Evaluation of pavement design in Virginia based on layered deflections, subgrade and its moisture content.

Studies were conducted to relate the deflection of flexible pavements to such environmental factors as temperature and moisture content of the pavements and their subgrade soils. Also considered were the thickness and the relative positions of the different components making up the pavement systems. Seven pavement designs were studied with respect to the above factors. The major conclusions of the study are: 1. The effect of a weak sandwiched layer in reducing pavement strength needs to be considered during pavement design and evaluation. 2. The air temperature considerably affects the pavement modulus. There is a great need for correcting dynaflect deflections for temperature in Virginia. 3. Another factor that affects the value of the pavement modulus is the rigidity of the support to the asphaltic concrete; the greater the rigidity, the, higher the pavement modulus. 4. The temperature sensitivity of the pavement modulus is directly proportional to the pavement modulus and the thickness of the asphaltic concrete layer. 5. The primary factor that affects the subgrade modulus appears to be the relative density of the subgrade soil. Low density soils cause high subgrade moisture and low subgrade modulus and high variations in both the moisture and modulus. The reverse is also true.