Quality Assurance Handbook for Rural Roads Volume-I - pmgsy

1.6 Estimating Optimum Moisture Content
Quality Assurance Handbook for Rural Roads
Take a handful of the wet soil on the palm of hand and attempt to make a ball out of it. The
moisture content at which the ball of wet soil can retain its round shape is approximately the
optimum moisture content. At moisture contents below the optimum, the ball tends to crumble
while at moisture contents wet of optimum, the water will tend to ooze out of the surface.
1.7 Pocket Penetrometer
Purpose
Procedure
Soil strength depends on dry density and moisture content. Pocket penetrometer is used to measure
soil compressive strength.
POCKET PENETROMETER
1. Select the test location with care to avoid gravel or other particles that would influence reading.
Avoid obviously disturbed areas. For saturated cohesive soils, it is important that readings be
taken in “fresh” samples or cut surfaces, since rapid drying will greatly influence the reading.
2. Return ring to back position against the penetrometer body.
3. Grip the handle firmly, insert the shaft 6 mm in depth with a smooth constant force into the soil
mass or sample until calibration mark is level with soil.
4. Take reading from the top of the indicator ring. Scale measures strength in kg per sq cm or tonne
per sq. ft.
Appendix-1/3