Moisture increase in pavement subsurface layers has a significant influence on granular material properties that affect the expected pavement performance. In-situ moisture variations in unbound base layer over time significantly depend on water infiltration after precipitation and pavement surface conditions. Consequently, base resilient modulus (MR) is decreased considerably, which leads to premature failure and reduced service life. This study presents Long-term Pavement Performance (LTPP) data analyses for quantifying the effect of moisture infiltration through surface discontinuities (cracks and joint openings) on flexible and rigid pavement performance. Subsurface moisture data obtained through Seasonal Monitoring Program (SMP) time domain reflectometry (TDR) are an excellent source to quantify the moisture-related damage in flexible and rigid pavements located in different climates. The artificial neural network (ANN) models were developed using SMP data for flexible and rigid pavement sections. The results show that higher levels of cracking and joint openings will lead to an increase moisture levels within base layer. Also, the moisture content increases with higher percentage passing # 200 sieve (P200), and higher precipitation levels, especially in wet climates. The MR of the base decreases significantly with an increase in moisture levels. For flexible pavements, the maximum reduction in base MR ranged between 40% to 175% for the pavement sections located in dry and wet regions, respectively. In rigid pavements, the maximum reduction in base MR may vary from 10% to 125% for the pavement sections located in dry and wet regions, respectively. The major reasons for higher base moisture variations in wet climates are higher levels of surface cracking and precipitation. The base moisture values do not vary significantly in dryer climates since the amount of precipitation and observed cracking levels were low in these regions. Due to increased moisture and a corresponding reduction in base MR values, the performance of pavement sections located in wet climates is adversely affected. The findings imply that an adequate and timely preservation treatment such as a crack sealing can enhance the pavements service life significantly, especially in wet climates. Therefore, cracks should be sealed when the extent of fatigue cracking is within 6% to 7% and between 10% to 11% for the flexible pavements sections located in wet and dry climates, respectively. In rigid pavements, the joints should be resealed when the damaged joint sealant length exceeds 50 to 75 meters.
Read
