“Shocrete v Guntie” What’s the difference……..????
Gunite - Dry Gunning:
Gunite to delineate this process dry gun concrete, it means spray-applied concrete. People often talk about a gunite pool, meaning a concrete pool where the concrete is pneumatically applied or sprayed in place using air pressure. Many contractors in the concrete spraying business have started using the term dry-gunned is a trade name for
Dry gun means the cement and sand are injected into an air stream conveying it to the nozzle. The nozzle operator then adds the water at the nozzle and has total control of the water-cement ratio. The delivery hose of the mix is generally quite light, as the hose is mostly filled with air containing the mix of cement and sand.
Dry gunning allows concrete to be placed drier than most wet gunning, but that is not always a plus for dome building. Often the concrete is stacked at a very heavy thickness. This can be a disaster for an Air-formed structure. Operator training is very critical and can mean the difference between success and failure of application. The danger of dry gunning the concrete on a Monolithic Dome increases as the size of the dome increases.
Shotcrete - Wet Gunning:
Wet gun means the wet (already mixed) concrete is pumped to the nozzle. Air is added at the nozzle to carry the concrete mix to the target – again pneumatically applied. Here too operator training is important, but not quite as technical for wet gunners. In Monolithic Dome Construction, application mistakes are usually far less critical than with dry gunning. Rebound, or the waste created by sprayed concrete falling to the floor, is usually half as much for shotcrete as compared to gunite.
Contractors use shotcrete for a number of building restorations and projects. It can spray applied on failing walls, tunnels, foundations and shear walls. It is used to bond to the old materials and lock them in place and seal them together. It works great for reinforcing old rock foundations, brick, block and stone.
Shotcrete is extremely suitable for soil stabilization. Since it is sprayed at high velocity, it seals much tighter than poured concrete often with no forming. Retaining wall with the addition spray soil-nailed anchors can hold back a mountain face. Shotcrete is sustainable, low impact and fast. Stabilization can increase the shear strength of a soil and/or control the shrink-swell properties of a soil, thus improving the load bearing capacity of a sub-grade to support pavements and foundations.
Swimming Pools, Simulated Rock and Waterfalls Designs. Shotcrete structures designed with curves and simulated rock. As well as spraying a simulated rock overlay on all types of surfaces. Shotcrete is very strong and stable. It is watertight and does not shrink like normal concrete. These properties and the fact that you can reinforce it with steel make it far superior to natural stone. Shotcrete lasts longer, is easier to waterproof, is more resistant to freeze thaw and it is stronger.
KINGISI will be onsite prior to Shotcrete / Concrete placement ensure that the Reinforcing Steel and Embedded accessories are secured in place per approved drawings. Verify reinforcing steel conforms to the material, size, and grade specified in the contract documents.
Reinforcing steel-resisting flexural and axial forces in intermediate and special moment frames, and boundary elements of special reinforced concrete shear walls and shear reinforcement. Inspect anchor bolts to be installed in concrete prior to and during placement of concrete where allowable loads have been increased or where strength design is used.
During Shotcrete / Concrete Placement, Verifying use of required design concrete mix/ materials. Check contractors Nozzelman has the correct documentation. At the time fresh concrete is sampled to fabricate specimens for strength tests, perform slump and air content tests, and determine the temperature of the concrete. Inspection of concrete and shotcrete placement for proper application techniques. Inspection for maintenance of specified curing temperature and techniques.
For more Information please check out the websites below.
American Shotcrete Association.
ACI: Certified Shotcrete Nozzle-man information.