Part 16 covers the laboratory California Bearing Ratio — the soil's penetration resistance expressed as a percentage of a standard crushed-stone value, tested at the design density and moisture (usually 4-day soaked for the worst case). CBR is the subgrade-strength input that governs flexible-pavement thickness design (IRC 37) and is a key earthwork acceptance parameter.
Key Requirements
•Test at the field/design dry density and moisture; usually 4-day soaked (worst-case saturated subgrade)
•CBR = (test load / standard load) × 100 at the specified penetration (2.5 mm / 5.0 mm), report the higher per the rule