Deformation monitoring on cement stabilized macadam with strain sensor during compaction

To analyze the longitudinal and transverse deformation of cement stabilized macadam in the process of rolling, fiber Bragg grating strain sensors are installed at the bottom of the base layer to study the change behaviors of longitudinal and transverse deformation of cement stabilized macadam during compaction. The results show that fiber Bragg grating sensing technology can successfully monitor the whole compaction process of cement stabilized macadam. During the compaction process, both the longitudinal strain and the transverse strain at the bottom of the base show predominantly tensile strain under the action of the compacting load. In the process of vibratory compaction, the peak values of longitudinal and transverse strain are more than two times of its corresponding average values of peak strain under static compaction, respectively, and the efficiency of vibrating compaction is more than two times of that of static compaction. With the increase of rolling times, the residual strain of the cement stabilized macadam increases gradually. At the end of vibrating compaction, the residual strain reaches its maximum value. At the final compaction stage, the residual strain of base gradually decreases. During the rolling process, the lateral deformation of cement stabilized macadam is greater than that of longitudinal, and the deformation performance of cement stabilized macadam base in compaction process is different from that in service period. Both longitudinal and transverse strains increase to a certain extent after 1 month of curing. The strain increasing in curing period is due to drying shrinkage and thermal shrinkage, and the shrinkage strain is non-uniform along the road. The deformation state at the end of compaction has an important influence on the development of cement stabilized macadam deformation during curing period, and increases the final deformation of cement stabilized macadam.