INFLUENCE OF OPEN POROSITY UPON THE RESISTANCE OF MORTARS AND CONCRETES TO AGGRESSIVE SOLUTIONS

WITH THE AID OF GRAPHS THE INFLUENCE OF OPEN POROSITY WAS DETERMINED BY MEANS OF GAS PERMEABILITY MEASUREMENTS. THE RESISTANCE OF MORTARS TO ATTACK BY SOLUTIONS CONTAINING SULPHATES IS INDICATED. AS CAN BE EXPECTED, A LOW PERMEABILITY TO GASES HAS A FAVOURABLE EFFECT IN THIS RESPECT. LOWERED RESISTANCE TO AGGRESSIVE ATTACK IS ATTRIBUTABLE TO THE FORMATION OF ETTRINGITE-LIKE PHASES, GYPSUM AND BRUCITE. THE CAUSE OF THE SULPHATE RESISTANCE OF PORTLAND CEMENTS CONTAINING NO TRICALCIUM ALUMINATE RESIDES PRIMARILY IN THE LOW RATE OF HYDRATION OF THE CALCIUM ALUMINATE FERRITES RICH IN IRON OXIDE, WHILE THE SULPHATE RESISTANCE OF PORTLAND BLAST-FURNACE CEMENTS WITH A HIGH CONTENT OF SLAG IS DUE TO THE REDUCED AVAILABILITY OF LIME. WITH BOTH TYPES OF CEMENT, HOWEVER, IT IS NECESSARY TO TAKE ACCOUNT OF THE FACT THAT NOT ONLY DO SULPHATE IONS PENETRATE INTO THE MORTAR BY DIFFUSION, BUT THAT CALCIUM AND HYDROXYL IONS ESCAPE FROM THE HARDENED CEMENT PASTE LIKEWISE BY DIFFUSION, SO THAT FINALLY - AS IN THE CASE OF SUPERSULPHATED CEMENT - THE CALCIUM AND HYDROXYL ION CONCENTRATION NEEDED TO FORM THE ETTRINGITE THAT CAUSES EXPANSION IS NO LONGER PRESENT. /AUTHOR/

• Supplemental Notes:
  • Vol 56, No 12, PP 555-561
• Authors:
  • Ludwig, U
  • Schwiete, H E
• Publication Date: 1967-12

Media Info

• Serial:
  • Zement-Kalk-Gips

Subject/Index Terms

• TRT Terms: Aluminates; Calcium compounds; Ettringite; Ferrites; Gases; Graphics; Hydration; Ions; Measurement; Mortar; Permeability; Porosity; Portland cement; Sulfate resisting cement
• Uncontrolled Terms: Graphical analysis
• Old TRIS Terms: Permeability measurement
• Subject Areas: Highways; Materials;

Filing Info

• Accession Number: 00212581
• Record Type: Publication
• Files: TRIS
• Created Date: May 1 1994 12:00AM