Technical Manual
ANNEXURE 3A
FLOW CHART OF CONSTRUCTION PROCEDURES
Page 106
Technical Manual
Flow Chart 5: Flow Chart of Construction Procedures
Preparation of imported
material or in-situ layer (2)
Preparation of layer
Imported material In situ layer
Rip, scarify layer
Compact under- (1)
lying layer to 97% of
M.D.D. (3)
Remove large stones or
break-down to -53mm
Transport material to
road
Mix material until
homogenous
Spread material to
specified depth
Apply levels, shape,
construct side drains
Place and spread stabilizer
Mix in stabilizer until a homogenous
mixture
Add water mixing in until a
Construction of stabilized layer
homogenous mixture
Grade layer to final level (shape)
Compact layer to 100% of MDD (3)
Allow layer to cure by lightly
wetting for ± 2-3 days
Page 107
Technical Manual
Note:
(1) An underlying layer is the layer or loose layer immediately under the layer to be stabilized
and could be i) the roadbed, ii) the foundation layer or iii) any existing pavement layer s uch as
the subbase or selected subgrade layers
(2) An in-situ layer will consist of any existing pavement layer to be stabilized without the
import of material.
(3) The M.D.D., maximum dry density, of the material is the standard density of that material
determined in the laboratory.
Page 108
Technical Manual
Figure 3.1(a): Illustrating a typical cross-section of an unpaved side drain.
3.3 Stabilization using RBI Grade-81
Stabilization using RBI Grade-81 (the process of improving the engineering properties of a
material by means of the addition of RBI Grade-81) is subject to the quality of materials
available and the impact of the environment (traffic, climate, etc.) on the structural design.
Stabilization with RBI Grade-81 endeavors to increase the quality of the project and reduce
construction costs by improving the properties of substandard, readily available material to
comply with the relevant specifications.
3.3.1 Materials
a) Stabilizer agent, RBI Grade-81
Should be kept under cover and protected from moisture from the time of purchase to the
time of use. If material has been left exposed to environmental elements, consult a RBI
Grade-81 representative.
b) Soil or Gravel
It is preferable to stabilize a soil with a continuously smooth gradation curve from the maximum
particle size to the smallest particle size with no excess or lack in certain particles. This will
ensure better interlocking capabilities of the soil particles resulting in increased density and
strength of the soil. It is recommended that the soil material have sufficient fine material (< 2.00
mm) to effectively stabilize the material with RBI Grade-81.
Page 80
Technical Manual
3.3.2 Water
Water used should be free from harmful substances that may affect the setting and
hardening process of the stabilizer. Water that is thought to encourage adverse reactions
should be tested for compatibility with RBI Grade-81. Potable water is most preferred.
3.3.3 Construction procedures
There are three methods for construction with RBI GRADE-81:-
1. Manual Method
2. Semi-Automatic Method
3. Automatic Method by WMM Plant/Batch Mix Plant
List of Machinery Required for Manual Method
a. Back Hoe Loader (JCB)
b. Single Drum Soil Compactor/ Earth Vibratory Compactor
c. Water Tanker with sprikler
d. Tractor with Rotary tiller ( rotavator)
e. Motor Grader
f. Tractor trolley/Tipper
List of Machinery Required for Semi-Automatic Method
a. Back Hoe Loader (JCB)
b. Single Drum Soil Compactor/ Earth Vibratory Compactor
c. Water Tanker with and without sprinkler
d. Automatic Stabilizing Machine
e. Motor Grader
f. Tractor trolley/Tipper
List of Machinery Required for Automatic Method
a. Back Hoe Loader (JCB)
b. Single Drum Soil Compactor/ Earth Vibratory Compactor
c. Water Tanker with and without sprinkler
d. WMM Plant/Batch Mix Plant
e. Paver Finisher
f. Motor Grader
g. Tractor trolley/Tipper
3.3.3.1 Construction Methodology-Manual Method
a. Preparing the Layer: Before construction of any stabilized layer and before any transported
material for stabilization is dumped on the road, the underlying layer should be investigated to
establish whether there is any damage, voids, wet spots or other defects. Any defects to the layer
should be rectified with the material of having similar properties with the native material before
the stabilized layer is constructed. Where the stabilized layer is constructed on the floor of a
pavement excavation or on the top of an existing pavement layer i.e. where the underlying layer
Page 81
Technical Manual
has not been reworked or reconstructed, the floor of the excavation or top of the existing
pavement layer should first be watered and the compaction of the layer should be carried when
layer become moist or comes at OMC. The material to be stabilized should be placed, or in the
case of existing pavement layer, scarified to the full depth specified, broken down and watered if
necessary and mixed to achieve a homogenous layer. Any oversize material (> 1/3 the thickness
of the layer to be stabilized) should be removed. Normally Maximum size of aggregate is 30mm.
Photo 3.1: Initial view of site
Photo 3.2: View of Bed Preparation in Progress
Photo 3.1 to 3.4 shows a stabilization site observed, tested and prepared for stabilization.
Page 82
Technical Manual
Photo 3.3: View of Checking of Existing Subgrade compaction by DCP
Photo 3.4: View of Spreading of Construction Material for Stabilized Layer
b. Applying the Stabilizing agent, RBI Grade-81: Dosage of Product (RBI Grade-81) should
be determined during the design before the product application. The product should be spread
uniformly over the layer to be stabilized by means of an approved type of mechanical spreader or
by hand. Material that has been exposed to the open air for the period of 4 hours or more should
not be used. The Bags of RBI Grade-81 should be accurately spaced at equal intervals, see photo
3.5, along the section to be stabilized to ensure uniform application of RBI Grade-81. The
stabilizing agent should be spread as evenly as possible over the entire surface, see photo 3.6.
RBI Grade-81 should not be applied in windy conditions otherwise it will lead to a situation
where the stabilizer becomes airborne and is wasted in such a manner that it becomes hazardous
to traffic, workmen, adjacent workers or adjacent property.
Page 83
Technical Manual
Photo 3.5: View of RBI Grade-81 bags laying
Photo 3.6: View of RBI Grade-81 Spreading
c. Dry Mixing: Immediately after the product has been spread it should be mixed with the
soil/material to the full depth of treatment. Special attention should be taken not to disturb the
compacted layer underneath and especially not to mix the stabilizing agent in below the desired
depth. Mixing should continue for as long as necessary and repeated as often as required to
ensure homogeneity and through mixing of the soil/material with RBI Grade-81 over the full area
of the application site. Mixing should be done using a rotary tiller (rotavator), see photo 3.7 or
equivalent equipment over successive passes of the layer. Specific attention should be made to
ensure that the mixing device does not cycle RBI Grade-81 and shift the majority of the powder
at the bottom of the layer to be constructed.
Page 84
Technical Manual
Photo 3.7: View of Dry Mixing with Rotavator
d. Wate ring: Watering equipment should be adequate to ensure that all the water required is
added and mixed with the soil/material being treated within the prescribed period to enable
compaction, see photo 3.8. Uniform mixing of the product and water is paramount to the success
of the stabilized layer. Particular care should be taken to ensure satisfactory moisture distribution
over the full depth, width and length of the section being stabilized and to prevent any portion of
the work from getting excessively wet after the stabilizing agent has been added. It should be
ensured that the moisture content of the mixture is not below the specified optimum moisture or
more than 2 percent above the specified optimum moisture content. If any portion of the section
becomes too wet during application of water as during rain or downpour, the application shall be
rejected. These portions should be allowed to dry out to the required moisture content and then
be scarified, re-stabilized and re-compacted.
Photo 3.8: View of water addition
Page 85
Technical Manual
Photo 3.9: View of RMM test in progress
e. Wet Mixing: As soon as the watering is done over the whole section, the wet mixing should
start with rotavator. In case of any problem faced during construction it should be kept in mind
that the time gap between the watering and wet mixing should not get more than prescribed. The
wet mixing, see photo 3.10, should be done in such a way that the moisture distribution must be
uniform along the surface as well as depth. . Mixing should continue for as long as necessary and
repeated as often as required to ensure homogeneity and through mixing at OMC. To check
OMC in the field, wet RBI Grade-81 and soil mix should be rolled into a ball, subject to the
condition that it should not break or split. Rapid Moisture meter as shown in photo 3.9 can also
be used for more accuracy.
Photo 3.10: View of Wet Mixing by Rotavator
f. Grading in Proper Profile: After the wet mixing is over, grading should be done with
motor grader to achieve the required profile, see photo 3.11. The surface should be smooth and
any big size stone or unbroken clumps if present on the surface should be removed. Once the
grading is done and proper profile is achieved, the stabilized surface is ready for compaction.
Page 86
Technical Manual
Photo 3.11: View of Grading in progress
g. Compaction: Compaction of the material in the pavement layer should be carried out within
4 hours after watering is done. The type of compaction equipment to be used and amount of
rolling to be done should be such as to ensure that specified densities are obtained without
damage being done to lower layer structures. Selection of correct compaction equipment should
be carried out by the contractor. Preferably Single Drum Soil Compactor/ Earth Vibratory
Compactor should be used, see photo 3.12. Compaction should be carried out in a series of
continuous operations covering the full width of the layer concerned. During compaction, the
layer should be maintained to the required shape and cross-section, and holes, ruts and
laminations should be removed. Loss of moisture from evaporation should be corrected by
further light applications of water over the surface. During final compaction, field density
determinations should be done to determine accurately the applied compaction effort and to
ensure the minimum compaction requirement has been obtained. Final density test should be
carried out within 24 hours of compaction completion or as suggested by EIC.
Photo 3.12: View of Compaction in progress
Photo 3.13 is showing the view of compacted surface.
Page 87
Technical Manual
Photo 3.13: View of Final surface
h. Curing: The existing moisture of the stabilized layer should not be allowed to evaporate. The
water shall be sprinkled, see photo 3.14, twice or thrice a day (the frequency of sprinkling of
water will also depend on the weather condition).
Curing period:-
i). Minimum 7 days.
or
ii). Till the next layer is laid, whichever is earlier
No traffic shall be allowed on the partially constructed pavement, even in case where it is
necessary to ply traffic on the stabilized surface the curing must continue.
Photo 3.14: View of Curing of Stabilized Layer
3.3.3.2 Construction Methodology-Semi-Automatic Method
Two options in Semi- Automatic Method:-
i. Stabilization ( New Layer)
ii. Cold Recycling
Page 88
Technical Manual
i. Stabilization
a. Preparing the Layer: The Subgrade or layer on which the stabilized layer is to be laid
must be made free of Wet/ loose spots unevenness/ surface irregularities. The surface shall be
compacted, see photo 3.15. Within the 24 hr. of final compaction, the compaction ratio shall be
obtained with Sand Replacement or other suitable Method. The compaction ratio must satisfy the
MORT&H specification, which requires the Sub Grade/layer compaction to be not less than
97/98%. The difference in crust thickness shall be compensated by adding an equal thickness of
subgrade layer only if required.
Photo 3.15: View of Preparing Subgrade
b. Spreading of Construction Material: After the preparation of the layer generally
Subgrade/GSB the quantity of construction material (complying with the design Submitted by
Alchemist Touchnology Limited) required should be spread on site, see photo 3.16. The
construction material i.e., soil & aggregate shall be transported to the site. The dumped material
should be spread evenly over the entire area of treatment using grader, see photo 3.17.
Photo 3.16: View of Dumping of Construction Material
Page 89
Technical Manual
Photo 3.17: View of Spreading of Construction Material
c. Initial Grading of Construction Material: The construction material should be spread (as
discussed above) and be graded to desired levels as per site requirement and the thickness of
layer. After the grading the 10-12 T compactor shall apply one plain pass to provide consistent
thickness to Stabilizing Machine. See photo 3.18
Photo 3.18: View of Initial Compaction of Construction Material
d. Mixing of RBI Grade-81 and Water: The Stabilizing machine is in general provided with
the basic inputs and connections as listed below:-
1. The rate of dispense of RBI GRADE-81. ( this is measured in per square meter)
2. Density of RBI GRADE-81
3. Speed of the machine
4. Water flow/discharge rate of water
5. The hopper of the machine that can be filled with RBI GRADE-81 regularly as
per construction requirement. See photo 3.20
6. The water hose that can be connected to the water tanker.
Note: The field moisture content is determined with Rapid Moisture Meter and only the
balance amount to OMC is added, see photo 3.19.
Page 90
Technical Manual
After the relevant inputs are fed into the control panel and the necessary connections made, the
stabilizing machine shall be aligned; the depth shall be adjusted and subsequently physically
verified by doing a small 5-10m trial at the start of the work. On actual site, operator shall start
the functions as required with provided input to the machine and move forward. The spreading of
RBI GRADE-81, water and mixing to the desired depth will all happen at the same time. The
section where the grinder moves gets raised in between the two rear wheels, see photo 3.21, this
upheaval shall be compacted using plain pass of 10-12T roller.
The machine meanwhile shall be shifted to the adjoining lane and the process shall be repeated as
per the site requirement.
Photo 3.19: View of Checking of Existing OMC
Photo 3.20: View of Filling of RBI Grade-81 in Stabilizing Machine
Page 91
Technical Manual
Photo 3.21: View of Stabilization by Stabilizing Machine of RBI Grade-81 layer
e. Grading and Compaction: - The finished product where the construction material, RBI
GRADE-81 and water are mixed should be graded to desired levels, see photo 3.22, and
compacted using a 10-12t vibratory roller, see photo 3.23. The density of the layer shall comply
with the prevailing IS codes in practice. The number of passes shall be determined by the
engineer in charge.
The compaction at no point in time shall get delayed by more than 4 hours since the water
is added in the mix. Photo 3.24 shows view of compacted surface
Photo 3.22: View of Grading of Stabilized Layer
Page 92
Technical Manual
Photo 3.23: View of Compaction of Stabilized Layer
Photo 3.24: View of Final Compacted Stabilized Layer
f. Curing: The existing moisture of the stabilized layer should not be allowed to
evaporate. The water shall be sprinkled, see photo 3.33, twice or thrice a day (the frequency of
sprinkling of water will also depend on the weather condition).
Curing period:-
i). Minimum 7 days.
or
ii).Till the next layer is laid, whichever is earlier. No traffic shall be allowed on the
partially constructed pavement, even in case whe re it is necessary to ply traffic on the stabilized
surface the curing must continue.
Page 93
Technical Manual
ii. Cold Recycling
Photo 3.25: Initial view of distressed pavement
a. Dumping and Spreading of Missing Component to achieve the required Gradation:
Based on the design the desired quantity of Missing component for achieving the required
gradation like 20mm/10mm/Stone dust should be placed on site and spread with the help of
grader at predefined average depth. See photo 3.26.
Photo 3.26: View of Spread Stone Dust on Existing Pavement
b. Applying the Stabilizing agent, RBI Grade-81: Once the desired depth, levels and
markings are established, the RBI Grade-81 bags should be placed as per the design dosage. The
bags should be placed as evenly as possible, see photo 3.27, for the even spread of stabilizer. The
bags should then be cut open and the powder should be spread evenly over entire area of
treatment, see photo 3.28.
Page 94
Technical Manual
Photo 3.27: View of Laying of RBI Grade-81 bags
Photo 3.28: View of Spreading of RBI Grade-81
c. Milling & Mixing of Existing Pave ment, Missing Component & RBI GRADE-81 at
OMC with Stabilizing Machine: The mixing of Existing Pavement, Stone Dust (can be other
aggregate size, as per mix design) & RBI GRADE-81 should be done with stabilizing machine ,
see photo 3.29. The water should be added through the inbuilt water sprinkle system in the
machine. The field moisture content should be determined with Rapid Moisture Meter on site at
different places and only the balance amount to OMC should be added during mixing.
Page 95
Technical Manual
Photo 3.29: View of Milling & Mixing with Stabilizing Machine
d. Grading and Compaction: The grades and slopes should then be maintained with the motor
grader, see photo 3.30, and the compaction shall be done with 12 T Single drum Vibratory
Roller, see photo 3.31. The density of the layer shall comply with the prevailing IS codes in
practice. The number of passes shall be determined by the engineer in charge.
The compaction at no point in time shall get delayed by more than 4 hours since the water
is added in the mix.
Photo 3.30: View of Grading of Recycled layer in progress
Photo 3.31: View of Compaction in Progress
Page 96
Technical Manual
The photo 3.33 below is showing view of completed cold recycled stabilized surface with RBI
GRrade-81.
Photo 3.32: view of Completed Cold Recycling
e. Curing of Stabilized Base Layer: Curing: The existing moisture of the stabilized layer
should not be allowed to evaporate. The water shall be sprinkled, see photo 3.33, twice or thrice a
day (the frequency of sprinkling of water will also depend on the weather condition).
Curing period:-
i). Minimum 7 days.
or
ii).Till the next layer is laid, whichever is earlier. No traffic shall be allowed on the
partially constructed pavement, even in case where it is necessary to ply traffic on the stabilized
surface the curing must continue.
Photo 3.33: View of Curing in progress
On top of stabilized base a wearing course shall be laid as per design, as shown in photo 3.34
Page 97
Technical Manual
Photo 3.34: View of finished surface of Cold Recycling
3.3.3.3 Automatic Method by WMM Plant/Batch Mix Plant
a. Preparing the Stabilized Layer: Before construction of any stabilized layer and before any
transported material for stabilization is dumped on the road, the underlying layer should be
investigated to establish whether there is any damage, voids, wet spots or other defects. Any
defects to the layer should be rectified with the material of having similar properties with the
native material before the stabilized layer is constructed. Where the stabilized layer is constructed
on the floor of a pavement excavation or on the top of an existing pavement layer i.e., where the
underlying layer has not been reworked or reconstructed, the floor of the excavation or top of the
existing pavement layer should first be watered and the compaction of the layer should be carried
at OMC, ±2%. The material to be stabilized should be placed, or in the case of existing pavement
layer, scarified to the full depth specified, broken down and watered if necessary and mixed to
achieve a homogenous layer. Any oversize material (> 1/3 the thickness of the layer to be
stabilized) should be removed. Normally Maximum size of aggregate is 30mm.
b. Calibration of WMM/Batch Mix plant: All the components of design that are like 20 mm
aggregate, 10mm aggregate, stone dust and RBI GRADE-81 shall be filled in the hoppers, as
suited for the type of material. The calibration shall be done, as is done for WMM/Batch Mix.
The special care must be taken to ensure the delivery of RBI GRADE-81 to the mixing unit, in
desired quantity and the optimized water content, Once the calibration is done, the actual mix
should be prepared
Note: For WMM plant the gate opening must be suitably adjusted.
c. Mixing: Only after the calibration is done, the Mixing of design component, see photo 3.35,
shall be done. Special care shall be taken to mix right amount of water to attain OMC, the
moisture should not be less than OMC, though +2% of OMC is preferred as some moisture gets
lost during transit. The mixed material shall be transported in tippers to site, immediately
Page 98
Technical Manual
Photo 3.35: View of WMM Plant
d. Laying: Laying shall be done with WMM paver, see photo 3.36. The proper thickness and
levels shall be maintained through regular check during laying.
Photo 3.36: View of Laying of RBI Grade-81 layer by Paver
e. Compaction: Compaction of the material in the pavement layer should be carried out within
4 hours after watering is mixed. The type of compaction equipment to be used and amount of
rolling to be done should be such as to ensure that specified densities are obtained without
damage being done to lower layer structures. The right compaction equipment that is vibratory
roller, see photo 3.37, is used. Compaction shall be carried out in a series of continuous
operations covering the full width of the layer concerned. During compaction, the layer shall be
maintained to the required shape and cross-section, and holes, ruts and laminations should be
removed. Loss of moisture from evaporation should be corrected by further light applications o f
water over the surface. During final compaction, field density determinations should be done to
determine accurately the applied compaction effort and to ensure the minimum compaction
requirement is attained. Final density test shall be carried out within 24 hours of compaction
completion or as suggested by EIC. Photo 3.38 shows the finished stabilized surface
Page 99
Technical Manual
Photo 3.37: View of Compaction
Photo 3.38: View of Final Surface
f. Curing: The existing moisture of the stabilized layer should not be allowed to evaporate. The
water shall be sprinkled twice or thrice a day (the frequency of sprinkling of water will also
depend on the weather condition).
Curing period:-
i). Minimum 7 days.
or
ii).Till the next layer is laid, whichever is earlier. No traffic shall be allowed on the
partially constructed pavement, even in case where it is necessary to ply traffic on the stabilized
surface the curing must continue.
Note:-Suitable and economical method out of the above discussed method can be selected.
3.3.3.4 Construction limitations
i) RBI Grade-81 should be applied only to a surface area ,the size of which will permit all
process, watering, compacting and finishing to be completed within a single working day.
ii) No stabilization shall be done during wet weather or windy conditions.
Page 100
Technical Manual
iii) Any rain falling on the working area during the process of stabilization may be sufficient to
damage area being constructed.
iv) No material for the stabilized layer may be placed if the underlying layer has been softened
by excessive moisture.
v) The minimum and maximum depths that should be stabilized in one section on a stable and
compacted sub-base or underlying layer are as follows:
- minimum: 75 mm
- maximum: 150 mm
Depths in excess of 150 mm can be completed provided that the correct mixing equipment and
compactor is utilized that can achieve an effort large enough to compact the lower regions of the
layer. Commonly, depths of more than the maximum of 150 mm should be constructed in two
separate layers in order to ensure that the minimum compaction requirement is obtained.
See figure 3.1(b): “Vibratory Compactors”.
3.4 Quality Control
The following are some of the important factors that can influence the outcome of an application ,
(1) Grading: During the production of the aggregate at the plant and depending on the
aggregate‟s porosity or hardness the production of fine material may differ from batch to batch
even though the grading overall is still in the grading envelope (specification) by either being on
the higher or lower limit.
Page 101
