Neoloy Geocells Increase Resistance With Reduced Thickness
Neoloy® Geocells provide greater reinforcement than geogrids, while using inferior soil and reducing the required pavement thickness.
There are numerous advantages to using Neoloy Geocells in Canada, in comparison to geogrids. Neoloy is more durable and resistant. At the same time, there are significant cost savings using Neoloy, which reduces pavement thickness and can deploy inferior soil.
Resistance and Dimensional Stability
|Resistance-deformation||Highly elastic behavior (resistance) before reaching high deformation||Small resistance at small deformation|
|Durability under cyclic dynamic loads||Vertical loads are translated to radial loads that are translated to hoop stress in geocell walls for very high dimensional stability and structural integrity||High level of deformation|
|Resistance zone||Resistance is achieved in a the three-dimensional “plane”||The resistance is limited to a thin plane, in one or two directions|
|Bending moment resistance||Depth of layer provides an increased bending moment resistance effective to at least the height of cell walls. Additionally the structural resistance and integrity of the Neoloy solution provides a better performance under concentrated or ”point” loads||Almost no resistance. Geogrids require a minimum of two layers to create a planer composite before gaining minor Bending Moment Resistance|
|Vertical soil interface friction||Large interface area of highly textured and perforated cell walls||Small height of active area|
|Lateral deformation||Lateral stresses on the cell walls are confined by stiff cell walls, while the passive earth resistance of adjacent cells provides additional resistance against the loaded cell. The result is a stiff beam with high bearing capacity.||The limitation of the lateral expansion is restricted to a very small section (unless the Geogrid can be used in a “wrap-around” fashion).|
|Stress and settlement||Neoloy distributes the surface load though the three-dimensional beam or semi-rigid slab as a unit, reducing stresses transferred to the subgrade by up to 50%. Also as the stress is more uniformly distributed in the mattress, total and differential settlements are greatly reduced.||Geogrids only respond to loading within a small effective radius. The load is distributed over a smaller area, and thus, the stress increases as does the possibility of total or differential settlements|
Infill Soil Types, Soil Retention, Drainage
|Reinforced/retained soils||Accepts a wide variety of soils, even inferior or poorly graded granular materials||Requires specific quality (and high-cost) aggregate fill type|
|Retained soil improvement||Improves the apparent cohesion of the soil, which significantly increases its resistance to imposed loading.||The improved area has a limited vertical range|
|Performance with abraded soils||Three-dimensional confinement reduces aggregate abrasion and attrition||Reduces attrition only if used with specific granular and graded soil|
|Drainage performance||Retains soil particles in a multi-axial range, thus allowing the natural passage of liquid flows in any direction while preventing those flows from leaching away the retained soil particles.||Retains soil particles in only thin layer consistent with its planer dimension. Liquid flows can easily leach soil particles away in all other directions.|
A key difference between the Neoloy Geocell and geogrid reinforcement in road construction is the thickness of the confined layer. The Neoloy 3D vertical zones of influence (full confinement) is at least 20 mm, whereas the geogrid reinforcement zone (interlock, not full confinement) is limited to 1-2 times the size of the granular material. Neoloy Geocell 3D confinement also minimizes lateral movement of soil better than geogrids.
Moreover, geogrid road reinforcement require specific and relatively expensive granular materials (ballast, crushed stone and gravel). They cannot reinforce fine grain “inferior” non-cohesive materials as there is no interlocking. Neoloy 3D confinement transforms the modulus of inferior (fine grained) fill to that of higher quality granular fill, such that they can be used for structural infill. This includes lower cost native soil, quarry waste, sand, and recycled construction waste.
Neoloy Geocells also create a reinforced mattress with a beam effect with unbounded base material. Comparative tests of Neoloy vs. geogrids in road construction demonstrated that the Neoloy Geocell improvement factor was higher than any of the seven leading geogrids tested.
Neoloy’s dramatic impact on the thickness of structural pavements was demonstrated in field trials conducted by KOAC–NPC (Netherlands). Neoloy was the only geocell tested against 7 leading geogrids and the only product tested with inferior aggregate infill.
Benefits of Neoloy Geocells vs. Geogrid Reinforcement
- 3D larger fully and partially confined zones of influence – more reinforcement
- 3D confinement better minimizes movement of soil in 3 directions
- Neoloy creates a beam effect that greatly increases bearing capacity
- Neoloy confinement enables use of range of inferior and recycled infill materials
- Can utilize granular materials with average particle size from less than 20 to10 mm or less
- Save infill costs by utilizing less-expensive, available granular infill
- More sustainable solution than geogrids
- Economically advantageous
The mean road-base thickness reduction factor (CBR =1.5) for Neoloy was 0.73, using the CROW design methodology (see chart). This value exceeded all previously known values for geogrid reinforcement. Even after truncating the test limits to 0.5 (the highest known values for geogrids) Neoloy achieved the highest reduction factors of all tested geogrids.