Grouting n gunintung
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Grouting and guniting are construction techniques used to fill voids and apply concrete coatings. Grouting involves placing a cementitious mixture into cavities to strengthen structures, fill gaps, and stop leaks. There are different types of grouts for various applications. The guniting process involves mixing cement and sand then projecting it at high pressure onto surfaces using compressed air. It can be used on vertical, overhead and horizontal surfaces to rehabilitate concrete structures. Both grouting and guniting are effective techniques for repairing and strengthening buildings and infrastructure.
Grouting n gunintung
- 1. 1 Subject: Advance construction technology (3350605) Topic: Grouting and Guniting Prepared by Bhavesh Hathila
- 2. INDEX 1. GROUTING DEFINTION 2. CATEGORIES OF GROUT 3. PROPERTISE OF GROUT 4. SPECIFICTION FOR GROUT 5. TYPES OF GROTING MATERIUS AND THEIR USE 6. APPLICTION OF GROUTING 7. TYPES OF GROUTS 2
- 3. 3 8. GROUTS WITH FILITERS 9. PROCEDURE OF GROUTING 10.GROUTING IN TUNNELS 11.SCHEMATIC PLAN GROUT PLANT 12. GUNITING 13. SPRAYING OF CONCRETE 14. GUNITING
- 4. Grouting • Grouting is the process of placing a material into cavities in concrete or masonry structure for the purpose of increasing the load bearing capacity of a structure, restoring the monolithic nature of a structural member, filling voids around pre cast connections steel base plates, providing fire stops, stopping leakages, placing adhesives and soil stabilization. • GROUT is a mixture of water, cement and optional material like sand, water reducing admixtures, expansion agents and pozzolans. The water to cement ratio is around 0.5. Fine sand is used to avoid segregation.
- 5. Categories of grout • Suspension Grout • Liquid Grout or Solution Grout. • Suspension grout is a mixture of one or several inert materials like cement, clays etc suspended in a fluid i.e water. Suspension grout is a mixture of pure cement with water. • Liquid grout or solution grout consists of chemical products in a solution or an emulsion form and their reagents. The most frequently used products are sodium silicate and certain resins.
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- 7. Properties of grout • Fluidity • Minimum bleeding and segregation • Low shrinkage • Adequate strength after hardening • No detrimental compounds • Durable 7
- 8. Specification for grout • The sand should pass 150 µm IS sieve • The compressive strength of 100 mm cubes of the grout shall not be less than 17 N/mm² at 7 days 8
- 9. Types of grouting materials and their use • Chemical grouting - control seepage - shut- off seepage - soil stabilization • Cementitious grouting - mass placement - structural(high strength) - caustic environments
- 10. - high temperatures Epoxy grouting - seal cracks - bolt anchoring - base plate levelling - acidic environment Polyesters - bolt anchoring Silicones - smoke seals - fire stops
- 11. Applications of grouting Repairing of cracks • The wide cracks may be repaired by filling them with portland cement grout. • The grout mixture may contain cement and water or cement, sand and water, depending upon the width of crack. • The water cement ratio should be kept as low as practicable to maximize strength and minimize shrinkage.
- 12. Strengthening existing walls • The lateral strength of buildings can be improved by increasing the strength and stiffness of the existing individual walls, whether they are cracked or uncracked.
- 13. For soil stabilization • Common methods are - chemical grouting - compaction grouting - jet grouting
- 14. Types of Grouts • Cement-based Grouts: – Cement-based grouts are the most frequently used in both water stopping and strengthening treatment. They are characterized by their water cement ratio and their Total Dry Matter / Water weight ratio. The properties and characteristics of these grouts vary according to the mix proportions used. However, they have the following properties and characteristics in common. • Stability and fluidity according to the dosage of the various components and their quality • Unconfined compressive strength linked to water cement ratio
- 15. • Durability depending on the quantity and quality of the components • Easy preparation and availability • Ease of use • Relatively low cost mixes 15
- 16. Pure cement grout It is an unstable grout. However, bleeding can be avoided with water cement ratio less than 0.67. Usual mix proportions are from water cement ratio 0.4 to 1 for grouting. Very high mechanical strength can be attained with this type of grout. During grouting, cement grains deposit in inter- granular voids or fissures is analogous to a kind of hydraulic filling. The grout usually undergoes a significant filtration effect. The grain fineness is an important factor for fine fissures.
- 17. Grouts with fillers Fillers are added in order to modify the viscosity of a given grout so as to obtain a low cost product to substitute the cement. The most commonly used fillers are the natural sands and fly ash from thermal power stations. The term “mortar” is commonly used to specify grouts with fillers that have a high sand content. Adding fillers reduces the grout penetrability, as the fillers are of larger grain sizes. Grouts with fillers are used when water absorption and/or the size of voids are such that filling becomes essential and when the leaking of grout into adjoining areas should be limited. In addition, fillers in grout will produce low slump grout with high viscosity for certain grouting purposes.
- 18. Procedure of grouting • A 1:2 cement-sand grout with a water-cement ratio between 0.6 and 0.8 is prepared using a mechanical mixer. • The mixture is then sent down under pressure (of about 120kg/cm²) through a 30-50 mm diameter pipe terminating into steel cages. 18
- 19. • As the grouting proceeds the pipe is raised gradually upto a height of not more than 60 cm above its starting level after which it is withdrawn and placed into the next cage for furthure grouting by the same procedure. • After grouting the whole area for a height of about 60 cm , the same operation is repeated, if necessary , for the next layer of 60cm and so on. 19
- 21. Hose. Flexible hose is most commonly used for suction and discharge lines. If the length of the discharge line is such that pipe is necessary, a short length of hose should be provided at the pump discharge and at the connection to the grout header. Piping. Black steel pipe and fittings 1-1/2 in. in diameter are normally suitable for pressure lines ; but where large quantities of grout are to be injected and the supply line is long, it may be desirable to provide a larger size pipe and connection hoses. .
- 22. Grout Header. The grout header is usually assembled as a unit in order—that it may be moved from one grout hole to another. The assembly consists of the operating valves, a pressure gage, pipe, and the necessary fittings to attach the header to the hole and to attach the grout supply and return lines. Pressure Gages. Reliable pressure gages are essential in pressure grouting. They constitute the principal index to the behavior of the hole and the stresses that are being produced in treated material. 22
- 23. Schematic Plan of Grout Plant 23
- 24. Guniting • Guniting is an effective technique, which has been extensively used in the rehabilitation of structurally distressed R.C members. There has been case of heavy rusting of the mesh in the form of powder or in the form of a sheet coming out. Distressing before restoration is possible only in case of overheads tanks which can be restored when the tanks are empty.
- 25. Gunite is also known as shotcrete or pneumatically applied mortar It can be used on vertical and overhead, as well as on horizontal surfaces and is particularly useful for restoring surfaces spalled due to corrosion of reinforcement Gunite is a mixture of Portland cement, sand and water, shot into the place by compressed air
- 26. Sand and cement are mixed dry in a mixing chamber, and the dry mixture is then transferred by air pressure along a pipe or hose to a nozzle, where it is forcibly projected on to the surface to be coated Water is added to the mixture by passing it through a spray injected at the nozzle The flow of water at the nozzle can be controlled to give a mix of desired stiffness, which will adhere to the surface against which it is projected
- 27. • A cement-sand mix, in the ratio 1:2 or 1:3 depending upon the requirement, is applied at high pressure over the surface with the help of specialized equipment. • Guniting is extensively used to rehabilitate concrete bridges, dams, spillways, buildings, marine structures, etc.
- 28. Spraying of concrete There are two different methods of spraying: – Dry process spraying – Wet process spraying Dry process spraying is the process in which the mixture of damp sand and cement is passed through the delivery hose to the nozzle and the water is mixed at that time. Water cement ratio should be between 0.33 and 0.50 This process is often used for repair work. It is because of its fast application process and restoration of structural strength at an early stage.
- 29. • The performance characteristics of dry sprayed concrete are they have good density and high strength. • It has very good bond to a suitable substrate. • These advantages make it more variable than conventional concrete and wet process sprayed concrete.
- 30. Guniting
- 31. Thank you