Pumping in rigid pavement can be defined as a traffic-induced subgrade soil migration into an overlying subbase layer, and/or redistribution of materials under slabs. Pumping may reduce the service life of pavement. This study aimed to assess the effectiveness of a geotextile layer in reducing the upward migration of subgrade soil particles to subbase and increasing service life in rigid pavements. A one-third scale model mobile load simulator (MMLS3), an accelerated pavement testing (APT) device, was used to simulate the repeated traffic loading on a scaled simulated pavement representing a typical rigid interstate highway. Two tests with identical configurations were conducted, except that a geotextile layer was placed at the interface of subgrade and subbase in one of the tests. In this study, pumping at a rigid pavement joint was investigated. Results of the tests were then compared. Materials used for construction of the scaled pavements were selected such that they represented an in situ stress condition. It was realized that the amount of migration increased with increased number of loading cycles. After 1,000,000 cycles of MMLS3 loading, approximately 70% reduction in the amount of subgrade migration and 52% reduction in the severity of joint faulting were observed when using geotextile at the subgrade-subbase interface of the pavement. This indicated that a geotextile separation layer was significantly effective in mitigating subgrade soil migration and could extend pavement serviceability.