Airport Pavement Reinforcement Produces Zero Settlement
Despite severe settlement and saturation, Neoloy®Geocells reinforced Mexico City airport pavement to effectively stabilize subgrade
Mexico City’s international airport was built over a lake; the soil is expansive clay with water content approaching 200%. Settlement is a severe problem and several airport runways necessitated a 4m asphalt layer thickness. A recently constructed airport platform using a conventional pavement was expected to settle 3 cm at the 3 vertical loading points of the airplane over two years. In fact it sank 3 cm in just two months!
Interjet airline needed to resolve this problem for the construction of a new airport platform – including apron, pavement reinforcement and working platform stabilization – for maintenance facilities of their A-320 airplane fleets. They asked Ancora Ingenieria, a leading pavement designer, for a solution to distribute the loads of the structural pavement over the problematic soil.
Soil excavation was ineffective by itself. Very thick concrete and asphalt layers were prohibitively expensive. Concrete at the subbase layer was subject to cracking from differential settlement. Ancora turned to Innovater for a geocell-based solution. After intensive technical reviews and engineering proofs between Neoloy. and an HDPE-based geocell, Ancora decided that Neoloy Geocells were the best possible solution.
Neoloy Geocell Solution
Neoloy Geocell was chosen as the only practical solution to the severe settlement and saturated soils (see illustrations above). After excavating 185 cm of subgrade, a working platform was constructed of 330-120-C 15cm high Neoloy filled with lean concrete. The “beam effect” of Neoloy Geocells acts as a semi-rigid platform over the soft subgrade to stabilize the subgrade to support the pavement structure.
Over a 125 cm subbase layer of tezontle aggregate (volcanic-porous rock average size 2”), another layer of Neoloy (12 cm height) was installed in the base layer and infilled with hydraulically bound materials (HBM). Compaction to 98-100% took much less repetitions than conventional construction materials. The surface layer was a thin 10 cm of asphalt over a 15 cm cement stabilized base.
Performance has been beyond expectations: Measurements undertaken by the airport authorities after 1.5 years showed zero settlement in the Neoloy reinforced pavement at the 3 loading points of the aircraft wheels!
- Resolved airport pavement ‘sinking’ – due to very wide load distribution
- Fast, simple installation – 8 weeks to install 21,500 sq m of pavement
- Cost savings – reduced need for very thick asphalt and concrete layers
- Improves modulus of infill – for heavy duty pavement for airplanes
- Confined drainage system – prevents degradation from saturated soil