Soft Soil Stabilization at Mexico's New International Airport
Even on saturated and sinking mud, soft soil stabilization With Neoloy®Geocells provided reliable pavement for less money.
The Challenge - How to Build an Airport over 30-60m Deep Soft Mud
This is the challenge facing the planners of the $9.5 billion NAICM (New International Airport Mexico City) project. The plan for the New Mexico City Airport is to be one of the largest, most futuristic and sustainable airports in the world. The project involves an international consortium of designers, engineers and a lot of national pride.
But the question was how to build one of the world’s most ambitious airports on unstable, saturated and sinking soil (CBR < 1%)? British architect Lord Norman Foster, leading one of the international design firms stated: "the soil has a high-water content and has little capacity to support large loads. In addition, the area is seismic, and the effects of ground movement are magnified by the soil type in the area. Finally, the site is subject to substantial settlement over time, from groundwater extraction for the city's drinking water supply.”
Construction machinery crack the 60 cm upper crust and sink into the deep soft clay mud.
Other Conventional Solutions Failed After 4 Months of Field Testing
Conventional construction and soil stabilization methods would simply not work in this terrain or are too expensive. The NAICM engineering authorities conducted a 4-month comparison test of several different soil stabilization solutions, such as multiple layers of geogrids, other geosynthetics products and other conventional solutions. At the end of this testing period the results were clear - after hundreds of passes of heavily loaded (45 ton) truck traffic over the Neoloy Geocells, the onsite demonstration section showed no surface deformation or potholes and no settlement.
Other geosynthetics and conventional solutions failed field testing
Neoloy Geocells – The Only Solution Qualified for Heavy Loads on Soft Soil
Neoloy Geocells are the only qualified solution for soil reinforcement in the New Mexico City Airport. The NAICM solution included integration of a “sacrificial” geogrid layer under the Neoloy Geocell. This acts as a stable working platform, which improves the performance of the geocell installed above it. Quality testing proved that structural layer stiffness and modulus increased by a factor of 3.5x, even though a lower quality infill material was utilized..
In addition, this innovative technology allowed the use of lightweight local volcanic rock called 'Tezontle' as infill material, which saved construction time and lowered the weight of the overall pavement structure, a critical factor in the construction.
Improve performance, reduce aggregates layer and use local infill
Neoloy Geocells can be installed in all-weather conditions. According to Mexico's Transportation Minister, it allowed construction during the rainy seasons, saving about ONE year of construction time. In his brief to the press, he stated that this "innovative technology enabled one of the most ambitious projects in the world to become a reality".
Neoloy Geocells reduced construction time by ONE year
- Better Pavement Performance– after a year the pavements show zero settlement, with no evidence of any rutting, hollows or bumps.
- 60% Less Structure Weight - the use of lightweight local infill and reduction of aggregate layer thickness reduced the overall structure weight, allowing it to "float" on top of the deep soft clay layer.
- Double Construction Speed - rain and wet soils do not impede installation. This makes construction twice as fast as other conventional solutions, which cannot be installed during the 6 months of the rainy season.
- 30% Less Asphalt Layer - structural layer stiffness and modulus increased by 3.5x, allowing the asphalt layer to be reduced by 30%.
- Reduce Construction Costs - the reduction of aggregate and asphalt thickness layers, the use of locally available infill materials, significantly reduced the construction costs.
- Reduce Construction Time by ONE Year - according to Mexico transportation minister, thanks to this innovative technology, the project could be built more effectively and throughout the year, saving one year of construction time.
- Less Maintenance Cycles by a factor of 4X - the increased structural layer stiffness and modulus ( by a factor of 3.5x) resulted in less deformations, thereby increasing the time between maintenance cycles by 4x.
- Lower Environmental Footprint - the use of Neoloy Geocells solution contributes to a lower environmental footprint (less quarrying, hauling, pollution, carbon) and aligns with the goal to design the world’s first sustainable airport.