Delhi Metro Rail Project 

The history of planning a Metro Project for Delhi dates back to the 70's. The concept plan envisaged a network of 58 km underground & 195 km surface corridors. The total network plan contains 16 sections to be implemented in a sequence based on passenger kilometer carried per kilometer length of each section, which is expected to be completed in three phases. The first phase of the network, which is now complete, comprises of 65.11 km of route length with 13.01 km underground called Metro corridor and 52.10 km surface / elevated called Rail Corridor. This network of 3 phases is expected to be complete by 2010.    

RHEODYNAMIC CONCRETE (SCC)

The use of Rheodynamic Concrete in DMRC project was primarily to reduce the construction time of the structures. Rheodynamic concrete was poured in a single lift around a central steel column with surrounding reinforcement and was constructed top down on a construction station box. Vibration was difficult but not impossible, however, due to the significant speed of placement advantage and the possibility for a 5m high pour to self compact under its own weight, construction time per column could be virtually halved versus two lifts of Normal Concrete. Another use of Rheodynamic concrete was the cross passage between the main tunnels of the rail network. Actually these cross passage provides the means of escape in case of emergency or danger in any one of the main tunnels. Rheodynamic Concrete was chosen as the pouring could be conducted from a single location and the concrete could be self compacted without the need for vibration.  In the construction of the domed station roof Rheodynamic Concrete was chosen because of the difficulty of placing and vibrating Normal Concrete in the curved domed surface. The requirement to maintain the integrity of the surface finish was also a factor.  Speed and ease of placement of SCC was a considerable advantage over Normal Concrete.  

ADMIXTURES FOR SCC  

The use of Poly Carboxylic Ether (PCE) based superplasticizer combined with Viscosity Modifying Agents (VMA) form a system for producing consistent Rheodynamic Concrete and is compatible with each other. It is the interaction of the respective PCE and VMA polymers that impart the property of resistance to segregation. 

The PCE based admixture - Glenium 51 used, was designed to optimize the mix and VMA, Glenium Stream 2, to avoid bleeding & segregation.  A retarder Pozzolith 300R was also used to assist in the control of retention time, which is especially important in the Delhi climate where temperatures reach 45 deg C.

Permanent Lining for Cross Passage between Delhi Metro tunnels	SCC for station Roof -   Domed Structure