IS 4990:1974 is the Indian Standard (BIS) for in-situ pressure grouting in rock foundations. This standard outlines the code of practice for pressure grouting into rock foundations to reduce their permeability and increase their strength. It details procedures for consolidation, curtain, and contact grouting, covering materials, drilling, injection methods, pressures, and control testing for large civil engineering structures like dams and tunnels.
Covers the principles and procedures for pressure grouting in rock foundations to improve strength and reduce permeability.
Overview
- Status
- Current
- Usage level
- Specialized
- Domain
- Geotechnical — Tunneling and Underground Structures
- Type
- Code of Practice
Also on InfraLens for IS 4990
Practical Notes
! The 'Rule of Thumb' for grouting pressure (0.23 kgf/cm²/m) is a starting point; final pressure must be carefully controlled to avoid hydraulic fracturing or lifting of the rock mass.
! Water pressure tests (Lugeon tests) conducted before grouting are critical for assessing rock mass permeability and designing the grouting program (mixes, pressures, hole spacing).
! Success of grouting is highly dependent on the site geology. Unexpectedly high or low grout 'take' requires immediate investigation and may necessitate changes in the grouting strategy.
Frequently referenced clauses
groutcementadmixturesrock
International Equivalents
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International Comparison — Coming Soon
We're adding equivalent international standards for this code.
Key Values5
Quick Reference Values
Typical Grouting Pressure Rule of Thumb0.23 kgf/cm² per metre of depth (or 1 psi/ft)
Lugeon Unit for Permeability1 litre per minute per metre of test section at 10 kgf/cm² pressure
Typical Grout Hole Diameter Range38 mm to 76 mm
Initial Water/Cement Ratio by Volume (Typical)1.5 to 2.0
Grout Refusal Criteria (Example)<1 litre/minute intake over a 10-minute period at final pressure
Tables & Referenced Sections
Key Clauses
Clause 3 - Types of Grouting
Clause 4 - Grouting Materials
Clause 5 - Drilling for Grouting
Clause 6 - Grouting Procedure
Clause 7 - Control and Records
Appendix A - Methods of Water Pressure Testing
Frequently Asked Questions4
What is the difference between consolidation and curtain grouting?+
Consolidation grouting treats the rock mass under a foundation to improve its strength and bearing capacity (Clause 3.1). Curtain grouting creates a narrow, deep, impermeable barrier to cut off seepage, typically under dams (Clause 3.2).
What is a typical starting grout mix?+
Grouting typically starts with a thin mix, such as a water-cement ratio of 1.5 to 2.0 by volume, and is progressively thickened based on the rate of grout consumption ('take') by the rock (Clause 4.3).
What is 'grout refusal'?+
It's the termination criteria for grouting a stage, defined as when the grout flow into the rock drops below a specified minimal value (e.g., 1 litre/min) for a set duration (e.g., 10-20 min) at the maximum specified pressure (Clause 6.5).
What is the purpose of packers in grouting?+
Packers are inflatable or mechanical devices used to seal a borehole at a specific depth, allowing a particular section (stage) of the hole to be grouted under pressure without grout escaping up the hole (Clause 6.2.2).
QA/QC Inspection Templates
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QA/QC templates coming soon for this code.