Mexico City, and its metropolitan area, was built over an area what was once an area of lakes. As it has grown the city has gained ground from the lakes and consequently it has faced the great problem of floods. At present, the installed capacity of the drainage system in the metropolitan area is insufficient and creates serious problems. Comparing the capacity it had in 1975 with the capacity today, which is 30% lower with almost double the population shows the need for an increase in the drainage capacity. Furthermore it is necessary to close the Central Emitter Outlet during the months of low water level for its repair and maintenance. Therefore it is necessary to have an alternative emitter outlet that allows maintaining the operation capacity of the system throughout the year since the current drainage system is insufficient for the actual needs of the Valley of Mexico.
Sika Mexicana is participated with the Mexican contractor company ICA in the final lining. The concrete for this final lining must comply with the following characteristics:
- Class I Structural Concrete
- Compressive strength of 34.3 MPa (350 kg/cm²)
- w/c-ratio: maximum 0.45
- Maximum aggregate size: 3/4″
- 3 hour of workability time
- Initial slump of 26 cm on arrival at the installation point with slump of 22 ± 3.5cm.
- Compressive strength after 12 – 14 hours must be higher than 3.4MPa (35kg/cm²)
The concrete will be pumped up to depth of around 95 m and over a maximal distance of 1000 m length. The volume of the segment done by ICA is of approximately 230,000 m³ of concrete.
The combined use of the the Sika ViscoFlow® technology in form of Sika ViscoFlow®-10, Sika ViscoFlow®-20 E, Sika Visco-Flow®-50 and Sika® Plastiment® Liquid resulted in a good quality concrete which fulfilled the requirement concerning workability retention time requirement. Furthermore the time requirement for the compressive strength has been exceeded by the combination of mix design and Sika admixtures.
In the end the proposed mix designs using the Sika ViscoFlow® technology fulfilled the project specification and were successfully used throughout the construction phase.