Proofrolling

Proofrolling is a construction verification technique used in geotechnical and pavement engineering to evaluate whether a prepared subgrade, subbase, or base layer is stable enough to receive further pavement construction. The process involves rolling the surface with a heavy roller to identify soft or pumping zones that could compromise the performance of the final pavement.

Typically performed after initial compaction of the base or subgrade, proofrolling uses a roller such as a pneumatic-tired or a steel-wheeled unit moved at a slow, controlled speed. As the roller passes, operators look for visible deflection, rutting, surface cracking, or water-pumped stains that indicate inadequate compaction or overly soft material. If soft spots are detected, the area is usually cleared, moisture is adjusted if necessary, material is reworked, and the spot is recompacted or replaced, after which the area is re-rolled.

Remediation may involve removing and replacing suspect material, improving drainage, or altering moisture content to achieve proper compaction characteristics. After remediation, proof rolling is typically repeated to confirm the area has achieved the required stiffness and uniform support for subsequent pavement layers.

Limitations and context: proofrolling is primarily a qualitative test based on observation of surface responses, and results can be influenced by moisture, weather, roller type, and operator judgment. It is often complemented by other in-situ tests or acceptance criteria specified by project standards or local regulations, such as AASHTO or ASTM guidelines, to provide a more quantitative assessment of subgrade performance.