone by wetting and drying: a process isolation study

“…Set 2b does not demonstrate the same trend for the experimental samples, but both experimental sample sets have lost more mass than the control set. Thus, Set 2a follows the intuitive assumption, while Set 2b conforms with the results found by Sumner and Loubser ().…”

“…However, the samples saturated for 3 h have experienced almost exactly the same level of mass loss as the samples saturated for 10 min. This confirms findings by Sumner and Loubser () and it is thus apparent that the amount of moisture a rock is subjected to is less important than the number of wetting/drying cycles.…”

“…() used an optical or electron microscope to measure surface fracture propagation. Hall and Hall () studied the manner in which the moisture was applied to the samples (full inundation, half inundation and sprayed samples), while Sumner and Loubser () investigated the effects of moisture saturation amplitude on rock breakdown. Wells et al .…”

The historical legacy of spatial scales in freeze–thaw weathering: Misrepresentation and resulting misdirection

“…Logan, 2004;Gómez-Heras, et al, 2006), wetting and drying (e.g. Sumner and Loubser, 2008), or their synergistic operation (e.g. Mutlutürk et al, 2004;Weiss, et al, 2004;Smith, et al, 2005;Hall, 2006b;Ruedrich and Siegesmund, 2007) despite the often simplistic statements to the contrary (e.g.…”

Rock weathering on the eastern mountains of southern Africa: Review and insights from case studies

“…Together with later wetting and drying at the concrete surface, differential strains can result in cracking (Roper, 1959;van Rooy and van Schalkwyk, 1993). Laboratory testing by Hall and Hall (1996) and Sumner and Loubser (2008) also confirm the susceptibility of the sandstone to wetting and drying cycles.…”