How to stabilize a road with on-site sub-soils and AggreBind
Here are the basic procedures of soil stabilizing a road using AggreBind.
Topsoil is a valuable resource and should never be used for soil stabilizing. All vegetation and tree roots must be removed from the area to be stabilized.
It is important to first carry out a standard sieve test that indicates the soil /stone particle sizes and the soils classification. ( sand/silt/clay etc).
The ideal soil stabilization analysis is 35% fines passing through a 200 sieve and no stone larger than 20% of the layer depth being treated.
Investigate the conditions below the area to be soil stabilized, particularly if the area is subjected to earth tremors, to ensure that there are no underground streams, services or natural faults. This can be accomplished by digging test holes or with a penetrometer or other below ground penetrating radar testing equipment.
If poor below ground conditions are detected these must be rectified before an AggreBind soil stabilized layer is installed.
Check the area for the availability of sea, river or mains water supplies as this is important when assessing the equipment required for the soil stabilization project.
Equipment to stabilize soil would include the following: Ripper/ crusher, grader, tanker with spray bar, smooth drum vibration compactor.
Determine the maximum load that the road will be subjected to as this will indicate the recommended layer depth for the stabilized base.
40 tonnes 150mm deep – 80 tonnes 200mm deep.
Stabilize Soil Procedures:
Carry out an on-site test to determine the optimum soils moisture content (OMC). The recommended AggreBind soil stabilization dosage rate is then mixed with sufficient water to bring the soils moisture level to OMC+5%
The road is ripped to the required depth, sprayed with the AggreBind/water mixture, that is mixed into the soil, graded and compacted for soil stabilization.
The stabilized soil surface is then sealed with a mixture of AggreBind +water.
The road is open to traffic when the AggreBind surface seal is dry, normally 1 to 2 hours.
Do not install if frost is forecast within 24 hours.
AggreBind makes soil stabilized roads affordable
AggreBind for sealed, water resistant, stabilized, on-site soil for rural roads and primary soil stabilized roads, and if desired, with an asphalt wear surface or concrete topping for primary roads and specialty applications, such as airports/arterial roads.
Existing Rutted Soil Road – Existing roads soften and erode when wet and are prone to potholing resulting in dangerous driving conditions. This type of road is never safe and requires constant maintenance. AggreBind has the soil stabilizing solution.
Preparation for Soil Stabilization – Equipment for Ripping/Breaking up Surface
Existing surface is ripped to the required depth (100mm, 150mm, 250mm based on tonnage). Take care not to dig too deep as this could result in uneven layer strength after soil stabilizing. An alternative is to use a roto-crusher that breaks up soil and rocks up to a required depth.
Preparation for stabilizing soil – Equipment to Break down Soil to Colloid Particles
Excellent and readily available, an Offset Disc Harrow can be used to break down the soil to produce a well graded mix. Graders and rota-tillers are equally good.
Visual Guide to Road Compressive Strength
THE STRENGTH OF AN AGGREBIND STABILIZE SOIL LAYER IS DEPENDENT ON THE FOLLOWING:
- The bearing capacity of the sub-base below the layer to be stabilized. If necessary this should be re-compacted before stabilizing the base layer.
- 50mm stabilized layers are for pathways only.
- 150mm stabilized layers are for vehicles up to 40 tonnes.
- 250mm stabilized layers are for all other applications and ideally, subject to the compaction equipment available, should be installed as 2 x 125mm layers. AggreBind has a bond-back capability so there will be no strength loss between the two treated layers.
- As a general rule there should +/-35% of fines and no stone larger than 20% of the layer depth being stabilized.
- Care should be taken to grade the surface of the road for drainage.
- If required any wearing surface can be applied to an AggreBind treated base layer.
- Any damage to an AggreBind treated layer can be easily repaired with hand tools. The polymers bond-back capability ensures that there is no strength loss.
Ideal protocol for preparing small laboratory AggreBind samples
Ideal size 75mm x 75mm x 75mm
Ideal soil mix
10% 4.75mm
20% +- 2.00mm
35% +- 1.5mm
35% – 0.075mm
This must be mixed together thoroughly before the AggreBind/water mixture is added. The AggreBind and water must be mixed together before being added to the soil mixture. This ensures that all the particle surfaces are treated with AggreBind.
Vibration compaction is preferred as this reduces the risk of air pockets. Round moulds are also preferred for laboratory testing.
Soil Stabilization – Basic tools to calculate OMC in the field
On site calculation is based on the fact that one m3 of soil/sand = +/- 1,800 kg.
Place 200gm of soil/sand in a bowl and add X grams of water to achieve compaction.
This is typically 3gm to 5gm of water.
Take that number and multiply it by a factor of 9.
This gives you the total amount of liquid liters required per m3 for good compaction.
Typically, 4ltr of AggreBind per m3 is required for stabilization.
Example: 4gm x 9 = 36ltr.
Combine 4ltr of AGB with 32ltr of water. Total liquid is 36ltr/m3.
Dispersion Rate (flow rate) per m2:
100÷0.15=6.66, so 36ltr÷6.66=+/-6ltr/m2
100÷0.20=5.00, so 36ltr÷5.00=+/-7ltr/m2
100÷0.10=10, so 36ltr÷10=+/-3.6ltr/m2
Spraying AggreBind & water solution
Know the size of your bowser or water truck. Know the truck’s dispersion rate. Add the AggreBind first and then add the water. Regulate the speed of vehicle to disperse the correct quantity of AggreBind and water evenly across the width of the road to be stabilized. It is important to calculate the area that each bowser load will treat as this will allow the mixing process to be implemented immediately. This also ensures that the surface will not dry out too fast between the mixing and the compaction phases.
Soil Stabilization Automated methods – AggreBind & water being applied and mixed
Mixing AggreBind into soil
The treated soils should be mixed immediately after the addition of the solution to prevent drying out. The treated soil must be mixed thoroughly.
Disc Harrows, Power Harrows, Roto-Tillers and Graders can used for this process.
Grading/Profiling Road
A road grader is used prior to, and during, the compaction process to create the correct road profile.
This is vital to prevent rainwater from constantly lying on the finished road surface as this is the main cause of potholes.
Vibro Compaction of Road
Vibration Compaction single drum smooth roller with rubber tractor tires which has to be driven backwards to remove tire indentations on the finished road surface.
A smooth drum dual tandem vibro roller is preferred.
Surface Sealing with AggreBind
Surface sealed with a single pass of the bowser. It is important that vehicles do not drive on the surface during the sealing process. Alternately, the surface can be rolled again, with NO vibration, when the surface is sufficiently dry that it does not stick to the roller drum.
Soil Stabilized Road – AggreBind Completed Sealed & Water Resistant Road
Completed sealed roads are stable and water resistant.
Typically, roads can be opened to traffic in 1 – 2 hours after being sealed.
Impermeable soil stabilizer AggreBind
Further information on soil stabilization of roads, dirt roads etc click on a link below:
Suggested Stabilized Soil Road Designs
Equipment
Recycling Asphalt, pothole repairs, chip seal
Soil Stabilization for Dirt Roads
Soil Stabilization – Considerations in polymer stabilized roads
Soil Stabilized Runways
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