WorldCat Identities

Seymour, J. B.

Overview
Works: 12 works in 17 publications in 1 language and 729 library holdings
Roles: Author
Classifications: TN23, 622.28
Publication Timeline
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Most widely held works by J. B Seymour
Field-use early-strength shotcrete test system( )

1 edition published in 2011 in English and held by 235 WorldCat member libraries worldwide

"Objective: To develop a practical method of measuring shotcrete early strength ansite in the first six hours after application using a partial beam test standard, ASTM C 1 16-90. Determining the early-strength development of as-sprayed shotcrete can improve mine safety by identifying appropriate reentry times and providing a convenient means of quality control during application. A more thorough understanding of shotcrete early strength will lead to improvements in ground support practices, thereby preventing ground falls and reducing mine roof-fall accidents. Background: When shotcrete is used as part of a multi component ground support system, it is important to know when the material has developed enough strength to be self-supporting and allow for reentry and emplacement of the remaining support elements that require drilling of the shotcrete layer without degradation. Typical reported values for this threshold strength for North American mines range from 1 to 1.6 MPa (145 to 233 psi) [O'Toole and Pope 2006], with a compressive strength equivalent to 1 MPa (145 psi) being the norm [Rispin et al. 2003; O'Toole and Pope 2006]. Typical ground control support includes a shotcrete flash coat 19- to 25-mm (3 /4- to 1-in) thick, followed by screen, plates, bolts, and a second layer of shotcrete bringing the combined thickness to 75 to 100 mm (3 to 4 in). In areas requiring rehabilitation, the second layer of shotcrete is plated and bolted as well. While testing cored samples after 24 hours is standard, this is not practical for the one- to six-hour period following application when shotcrete unconfined compressive strengths are less than 10 MPa (1,450 psi). Indirect methods are typically used to determine shotcrete strength during the early stages of curing because the partially cured or green material is difficult to sample and test. While problems with inconsistent test results have been reported with the penetrometer-type devices, beam molds have been used successfully for creating shotcrete test specimens in the United States and Canada. Operating the Partial Beam Test System: The test unit is a self-contained, servo-controlled, stiff-frame press. Partial beam test samples are obtained by spraying shotcrete into 102- x 102- x 152-mm (4- x 4- x 6-in) mold boxes. After the samples have been sprayed, tests are conducted at one-hour intervals over the next six hours (one- through six-hour tests). The shotcrete samples are carefully demolded by disassembling the mold fixtures and removing the enclosed sample. Next, a shotcrete sample is placed in a specialized testing fixture and centered under the loading head of the test machine. When the test sequence is initiated, a programmable-logic-controller- (PLC) driven press applies a fixed-rate load to the sample. The load profile is shown on a graphical output display, and the measured test parameters (time, displacement, and load) are stored on a thumb drive. Once the operator observes a well-defined peak in the load profile curve, the test is completed and the test machine's loading platen can be returned to its initial starting position. Peak load is typically reflected by the development of large vertically oriented cracks along the platen-to sample contact edges, which are indicative of the failure plane. There is a marked difference in early-strength gain between sprayed and cast shotcrete. The cast shotcrete samples have a similar strength gain profile to that of cast concrete samples."--NIOSHTIC-2
Field-expedient shotcrete adhesion test system( )

1 edition published in 2011 in English and held by 235 WorldCat member libraries worldwide

"Objective: To develop a practical method of measuring shotcrete adhesion strength in underground mines. A more thorough understanding of the in-situ strength properties of shotcrete, particularly the bond strength of shotcrete to the rock, will lead to improvements in ground support practices, thereby preventing ground falls and reducing mine roof-fall incidents. Background: When shotcrete is used as an integral part of a mine's ground support system, it is important to know the strength properties of the in-place shotcrete. To quantify the bond strength of the shotcrete to the rock, a shotcrete adhesion test system has been developed for use in underground mines. The test system consists of readily available components, primarily a small stand-mounted core drill and a pulling unit equipped with a precision pressure gauge. All of these components are rugged and portable, and they can reliably be used to measure the adhesion strength of shotcrete app lied to the surface of an underground mine opening. With this test method, a direct tensile load is applied to a core drilled through the shotcrete into the underlying rock. As this load is gradually increased, the test core typically breaks or fails in tension. This tensile failure can occur in the shotcrete, at the bond surface (interface), in the rock, or at some combination of these locations. As a result, the tensile-strength values derived from these tests provide important information about the quality of the applied shotcrete and the competency of the underlying rock, as well as the bond strength of the shotcrete to the rock. Conducting the Shotcrete Adhesion Test: Once a desired test site has been selected, a hand-operated rotary percussive drill is used to drill a 16-mm x 51-mm (0.625- in x 2-in) hole for anchoring the drill stand. After installing a 13-mm- (0.5-in- ) diameter threaded stud and expansion anchor in this hole, the drill stand is leveled and secured in position. Three holes are then drilled from this drill setup ensuring that all of the holes are parallel and concentric. First, an 11.1-mm- (0.4375-in- ) diameter hole is drilled dry into the shotcrete using a rotary percussive bit, to a depth of 60 mm (2.375 in), assuming a shotcrete thickness of 75 mm (3 in). Next, the hole is cleaned, filled with a quick-setting, two-part epoxy adhesive, and a 9.5-mm- (0.375-in- ) diameter pull anchor is inserted. After the epoxy has initially set or gelled (about 15 min), a 102-mm- (4-in- ) diameter diamond core bit is used to wet drill a second hole through the shotcrete to a depth of about 25 to 50 mm (1 to 2 in) into the underlying rock. Finally, a 127-mm- (5-in- ) diameter diamond core bit is used to wet drill a shallow kerf for seating the base of the pulling fixture. After the epoxy has fully set (30-60 min), a threaded extension rod is connected to the pull anchor with a coupling nut; the pulling fixture is then carefully placed over the core sample with the base of its reaction ring positioned in the kerf of the outer drill hole. Next, a collet and a slip-on, quick-threading locknut are connected to the threaded extension rod to serve as a mechanical stop for the pulling fixture's ram. The hydraulic hose from the hand pump is then connected to the loading ram, and the pressure gauge is zeroed. To conduct a test, an increasing tensile load is applied to the core sample through a slow and steady movement of the pump handle until the core breaks. The adhesion strength of the test core is determined by converting the maximum hydraulic pressure value, saved on the pressure gauge's digital display, to the maximum tensile stress acting normal to the core's failure surface. Typical adhesion test results comparing tensile strength with shotcrete curing age are shown in Figure 4"--NIOSHTIC-2
Evaluation of in situ cemented backfill performance by Douglas R Tesarik( Book )

5 editions published in 1991 in English and held by 158 WorldCat member libraries worldwide

Material properties of retested specimens composed of tailings, cement, and blast-furnace slag by D. R Tesarik( Book )

2 editions published in 1996 in English and held by 92 WorldCat member libraries worldwide

Index to principal plate varieties in one penny and twopence imperforate. Abstracted from the text of the second edition of The postage stamps of Great Britain, part I by Royal Philatelic Society (Great Britain)( Book )

1 edition published in 1951 in English and held by 3 WorldCat member libraries worldwide

Index to principal plate varieties in one penny imperforate. Abstracted from the text of the third edition of the postage stamps of Great Britain, part 1 by J. B Seymour( Book )

1 edition published in 1968 in English and held by 2 WorldCat member libraries worldwide

Postage stamps of great britain pt 1 by J. B SEYMOUR( Book )

1 edition published in 1967 in English and held by 1 WorldCat member library worldwide

Temperature corrections to earth pressure cells embedded in backfill by D. R Tesarik( Book )

1 edition published in 2006 in English and held by 1 WorldCat member library worldwide

"Determining backfill stress is an important part of evaluating mine safety, whether personnel are working in proximity to backfill or in other areas of the mine where backfill is an integral part of regional support. To assist in determining stress in backfill more accurately, researchers from the NIOSH Spokane Research Laboratory, Placer Dome, Inc. (Turquoise Ridge Mine), Peabody Energy Co. (Foidel Creek Mine), and Hecla Mining Co. (Lucky Friday Mine) used temperature readings recorded by thermistors to correct for the influence of temperature on stress data. These thermistors were positioned in the stems of earth pressure cells installed in backfill. Corrections were then calculated and compared using four different methods: polynomial equations fit to temperature-versus-stress plots before the pressure cells were loaded by overburden, a factor provided by the manufacturer, a theoretically derived factor, and a linear correction factor based on information collected during periods when no mining was taking place. To evaluate the accuracy of these methods, corrected stresses were calculated using each method and results compared to cumulative stresses caused by blasting at one of the mines. Results indicated that only a small percentage of the temperature effect on stress was corrected using the factor from the manufacturer because that factor accounted for only the pressure transducer and not the entire instrument body. Stresses adjusted with a linear correction factor based on information collected during periods when no mining was taking place were the most accurate. Stresses recorded at two other mines were corrected using the theoretical method and the polynomial equations method; the two methods produced similar results. For some time intervals, the results were identical."--Page 1
Stamps of great britain pt 1 the line-engraved issues 1840-1853 by J. B SEYMOUR( Book )

1 edition published in 1950 in English and held by 1 WorldCat member library worldwide

Field-use round determinate panel test system( )

1 edition published in 2011 in English and held by 1 WorldCat member library worldwide

"Objective: To develop a portable field-use testing system for conducting ASTM-1550-05 round determinate panel tests. The test system can be used at the mine site to obtain shotcrete toughness strengths that are required for determining the support requirements for mine openings, minimizing falls of ground, and reducing mine roof-fall incidents. Background: When shotcrete is used as part of a ground support system in mining, it is important to know the placed strength of the shotcrete. The round determinate panel test (RDPT) was developed to quantify the resistance to tensile failure and toughness of fiber-reinforced shotcrete. The tension cracks produced by the RDPT represent the failure type observed in underground tunneling and mining. There are two design values obtained from the RDPT, the load profile and the energy. Both of these values are used when designing ground control for underground openings. While many methods have been tested for measuring strengths, RDPT is the preferred method for directly measuring determinate breaks and providing resultant toughness. Operating the Portable Round Determinate Panel Test System: Round panel samples are formed by spraying shotcrete into 75 x 800-mm (3 x 31.5-in) mold rings. The upper surface of each panel is leveled with a screed to a flatness tolerance of within 5 mm (0.2 in). Each sample must measure between 70 to 90-mm (2 .75 to 3.5-in) high and 750 to 850-mm (29.5 to 33.5-in) in diameter, with correction factors available for variances. Three samples are usually made for each test interval, and tests are typically conducted after the shotcrete has cured for 7, 14, and 28 days. The portable RDPT system is a self-contained, closed-loop, servo-controlled, stiff-frame press. To conduct a test, a cured sample is positioned on three support pins centered below the test system's ram. After the ram is lowered to a position just above the sample, an automated test cycle is initiated by depressing the green start button, which initiates the test and also starts the data acquisition system. The ram is set at a stroke rate of 4.00 mm/min (0.16 in/min) as per ASTM specifications; a full test stroke is 45 mm (1.77 in). During the test, the operator observes the sample for the development of three tension cracks. The cracks usually develop at less than 5 mm (0.2 in) of ram displacement. After a full test stroke, the press head automatically retracts to unload the sample. The test specimen is then measured in 10 spots for thickness, and a relative fiber count is conducted on the broken face of the sample. Data for load and displacement is gathered using an Eaton data logger."--NIOSHTIC-2
Postage stamps of Gt Britain. 3rd ed. Pt. 1 by J. B Seymour( Book )

1 edition published in 1967 in English and held by 0 WorldCat member libraries worldwide

Stamps of Gt Britain ... Pt. 2 by J. B Seymour( Book )

1 edition published in 1937 in English and held by 0 WorldCat member libraries worldwide

 
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English (17)