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Report of Investigations 8814: Factors Affecting the Dissolution of Gypsum-Bonded Roof Bolts

Public Domain
File Language:
English


Details

  • Journal Article:
    NTIS: PB84/140318
  • Personal Author:
  • Description:
    In support of its objective to improve mine safety, the Bureau of Mines has searched for better materials and systems to anchor roof bolts. This report describes a study on the effects of mine waters upon accelerated gypsum, one of the materials under consideration. The accelerated gypsum dissolved at an appreciable rate relative to an assumed 10-yr life span of a roof bolt. Surface orientation, initial ion concentration of a dissolving solution, and flow rate of the solution had substantial effects on the dissolution rate. Factors such as water-cement ratio, accelerator content, wax capsule additions to the gypsum in cartridge-installed bolts, surface area, temperature, and curing duration had little effect. In an actual roof-bolt environment, dissolution will occur in static solutions to the solubility limit of gypsum ( 2g/l) and cease, resulting in minimal damage; but in flows of unsaturated solution as slow as 1 l per month, a loss of up to 10 pct will occur in 2 yr. Since miners cannot readily measure the flow or ion concentration of static- appearing water at every roof-bolt site, all such water must be assumed to be pure and flowing. It is recommended that gypsum- bonded roof bolts be confined to dry roofs only. [Description provided by NIOSH]
  • Subjects:
  • Source:
    NTIS: PB84/140318; :1-12
  • Series:
  • Subseries:
    Report of Investigations
  • Document Type:
    Text
  • Genre:
    Report
  • Place as Subject:
    United States
  • CIO:
    National Institute for Occupational Safety and Health (NIOSH)
  • Division:
    ALRC - Albany Research Center
  • Topic:
    Workplace Safety & Health
  • Location:
    North America
  • Pages in Document:
    17 pdf pages
  • NIOSHTIC Number:
    nn:10003158
  • Federal Fiscal Year:
    1983
  • Peer Reviewed:
    False
  • Collection(s):
  • Main Document Checksum:
    urn:sha-512:a273bba69cd3516599bfdd42f60459d8696def38d7e5461b47f446b9c890e020f93f906a6843a0d751cb2685bba8f2c2e90e258db98f7e2211e4b38fd34b9bcc
  • Download URL:
  • File Type:
    Filetype[PDF - 3.24 MB ]
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