THE CAIRO MONORAIL

The fluid concretes of piles and columns, as well as self-compacting concrete of columns, closures (part joining two beams together) and prestressed beams, have been requiring specific performance, including 2 to 3 hours of workability, low viscosity and excellent pumpability and placeability. All these requirements, as well as excellent robustness to variations of sand and aggregates qualities, have been met with the use of CHRYSO®Optima and CHRYSO®Delta superplasticizers.

The 8,000 prestressed beams have been precast using a sophisticated concrete mix design with high cement and silica fume content and a very low water-to-cement ratio. Tailor made CHRYSO®Premia superplasticizers and CHRYSO®Xel accelerators have allowed to obtain the very high early strengths required (> 10 MPa after 10 hours, > 30 MPa after 30 hours, without steam/heat curing), combined with 2 hours of workability retention, excellent pumpability and placability, in a context of large temperature variations (5°C in winter and 40°C in summer). Finally, excellent faire-faced concrete has been achieved by using CHRYSO®Dem Ekla 12, a safe and environmentally friendly demolding agent.

The closures, connecting beams to each other, have been manufactured by using a CHRYSO®Optima superplasticiser and CHRYSO®Serenis, a very powerful Shrinkage Reducing Admixture. CHRYSO’s solution has been designed to provide the concrete with long workability retention, low viscosity, excellent pumpability, as well as perfect dimensional and mechanical compatibility with the adjacent hardened beams.