HARDENED CEMENT PASTES OF LOW POROSITY

TYPE I AND TYPE II PORTLAND CEMENT CLINKER WERE GROUND TO BLAINE SURFACE AREAS OF 6800 TO 8500 SQ CM/G, USING FOUR DIFFERENT GRINDING AIDS. THE AMOUNT OF GRINDING AID WAS 0.5% OF THE WEIGHT OF THE CLINKER. THE GROUND CLINKER WAS DRY- MIXED WITH 1.0% CALCIUM LIGNOSULFONATE FOR THE TYPE I AND 0.5% FOR THE TYPE II CEMENT. POTASSIUM CARBONATE, 0.5% OF THE WEIGHT OF THE CLINKER, WAS DISSOLVED IN THE MIX WATER. WITH THE HELP OF THE THREE ADDITIVES, PASTES OF EXCELLENT CONSISTENCY OR WORKABILITY WERE OBTAINED WITH WATER-CEMENT RATIOS (W/C) AS LOW AS 0.2. MOST OF THE EXPERIMENTS WERE CONDUCTED WITH PASTES PREPARED WITH W/C=0.2, BUT IN A PART OF THE EXPERIMENTS 0.3 WAS EMPLOYED. SUCH PASTES WERE DESIGNED AS LOW-POROSITY PASTES, IN CONTRAST WITH NORMAL PASTES OF 0.4 AND HIGHER. THE LOW-POROSITY PASTES HAD MUCH HIGHER COMPRESSIVE STRENGTHS THAN NORMAL PASTES. WITH W/C=9.2, THE MAXIMUM COMPRESSIVE STRENGTHS OBTAINED WERE 36,400 AND 40,000 PSI AT HYDRATION TEMPERATURES OF 25 AND 50C, RESPECTIVELY, AND WITH W/C=0.3, THE MAXIMUM VALUE AT 25 C WAS 29,000 PSI. DIMENSIONAL CHANGES WERE DETERMINED ONLY FOR LOW-POROSITY PASTES OF W/C=0.2, HYDRATED AT 25 C. THE LENGTH CHANGES WERE ONE-THIRD TO ONE-HALF AS LARGE AS THOSE OF PASTES MADE FROM THE SAME CEMENT WITH W/C=0.4, AND ONE- FOURTH TO ONE-THIRD AS LARGE AS THOSE OF PASTES WITH W/C=0.6. THE EFFECTS OF THE TYPE OF CEMENT, THE SURFACE AREA OF THE CEMENT, THE NATURE OF THE GRINDING AID, THE AMOUNT OF THE CALCIUM LIGNOSULFONATE, THE WATER-CEMENT RATIO, AND THE TEMPERATURE OF HYDRATION ON THE DEGREE OF HYDRATION, ON THE EXPANSION OF THE PASTE DURING HYDRATION, ON THE TOTAL POROSITY, AND ON COMPRESSIVE STRENGTHS WERE DETERMINED AT AGES RANGING FROM 1 HOUR TO 180 DAYS. PORE STRUCTURE ANALYSES WERE MADE FOR 25 LOW-POROSITY PASTES BY WATER-VAPOR ADSORPTION AND, FOR 8 OF THE 25 PASTES, BY NITROGEN ADSORPTION. THIS INCLUDED DETERMINATION OF THE SURFACE AREAS AND PORE VOLUME OF THE PASTES, AND THE DISTRIBUTION OF SURFACE AND VOLUME IN PORES OF DIFFERENT WIDTHS. /AUTHOR/

Subject/Index Terms

Filing Info

  • Accession Number: 00212120
  • Record Type: Publication
  • Source Agency: Federal Highway Administration
  • Report/Paper Numbers: Study No 38-1
  • Files: TRIS, USDOT, STATEDOT
  • Created Date: May 9 1972 12:00AM