Spontaneous Capillary Imbibition of Water and Nonaqueous Liquids into Dry Quarry Limestones
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Spontaneous Capillary Imbibition of Water and Nonaqueous Liquids into Dry Quarry Limestones Christopher Hall1 · Victoria Pugsley1 Received: 9 August 2020 / Accepted: 9 October 2020 © The Author(s) 2020
Abstract Rates of spontaneous imbibition of water and nonaqueous liquids into dry limestones have been measured at 25 °C. Thirteen English and French limestones were used, with eight liquids (water, decane, dodecane, sec-butanol, iso-propanol, tetrahydrofuran, perfluorodimethylcyclohexane, ethanediol). For the nonaqueous liquids, the measured sorptivity generally scales as (surface-tension/viscosity)1∕2 (here called F-scaling). Water sorptivities deviate from F-scaling, indicating partial wetting. A wetting coefficient (wetting index) is derived. Data show that there is little difference in the Hirschwald saturation coefficient measured with the different liquids, although there is a large variation between stones. Results suggest that physicochemical alteration of exposed pore surfaces strongly (and unpredictably) influences the capillary absorption of water by limestones. Keywords Imbibition · Hirschwald coefficient · Limestones · Sorptivity · Wettability · Wetting coefficient
1 Introduction In this paper, we report and discuss some results from two series of experiments on the spontaneous imbibition of liquids by capillary rise in small blocks of quarry limestones. These experiments were designed to explore the short-term primary imbibition that is driven by Lucas–Washburn capillarity, in particular how the sorptivity S which describes the kinetics of imbibition depends on the surface tension 𝜎𝓁 and viscosity 𝜂𝓁 of the imbibed liquid. Earlier work (Taylor 1998; Taylor et al. 2000) had shown that water imbibition in some limestones is slower than expected from a simple (𝜎𝓁 ∕𝜂𝓁 )1∕2 scaling, pointing to partial (or incomplete) wetting by water in these materials. But the results reported here are more extensive: more stones and more liquids. Many of these experiments were of long duration, carried out to investigate not only the primary imbibition but also the long-term secondary imbibition that is controlled by the slow diffusion of air trapped in the primary process. While the timescale of the primary imbibition on small blocks is rarely more than a day, the secondary process may * Christopher Hall [email protected] 1
School of Engineering, University of Edinburgh, Edinburgh EH9 3JL, UK
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last several years. Some observations of the long-term secondary imbibition of water are described elsewhere (Hall and Hamilton 2018). This paper deals only with the primary process, while the long-term imbibition of nonaqueous liquids will be the subject of another publication. Materials in context Limestones have been widely used as materials of construction for many centuries, on all inhabited continents, and in all building types. Durability is a requirement and a preoccupation in specification, maintenance and conservation. Deterioration and decay is largely me
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