Soil Improvement and Inspection Techniques for the Base Course of Rigid Pavement for an Airport Runway

The Taiwan Taoyuan International Airport (TTIA) has been in service for more than $40\mathrm{years}$. Some visible defects on the rigid pavement runway have been observed in recent years. In this paper, the authors aim to provide a practical and reliable method to improve the soil condition under the rigid pavement of a damaged airport runway. In addition, the authors present an inspection technique with excellent results, which could be evidence for the high efficiency of the proposed improvement work. The defects included surface settlement, slurry leakage through the gaps between panels (pumping), concrete panel cracks, and so on. In this TTIA case, the underpanel grouting method (UPGM) was selected to solve these problems. Grouting flow and pressure were well controlled, and the soil in the base course was successfully reinforced, with the gaps between the concrete panels and the aggregate base course filled. Under the application of the UPGM, 7,170 grouting holes were drilled, and $\mathrm{1,453,723}\mathrm{kg}$ of grouting materials were used to improve the soil conditions under the rigid pavement runway 23L-05R. For verification of its effectiveness, a ground-penetrating radar (GPR) and a falling weight deflectometer (FWD) were used. No noticeable deviation was observed in the GPR reports. Besides, the test results of FWD for concrete panel 71-6—the deflection ratios of the corner/center, which were tested before and after grouting—are 188% and 109%, respectively. All the test results show excellent efficiency of the UPGM.