RBI Grade-81 has the ability to stabilise sub-standard
track formation and embankment materials to bring
them up to an acceptable standard and strength for
a reliable rail track. The product achieves the
I. Improving the ability to compact formation
(track bed) materials
II. Substantially increasing the resilient strength and elastic modulus of the base (shock absorbent capability of the base)
III. Improving the bond strength between formation (track bed) particles
IV. Absorbing dynamic stress at a much greater rate than normal formation (track bed) material, reducing the risk of excess loading on subgrades, thus preventing failure of formation
V. The stabilisation is available for immediate full loading after compaction.
High clay content materials may be up-graded to a high standard by stabilisation with RBI Grade-81. It is suitable for rail track formation and categorised as follows:
a) New construction- rail track formation and embankments
b) Reconstruction and strengthening of existing formation
c) Repair of failed formation under points, crossing, etc.
Application techniques are simple and safe, requiring a minimum of basic plant and equipment.
The following options are available:
1. Powder mix of RBI Grade-81 using normal plant for
pavement (track bed) depths 100mm or greater
a. Blade-mix with a grader - in this case RBI Grade-81 powder is applied and mixed into the formation with a grader to the required depth
b. Premix off site at the material source (gravel pit), or adjacent to the formation. Powder is mixed into the gravel using a front-end loader, by the heap mixing method.
2. Powder mix of RBI Grade-81 using fully mechanised stabilising machinery for pavement depths 100mm or greater
a. Using a stabilising rotary mixer machine and water cart attached, plus a spreader truck to spread the powder
b. Mixing pavement material (gravel) from off site or adjacent to site in a pug mill.
3. Slurry Injection
RBI Grade-81 may be injected under gravity or pressure into track bed capping layers and formation to strengthen the existing compacted soil. This will eliminate removal of track and ballast when rehabilitation and strengthening are needed.
GOOD DRAINAGE and GOOD COMPACTION are the keys to the successful performance of RBI Grade-81 stabilisation. This applies to any reliable formation construction.
RBI Grade-81 may be used in combination with cement where the two products are
complementary, eliminating some of the restricting features of each individually. The
additional expense may be justified in certain circumstances.
The thickness of the formation (track bed) is often reduced by up to 50% with RBI Grade-81 stabilisation. This is achieved by the flexibility, greater capacity for absorbing shock, and resilience in a RBI Grade-81 formation.
If high quality materials are not readily available, RBI Grade-81 can be used to up-grade otherwise sub-standard local materials, with overall cost savings often exceeding 50% In most instances stabilisation depth below the top of the formation is likely to be in the 100mm-200mm range. It is unlikely - except at points, crossings, adjacent to bridge abutments, or over very poor swamp country - that the depth of stabilisation will need to exceed 200mm.
Where it is considered necessary to cover track bed formation with a bitumen and stone or asphalt seal, RBI Grade-81 should be used as a track bed stabiliser first. RBI Grade-81 and bitumen and/or asphalt are fully compatible and inter-react to form an extremely strong, resilient, and inseparable bond. (Priming is not needed and should not be used). The bonding to the track bed is stronger than bitumen or asphalt itself.