What is the typical thickness of a soil layer (lift) before compaction?

Generally 25 cm to 40 cm for mechanical compaction, but can be as low as 20 cm. This depends on the soil type and roller capacity (Clause 6.3).

What is the required level of compaction for canal embankments?

Typically specified as 95% to 98% of the Maximum Dry Density (MDD) determined by the heavy compaction test (IS 2720 Part 8), as per project specifications (Clause 7.5 & Table 1).

How should the ground be prepared before starting the fill?

The foundation area must be cleared of all vegetation, topsoil, and deleterious materials. The surface should then be scarified to a depth of 15 cm to ensure a good bond with the first fill layer (Clause 5).

What checks are required during compaction?

Regular checks on lift thickness, number of roller passes, moisture content, and in-situ field density are required as part of quality control (Clause 8).

IS 6932 Part 2

: 1973

Code of Practice for Earthwork - Part 2: Filling, Forming and Compaction

CurrentFrequently UsedCode of PracticeBIMGeotechnical · Irrigation and Canal Structures

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This standard outlines the code of practice for earthwork involved in canal construction, specifically focusing on the filling, forming, and compaction processes. It provides guidelines on material suitability, foundation preparation, placement of fill in layers (lifts), and the methods and equipment for compaction to achieve required density and stability.

Covers methods for filling, forming, and compaction of earthwork for various civil engineering purposes.

Quick Reference Values

Minimum degree of compaction for embankments95% to 98% of Maximum Dry Density (MDD)

Allowable moisture content variation from OMC±2% of Optimum Moisture Content (OMC)

Maximum loose lift thickness for roller compaction25 cm to 40 cm

Depth of scarification for foundation surface15 cm

Frequency of field density tests (typical)1 test per 1000 to 2500 m³ of fill

Practical Notes

Achieving the specified degree of compaction is highly dependent on maintaining the soil moisture content near the Optimum Moisture Content (OMC).

The choice of compaction equipment is critical and must be matched to the soil type (e.g., sheepsfoot rollers for cohesive soils, vibratory rollers for cohesionless soils).

Proper preparation of the foundation by stripping unsuitable material and scarifying the surface is essential to prevent slip-plane failure between the foundation and the embankment.