Overview
Dynamic CBR from ZORN INSTRUMENTS is available as an add-on for Light Weight Deflectometer (LWD) models ZFG 3.1 and ZFG 3000 and as a stand-alone device. Dynamic CBR is a combination of a LWD falling weight section and an original 50 mm CBR plunger. Dynamic CBR is simple, quick and delivers repeatable results, especially if compared with the original CBR field test according to ASTM D4429.
ZORN Dynamic CBR can be performed safely, even by less experienced operators. Compared to conventional CBR, the in-place field test does not require a counterweight. Users get a safe and reproducible result in less than five minutes (including set-up). Dynamic CBR is suitable for classic road building materials but also for aggregate from recycled concrete, steel mill slag and fly ash. In addition to assessing the material strength, Dynamic CBR also helps to analyze the frost sensitivity of soil and the effect of soil improvement measures. In the case of soil impro-vement and soil consolidation, Dynamic CBR can replace time-consu-ming laboratory tests and the binding process can be monitored on site.
A small device for a large task
This ZORN MINI 3.1 is especially suitable for the safe quality testing of both bedding layers and backfill in so-called mini trenches that are significantly narrower and shallower compared with conventional cable trenches.
This specialised Light Weight Deflectometer can be used for testing on the trench base and on compacted refill just as comfortably as with a ZORN ZFG 3.1 or ZFG 3.000 in standard trenches.
Adapted skills for new challenges
The base plate of the ZORN MINI 3.1 has an oval shape to match the geometry of mini trenches e.g., for fiberoptic cable that can be as narrow as 110 mm. The maximum ground pressure under the load plate of the ZORN MINI 3.1 is 0.2 MPa (MN/m2), corresponding to a standard 150 mm round plate.
The load plate can be coupled to the loading device via a bayonet transport lock. This makes it easy for the operator to lift the ZORN MINI in and out of a trench.
Even though mini cable trenches are not as deep as frost-save standard trenches, backfill material is still laid and compacted in layers. With 150 to 200 mm, thicknesses of these layers is smaller than with conventional excavations. As a result, the ZORN MINI 3.1 is equipped with a reduced drop weight of 5 kg. The impact force generated by this weight is 3.535 kN, which has proven to be an optimum for testing such thin layers.
Dynamic CBR Field test set consisting of:
- 50 mm CBR stamp with handles
- Connecting disk for accelerometer housing
- CBR stamp guide tube and support plate
- Robust transport case
Dynamic CBR Laboratory test set consisting of:
- 50 mm CBR stamp with handles
- Connecting disk for accelerometer housing
- Compaction collar
- Annular half-disk surcharge weights
- Stamp guide collar
- Stamp guide
- CBR mould body
- Non-perforated mould base
- Perforated mould base
Dynamic CBR Lab and Field test set consisting of:
- 50 mm CBR stamp with handles
- Connecting disk for accelerometer housing
- CBR stamp guide tube and support plate
- Robust transport case
- Compaction collar
- Annular half-disk surcharge weights
- Stamp guide collar
- Stamp guide
- CBR mould body
- Non-perforated mould base
- Perforated mould base
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