South Africa-based Polyroads distributes its entire range of Smart Materials, including its flagship SoilTech Mk. III stabilizer for road construction, through local partner Kaveri Ultra Polymers in India
SoilTech Mk. III is a third generation nano polymer binder used for stabilizing soil and improving its strength and, thereby, the road’s stability. It was specifically developed for mine haul-road stabilization, where excessive loading occurs and where all-weather roads are required. This technology is now used in commercial road design.
SoilTech Mk. III stabilizing polymers are elastomers that gain strength from mechanical compaction and do not become brittle when cured. The elastomers are flexible in nature and allow certain amount of flex under load, and do not become brittle unlike cement stabilization. They do not crack under excessive loading, an aspect that reduces layer work in design phases. In most cases, the soil in the area can be used for stabilization. In-situ materials, which would normally be classified as unusable or waste materials, can be transformed into suitably modified aggregates for use in base and sub-base layer construction.
SoilTech Polymers are at the forefront of binding marginal soils and turning these materials into useable road construction aggregates. The product has been tested with in-situ materials in various parts of the world, and extensively utilized in base and sub-base stabilization. Designed to penetrate the road’s base layer and into the sub-base layer via capillary action and bind the loose particles to one another, it provides strength and cohesion.
The nano polymers are 0.5µm in size and are far more effective in coating and binding aggregates. When mixed with water, they act as a means of transport and facilitate the polymer in coating the soil particles. Once the water disperses, the polymers interlock and form a bond which gains strength under mechanical compaction. The greater the compaction, the better the binding.
Stabilized roads are opened to traffic 24 hours after construction. The kneading effect of vehicle traffic further accelerates the evaporation process of the surfactants and coalescing solutions surrounding the polymer chains. The polymers start binding when exposed to air and the surfactant (aided by an alcohol mix) starts to evaporate.
SoilTech Mk. III Polymer is used for stabilizing base and sub-base layers of sealed and unsealed roads; mine haul roads, railway embankments, hard stands, parking lots and airstrips. It provides solutions for Asphalt Roads, Rural & Feeder Roads (Sealed or Unsealed), Mine Haul Roads, Container Depots & Parking Lots.
FACTORS INFLUENCING SOILTECH POLYMER STABILIZATION
|Material or Aggregate||It stands to reason that better the quality of aggregate used, better the results. Having said that, SoilTech has been designed to work with marginal materials.
|Percentage of SoilTech Mk. III polymer applied||Normally SoilTech would be applied at 0.5% per MOD of the material:
|Compaction||Compaction is critical. SoilTech polymer binders do not form chemical crystallization bonds such as concrete when curing. SoilTech needs mechanical compaction. One needs above average heavy compaction at OMC level, using a 12-ton vibrating roller or heavier.|
- Reduced carbon footprint: SoilTech Mk. III stabilization technology reduces blasting operations required to create pit/quarries for aggregates, reduces use and movement of construction machinery by reducing the length of construction period, which in turn reduces CO2 emissions.
- Reduced road crust speeds up construction time: With stabilization, the amount of layered work normally associated with convectional flexible pavement/cement stabilized roads can be reduced. The thickness of granular sub base layer can be reduced and granular base layers eliminated. Reduction in crust layer reduces the total construction time when compared to conventional road construction, along with reduction in CO2 emission from construction activities.
- Reduced construction costs: Reduced crust layers and thickness results in reduced construction cost and makes the project cost effective.
- Reduced maintenance: As long as the asphalt wearing course layer is maintained, the structural integrity of the road will be preserved, with the road pavement remaining rut-free and eliminating need for base or sub-base maintenance.
- Increased strength and stability of base & sub-base layer: Stabilized base gives resistance to consolidation and movement due to repeated wheel loading, and prevents rutting due to deformation in sub-base & sub-grade layers. Structural strength achieved exceeds international single axle loading (80kN) standards by several hundred percent. Apart from the high load bearing strength achieved, the elastomeric properties of SoilTech also provides unsurpassed tensile performance for road stabilizing products.
- Engineers are now able to reduce the number of supporting layers traditionally used to support the conventional rigid or flexible pavement designs. SoilTech is normally mixed into the base layer, assuming that the sub-grade offers reasonable support. In some instances, the sub-base may also be stabilized with a lower dosage of SoilTech to provide further strength to in-situ materials.
- Minimal environmental impact: Reducing consumption of quarry aggregate in road construction can minimize environmental impact. Aggregate is mined from the earth, either dug out of pits or blasted out of quarries. Making pits or quarries requires removal of almost all the natural vegetation, top soil and subsoil to reach the aggregate underneath. Pits and quarries disrupt the movement of surface water and groundwater; interrupt natural water recharge; and can lead to reduced quantity and quality of drinking water for residents and wildlife near or downstream from a quarry site.
QUALITY & RESOURCE COMPARISON
CONVENTIONAL DESIGN (IRC-37) vs. ALTERNATE DESIGN (STABILIZED)
1. Durability and Strength
(i). Real Time Case History of NH-1, Panipat - Jhalandhar; Km 96.000 TO 387.000 in the State of Haryana & Punjab
|Description||Test results of Borrow Soil without SoilTech Mk. III||Test results of Borrow Soil after blending with 0.5% SoilTech Mk. III||Remarks|
|Resilient Modulus (Mpa)||154||3264|
|Unconfined Compressive Strength (Kpa)||423||1868|
|California Bearing Ratio (%)||18.56||218|
(ii) Research and Test Reports from Premium Institute
2. Construction Time, Man, Material & Machinery
|Description||Requirement as per Conventional Crust for Per Km of 5.5 mtr Road||Requirement as per Alternate Design per Km of 5.5 mtr Road||Total Saving|
|Construction Time (Day)||28||18||10||36|
|Man Power (Man Days)||784||468||316||40|