STUDIES OF PHOSPHATIC PORTLAND CEMENT

Earlier studies of high temperature phase equilibria in the system ca0-si02-p205 have provided a fundamental basis for understanding the role of phosphate in the manufacture of portland cement from phosphatic raw materials. The special importance of fluorides as mineralisers in the manufacture of phosphatic cements was also elucidated. Phosphatic raw mateials of diverse origin have recently been assessed for cement manufacture and the results have confirmed that the maximum practical level of p205 which could be tolerated in portland cement, if cement of acceptable quality is to be obtained, is about 2.5 per cent. Above this limit, setting times become unacceptably long and early strength (1 and 3 days) very low, although strength at later ages (28 days) may remain acceptable, New results also indicate that for a wide range of phosphatic raw materials the lea and parker lime saturation factor (ca0/(2.8si02 + 1.18a1203 + 0.65fe203)) should serve as a practical guide to raw meal prooportioning despite the fact that it makes no allowance for the effects of p205 and fluoride on high temperature phase equilibria. This applicability of the lsf is fortuitous since the compound composition predicted by the related bogue equations is incorrect. Mineralogical examination of clinkers suggests the existence of dicalcium silicate solid solutions with p205, al203 and fe203 in combination and the possibility that these are of the general form (ca0)2 (si02) 1-4x (p205)x (a1203, fe203)x ie substitution of p5+(al,fe)3+ for 2SI4+ is being investigatee. The heat evolution of phosphatic cements has been followed using continuous conduction calorimetry. (Author) /TRRL/

  • Supplemental Notes:
    • This paper was presented at the 6th International Symposium on the Chemistry of Cement, Moscow, September 1974.
  • Corporate Authors:

    Building Research Establishment

    Building Research Station, Garston
    Watford WD2 7JR, Hertsford,   England 
  • Authors:
    • Grutt, W
  • Publication Date: 1974

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 19 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00132644
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Paper No. CP95 Monograph
  • Files: ITRD, TRIS
  • Created Date: Nov 9 1977 12:00AM