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Construction Process:
Assuming that the specified layer (15 cm) material is either in place on the road (therefore requiring ripping or scarifying for mixing to take place) or sufficient material brought from borrow pits and dumped alongside road edge for 15 cm layer to be cut in from dumped piles by grader when mixing.

Average daily production is about 300 to 750 meter length x 7-9 meter width x 15 cm thickness or about 1.2 km - 1.5 km / week. (i.e., 2,000 - 5,000m2 / day or 10,000 - 25,000 m2/week).

1.  Clearing the road of any vegetation and organic topsoil to ensure construction is possible within the boundaries.

 2.  Sides have to be excavated for new roads and cleared for existing roads.

 3.  Shape the road to ensure at least 4-6% side slope for drainage.

 4.  Layer thickness must be in multiples of 15cm, and where more than one layer is to be treated, windrow the top layer to expose the lower layer.

 5.  Imported material, where recommended, must be placed and spread.

 6.  The layer material must be scarified with a grader to loosen and break down lumps or clods as much as possible. Where necessary a rotorvator or disc harrow must be used to help loosen and break down lumps.

 7.  Determine the required quantity of CON-AID needed to treat the area of road open and also determine the quantity of water required to raise the moisture content of the soil to 1% above OMC.

 8.  Equally distribute the quantity of CON-AID into the water tankers before the mixture is sprayed evenly over the open area. The CON-AID is fully soluble in water and must be added to tanker only after (not before) the tanker has the full or required quantity of water in it.

 9.  Mixing of the water and CON-AID in the tanker can be facilitated by circulating the water with the pump, or where no pump is fitted, to drive the tanker backwards and forwards over a short distance.

 10.  The diluted mixture is sprayed onto the layer while being processed by grader, disc harrow, or rotorvator until the layer of soil has been well mixed.

 11.  After re-shaping the road, compaction can begin with a roller. Where heavy clays are present, compaction must be by pad foot and in layers of 5-7cm, from the bottom up.

 12.  Final shaping with the grader is followed by final rolling, usually with a pneumatic roller.

Curing:

 After the stabilized layer has been compacted to the required density and brought to the required lines and grades in accordance with the typical cross section, the completed section should be cured. This curing is accomplished by the daily application of water with the water tanker, depending upon the climate and the depth of treatment, usually for seven to ten days after completion date.
During this period traffic may use the stabilized road.
Please note that during this period small quantities of CON-AID remain on the surface which may create a slippery face in some instances during rainfall and depending upon the type of soil stabilized. This slipperiness is normal and usually disappears after the curing period or a few rainstorms.

Maintenance:

Eng Translation below

CON-AID Treatment Process

  1. Application Of Con-Aid.                
  2. 2- Spread The Water and Leave it for dry.
  3. Open for Trafic                                 
  4. 4- Re-Stabilized Particles.

One of the major advantages of CON-AID over other soil stabilizers is the fact that CON-AID can be repaired.

CON-AID is not cementitious. Normal wear of the gravel road surface i.e., gravel loss, rutting and dust can be expected. To repair the road to its original state, wet the road surface thoroughly and follow normal grader blade maintenance procedures. Provided no untreated material is brought into the road from the sides during grading, the traffic will re-compact the road again without re-treatment with CON-AID.

 If untreated material from the road side is brought onto the road during maintenance grading, the surface should be treated with a very small dosage of CON-AID.

Surfacing:
If surfacing of the treated road surface is required, the field moisture content of the stabilized layer must be allowed to stabilize between 50 to 60 % of optimum moisture content. Depending on the soil type, climate and temperature (including rainfall during this curing period), this may take between 6 to 12 weeks or longer.

 

Life span of CON-AID Stabilized Layer:
The change in the treated clay is permanent and will not reverse itself due to leaching. In theory therefore, the CON-AID treated road should last forever if the construction procedure and instructions are followed properly, but in reality special variability of subsoil and drainage is expected. Normal wear and tear prevails and the roads built with CON-AID stabilized soil will require some maintenance.

 The resultant road should however present a significantly improved ride-ability, particularly in wet weather, and substantial reductions in maintenance.

 There are some CON-AID stabilized roads in existence, which have been used continuously for over twenty years.
Rehabilitation:
The rehabilitation treatment process is as follows:

  • Before starting the project, the road has to be checked to ensure that all drains and drainage is clear, and that there will be no standing water in the drains.  This is imperative as particularly with high silty soils and heavy axle loads the soil will become water logged through capillary action and cause the base to fail, usually starting at the shoulders.   The road also has to be checked for deep base failure areas to be repaired prior to treatment.

 

  • If the road is 10 meters or more, Scarify the road to half the width on one side, including shoulders, to a depth of 20cm using graders or a rotormixer.  This allows the traffic to continue using the other half of the road.  F the road can be closed the whole width can be scarified.  If the road is not wide, scarify the whole width.
  • Calculate the amount of CON-AID to be added for the open scarified area.  (Length X width X dosage rate as supplied by CON-AID)

 

  • Add the specified amount of CON-AID to the water tanker, which contains a predetermined specified amount of water.  
  • NB: It is necessary to make decisions regarding the amount of water to be added to the area to be treated on the particular day, to raise the soil moisture content to just above OMC.  If the in situ soil is wet, one may add only a small amount of water for the water / CON-AID Mixture.  If the day is hot and windy it may be necessary to add additional clean water (without CON-AID) to the soil to raise the moisture content to the required OMC +1%.

 

  • Spray the water CON-AID mixture evenly onto the surface of the scarified section.  Add more clean water if moisture content has not reached Optimum Moisture Content (OMC).  
  • Mix the soil with the rotormixer again to render uniform moisture content in the treated layer.  Alternatively run the graders to blade mix the areas where the CON-AID has been applied to mix the water/ CON-AID evenly into the 30cm layer.

 

  • With the grader the 10cm top layer has to be windrowed and the remaining lower layer of 5cm is compacted with a padfoot and wobbly.  
  • When the layer is compacted, a further layer of 5cm is brought onto the surface from the windrow and compacted.  Continue to compact in 5cm lifts until the final layer from the windrow is then placed, shaped for crown and compacted. A minimum crown of 4% is required.  (5% is desirable)

 

  • Final rolling of the shaped surface is then done with the wobbles.
  • Repeat the same procedure for the other half of the road.

 

  • Ensure that in the final shaping of the road the 4% slope of the surface is maintained.
  • A thin layer of gravel (3/4” Minus) has to be placed on the surface and rolled into the surface to avoid slipperiness and provide traction for vehicles.  The gravel will also provide a better surface and make the road last longer.

 

  • Depending upon the weather, it would be necessary to lightly spray the surface of the road with clean water for 3-5 days after completion to avoid wafering on the surface and to avoid premature surface compaction and so ensure that the moisture can evaporate effectively from the lower treated layers of the base. Severe cracking may also occur if insufficient water is added at this curing stage.

Equipment required:
The equipment required for this project is as follows:

  • 1-Rotormixer
  • 1-Water Tanker with spray bar (100 barrel capacity or similar)
  • 1-Grader with Ripper Teeth (Two would be preferable.)
  • 1-Padfoot Compactor
  • 1-Smooth Drum Compactor
  • 1-Wobbly Wheel Pneumatic Roller
  • 1-Disc plow with tractor (if available)
  • Operators for this equipment

Where no rotor-mixer is available, the road can be scarified using a grader and then mixing the scarified layer either with a disc or with a disc and grader.

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