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U.S Crops of Engineers Gyratory Testing Machine



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The GTM is combination compaction and simple-shear testing machine, suited to use with cylindrical specimens of soils and base course materials as well as bituminous mixes, Desired vertical loading (anticipated maximum tire contact pressure for bituminous surface course) and degree of shear strain (gyratory angle) are selected. Then sample material is placed in the mold, the mold is clamped in the chuck, and the machine is started. Upper and lower rollers travel around the chuck flange to transmit a gyrating kneading motion to the specimen based on a user preset gyratory angle from 0° to 3° between the rollers. While this machine induced angle is fixed, the angle developed by the floating mold chuck varies depending on quality of the sample mix. The magnitude of the floating angle is due to dilation of material during the shearing process and represents shear strain. The weaker the material, the higher the floating angle. At the same time, the measured GTM roller pressure decreases as an indicator of reduced shear strength. when voids become over-filled due to excessive densification or excessive voids filling medium (Water in soils or bitumen in pavement mixes), the floating angle increases (excess plasticity) and roller pressure decreases (reduced shear strength). Upper limit of bitumen content at a selected design stress (vertical pressure) is determined as that mix content when the floating angle begins to increase.


• Determines Gyratory Stability Index (GSI), a measure of plasticity (loss of stability) during densification. Optimum bitumen content is identified independently of voids criteria via floating angle measurements.
• Establishes unit mass (compaction) requir


 

Product #ProductNameStandardsPower RequirementsSpecimen Sizes(Inch)Specimen Sizes(mm)Aggregate Max Size(Inch)Aggregate Max Size(mm)Extra Moulds Dim (Dia x H)(Inch)Extra Moulds Dim (Dia x H)(mm)
  GHM-604CGHM-604C Gyratory Testing MachineASTM D 3387, D 3496, D4123, P233230V, 3 Phase, 50 or 60 Hz.4 Inch102 mm1 Inch25.4 mmN/AN/A
  GHM-606CGHM-606C Gyratory Testing MachineASTM D 3387, D 3496, D4123, P233230V, 3 Phase, 50 or 60 Hz.4 Inch 6 Inch102 mm 152 mm1 Inch 1.5 Inch25.4 mm 38.1 mmN/AN/A
  GHM-608CGHM-608C Gyratory Testing MachineASTM D 3387, D 3496, D4123, P233230V, 3 Phase, 50 or 60 Hz.4 Inch 6 Inch 8 InchN/A1 Inch 1.5 Inch 2 Inch25.4 mm 38.1 mm 50.8 mmN/AN/A
  GHMA-642CGHMA-642C Gyratory Testing MachineASTM D 3387, D 3496, D4123, P233230V, 3 Phase, 50 or 60 Hz.4 Inch102 mm1 Inch25.4 mm4x8 Inch101.6 x 203.2 mm
  GHMA-661CGHMA-661C Gyratory Testing MachineASTM D 3387, D 3496, D4123, P233230V, 3 Phase, 50 or 60 Hz.4 Inch 6 Inch102 mm 152 mm1 Inch 1.5 Inch25.4 mm 38.1 mm6x10 Inch152.4 x 250.4 mm
  GHMA-682CGHMA-682C Gyratory Testing MachineASTM D 3387, D 3496, D4123, P233230V, 3 Phase, 50 or 60 Hz.4 Inch 6 Inch 8 InchN/A1 Inch 1.5 Inch 2 Inch25.4 mm 38.1 mm 50.8 mm8x12 Inch203.2 x 304.8 mm