GREY AREA

Louis Fraser, Founder and CEO of T&M Specialists, gives some insights into sprayed concrete, by far the fastest growing and most effective method of temporary and permanent??ground support in the construction industry today.?The present market value of US$7.6B is projected to reach US$14.3B by 2028, and underpins the need to increase our knowledge and understanding of sprayed concrete.

Sprayed concrete, if understood and applied correctly, manages the safety concerns normally associated with ground support, by an efficient and effective support to provide a safe environment to allow faster progress in tunnelling and mining construction.

The evolution of sprayed concrete has been phenomenal, and continues, with the following aspects playing some of the key roles.

Equipment

When Louis started some 25 years ago, spraying concrete by hand at a high velocity with high air pressured hoses was dubbed ?"wrestling with the black mamba" given its liking to the thrashings of the aggressive snake. ?It was physically difficult, dusty, dirty, silica fumed and unpredictable work.

The equipment now is state of the art with many features to improve applications – such as low pulsating pumps, smoother boom movements, automatic functions such as oscillators, scanners to??reduce over-spray and?optimise usage, and data recording functions working on sensors.?Some of the modern equipment allow the operator to operate from within a cab which, a fantastic solution for removing the operator from?harmful environments caused by dust and fumes.

Mix Design/Chemicals

The concrete mix designs have advanced dramatically, thanks to intensive work by concrete technologists, allowing more workable mixes with higher strengths. Retarders allow longer open times; superplasticisers give more flowable mixes while still reducing water content; additives such as fly ash, silica fume or GGBS allow reduced cement content and reduce carbon emissions; and set accelerators are advancing all the time allowing to kill the slump for faster applications and?setting times which is critical for re-entry.

?Standards/Certification

Standards and certifications such as EFNARC for robotic spraying and ACI for hand spraying are helping to raise and maintain higher standards – and projects are starting to stipulate these in tenders.

After becoming an EFNARC Examiner in 2013, Louis has helped to train many good nozzleman to become experts?in sprayed concrete - to have better control of the behaviour of the concrete mix, additives and equipment, to better deal with issues and situations as they arise on site to ensure the quality of the end product.?These aspects are dealt within the standards.

Digital Platform

With all of the wide and varied experiences Louis gained during his time on projects around the world, he is the brain behind developing T&M’s digital platform “Sprayed Concrete Management System” which helps improve the work and cost efficiency of sprayed concrete applications; by recording and analysing appropriate data, it helps regulate aspects such as equipment performance, personnel performance and behaviours and patterns, mix issues, minimising wastage of materials, monitoring procedures and quality control, etc. for much better control on outcomes on projects.

Conclusion

Choosing the correct equipment, mix design and additives for your project requirements, then choosing appropriate applicators certified to the relevant standards, and using a digital platform to manage the work would surely help eliminate any “Grey Area” surprises and help you to a successful completion of your project!