DETERMINATION OF THE STRUCTURE OF AIR VOIDS IN THE AIR-VOID CEMENT PASTE SYSTEM BY MEANS OF ELECTRON MICROSCOPY

ERFASSUNG DER STRUKTUR UND DES AUFBAUES VON LUFTPOREN IM LUFTPORENZEMENTSTEINSYSTEM MIT HILFE DER ELEKTRONENMIKROSKOPIE

BY MEANS OF A RECENTLY DEVELOPED TECHNIQUE IT IS POSSIBLE TO BREAK DOWN THE AIR-VOID CEMENT PASTE SYSTEM SIGNIFICANTLY BETTER THAN IS POSSIBLE WITH THE LIGHT MICROSCOPE. BY MEANS OF FREEZING SHOCK, FREEZING FRACTURE, FREEZING CUTTING AND CAUSTIC FREEZING TESTS THE ELECTRON MICROSCOPE CAN BE USED TO LOOK AT THE BREAKDOWN PROCESSES AND THE ICE FORMATION. THE USE OF ELECTRON MICROSCOPY FACILITATES THE COMPARISON OF AIR ENTRAINING AGENTS BASED ON VINSOL RESIN WITH "SYNTHETIC AIR-ENTRAINING AGENTS", AND/OR WITH ADMIXTURES OF PLASTIC MATERIALS BASED ON FOAM OR MICROCAPSULES; THE PRECIPITATION OF CALCIUM HYDROXIDE INTO AIR VOIDS CAN ALSO BE OBSERVED. CLARIFICATION OF THESE RELATIONS SHOULD ENABLE CONCLUSIONS TO BE DRAWN REGARDING THE EXTENT TO WHICH THE PROPORTION OF SMALL AIR VOIDS CAN BE INCREASED.