Effects of the reinforcement content and reinforcement scale on the shear strength characteristics of mechanically biologically treated waste

Mechanical and biological treatment (MBT), which can be used for waste reduction and for the burning of methane from biological treatments to generate electricity and heating, has become a popular research topic in environmental geotechnical engineering. This study investigated the mechanical behaviour of MBT waste and the effects of different reinforcement contents and reinforcement scales on its shear strength characteristics, and 68 groups of MBT waste samples from the Hangzhou Tianziling landfill were tested in the laboratory with a direct shear test apparatus. The samples exhibited displacement hardening behaviour in their mechanical response. The results show that the content and scale of the reinforced materials in MBT waste play an important role in the strength characteristics of MBT waste, and graphs showing the variation of the MBT waste shear strength and shear strength parameters with different reinforcement contents and reinforcement scales are shown. The range of cohesion c is 6.0-12.0 kPa, and the internal friction angle φ is 15.6-26.6°, respectively. The results of this study provide a reference for the assessment of slope stability at MBT landfills.

Evaluating the reinforcement content and elastic properties of Mg-based composites using dual-mode ultrasonic velocities

Based on the wave-mode-converted principle, an immersion-focused transducer is employed to determine the longitudinal wave and shear wave velocities. The experimental condition is then investigated to obtain the converted shear wave, which is used to analyze the relationship between the reinforcement content and the dual-mode ultrasonic velocities. In addition, the elastic modulus is calculated. Magnesium-based composite samples with different reinforcement contents are manufactured to conduct an ultrasonic experiment, wherein the dual-mode velocities vary with the change in the reinforcement content; the correlation coefficient is 99.17%. An ultrasonic dual-mode velocity model is developed to analyze the distribution of the reinforcement content. By employing the measured values obtained from the destructive method, the largest errors in the reinforcement content and elastic modulus evaluated using the proposed method are found to be -5.76% and 5.85%, respectively. The shear wave velocity determined using a normal-incidence shear-wave transducer reveals the accuracy with which the errors are measured. This method provides an effective tool to nondestructively evaluate the microstructure and elastic properties of Mg-based composites.