Predicting mechanical strength loss of natural stones after freeze–thaw in cold regions

2012 ◽  
Vol 83-84 ◽  
pp. 98-102 ◽  
Author(s):  
Fatih Bayram
Keyword(s):  
Mechanical Strength ◽  
Strength Loss ◽  
Cold Regions ◽  
Freeze Thaw ◽  
Natural Stones

scholarly journals The Effects of Particle Gradation on Salinized Soil in Arid and Cold Regions

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 236
Author(s):  
Xuebang Huang ◽  
Zizhao Zhang ◽  
Ruihua Hao ◽  
Zezhou Guo
Keyword(s):  
Particle Size ◽  
Soil Samples ◽  
Frost Heaving ◽  
Particle Content ◽  
Cold Regions ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Salinized Soil ◽  
Size Grading

Particle size grading impacts salt-frost heaving and dissolution collapse events of salinized soil on northwestern China’s arid and cold region highways. However, the influencing mechanisms remain unclear and the impact of varying particle size grading needs further investigation. Hence, this study focused on these effects and the number of freeze–thaw cycles on the characteristic changes in highway salinized soil in arid and cold regions. Three soil columns with different gradations were prepared to explore the gradation and the number of freeze–thaw cycle affects on salinized soil’s salt-frost heaving and dissolution collapse characteristics. The multi-functional physical simulation platform conducted multiple freeze–thaw cyclic tests in the laboratory. Test results confirmed significant and conclusive effects of gradation and the number of freeze–thaw cycles on salinized soil’s salt-frost heaving and dissolution collapse behaviors. Poorly graded salinized soil with high coarse particle content caused repeated freeze and thaw engineering hazards, significantly affecting salinized soil’s displacement and deformation behaviors during freezing. Contrarily, an increased range of fine particles more easily involved the characteristics of salinized soil during thawing. Therefore, the fourth freeze–thaw cycle was a crucial time node. After four freeze–thaw cycles, the displacement and deformation of original salinized soil and B-grade salinized soil samples (poorly graded with high fine particle content) tended to be stable. In contrast, the displacement and deformation of A-grade salinized soil samples (poorly graded with high coarse particle content) increased the growth rate. The present research results contribute to in-depth knowledge of the effects of gradation and freeze–thaw cycles on the characteristics of salinized soil in northwestern China, providing excellent referenced data support for the prevention and control of highway salinized soil failures and other engineering projects in arid and cold regions of northwest China.

scholarly journals Geomechanical and Acoustic Properties of Intact Granite Subjected to Freeze–Thaw Cycles during Water-Ice Phase Transformation in Beizhan’s Open Pit Mine Slope, Xinjiang, China

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2309 ◽  
Author(s):  
Yu Wang ◽  
Wenkai Feng ◽  
Huajian Wang ◽  
Jianqiang Han ◽  
Changhong Li
Keyword(s):  
Energy Balance ◽  
Fatigue Damage ◽  
Frequency Band ◽  
Open Pit Mine ◽  
Acoustic Properties ◽  
Open Pit ◽  
Cold Regions ◽  
Detection Techniques ◽  
Freeze Thaw ◽  
Energy Balance Approach

The deterioration of rock geomechanical behaviors subjected to freeze–thaw (F–T) action is a determining factor for rock engineering and rock structures in cold regions. In this work, taking six groups of granite obtained from an open pit mine as the research object, F–T cycle treatment, in-situ AE (acoustic emission) monitoring and ultrasonic detection techniques were performed to experimentally reveal the effects of F–T fatigue damage on the mechanical and acoustic properties of granite. The results indicate that the F–T action impacts the rock’s mesoscopic structure, deformation, strength, P and S-wave velocities, AE pattern and energy release. The accumulated AE counts and accumulated AE energy show a decreasing trend as the F–T cycle increases. The frequency spectrum revealed that the width of the low frequency band decreases and the high frequency band increases with increasing F–T cycles, indicating that there is an increase in large-scale cracks for a sample with high F–T treatment. In addition, energy balance analysis further illustrates the energy dissipation and release mechanism. The energy proportion used to drive the crack propagation is relatively small with high F–T treatment, and the final released energy becomes the minimum. The energy evolution characteristics analyzed by the energy balance approach is in good agreement with AE results. It is suggested that the F–T fatigue damage influences the rock energy storage and release characteristics and the instability of rock in the cold regions.

Mechanical and electrical properties of coarse-grained soil affected by cyclic freeze-thaw in high cold regions

2020 ◽  
Vol 27 (3) ◽  
pp. 853-866
Author(s):  
Yong-long Qu ◽  
Wan-kui Ni ◽  
Fu-jun Niu ◽  
Yan-hu Mu ◽  
Guo-liang Chen ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Coarse Grained ◽  
Cold Regions ◽  
Freeze Thaw ◽  
Mechanical And Electrical Properties ◽  
Coarse Grained Soil

scholarly journals Effect of Moderate Temperature Thermal Modification Combined with Wax Impregnation on Wood Properties

2020 ◽  
Vol 10 (22) ◽  
pp. 8231
Author(s):  
Jing-Wen Zhang ◽  
Hong-Hai Liu ◽  
Lin Yang ◽  
Tian-Qi Han ◽  
Qin Yin
Keyword(s):  
Mechanical Strength ◽  
Dimensional Stability ◽  
Color Change ◽  
Strength Loss ◽  
Wood Properties ◽  
Thermal Modification ◽  
Moderate Temperature ◽  
Modulus Of Rupture ◽  
Internal Surfaces ◽  
Higher Temperature

Thermal modification (TM) improves the hydrophobicity, dimensional stability, and durability of wood, but TM commonly results in severe color change and mechanical strength loss as wood is treated at higher temperature. In this study, Pterocarpus macrocarpus Kurz wood was thermally modified at moderate temperature (150 °C) and higher temperature (200 °C), and subsequently TM wood at 150 °C was subjected to wax impregnation (WI), the effect of a combination of TM and WI on the hygroscopicity, dimensional stability, and mechanical properties, as well as the micro-structure of wood, were investigated and compared. The results showed that the mass loss of wood was slight at 150 °C TM, while it became severe at 200 °C TM conditions. TM conditions affected the amount of the subsequent wax impregnation; the equilibrium moisture content (EMC), water absorption ratio, and adsorption and absorption swelling of the 150 °C TM + WI group were lower than that of 200 °C TM, and presented the lowest value. Moderate temperature TM could improve the hydrophobicity and dimensional stability of wood, but WI played a key role in the improvement. TM decreased the modulus of rupture (MOR) of wood, while WI improved the MOR. TM increased the modulus of elasticity (MOE) of wood, but WI had little effect on MOE; Scanning electron microscope (SEM) observation showed that the wax was successfully impregnated into the wood interior, and presented an even distribution on the internal surfaces of wood cells; Fourier-transform infrared spectroscopy (FTIR) spectra verified the changes of –OH and C=O after TM and TM + WI, which contributed to decreasing hygroscopicity and improving the dimensional stability of the wood. Impregnated wax improved wood mechanical strength, but decreased the lightness, and deepened the color of wood. The combination of thermal modification at moderate temperature with subsequent wax impregnation is a practical approach for improving wood properties.

scholarly journals Research on the Pore Evolution of Sandstone in Cold Regions under Freeze-Thaw Weathering Cycles Based on NMR

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Zheng Pan ◽  
Keping Zhou ◽  
Rugao Gao ◽  
Zhen Jiang ◽  
Chun Yang ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Pore Structure ◽  
Western China ◽  
Cold Regions ◽  
Abrupt Decrease ◽  
Evolution Law ◽  
Red Sandstone ◽  
Freeze Thaw ◽  
Evolution Characteristics ◽  
Pore Evolution

The evolution of the rock pore structure is an important factor influencing rock mechanical properties in cold regions. To study the mesoscopic evolution law of the rock pore structure under freeze-thaw weathering cycles, a freeze-thaw weathering cycle experiment was performed on red sandstone from the cold region of western China with temperatures ranging from -20°C to +20°C. The porosity, T2 spectral distribution, and magnetic resonance imaging (MRI) characteristics of the red sandstone after 0, 20, 40, 60, 80, 100, and 120 freeze-thaw weathering cycles were measured by the nondestructive detection technique nuclear magnetic resonance (NMR). The results show that the porosity of sandstone decreases first and then increases with the increase of the freeze-thaw weathering cycles and reaches the minimum at 60 of freeze-thaw weathering cycles. The evolution characteristics of porosity can be divided into three stages, namely, the abrupt decrease in porosity, the slow decrease in porosity, and the steady increase in porosity. The evolution characteristics of the T2 spectrum distribution, movable fluid porosity (MFP), and MRI images in response to the freeze-thaw weathering process are positively correlated with the porosity. Analysis of the experimental data reveals that the decrease in the porosity of the red sandstone is mainly governed by mesopores, which is related to the water swelling phenomenon of montmorillonite. Hence, the pore connectivity decreases. As the number of freeze-thaw cycles increases, the effect of the hydrophysical reaction on the porosity gradually disappears, and the frost heaving effect caused by the water-ice phase transition gradually dominates the pore evolution law of red sandstone.

scholarly journals Characteristics of Unloading Creep of Tuffaceous Sandstone in East Tianshan Tunnel under Freeze-Thaw Cycles

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Zhijun Zhou ◽  
Haochen Zhan ◽  
Jiangyang Hu ◽  
Chenning Ren
Keyword(s):  
Creep Rate ◽  
Surrounding Rock ◽  
Cold Regions ◽  
Freeze Thaw ◽  
Rock Samples ◽  
Thaw Cycle ◽  
Short Period ◽  
Macro Scale ◽  
Freeze Thaw Cycle ◽  
East Tianshan

The physicomechanical properties of tunnel surrounding rock are influenced by many factors such as the external environment and freeze-thaw cycles, especially in engineering in high cold regions. To understand the characteristics of freeze-thaw cycles on the creep properties of rocks in high cold regions, a freeze-thaw test, SEM test, triaxial compression test, and triaxial unloading creep test were carried out for tuffaceous sandstone in the G575 East Tianshan Tunnel in Hami, Xinjiang. The results show the following: (1) the freeze-thaw cycle reduces the degree of cementation of mineral particles in a microcosm, manifested on a macro scale by the scaling mode and crack propagation mode; (2) the effect of freeze-thaw cycles reduces the compressive strength and shear strength of rock samples (i.e., ductility enhancement); (3) for tuffaceous sandstone, the unloading process and freeze-thaw cycle each lead to improved creep deformation in rock samples, and radial deformation is more sensitive to rock deformation and failure; and (4) the creep rate of surrounding rock can be reduced by confining pressure. The peak creep rate increased with freeze-thaw time, as did the overall creep rate. Attention should be paid to deformation within a short period, and necessary supporting and protection measures should be taken to reduce creep.

Influence of Silane Treatment on the Freeze-Thaw Resistance of Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 565-568 ◽  
Author(s):  
Xiao Jian Gao ◽  
Hong Wei Deng ◽  
Ying Zi Yang
Keyword(s):  
Surface Treatment ◽  
Water Adsorption ◽  
Concrete Structures ◽  
Air Entrainment ◽  
Concrete Surface ◽  
Silane Treatment ◽  
Cold Regions ◽  
Bonding Force ◽  
Freeze Thaw ◽  
Surface Impregnation

The influences of silane impregnation on water adsorption, bonding force between ice and concrete surface and resistance to freeze-thaw of concretes were studied. Two strength grades (C30 and C50) and the air entrainment were considered for concrete preparation. The results show that surface impregnation with silane reduces the final water adsorption of concrete by more than 90% when compared with the untreated specimen. The silane treatment significantly decreases the bonding force between ice and concrete surface. The resistance to freeze-thaw of both new and old concretes can be improved by the silane treatment. Therefore, the surface treatment with silane is suggested as an effective method to improve the durability of concrete structures in cold regions.

scholarly journals Strength, Permeability, and Freeze-Thaw Durability of Pervious Concrete with Different Aggregate Sizes, Porosities, and Water-Binder Ratios

2018 ◽  
Vol 8 (8) ◽  
pp. 1217 ◽  
Author(s):  
Hanbing Liu ◽  
Guobao Luo ◽  
Haibin Wei ◽  
Han Yu
Keyword(s):  
Compressive Strength ◽  
Mechanical Strength ◽  
Aggregate Size ◽  
Pervious Concrete ◽  
High Porosity ◽  
Range Analysis ◽  
Freeze Thaw ◽  
Binder Ratio ◽  
The Impact ◽  
Water Binder Ratio

Pervious concrete (PC), as an environmental friendly material, can be very important in solving urban problems and mitigating the impact of climate change; i.e., flooding, urban heat island phenomena, and groundwater decline. The objective of this research is to evaluate the strength, permeability, and freeze-thaw durability of PC with different aggregate sizes, porosities, and water-binder ratios. The orthogonal experiment method is employed in the study and nine experiments are conducted. The compressive strength, flexural strength, permeability coefficient, porosity, density, and freeze-thaw durability of PC mixtures are tested. Range analysis and variance analysis are carried out to analyze the collected data and estimate the influence of aggregate size, porosity, and water-binder ratio on PC properties. The results indicate that porosity is the most important factor determining the properties of PC. High porosity results in better permeability, but negatively affects the mechanical strength and freeze-thaw durability. PC of 15% porosity can obtain high compressive strength in excess of 20 MPa and favorable freeze-thaw durability of 80 cycles without sacrificing excessive permeability. Aggregate size also has a significant effect on freeze-thaw durability and mechanical strength. Small aggregate size is advantageous for PC properties. PC with 4.75–9.5 mm coarse aggregate presents excellent freeze-thaw durability. The influence of the water-binder ratio on PC properties is not as significant as that of aggregate size and porosity. An optimal mix ratio is required to trade-off between permeability, mechanical strength, and freeze-thaw durability.

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