The effect of joint properties on interlocking block pavement performance

Joints play an important role in Interlocking Block Pavement (IBP) performance as they facilitate load transfer between the blocks, enhancing the pavement's ability to disperse loads and resist deflection. Previous laboratory model tests have aimed to identify the optimal joint width for effective load transfer. However, the findings vary due to differences in the geotechnical properties of the joint sand used in these tests, such as mineralogy, grain size distribution, and relative density, which are often overlooked and not clearly defined. Therefore, this study conducted repeated loading tests and pull-out tests on IBP with varying joint widths, focusing on the geotechnical aspects of the joint sand. Additionally, a newly designed 2D chamber enabling particle image velocimetry analysis was employed to evaluate the impact of joint properties on sublayer deformations. The test results indicated that narrow and dense joints exhibited higher deflection resistance and load dispersion ability, attributed to increased shear resistance at the joints as estimated from pull-out tests. Based on the PIV analysis results, it resulted in sublayer settlements spreading over a wide area at a shallow depth. In contrast, wider and looser joints demonstrated significant settlements extending to the base layer, indicating a potential for rutting failure.