Fresh concrete is generally considered no-slump if it has a slump less than 2 cm and a VeBe time longer than 5 sec. approx. Therefore it consists of a stiff mass that has to be compacted by means of pressure combined with vibration, rolling and/or extrusion, generally a shear movement in order to grant a good interlocking between the aggregate particles. Gyratory Testing Machine will reproduce in laboratory the compaction of no slump concrete by mean of vertical pressure combined with the gyratory movement. Since 1985 the gyratory compactor has been used for concrete materials in Finland and Scandinavia. The method is used for mix design and quality control mainly in concrete product plants, where low workable and zero slump concrete is used (for such products as hollow-core slabs, tubes and paving blocks)
The field of application of the Gyratory Testing Machine includes the manufacture of concrete elements, as well as road and dam construction. Basically the characteristic of compacted fresh no-slump concrete used for concrete elements such as paving blocks, hollow core blocks, slabs, pipes, roofing tiles and concrete road pavements, is to be free of shrinkage effects such as cracks and volume change, to maintain its shape after stripping from the form and to grant and maintain good aesthetic level of the product.
As regards concrete dam and road sub base concrete, the base characteristics is the consistency of density with mechanical properties, as compression and splitting tensile strength at various age. Small variations of the components of the mix cause remarkable change in performance. Therefore accurate mix design with fine tuning of components and frequent QC of production is essential. The Gyratory Testing Machine is particularly useful on the purpose, because it deals with the subject by examining the volumetric properties of no-slump concrete mix during compaction.
The method is used for:
- Mix design simulating selected production processes
- Specimen preparation for strength tests (fresh and cured)
- Research of mix related phenomena (workability, curing time, admixtures, etc.)
Two Versions with pneumatically operated vertical pressure are available:
- 54-C0252/C Gyratory compactor for cement and concrete.
- 54-C0251/A Gyratory compactor for cement and concrete. Research version with shear resistance measurement
The machines are supplied complete with one 100mm dia mould and accessories to perform the test. Both the models are supplied complete with WIN-ICT software for the machine control, Data acquisition and compaction curve processing and Excel Macro for gyratory compaction test complete for data procession. PC not included.
|Specimen size||100 mm dia. x 90÷130 mm height|
|Gyratory angle (calibrated by Internal Load Simulator)||40mrad (2° 17'') fixed||Adjustable from 0 to 50mrad (2° 86'')|
|Number of cycles||Adjustable from 2 to 512|
|Rotation speed||30 to 120 cycles/min, adjustable|
|Vertical pressure||60 to 320 kPa, adjustable|
|Air cylinder(s)||63 mm diameter||Twin 50 mm diameter each|
|Working air pressure||8 bar|
|Max. air pressure supply||10 bar (a 5 mm filter included)|
|Vertical pressure gauge||Range 0-10 bar||Two gauges: range 0-10 and 0-4 bar|
|Shear force measurement||No||Yes, by load cell installed|
|Weight||55 kg approx||95 kg approx|
|Dimensions||35x48x93 cm approx||50x60x110 cm approx|