Effect of aging on dynamic properties of municipal solid waste: A case study of Kahrizak Landfill, Tehran, Iran

The effect of aging on dynamic properties of Municipal Solid Waste (MSW) including damping ratio and shear modulus was investigated in the current research. For this purpose, a series of cyclic Consolidated Undrained (CU) triaxial tests were performed on fresh and old reconstituted cylindrical specimens, taken from Mansoory Prototype Landfill (MPL) placed in Kahrizak Landfill, Tehran, Iran. The results showed that theshear modulus of old samples (7.5 years old) was more than that of the fresh ones. This trend can be attributed to decomposition of waste over time, which leads to reduction in organic content and, consequently, increment of fibrous waste particles (plastics) of the old samples. On the other hand, the results also indicated that the damping ratio was partially dependent on the composition of the specimen and it slightly decreased with increasing the age of MSW. The high percentage of organic content in fresh specimens can be considered as the main reason for this behavior. Finally, the normalized shear modulus reduction and strain-dependent material damping curves were prepared for both ages of retrieved MSW from Kahrizak Center Landfill (KCL). The results of the current study are in the  rangeb reported in the technical literature and can be used as reliable data for seismic purposes.