Analysis of pavement residue properties under moisture induced attack at Tuen Mun highway, Hong Kong: Fid-Bau Portal

Analysis of pavement residue properties under moisture induced attack at Tuen Mun highway, Hong Kong

Hung, Wing-tat / Wong, Wing-gun / Tang, Sau-veng

AbstractTuen Mun Road (TMR), some 15 km in length, is a major urban highway linking Kowloon Peninsula and Tuen Mun New Town. TMR was constructed along the terrain slope, with many cut and fill sections, in the mid-1970s. More than 100 million commercial vehicles or 254 million standards axles were recorded between the years, 1978 and 2001. This cumulative traffic load is well above the original design capacity. Moisture induced damages are observed and sections of TMR were resurfaced from one to five times over the years and currently it still provides a reasonable level of service. This research intends to find out the residual properties of this road, in particular the effects of re-surfacing on the resistance of moisture attack, which is a common cause of pavement defects in Hong Kong. Core samples of the pavement were obtained from both driving directions of TMR at a 500-m interval. Specimens cut from these samples were subjected to a series of testings to find out the air void, grading, binder content, and indirect tensile stiffness modulus (ITSM). Stiffness modulus ratio (MRR), which is defined as the ratio of ITSM of moisture-treated specimen to untreated specimen, is employed as an indicator of the structural resistance to moisture attack. The results show that the MRR increases as the number of resurfacing increases, indicating resurfacing on the in-service pavement is effective in protecting the structural integrity of the pavement. The aggregate used for constructing the roadbase is finer and the bitumen content is richer than the recipe mix design.