Shotcrete, also called (trademark) Gunite, concrete applied by spraying. Shotcrete is a mixture of aggregate and Portland cement, conveyed by compressed air to the nozzle of a spray gun, where water is added. The wet mixture is then sprayed in place and may be carved or troweled almost immediately.
Types of Shotcrete :
Dry Mix Shotcrete (DMS)
Wet Mix Shotcrete (WMS
Pre-Guniting / Shotcrete Work:
Checking of scaffolding shall be done as per as per specification.
Removing loose stone, murum from hill slope area.
Necessary latest drawings shall be made available on site.
Availability of necessary raw materials and equipment shall be ensured.
Pre-guniting/shotcrete approval:
No guniting/shotcrete pour shall commence without approval of the Engineer/Project Manager in writing. Approval of commencement of guniting/shotcrete placement is documented through approval of a checklist
During Guniting / Shotcrete Work:
Before starting of Guniting/shotcrete work fixing of MS weld mesh of size 50mmx50mmx3mm thickness shall be fixed by using 6mm & 8mm reinforcement of grade FE-500.
Rock anchoring should be done by providing 40mm dia. hole with length 2.5m & 500mm L by using 20mm dia reinforcement grouting by using Non-Shrink Grout (with GP2). The water cement ratio should be as per manufacturer recommendation.
Threaded bar anchoring by providing 40mm dia. Hole with length 2.7m by using 20mm dia threaded bar by providing alternatively grouting by using non shrink grout (with GP2) & Sodium silicate. The water cement ratio should be as per manufacturer recommendation.
And then fixed weep holes pipes of 75mm dia. of min 8 to 9” in length by using binding wire.
Guniting/Shotcrete work mix proportion should be (1 Part Crushed sand: 3 part Cement) dry mix mixing of GP2 powder of 100gm/ 1 bag of cement & sodium silicate 50gm/1 bag of cement as per required consistency of water by using high pressure nozzles.
After Guniting work Heavy Rock Fall net (of size 500x500x9mm of HEA panel net to prevent boulders of capacity 8 to 10 ton.) should be fixed with 6mm MS plate of size 150x150mm fixed with Nut & washer.
Thickness of guniting/shotcrete must be min avg.75mm as per GFC drawing. If 75mm thickness not deposited in one layer, subsequent layer should be apply to achieve min avg 75mm thickness of mortar
Post Guniting / Shotcrete Works:
Shotcrete thickness shall be min 75mm avg.
Rock anchoring grouting should be done by using GP2 Material only.
Hight strength rock fall net shall be 500x500x9mm.(Make-As per approved make)
MS weld mesh shall be of size 50mmx50mmx3mm thickness
