On the Hysteresis in Moisture Storage and Conductivity Measured by the Instantaneous Profile Method

Abstract

The relative humidity (or the capillary pressure) and volumetric water content can be determined at specific locations inside a porous medium by means of the proposed instantaneous profile method (IPM). The measurements are carried out with temperature and relative humidity (RH) sensors as well as with time domain reflectometry probes during the whole duration of the experiment. Thus, the IPM allows a transient measurement of the moisture retention characteristic. In addition, from the spatial and temporal distributions of moisture content and RH one may calculate the moisture conductivity as a function of moisture content and RH as well.

The adsorption and successive desorption experiments presented in this article have been performed on calcium silicate (a capillary active material). The results show a hysteretic behavior that appears to depend on the nature of the process. The moisture conductivity as function of RH shows a significant hystereses; however, the moisture conductivity in relation to the moisture content appears to be non-hysteretic.

Keywords

material properties hygrothermal properties transient conditions hysteresis time domain reflectometry

Get full access to this article

View all access options for this article.

References

Adolphs, J. (1994). Thermodynamische Beschreibung der Sorption, PhD Thesis, University of Essen.

Adolphs, J. and Setzer, M. (1996). Energetic Classification of Adsorption Isotherms , Journal of Colloid and Interface Science, 184: 443-448 .

Burch, D.M. , Thomas, W.C. and Fanney, A.H. (1992). Water Vapor Permeability Measurements of Common Building Materials , ASHRAE Transactions, 98(2): 9 .

Derjaguin, B. and Chuarev, N. (1976). Polymolecular Adsorption and Capillary Condensation in Narrow Slit Pores , Journal of Colloid and Interface Science, 54: 157-175 .

Jaynes, D. (1984). Comparison of Soil Water Hysteresis Models , Journal of Hydrololgy, 75: 287-299 .

Mualem, Y. (1986). Hydraulic Conductivity of Unsaturated Soils: Prediction and Formulas. American Society of Agronomy-Soil Science Society of America, In: Methods of Soil Analysis, Part 1. Physical and Mineralogical Methods, Agronomy Monograph no. 9, pp. 799-823.

Plagge, R. (1991). Bestimmung der ungesättigten hydraulischen Leitfähigkeit im Boden. Diss. Fakultät Landschaftsplanung der Technischen Universität Berlin, Bodenökologie und Bodengenese, Heft 3, p. 152.

Plagge, R., Roth, C.H. and Renger, M. (1991). Hysteresis der ungesättigten Wasserleitfähigkeit und der pF-Kurve unter instationaren Bedingungen. Mitteilungen Dt. Bodenkundl, Gesellsch. 66, I: 201-204.

Plagge, R., Roth, C.H. and Renger, M. (1995). Eine Labormethode und ein Berechnungsverfahren zur schnellen Ermittlung der Hysteresis von hydrophysikalischen Eigenschaften poröser Medien unter instationären Bedingungen, In: Feuchtetag BAM 1995 Berichtsband ‘Feuchtigkeit in Baustoffen und Bauteilen, Messen - Rechnen - Anwenden’, pp. 254-263.

10.

Plagge, R. , Renger, M. and Häupl, P. (1997). Effect of Transient Conditions on Hydraulic Properties of Porous Media , In: van Genuchten et al. (ed.), Proceedings of the International Workshop on Characterization and Measurement of the Hydraulic Properties of Unsaturated Porous Media, Riverside (California) USA, pp. 905-912 .

11.

Plagge, R. , Grunewald, J. and Häupl, P. (1999). Simultaneous Determination of Water Retention Characteristic and Moisture Conductivity using Instantaneous Profile Techniques , In: 10. Bauklimatisches Symposium, Technische Universität Dresden, Tagungsband, p. 11 .

12.

Plagge, R. (2003). Bestimmung von Materialfeuchte und Salzgehalt in kapillarporösen Materialien mit TDR. Textbeiträge zum Workshop: Innovative Feuchtemessung in Forschung und Praxis. Sonderband ‘Wasser- und Geotechnologie’ Aedification Verlag, ISSN, p. 28.

13.

Poulovassilis, A. and Tzimas, E. (1974). The Hysteresis in the Relationship between Hydraulic Conductivity and Suction , Soil Sci., 117: 250-256 .

14.

Poulovassilis, A. and Tzimas, E. (1975). The Hysteresis in the Relationship Between Hydraulic Conductivity and Soil Water Content , Soil Sci., 118: 327-331 .

15.

Richards, R.F. , Burch, D.M. and Thomas, W.C. (1992). Water Vapor Sorption Measurements of Common Building Materials , ASHRAE Transactions, 98(1): 11 .

16.

Tinga, W.R. , Voss, W.A.G. and Blossey, D.F. (1973). Generalized Approach to Multiphase Dielectric Mixture Theory , J. Appl. Phys., 44: 3897-3902 .

17.

Topp, G.C. and Miller, E.E. (1966). Hysteresis Moisture Characteristics and Hydraulic Conductivities for Glass-bead Media , Soil Sci. Soc. Am. Proc., 30: 156-162 .

18.

Topp, G. , Klute, A. and Peters, D. (1967). Comparison of Water Content/Pressure Head Data Obtained by Equilibrium Steady-state and Unsteady-state Methods , Soil Sci. Soc. Am. Proc., 31: 312 .

19.

Topp, G.C. (1969). Soil Water Hysteresis Measured in a Sandy Loam and Compared with the Hysteresis Domain Model , Soil Sci. Soc. Am. Proc., 33: 645-651 .

20.

Viaene, P. , Vereecken, H. , Diels, J. and Feyen, J. (1994). A Statistical Analysis of Six Hysteresis Models for the Moisture Retention Characteristic , Soil Science, 157(6): 345-355 .