Analysis of Factors Affecting the Rheological Properties of Muddy Flow and Their Measurement Method

Abnormal weather phenomena debris damage has recently been increasing worldwide. As primary rheological properties, the yield stress and plastic viscosity of muddy materials affect the flow distance and velocity. Therefore, in this study, direct and indirect measurement test methods for rheological properties and factors affecting the these properties were analyzed. Measurement methods utilize rheometers, shear creep, fall cones, inclined planes, direct shear, and ring shear, with each method having its respective advantages and disadvantages. Factors that affect rheological properties are water content, liquidity index, and the size of soil particles. This study enables determination of the best test and rheological properties suitable for the selected range and selected object.

Experimental Study on Shear Stress-Displacement, Creep and Shear Slip Instability Behavior of Rock Fractures

Rock mass inherently contains discontinuities, and shear sliding of rock masses along discontinuities is the most common failure mode of rock mass in engineering practice (such as slope, dam and tunnel). In this study, the mechanical and failure properties of rock fractures were examined through direct shear tests, pre-peak tiered cyclic shear tests and multistage loading shear creep tests. The results show that the deformable memory of rocks can be observed from shear stress-shear displacement curves, namely reloading curves continued to increase along the loading curve of the last cycle under the pre-peak tiered cyclic shear loading. The envelopes of shear stress-shear displacement curves were similar to the variation trend of shear stress-shear displacement curves obtained in the direct shear test. Besides, the variation trend of residual shear displacement (RSD) and relative residual shear displacement (RRSD) before slip instability were obtained by the data analyses of rock mass under pre-peak tiered cyclic shear tests. It is found that the change in the friction and sliding state of rock fracture is the main reason for the fluctuation of shear stress-shear displacement curves. The Chen's method was used to process the multistage loading shear creep curves and the three creep stages were analyzed. Moreover, the complex creep models in some previous studies were discussed and the data of shear creep tests were successfully fitted to the classical Burgers model. This study provides a guidance for the study on the shear instability of rock fractures under different shear loading paths.

Enhanced Acceptance Specification of Asphalt Binder to Drive Sustainability in the Paving Industry

Testing small amounts of extracted and recovered asphalt binder as used in construction allows for the acceptance of materials in accordance with traffic and climate requirements. This approach facilitates the sustainable use of resources and thus prepares the paving industry for the true circular economy. Oscillatory, creep, and failure tests in a rheometer are compared for the performance grading of 32 asphalt binders extracted and recovered from real-world contract samples. Films 8 mm in diameter and 0.5 mm thick were tested from 35 to −5 °C in dynamic shear, followed by shear creep at 0 and 5 °C, and finally in tertiary tensile creep at 15 °C. The enhanced protocol uses a very small amount of material in contrast to current methods, yet it provides comparable results. Phase angle measurements appear to be optimal for performance grading, but further field study is required to determine if additional binder properties such as stiffness and/or failure strain would be required for the control of cracking.