There has been an increase in road construction and maintenance across South Africa to heed President Cyril Ramaphosa’s call for infrastructure development to drive economic growth and recovery. These efforts comprise numerous projects including improvements made to the Huguenot Tunnel located on the N1 in the Western Cape. Plans are currently in design to commission a second tunnel, adjacent to the current one, to align the tunnel with international standards.
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!
These key elements 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 the leading concrete spraying equipment manufacturers in the world.
Contact our compressed air team for enquiries.
Contributor: ELGi
