For high-rise structures and more concrete requirement, higher capacity pumps of 73 cu m/hr to 90 cu m/hr, are used, says Samar Ghoshdastidar, Technical Director, Simplex Infrastructures. Excerpts from the interview....

Brief us on the projects where you have used concrete pumps.
There are almost 250 project sites in India and abroad and mostly everywhere concrete pumps are used. Most of the pumps are stationary of different capacities based on application. There are some truck-mounted boom pumps of varying boom length and capacity. A few self-climbing boom placers are also used in high-rise structures.

We are executing different civil projects in India and abroad from piles foundation to superstructures and all civil works for power plants, refineries, fertiliser and chemical plants, bridges and flyovers, metro rail, roads, berths in ports and other marine structures, buildings and high-rise structures etc.

Most of the stationary pumps are of 40-45 cu m/hr capacity used for normal civil works where vertical pumping heights are not more than 45 m. In the case of high-rise structures and more concrete requirement, higher capacity pumps of 73 cu m/hr to 90 cu m/hr, etc are used.

What is your take on pumping concrete up to and above 300 m heights?
We have one prestigious high-rise building project at Mumbai (supposed to be the highest residential building in the world) where vertical pumping height is in excess of 300 m. In this project we are using self-climbing placer booms with required capacity of Sany-make stationary pumps of model HBT 90C.

What is the importance and utility of self-climbing boom placers in high-rise projects?
Self-climbing boom placer for high-rise projects is a good utility overcoming the limitations of truck mounted boom placer (which generally have a maximum of 75 m reach). With a floor climbing placer, concreting to almost any height is possible, as the placer boom also climbs up as the building height is increasing. The limitation factor is the pumping height capability of the concrete pump.

What are most preferred brands?
Schwing Stetter, Putzmeister, Sany etc are the most used brand for us. All have different sizes of stationary pumps as well as boom pumps (refer table for details).

Is mass concreting a major challenge? If yes, how do you meet the same?
Mass concreting is always a challenge. It involves mass production of concrete, transportation and pumping/pouring of concrete. We generally used 2-3 batching plants of suitable capacity, during mass concreting for producing concrete of suitable grade and we place sufficient numbers of transit mixer, depending on the distance for transporting the concrete to location and 4-6 concrete pumps at different locations for pouring the concrete. Suitable approach roads are very important for smooth movement of transit mixers.

What are the challenges in mass concreting using large size aggregates?
Large size aggregates are used in dams, barrages, etc for which batching plant may require some modification to handle large aggregates which is not very difficult. However, pumping of concrete with large size aggregates is really a difficult proposition and pumping of concrete is restricted up to a certain size of aggregates and mix design of concrete. In case of very large size aggregates, conveyor placer is used instead of pumps/placers.