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Testing Materials for Support-wall Construction.

Hay KE; Johnston JL
MISSING :11 pages
The Bureau of Mines collected coal and coal waste aggregate material from two different mine sites to determine their strength characteristics for use in concrete. The concrete would be placed underground as support walls for ground control in adverse conditions or unique mining applications. A standard mix design was established for a "wet" mix using a water-to-cement (w/c) ratio of 1.0 To facilitate pumping into place. Later, material was collected from four more mine sites and used to make 2- by 2- by 2-ft test blocks with the same w/c ratio. A pullout cone device and borehole shear tester were used to determine the in situ material strength of the test blocks. These techniques will provide a simple and quick way of determining support wall strength in an underground environment. Test results from the pullout cone device showed a good correlation of 0.98 To test cylinder compressive strengths of the same mix. Results of the borehole shear tester were inconclusive.
Publication Date
Document Type
IH; Report of Investigations
Fiscal Year
Identifying No.
RI 9038
NIOSH Division
Source Name
Page last reviewed: November 19, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division