FLOW OF WATER IN HARDENED - PORTLAND CEMENT PASTE

LIABLE TO BE COMPLICATED BY EFFECTS OF OSMOTIC PRESSURE. STUDIES OF THE PERMEABILITY OF HARDENED CEMENT PASTE TO LIQUID WATER WERE CARRIED ON AS ONE OF SEVERAL MEANS OF STUDYING THE COLLOIDAL STRUCTURE OF HYDRATED CEMENT PASTE. EXPERIMENTAL METHODS AND RESULTS ARE DESCRIBED GIVING THE THEORETICAL BASIS OF ANALYSIS. THE APPARATUS USED FOR DETERMINING COEFFICIENTS OF PERMEABILITY IS DESCRIBED. RESULTS SHOW THAT THE FLOW OF WATER THROUGH A GIVEN SPECIMEN OF HYDRATED CEMENT PASTE COMPLIES WITH DARCY'S LAW, BUT IS WITHIN THE RANGE OF PASTE POROSITY INCLUDED, PART OF THE EVAPORABLE WATER IS ABSORED. AVERAGE VISOCISITY OF WATER IN HYDRATED CEMENT PASTE IS A FUNCTION OF GEL-PARTICLE CONCENTRATION AND TEMPERATURE. TEMPERATURE DEPENDENCE OF RATE OF BELOW AND PASTE INDICIATES A RELATIVELY HIGH ACTIVATION ENGERGY FOR FLOW, REFLECTING THE EFFECT OF ADSORPTION. THE THEORY OF PERMEABILITY BASED ON THE CONCEPT OF VISCOUS DRAG ON PARTICLES AS DEVELOPED BY STEINOUR, BUT MODIFIED TO ALLOW FOR VARIABLE VISCOSITY, AND MODIFIED BY CONSIDERATIONS ADVANCED BY HAWKSLEY, GIVES A GOOD FIT TO THESE DATA. THE PARTICLE SIZE AND SHAPE INDICATED BY PERMEABILITY DATA, COMBINED WITH ADSORPTION DATA, ARE: SPHERICITY FACTOR 0.36, VOLUME DIAMETER 264A, SURFACE DIAMETER 440A, STOKES DIAMETER 205A, SPECIFIC SURFACE DIAMETER 95A. THESE DATA ARE COMPATIBLE WITH ELECTRON-MICOGRAPHS. THE SPHERICITY FACTOR OBTAINED BY COMBINING PERMEABILITY DATA WITH ADSORPTION DATA INDICATE THE PARTICLES TO BE SHEETS, OR FIBERS, OR BOTH, IN AGREEMENT WITH ELECTRON-MICOGRAPHS. ALL THE EVAPORABLE WATER APPEARS TO ME MOBILE. THE PARTICLES GIVING RISE TO VISCOUS DRAG IN THE PERMEABILITY TEST ARE APPARENTLY THE SAME PARTICLES, WHICH, WHEN DRY, ADSORB WATER VAPOR. IN THE SPECIMENS STUDIED, THERE APPARENTLY WERE NO CONTINOUS CAPILLARIES BYPASSING CLUSTER OF GEL PARTICLES.

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  • Accession Number: 00235722
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Aug 17 1970 12:00AM