Missouri University of Science and Technology. Dept. of Civil, Architectural, and Environmental Engineering

cmr 16-004

Tech Report

Missouri

Missouri. Dept. of Transportation. Division of Construction and Materials

Pavement performance models describe the deterioration behavior of pavements. They are essential in a pavement management

system if the goal is to make more objective, reliable, and cost-effective decisions regarding the timing and nature of pavement

maintenance activities. The general objective of Task 2 was to develop performance models for a variety of pavement families and

pavement preservation treatments used by the Missouri Department of Transportation (MoDOT). Using the data collected in Task

1, linear least-squares regression techniques were used to generate deterministic models that predict the International Roughness

Index (IRI), the pavement condition measure most widely used today. Family IRI-prediction models were developed for full-depth

asphalt (FDA), concrete (PCC), and composite (Comp) pavements. Treatment IRI-prediction models were developed for 1-in.

overlays on FDA pavements, chip seals on FDA pavements, and 3.75-in. overlays on PCC pavement. Predictor variables

consistently shown to be highly significant in predicting IRI for both FDA and Comp pavements were initial IRI (IRIo or the IRI

value right after treatment) and pavement surface age (SA). The majority of the PCC pavement sections selected were so old that

IRIo could not be determined (or estimated with any confidence), therefore SA was the dominant predictor variable in the PCC

pavement family model. Terminal IRI (IRIt

which was the IRI just prior to a treatment) was also a significant predictor of IRI and

was directly or indirectly included in the FDA and Comp family and treatment models. Additional significant IRI predictors

(depending on the model) were the climate parameters DT32 (days/year that air temperature was below freezing), FT (freeze/thaw

cycles per year), and DP01 (days/year that precipitation was at least 0.1–in.), subgrade soil parameters P200 (percent passing the

#200 sieve) and Pclay (percent clay-size soil), and LstTrtThk (the last treatment thickness).

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