Pavement Evaluation & Overlay Design: Structural Deflection Kinetics, Benkelman Beam Dynamics, and Mechanistic-Empirical Fatigue Modeling
Pavement evaluation and overlay structural design assess the functional and structural degradation of existing flexible and rigid highway pavements over their design life. Repeated dynamic axle loadings, combined with environmental moisture variation and thermal cycling, induce fatigue cracking in asphalt layers and subgrade rutting deformation. Structural evaluation quantifies pavement surface deflections under standard wheel loads to determine the required overlay thickness for structural restoration. In surface deflection testing using the Benkelman Beam Test (BBT) or Falling Weight Deflectometer (FWD) , the rebound deflection ($D$) measured under a dual-wheel axle load is normalized to standard temperature conditions ($25^\circ\text{C}$ or $35^\circ\text{C}$). The characteristic rebound deflection ($D_c$) incorporates statistical variation across a homogeneous road section: $$D_c = \bar{D} + k \cdot s$$ Where $\bar{D}$ is mean rebound deflection, $s$ is standard deviation o...