CHERT AS A DELETERIOUS CONSTITUENT IN INDIANA AGGREGATES

REPRESENTATIVE SAMPLES OF CHERT FROM PRACTICALLY ALL PRODUCERS OF STONE AND GRAVEL AGGREGATES IN INDIANA WERE OBTAINED, TOGETHER WITH SOME MATERIALS FROM SURROUNDING STATES. LEDGE CHERTS WERE OBTAINED FROM QUARRIES AND EXPOSED STONE FACES, AND IDENTIFIED GEOLOGICALLY. A RECORD WAS MADE OF THE VISUAL APPEARANCE OF EACH SPECIMEN, INCLUDING COLOR, LUSTER, TEXTURE, AND FRACTURE. PERFORMANCE WAS DETERMINED BY IMBEDDING THE CHERT IN MORTAR CUBES AND SUBJECTING THEM TO ALTERNATE CYCLES OF FREEZING AND THAWING. INDENTIFICATION TESTS CONSISTED OF SPECIFIC GRAVITY, ABSORPTION, DEGREE OF SATURATION, DYE PENETRATION, UNCONFINED FREEZING AND THAWING, CHEMICAL ANALYSES, AND MICROSCOPIC EXAMINATION OF THIN SECTIONS. THE RESULTS REPORTED PRIMARILY COVER INDIANA STONE CHERTS. IT WAS OBSERVED THAT THE CHARACTERISTICS OF CHERTS VARY WIDELY IN DIFFERENT REGIONS AND CONSEQUENTLY A STUDY OF CHERT SHOULD BE RESTRICTED TO A DEFINITE GEOGRAPHICAL AREA. MATERIALS FROM INDIANA VARIED WIDELY IN PERFORMANCE AND PROPERTIES. THE MOST UNSOUND CHERTS HAD A RATIO OF 0.85 OR MORE BETWEEN THE ABSORPTION BY ONE HOUR EVACUATION AND 23 HOURS' IMMERSION AND THAT CALCULATED FOR ONE HUNDRED PER CENT SATURATION. THEY HAD AN ABSORPTION OF 3 PER CENT OR MORE, AND A BULK SPECIFIC GRAVITY, SATURATED SURFACE-DRY, OF LESS THAN 2.50, BY A.S.T.M. METHOD C 127-39. THE INVESTIGATION CONFIRMS, IN PART, THE WORK OF OTHER INVESTIGATORS IN REGARD TO BULK SPECIFIC GRAVITY, ABSORPTION, AND DEGREE OF SATURATION AS MEANS OF DISTINGUISHING SOUND FROM UNSOUND CHERTS. THE CHERTS WHICH SHOWED DISRUPTIVE TENDENCIES ALSO HAD AN EOSINE DYE PENETRATION OF ONE-HALF INCH OR MORE AFTER 20 HOURS' IMMERSION, AND WERE PREDOMINANTLY LIGHT IN COLOR. THE RESULTS INDICATED THAT FREEZING OF WATER IN THE VOIDS WAS THE PRIMARY CAUSE OF DISRUPTION. THE PERFORMANCE OF THE CHERTS WAS DEPENDENT ON THE DEGREE OF SATURATION. THIS OBSERVATION CONSTITUTES SOMEWHAT OF A CRITICISM OF THE ACCEPTED METHODS FOR SPECIFIC GRAVITY AND ABSORPTION DETERMINATION AND PREPARATION FOR THEFREEZING AND THAWING TEST, BECAUSE OF THE LACK OF CONSIDERATION GIVEN TO THE DEGREE OF SATURATION OF THE MATERIALS TESTED. /AUTHOR/

  • Supplemental Notes:
    • Vol 20, pp 599-620, 8 FIG, 9 TAB, 21 REF; part of Report of Committee on Mineral Aggregates
  • Authors:
    • SWEET, H S
  • Publication Date: 1941

Media Info

  • Monograph Title: Proceedings of the Twentieth Annual Meeting of the Highway Research Board Held at Washington, D.C. December 3-6, 1940
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00217870
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Aug 15 1971 12:00AM