scholarly journals Influence of Freeze-Thaw Cycles on Engineering Properties of Tonalite: Examples from China

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Su-Ran Wang ◽  
You-Liang Chen ◽  
Jing Ni ◽  
Mu-Dan Zhang ◽  
Heng Zhang
Keyword(s):  
Fracture Toughness ◽  
Young’S Modulus ◽  
Minimum Temperature ◽  
Young's Modulus ◽  
Physical And Mechanical Properties ◽  
Frost Damage ◽  
Engineering Properties ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

The deterioration of the physical and mechanical properties of tonalites subjected to freeze-thaw cycling under three different temperature ranges was explored using several experimental techniques. Uniaxial compression and three-point bending tests were conducted on untreated and treated tonalite specimens. Clear decreases in uniaxial compressive strength (UCS), Young’s modulus, and fracture toughness were observed in tonalite specimens with frost damage. Although Young’s modulus and fracture toughness did not show clear decreases as the minimum temperature of the freeze-thaw cycle decreased from −30°C to −50°C, the UCS decreased almost linearly. The macromechanical characteristics of the tonalites can be explained by changes in mineral content and microstructure. The intensity of X-ray diffraction (XRD) peaks of minerals in tonalites that had not been freeze-thaw cycled were approximately 10 to 20 times higher than the peaks for the specimens subjected to freeze-thaw cycling, implying that the internal structure of tonalite is less compact after frost damage. The microstructures of the tonalite specimens were also examined using scanning electron microscopy (SEM). Increased amounts of fragmentation and breaking of structural planes were observed as the minimum temperature of the freeze-thaw cycle decreased.

scholarly journals Effect of freeze–thaw cycle on physical and mechanical properties and damage characteristics of sandstone

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Longxiao Chen ◽  
Kesheng Li ◽  
Guilei Song ◽  
Deng Zhang ◽  
Chuanxiao Liu
Keyword(s):  
Mechanical Properties ◽  
Shear Failure ◽  
Triaxial Compression ◽  
Physical And Mechanical Properties ◽  
Freeze Thaw ◽  
Damage Characteristics ◽  
Large Pore ◽  
Natural Rock ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

AbstractRock deterioration under freeze–thaw cycles is a concern for in-service tunnel in cold regions. Previous studies focused on the change of rock mechanical properties under unidirectional stress, but the natural rock mass is under three dimensional stresses. This paper investigates influences of the number of freeze–thaw cycle on sandstone under low confining pressure. Twelve sandstone samples were tested subjected to triaxial compression. Additionally, the damage characteristics of sandstone internal microstructure were obtained by using acoustic emission (AE) and mercury intrusion porosimetry. Results indicated that the mechanical properties of sandstone were significantly reduced by freeze–thaw effect. Sandstone’ peak strength and elastic modulus were 7.28–37.96% and 6.38–40.87% less than for the control, respectively. The proportion of super-large pore and large pore in sandstone increased by 19.53–81.19%. We attributed the reduced sandstone’ mechanical properties to the degenerated sandstone microstructure, which, in turn, was associated with increased sandstone macropores. The macroscopic failure pattern of sandstone changed from splitting failure to shear failure with an increasing of freeze–thaw cycles. Moreover, the activity of AE signal increased at each stage, and the cumulative ringing count also showed upward trend with the increase of freeze–thaw number.

Waste Tile Usage Effect on the Sandy Subgrade Stabilized with Emulsion Bitumen Performance

2021 ◽  
Vol 47 (1) ◽  
pp. 164-173
Author(s):  
Mohammad Mehdi Khabiri ◽  
Bahareh Ebrahimialavijeh
Keyword(s):  
Bearing Capacity ◽  
Compression Strength ◽  
Engineering Properties ◽  
Coarse Grained ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Number Of Cycles ◽  
Surface Analysis Method ◽  
Drop Rate

Improving the subgrade performance and increasing their efficiency can lead to improving the operation and increasing the life of the pavement. One of the common solutions to improve the resistance and engineering properties of the soils is using the stabilizing materials. Using the waste materials as a stabilizer in the soil can lead to a reduction in project costs and help the protection from the environment. In this study, emulsion bitumen and crushed waste tile are used to stabilize the sand dune which is soil with low bearing capacity and resistance properties. In the present study, the emulsion bitumen and crushed waste tile have been used. The effect of dimensions and percentage of crushed tile with different percentages of emulsion bitumen on the compressive pressure and bearing capacity as well as the compressive strength after applying freeze-thaw cycle. The results indicate that the addition of crushed waste tile increases the compression strength and bearing capacity and the tile with a higher dimension has shown more effectiveness. Applying the freeze-thaw cycle has reduced the compression strength and increasing the number of cycles has increased the resistance drop rate. Soil stabilized with coarse-grained tile has more resistance drop rate which increases by increasing the tile percentage. Then, the 3D graph and the recommended function related to each parameter investigated in the test were provided using the response surface analysis method.

Influence of B4C, SiC and Si3N4 Additions on Microstructures and Selected Properties of Titanium Nitride Matrix Materials Obtained by HPHT Method

2014 ◽  
Vol 89 ◽  
pp. 109-114
Author(s):  
Jolanta Cyboroń ◽  
Piotr Klimczyk ◽  
Pawel Figiel ◽  
Małgorzata Karolus
Keyword(s):  
Fracture Toughness ◽  
High Pressure ◽  
Phase Composition ◽  
High Temperature ◽  
Titanium Nitride ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Physical And Mechanical Properties ◽  
Ceramic Phase ◽  
Ultra High Temperature Ceramics

The paper presents the results of the High Pressure and High Temperature (HP-HT) sintering and investigation of Ultra High Temperature Ceramics (UHTC) composites of titanium nitride matrix. The aim of this studies were to determine the influence of additives on the ceramic phase composition, microstructure and selected properties. Three different kind of mixtures were prepared. 8 to 22 wt% B4C, SiC and Si3N4were added. Composites were sintered under high-pressure high-temperature conditions (HP-HT) using a Bridgman-type apparatus under pressure about 6 GPa. Materials were sintered at the range of 1450 to 1690 ° C, duration of sintering was 60s. The phase composition, microstructure, and the apparent density, Young's modulus, hardness and fracture toughness KIC (HV), using the Vickers indentation method were examined. Sintered titanium nitride with the 22 wt% silicon carbide participation was characterized the best physical and mechanical properties. For this material the relative density is 99%, the Young's modulus 435 GPa, Vickers hardness 18.3 GPa HV1 and fracture toughness 5.5 MPa∙m1/2.

scholarly journals Freeze-Thaw Behavior of Stabilized Clayey Soil with Red Mud and Cement

2022 ◽  
Vol 11 (01) ◽  
pp. 27-30
Author(s):  
Ekrem Kalkan
Keyword(s):  
Red Mud ◽  
Clayey Soil ◽  
Expansive Soil ◽  
Engineering Properties ◽  
Clayey Soils ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Cement Additive ◽  
Additive Materials

The clayey soils in areas with seasonal frost are exposed to at least one freeze-thaw cycle every year and worsen their engineering properties. To prevent the engineering properties of clayey soils, it is necessary to improve the freeze-thaw resistance of them. In this study, the clayey soil was stabilized by using red mud and cement additive materials. Prepared samples of clayey soil and stabilized clayey soil were subjected to the unconfined compressive test. To investigate the effects of red mud and cement additive materials on the freeze-thaw resistance of clayey soil, the natural and stabilized expansive soil samples were exposed to the freeze-thaw cycles under laboratory conditions. The obtained results showed that the red mud and cement additive materials increased the freeze-thaw resistance of clayey soil. Consequently, it was concluded that red mud and cement additive materials can be successfully used to improve the freeze-thaw resistance of clayey soils.

scholarly journals Laboratory Testing to Research the Micro-Structure and Dynamic Characteristics of Frozen–Thawed Marine Soft Soil

2019 ◽  
Vol 7 (4) ◽  
pp. 85 ◽  
Author(s):  
Zhi Ding ◽  
Bowen Kong ◽  
Xinjiang Wei ◽  
Mengya Zhang ◽  
Baolong Xu ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Dynamic Characteristics ◽  
Dynamic Properties ◽  
Soft Soil ◽  
Point Of View ◽  
Engineering Properties ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Ground Freezing ◽  
Freeze Thaw Cycle

The use of artificial freezing can change the mechanical properties of marine clay. In the construction of cross passages in metro tunnels in which the artificial ground freezing (AGF) method is applied, freeze–thaw circulation and cyclic loading could weaken the engineering properties of the clay, thus resulting in differential settlement. In this paper, the authors studied the dynamic properties of frozen–thawed soils under cyclic loading, with the help of dynamic triaxial testing. According to the dynamic triaxial test results and the images from scanning electron microscopy (SEM), the authors explained the weakening effect of both the freeze–thaw cycle and dynamic loading on soft soil. After freezing, the number of large pores increased. In addition, after cyclic loading, the pore structure of the soil showed a tendency towards compaction, which led to the large pores breaking into small ones. Subsequently, the potential reasons for the change of macroscopic dynamic characteristics were explained from a micro-scale point of view.

A Preliminary Research on Alkali-Activated Slag Concrete as Tunnel Lining in Severe Frigid Regions

2013 ◽  
Vol 668 ◽  
pp. 65-69 ◽  
Author(s):  
Heng Shu
Keyword(s):  
Frost Damage ◽  
Sem Analysis ◽  
Tunnel Lining ◽  
X Ray Diffraction ◽  
Alkali Activated Slag ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Activated Slag ◽  
Alkali Activated

The main structure materials of tunnel lining are concrete and steel, and the concrete frost damage is a typical degradation phenomenon of the tunnel linings in cold regions. Alkali-activated slag concrete (ASC) has a better freeze-thaw resistance, which can be used for tunnel lining in severe frigid regions. Freeze-thaw resistance, performance mechanism of ASC and microstructure were investigated by freeze-thaw cycle, X-ray diffraction (XRD) and Scanning electron microscope (SEM) analysis. The experimental results show that, ASC has excellent freeze-thaw resistance, and hydration products of ASC are mostly C-S-H, alkaline aluminosilicate. ASC has a good compact degree and uniformity of structure, and its high compressive strength also makes high freeze-thaw resistance. ASC may be selected as tunnel lining production materials in severe frigid regions because of the less reduction in the dynamic elastic modulus and mass loss of concrete.

Experimental Study on Damage Deterioration and Tensile Characteristics of Rock under Freeze-Thaw Environment

2012 ◽  
Vol 518-523 ◽  
pp. 1749-1752
Author(s):  
Hui Mei Zhang ◽  
Geng She Yang ◽  
Yuan Liang
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
Mechanical Problem ◽  
Mode Fracture ◽  
Red Sandstone ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Tensile Experiment ◽  
Cycling Experiment

The basic mechanical problem facing of environmental geotechnical engineering in cold regions is the physical and mechanical properties of rocks under freeze-thaw conditions. The freeze-thaw cycling experiment was conducted first for two types of rock which are red sandstone and shale, then the splitting tensile experiment on different freeze-thaw cycles. The damage deterioration and breaking behavior under freeze-thaw conditions was investigated, and the influence of lithology and freeze-thaw cycle on anti-tensile characteristics of rock was studied. It is shown that three freeze-thaw damage deterioration modes of two kinds of rock are spalling mode, fracture mode and crack mode. The freeze-thaw cycle leads to irreversible deterioration on physical and mechanical properties for rock, but the damage of red sandstone is more serious than that of shale by the number of freeze-thaw cycles. The regularity of freeze-thaw effects of compression and tensile characteristics for two rocks are identical, but the tensile characteristic is more sensitive to freeze-thaw cycle.

scholarly journals Microscopic mechanism of sandstone hydration in Yungang Grottoes, China

2020 ◽  
Vol 12 (1) ◽  
pp. 598-609
Author(s):  
Jiawei Chen ◽  
Jinming Xu ◽  
Jizhong Huang
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Open Data ◽  
Physical And Mechanical Properties ◽  
Engineering Properties ◽  
Microscopic Mechanism ◽  
Data Set ◽  
Young’S Moduli ◽  
Yungang Grottoes

AbstractThe macroscopic engineering properties of sandstone are dominated primarily by mineral features in a microscopic scale. This study will investigate the microscopic physical and mechanical properties of the main minerals (quartz, K-feldspar, Na-feldspar and kaolinite) in Yungang Grottoes sandstone, using the molecular mechanics and the molecular dynamics simulations. The microscopic physical properties were represented by density and volume. The microscopic mechanical properties were represented by Young’s modulus and Poisson’s ratio. The microscopic mechanical properties of the minerals in various directions were then explored. The influences of water molecules and the surrounding temperature on the microscopic physical and mechanical properties of the minerals were furthermore investigated. It is found that the differences in the microscopic densities between the simulated results and those from the open data set are, respectively, 0.37%, 1.15% and 9.16%, for the quartz, Na-feldspar and kaolinite cells; the microscopic mechanical properties of various minerals have a significant anisotropy; the Young’s modulus of halloysite decreases by 75.86% compared with that of kaolinite; as the water molecule number increased from 0 to 5, the Young’s moduli of K-feldspar, Na-feldspar and kaolinite cells decreases by 31.31%, 55.05% and 42.60%, respectively; for each mineral, as the temperature increases from 243.15 to 303.15 K under one atmospheric pressure, the volume increases and the density decreases. Those results may have a theoretical significance for the analysis of microscopic mechanism of hydration in the Yungang Grottoes sandstone.

scholarly journals SPS sintering of nitride ceramics

Mechanik ◽  
2019 ◽  
Vol 92 (5-6) ◽  
pp. 366-370
Author(s):  
Piotr Wyżga ◽  
Piotr Klimczyk ◽  
Jolanta Cyboroń ◽  
Paweł Figiel
Keyword(s):  
Fracture Toughness ◽  
Silicon Nitride ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Physical And Mechanical Properties ◽  
Initial Mixture ◽  
Fast Method ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Field Assisted Sintering

Due to the unique properties of ceramics materials based on nitride, it could be used in the broadly understood technique. However, obtaining silicon nitride materials requires it to use the advanced methods of manufacturing, mostly because this material is difficult to sinter. Dense ceramic sinters were obtained from the system Si3N4-Al2O3-Y2O3 by applied pulsed current – SPS/FAST method (spark plasma sintering/field assisted sintering technique). The sintering parameters of the initial mixture were optimized to obtain the highest possible sinter properties, such as: density, Young’s modulus, hardness and fracture toughness. In the presented work the influence of pressure and pulse current, used in the SPS/FAST method, on sinterability and on selected physical and mechanical properties of the obtained materials was analyzed. The purpose of introducing the Al2O3 and Y2O3 additions to the Si3N4 matrix was to activate the hard-to-sinter silicon nitride powder and consequently to achieve a high density of the sintered samples. The best properties were characterized by sinter obtained in 1700°C and under pressure 63 MPa; the holding time at sintering temperature was 15 min. The density of the obtained sample has reached 98% theoretical value, and the other parameters were: Young’s modulus – 298 GPa, Vickers hardness – 17,7 GPa, fracture toughness – 6 MPa∙m1/2.

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