Last week we published the article INSTALLATION SYSTEMS OF UNSHAPED REFRACTORY MATERIALS, where we covered the division of the installation systems of refractory concretes into two categories: casting and gunning.
So far we described four installation systems: application by vibrocast, application by pumping, application by self-flowing and application by dry projection or gunning. And today we covered four additional techniques.
5. APPLICATION BY HIGH-PRESSURE GUNNING
Improved variation of Application by dry projection or gunning. In this variant we introduce the use of a high-pressure pump for the addition of water or bonding liquid, where the mix with the dry concrete happens approximately 1 metre before the outlet nozzle, achieving higher performance and lower rebound/reject of material.
6. APPLICATION BY WET PROJECTION OR “SHOTCRETING”
In this method the concrete, of self-flowing properties, is previously mixed with the wate ror bonding liquid, and pumped in wet condition through a double-piston pump towards the gun, where compressed air and a flocculant additive are introduced in order to achieve the necessary consistency so the concrete gets adhered to the lining surface.
Mainly used at large scopes of works, where a big amount of concrete must be installed in a reduced time.
7. APPLICATION BY MANUAL PATCHING
Traditional system of application of concretes for minor repairs o small scopes, through trowel or shovel, similar to plastering.
8. APPLICATION BY RAMMING
It does not require concrete mixing, as this comes on ready-mix basis, either dry or pre-wet (plastic mass). The concrete is compacted using small pneumatic hammers.
Finally, it must be considered that the selection of an installation system of refractory concrete determines mainly the works planning, its costs and execution times, as well as the cost and performance of the refractory concretes.