Calcination of Marls to produce Roman cement

Identified from a range of European sources and assessed for their Cementation Index, as proposed by Eckel, marls are the subject of this research. Two marls were selected for calcination in a laboratory kiln; one from Lillienfeld in Austria (CI 2.03) and one from Folwark in Poland (CI 1.75). While not revealing precise kiln conditions, analysis of historical documents does suggest that they were such as not to yield complete decarbonation of the calcite. As a result, a series of calcinations was undertaken in which the peak temperature control of the kiln was set in the range 730 degrees Celsius to 1100 degrees Celsius, with residence times in the range 150 to 1250 minutes. The airflow through the kiln was sufficient to maintain a minimum oxygen content of at least 12%. The clinker resulting was ground to comply with the 19th century Austrian Norme. Pastes were produced at w/c = 0.65 and assessed for setting time and strength development (6 h to 1 year). Both parameters were highly dependent upon calcination conditions with both "low" and "high" calcinations producing slower setting and slower strength development than intermediate conditions. Two strength development profiles were identified; one was the expected continuous increase of strength, even though it had a declining rate of increase with time, while the other showed a three-step sequence of high initial strength, a dormant period which could last for many weeks, and a final increase in strength to an age of one year. Comparisons were made of the cements using X-ray diffraction (XRD). Variation of a considerable amount in the composition was noted and related to the calcination conditions. The formation of both α'-belite and β-belite under differing calcination conditions were of particular interest. Also compared using the SEM in back-scattered electron imaging mode were clinker particles, and observations of the development of morphology were made.

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• Corporate Authors:

  ASTM International

  100 Barr Harbor Drive
  West Conshohocken, PA  United States  19428-2959
• Authors:
  • Hughes, D C
  • Jaglin, D
  • Kozlowski, R
  • Mayr, N
  • Mucha, D
  • Weber, J
• Publication Date: 2008-3

Language

• English

Media Info

• Media Type: Print
• Features: Figures; References; Tables;
• Pagination: pp 84-95
• Monograph Title: Natural Cement

Subject/Index Terms

• TRT Terms: Calcines; Clay soils; Marl; Mineralogy; Strength of materials
• Uncontrolled Terms: Calcination; Roman cements; Strength development
• Geographic Terms: Folwark (Poland); Lilienfeld (Austria)
• Subject Areas: Geotechnology; Highways; Maintenance and Preservation; Materials; I32: Concrete;

Filing Info

• Accession Number: 01351807
• Record Type: Publication
• ISBN: 9780803134232
• Files: TRIS
• Created Date: Sep 14 2011 11:13AM