The line-up of key concrete equipment available today spans pumps, vibrators, batching plants and mixers. Do these machines adequately meet user demands or are some features missing? Should this line-up include other equipment? CW provides some answers.
“Shotcrete is an excellent example wherein materials have to be specifically sourced to suit the machine requirements,” says Patel.
The construction industry already has concrete pumps that can pump from 30 cum/hr to 150 cum/hr, horizontally, to more than 500 m and, vertically, more than 150 m, protected by new safety features, observes Chaitanya Bhagde, Manager Plant and Machinery, Shapoorji Pallonji and a Chartered Mechanical Engineer. “But with buildings touching new heights, concrete pumps must perform better.”
Bhagde elucidates the need for higher pressure capacity pumps and pumps that can efficiently push various grades of concrete, which are also in the process of upgradation. Also, wireless remote-control technology is a useful solution when a pump is used at a height and distance where the operator can’t see the actual picture.
“We need better safety features in the concrete pump such as a limit switch for the hopper to stop the agitator immediately,” says Pramod B Joshi, Additional General Manager (P&M Head, All India), Ahluwalia Contracts India.
Concrete pumps choke when we use them for concreting 10m below the ground, adds Joshi. “Some special arrangement should be made so that this doesn’t happen.”
Ideally, the concrete pump should calculate the quantity of concrete needed so that the productivity and the concrete received from the ready-mix concrete (RMC) vendor or batching plant can be calculated, Joshi continues. “At present, we calculate the quantity of concrete manually. Also, concrete pumps and boom placers should display the quantity of concrete pumped. Without this, we cannot figure out the quantity of concrete wasted or received from the RMC vendor. An energy meter with the RMC plants would help calculate the electricity consumed to identify the cost of production.”
How does continuous concreting work? Bhagde shares his experience: “We placed the concrete pump directly below a concrete batching plant with the arrangement of a revolving chute. After some trials and errors, we started continuous concrete. This approach helped maximise the productivity of the plant and pump, and save on time and concrete transportation costs. As some concrete pumps don’t have a cable remote, we developed and used a remote control to operate the pump from a distance where the operator could monitor the placement and pump. This helped avoid communication errors.”
Concrete vibrators that are currently available don’t show how much compaction has been done; this is handled by the workers, adds Joshi. “This can be improved.” The use of needle vibrators is questionable because they cause the aggregate to settle, which, in turn, brings about internal changes in the concrete matrix and affects its structural behaviour, opines Patel.
The efficiency of vibration depends more on the operator than the machine itself, he continues. “However, code limitations for working conditions for laying and spreading concrete are never followed and, frequently, non-technical people are involved in the process, which is counterproductive.”
Almost all manufacturers now offer automated versions of batching plants that yield more precise results than the typical old configuration of analogue-controlled machines, notes Bhagde. While the production cycle time can’t be modified much, as IS standards must be adhered to, he believes the lead time and other contributory factors can be taken care to increase the productivity and dependability of the plant. Compact design installations could be introduced for congested locations.
When concrete is pumped directly from a batching plant, a special chute should be provided by the plant manufacturer to allow pumping operations to continue even while a transit mixer is simultaneously being loaded, adds Joshi.
While existing mixer technology is useful, Patel is hopeful of advancement in the efficient and frictionless mixing of concrete.
“Digital technology in equipment augurs more accurate measurements and precision in quantifying loads and generating online records,” adds Bhagde. “This, in turn, can help improve the quality of the outcomes and safety; reduce the cost and time taken to do a job; increase profit; and predict the need for machine maintenance.” Coming to examples of digitisation in concrete equipment, he points to automation in the controller system of batching plants, programmable logic controller (PLC) units in pumps and mixer motors and automated greasing system in pumps.
While examples of digitalised equipment exist, “the concrete equipment models currently available do not incorporate digital technology sufficiently,” says Kumar. He believes digital is now well understood by everyone onsite including the workmen and, so, it must be promoted. Digitalisation clearly shows if things are going right or wrong. At present, this is left to the understanding of the workmen. Further, digitalisation makes it easier to work with machines and handle complex tasks and thus reduces the need for in-depth training while increasing productivity and accuracy.
“India seriously lacks the training infrastructure required to make people industry-ready”, adds Patel. He believes the construction industry is in a nascent stage as far as training is concerned. The construction industry needs to learn from the IT industry and adopt its continuous in-house training models and induction programmes.
Training by OEMs should include quarterly or half-yearly refresher sessions to upgrade operator skills and knowledge, proposes Bhagde.
Operators are inadequately trained today, affirms Kumar. “Most operators engaged with making, transporting, pumping and placing concrete don’t know concrete well and only focus on machine care. This leads to concrete being mishandled at critical times.”
Manufacturers should offer training in the use of machines as well as interaction with concrete, believes Kumar. “Operators must be provided an understanding of concrete, control measures and procedures for handling adverse situations, including variations in concrete.”