NDT measurement of pavement surface deflections provides information that can be used for the structural evaluation of new or in-service pavements. These deflection measurements may be used to determine the following pavement characteristics:

5.1.1 Modulus of each layer.

5.1.2 Overall stiffness of the pavement system.

5.1.3 Load transfer efficiency of PCC pavement joints.

5.1.4 Modulus of subgrade reaction.

5.1.5 Effective thickness, structural number, or soil support value.

5.1.6 Bearing capacity or load carrying capacity of a pavement.

These parameters may be used for the analysis and design of reconstructed and rehabilitated flexible and rigid pavements, pavement structural adequacy assessment including joint efficiency of PCC pavement, void detection in PCC pavement, research and/or network structural inventory purposes.

1.1 This guide provides procedural information for measuring pavement surface deflections, directly under, or at locations radially outward (offset) from a known static, steady-state, or impulse load. Deflections are measured with sensors that monitor the vertical movement of a pavement surface due to the load. This guide describes procedures for the deflection measurement using various deflection testing devices and provides the general information that should be obtained regardless of the type of testing device used.

1.2 This Guide is applicable for deflection measurements performed on flexible asphalt concrete (AC), rigid portland cement concrete (PCC), or composite (AC/PCC) pavements. Rigid pavements may be plain, jointed, jointed reinforced, or continuously reinforced concrete.

1.3 The values stated in SI units are to be regarded as standard. Inch-pound units given in parentheses are for information purposes only.

1.4 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.