AN EVAPO-TRANSMISSION METHOD FOR DETERMINING RELATIVE PERMEABILITY OF CONCRETE
The equipment for this simple and inexpensive procedure consists of a glass cell assembly comprised of a dry cell and a wet cell between which an unsealed area of a test sample is sandwiched. A capillary tube is attached to the wet cell to measure drawdown. Both the capillary and the wet cell are filled with distilled water. A desiccant, anhydrous magnesium perchlorate, is put in the dry cell to provide 0% relative humidity. Differences in relative humidity between sides of the test sample provides the driving force for water or water vapor movement. Under the influence of this force water is transmitted through the test slab from the wet side toward the dry side where it evaporates. There are two test procedures: one involves soaking of the test sample prior to the test and the second does not. The second procedure reflects more closely the actual field conditions most frequently existing. In both the procedures there is an initial period of varying rate of drawdown before a steady-state is reached. The data obtained during the steady-state indicated the evapo-transmission for the sample. Evapo-transmissions should be compared only to those determined using the same procedure, hence the term "relative permeability". A computer program was developed which uses the least squares and regression method to determine the orientation of the best fit line. The slope of the best fit line during the steady-state indicates the evapo-transmission or relative permeability for the test sample.
- Sponsored by Kansas Department of Transportation, this report is part of a Kansas HPR Study "Electro-Osmotic Techniques for Removal of Chloride from Concrete and for Emplacement of Concrete Sealants," prepared in cooperation with the Department of Transportation, Federal Highway Administration.
Topeka, KS United States 66612
- Morrison, G L
- Gilliland, W J
- Bukovatz, J E
- Jayaprakash, G P
- Seitz, R D
- Publication Date: 1979-4
- Pagination: n.p.
- TRT Terms: Computer programs; Concrete; Evapotranspiration; Humidity; Permeability; Steady state; Water vapor
- Subject Areas: Highways; Materials;
- Accession Number: 00300363
- Record Type: Publication
- Source Agency: National Technical Information Service
- Report/Paper Numbers: FHWA-KS-79-1 Intrm Rpt.
- Contract Numbers: Study No. 74-1
- Files: TRIS, STATEDOT
- Created Date: Nov 27 1979 12:00AM