Method and benefits of Guniting
Guniting refers to a construction method useful for slope stabilization and specific rehabilitation purpose. The method is primarily utilized in building up the retaining walls, swimming pool construction, tunnel construction, in fluid tank construction and some of the concrete repair works.
Method and Guniting Requirements:
The guniting is also known as the dry-mix shotcrete process to carry dry material from a machine to surface of application via a nozzle with the help of compressed pressure and high velocity.
To make the application more effective, water is added at the nozzle area. The outcome of the final mix is an amalgamation of dry material and water. The operator keeps the control on the inclusion of water and the amalgamation of water content.
The cement mortar mix is the prime material in guniting. On the basis of the use and needs of the area, discrepancies may occur. In the following figure, demonstration for standard arrangement of a guniting or dry-mix shotcrete system is given.
The dry ingredients are blended in a bin and preserved in a cement gun. At the time of application, the dry mix is injected with the pressure and high velocity, and the water is inducted at the nozzle, just prior to blast off the mix.
A water supply pressure tank exists to stream water with sufficient pressure to the nozzle as demonstrated.
The followings are the usual necessities for undertaking a superior quality guniting process are:
1. With cautious and competent operation along with keeping control of the nozzle, a superior quality finished work via guniting can be produced.
2. The surface of application does not contain any mud, grease or any other imperfect materials. High pressure water jet or air blast should be employed to make it clean and clear.
3. Sand blasting is accomplished with the surface of application prior to undertake guniting. It facilitates eliminating rust on the reinforcement.
4. If the surface of treatment contains high adsorption, then keep it wet for a time period of 6 hours prior to undertake guniting.
5. The mix ratios toward guniting are 1:3 and 1:4:5. There is usually a water cement ratio of 0.30. A 1:3 mix will retain a strength of 70MPa in the 7th day after application.
6. The size of fine aggregate that is utilized in the mix is 10mm.
7. Enhance the resistance capacity against weather and chemical attack to minimize permeability. For this purpose, superior quality mortar should be used.