For me, this is one the most expensive road construction methods since it utilizes basal reinforcement geotextile and geogrid/geocell. When i was working with my ex-company, i was part of the team who uses other method to strengthen and stabilized road embankment. CBR 3% is not recommended and the minimal required strength would be 5% or as the basis of pavement design when correlating it in Figure 2. The increase of 2% CBR most of the time requires proper granular fill around 2m depth through compaction without the need for consolidation. Unless proven with high possibility of consolidation through time based on oedometer test, basal reinforcement may be needed. Instead of using enzyme chemical stabilization or geotextile to increase strength through compaction, we adopted the use of crystallization for the bonding of molecular structures. The total strength through crystallization is four times more than this method, 2MPa instead of 0.5MPa. Remark: For standard axle loading, a minimal should be around 0.09MPa. Chemical stabilization in most of the palm oil estates failed because of its seepage/leeching which deteriorates the bonding. Secondly, the suitability of geocell is in doubt when the soil is highly plastic clay which able to swell. It depends on the finding when conducting triaxial test for shear as well as oedometer for consolidation. The formation of the project site is another issue. In Sabah, this geocell is problematic for Wariu and Garinono formation since these have different properties when it comes to shearing behavior and planar failure due to its internal friction angle. The undrained condition reading from triaxial will be great for these formations but it will be marginal when it comes to drained condition. |
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