Tunnel construction has picked up pace in the past four-five years in India, on account of an increased number of projects involving longer tunnel lengths in some of the world’s most difficult terrain conditions! The scope of tunnel projects is also expanding as a result of growing urbanization and the rising demand for better infrastructure.
Tunnel development is majorly driven by investments in the metro rail, railway, roads and highways, hydropower, underground crude oil storage and water & sewerage segments. And with the increasing investments in the sector, the size of tunnelling projects has also witnessed a substantial increase!
Etched in concrete
Concrete spraying is one of the most demanding application tasks in underground mining and tunnel construction. It has become the industry standard for initial and final support in underground construction, as it provides a safe working environment for operators and significantly reduces material and time-related costs onsite.
Compressed air for concrete spraying:
Basic requirements for a high-quality application of sprayed concrete include surface preparation, continuous concrete flow, exact dosing of the accelerator, and correct amount of compressed air!
Now let’s look into the key elements that play an important role in compressed air systems for construction:
- To reduce the rebound to a minimum, the nozzle must point perpendicular to the surface
- To achieve a good compaction of the concrete on the surface, the stand-off distance between the nozzle and surface must be kept between 1-2 m.
- The spraying process should always take place from bottom to top, allowing especially when spraying thick layers, the previous sprayed concrete to support the next layer, and to prevent spraying of areas that received rebound.
Role of compressed air?
Compressed air is utilized to accelerate the concrete to a speed suitable for positioning the nozzle from the rock surface. Special chemicals known as accelerators are frequently added to speed up the hardening of the sprayed concrete.
ELGi’s electric compressor PG 55ES with 325cfm and 9.5bar working pressure plays a vital role in the concrete spraying application by running as an onboard compressor option to one of leading concrete spraying equipment manufacturers in the world.
