Frost resistance of rock materials

岩石材料的抗冻性

Construction and Building Materials, Volume 148, 1 September 2017, Pages 704-714

Zbigniew Rusin, Przemysław Świercz

Abstract：A precise classification of rock raw materials with respect to frost-resistance is still an issue. The knowledge of the rock’s origin and its mineral composition and structure is not an effective diagnostic tool. This paper discusses the possibility of applying the capillary absorption and volumetric strain of a frozen rock sample for diagnostic purposes. Twenty one different volcanic, metamorphic and sedimentary rocks were used in the study. The strain caused by the phase change of water into ice was determined by the Differential Analysis of Volumetric Strains (DAVS). The following basic physical properties were also examined: porosity, absorbability, density, capillary absorption and frost resistance determined by the freeze-thaw testing. The mineral composition and microstructure of rocks were investigated using the X-ray method, derivatographic test, and microscopic observation. The (αr) coefficient has been proposed, which in certain circumstances can be considered as a material constant, defining the ratio of the mass of water causing the rock strain during the phase change to the total volume of water in the material pores. The diagnostics criteria enabling the frost-resistance prediction have been presented.

Ultrasonic time-frequency method to evaluate the deterioration properties of rock suffered from freeze-thaw weathering

基于超声时频方法的冻融风化作用下岩石损伤劣化评估

Cold Regions Science and Technology, Volume 143, November 2017, Pages 13-22

Peng Wang, Jinyu Xu, Xinyu Fang, Peixi Wang, Ming Wen

Abstract：Cyclic freeze-thaw (F-T) is a serious natural weathering mechanism for rock engineering and stone constrictions in cold regions. Considering the universality and destructiveness of rock F-T weathering, evaluation of rock deterioration is of vital importance. In this work, ultrasonic detections and mechanical experiments including uniaxial compression, splitting tension and angle-changed shear tests were carried out on red-sandstone specimens without and after different F-T cycles. Attenuation occurred to almost all of the indexes of red-sandstone after F-T weathering, including mechanical properties such as uniaxial compressive strength (UCS), deformation modulus (Ed), splitting tensile strength (STS), cohesion (C) and friction angle (ϕ), and ultrasonic properties such as the P-wave velocity (Vp), head-wave amplitude (Ah), centroid frequency (fc) and kurtosis of frequency spectrum (KFS). After 25 F-T cycles, the UCS, Ed, STS, C, ϕ, Vp, Ah, fc and KFS decreased by 42.5, 63.0, 87.3, 33.7, 22.6, 50.6, 24.6, 38.3 and 0.56%, respectively. With increasing number of F-T cycles, similar convergent decrease tendencies between the UCS, Ed, STS, C and the Vp, Ah, fc, KFS were found, confirming the effectiveness of the ultrasonic time-frequency method to estimate the deterioration of rock suffered from F-T weathering. Similar degradation behavior in ultrasonic time-frequency properties and in mechanical properties resulted from the microscopic damages of red-sandstone suffered from F-T weathering. An ultrasonic evaluation auxiliary graph is suggested as a convenient practical evaluation method in rock engineering.

Thermal conductivities of frozen and unfrozen soils at three project sites in northern Manitoba

加拿大曼尼托巴北部三工程场地冻土与非冻土的热传导性

Cold Regions Science and Technology, Volume 140, August 2017, Pages 30-38

David Kurz, Marolo Alfaro, Jim Graham

Abstract：If acceptable performance is to be obtained from new highway embankments in cold regions, thermal modeling during initial design needs to simulate the effects of climate warming and changes in air-to-ground heat transfer on future ground temperatures, thawing, and resulting deformations.

The authors' research involved geothermal modeling of current and future seasonal ground temperatures under highway embankments and transmission line towers on degrading permafrost in northern Manitoba, Canada. This paper describes a part of the larger study that used a thermal needle to measure thermal conductivities of samples taken from three sites. Analyses that used these measured thermal conductivities produced better modeling of seasonal temperatures than analyses that used empirical values from the research literature.