1.Dewanckele, J., Boone, M.A., De Kock, T., De Boever, W., Brabant, L., Boone, M.N., Fronteau, G., Dils, J., Van Hoorebeke, L., Jacobs, P., Cnudde, V.
Holistic approach of pre-existing flaws on the decay of two limestones
整体分析两种石灰岩预置变形裂纹
(2013) Science of the Total Environment, 447, pp. 403-414. 被引用 2 次.
摘要: This study aims to understand the influence of the microfacies and the determination of pre-existing flaws on the weathering behavior of two types of limestones. Therefore, both Lede and Noyant limestones were independently weathered by strong acid tests and freeze-thaw cycles. In order to characterize the weathering patterns inside the stones, a combination of high resolution X-ray CT, SEM-EDS and thin section microscopy was used. The advantage of high resolution X-ray CT is its non-destructive character and the obtained 3D structural information. By using this technique, a time-lapse sequence of the weathering patterns was obtained for both gypsum crust formation as well as crack formation due to freezing and thawing. This way, a clear link could be made with the initial non-weathered state. Thin section microscopy and SEM-EDS provided additional chemical information. The focus of this study lies in the processes that occur in the bioclast fragments in the stone and the influence of the surrounding cement or matrix. The results show that weathering patterns vary for both limestones although the causes of weathering were similar. In case of the Noyant stone, the weathering by crystallizing gypsum was mainly restricted to the microporous matrix of the stone, while in case of the Lede stone, several foraminifera and shell fragments were preferentially recrystallized. In general, the underlying microstructure determines the weathering pattern of the stone. © 2013 Elsevier B.V.
作者关键字: Freeze-thaw weathering; Gypsum crystallization; Natural building stone; Time lapse X-ray CT
2.Yi, C., Lai, S.L., Zhu, H.G., Yan, S.H., Liu, J.X., Dong, X.
Freeze-thawing damage model of new-to-old concrete with different rough interfaces
表面粗糙程度不同的新旧混凝土冻融损伤模型
(2013) Applied Mechanics and Materials, 405-408, pp. 2707-2714.
摘要: New-to-old concrete freeze-thawing durability affects the safety and normal service of structure. In this paper, the freeze-thawing resistance of new-to-old concrete with different rough substrate surfaces was studied. The roughness of substrate surface was characterized by fractal dimension. Test results show that freeze-thawing damage of new-to-old concrete has two stage changes: first stage, freeze-thawing damage increases rapidly, mainly caused by the damage of interface; second stage, freeze-thawing damage increases slower, mainly reflects damage of substrate and overlay. Compared with smooth surface, rough surface can significantly improve freeze-thawing resistance of new-to-old concrete. In a certain range, with the increase of fractal dimension, the freeze-thawing resistance improves. When the fractal dimension is beyond the range, the freeze-thawing resistance impairs while the fractal dimension increases. A freeze-thawing damage model applied to new-to-old concrete is proposed, and a good correlation is found between the model and experimental results. © (2013) Trans Tech Publications, Switzerland.
作者关键字: Fractal dimension; Freeze-thawing damage; New-to-old concrete; Resistance to freeze-thawing; Rough surface
3. Swan, C.W., Grant, A., Kody, A.
Characteristics of Chicago Blue Clay subjected to a freeze-thaw cycle
受到冻融循环作用的芝加哥蓝粘土的特性
(2013) ASTM Special Technical Publication, 1568 STP, pp. 22-32.
摘要: This paper presents the preliminary results of a laboratory study on the impact of one freeze-thaw cycle on the engineering properties of natural samples of Chicago Blue Clay (CBC). Freezing was performed in a closed system with freezing occurring simultaneously in all directions. Two types of consolidation tests were performed: incremental loading and long-term compression under a constant load. These tests were performed on specimens subjected to a cycle of freeze-thaw with results compared to tests on CBC in its natural state. For constant load consolidation tests, freezing and subsequent thaw of specimens was performed under the applied stress. Additionally, the Atterberg limits of CBC, in its natural state and after one freeze-thaw cycle, were also determined. Based on the test results in this study, it is clear that one cycle of freezing and thawing impacts both the consolidation behavior and limits of the samples. Specifically, for both the incremental and constant loading tests there is a significant increase (between 25% and 40%) in settlement during consolidation versus results of tests on CBC in its natural state. There is also a notable increase in the virgin compression ratio (Cc) and coefficient of consolidation (cv) upon thawing. Results of Atterberg limits indicate a decrease in the CBC's liquid limit that explains, in part, the increase in cv. Overall, the results indicate that the freezing and subsequent thawing of CBC has a severe impact on its consolidation behavior. The writers recommend that more testing be performed to verify and expand on the results determined from this preliminary evaluation. Copyright © 2013 by ASTM International.
作者关键字: Chicago Blue Clay; Cohesive soils; Consolidation; Freeze-thaw cycle
4. Hu, X.D., Wang, J.T., Yu, X.F.
Laboratory test of uniaxial compressive strength of shanghai frozen soils under freeze-thaw cycle
冻融循环作用下上海冻土的单轴抗压强度实验室测试
(2013) Advanced Materials Research, 716, pp. 688-692.
摘要: The artificial ground freezing (AGF) is now widely employed in constructions with the expanding underground space exploitation in Shanghai. In order to avoid geological disasters which might appear in the AGF practice, it is urgently needed to do laboratory tests on the physical and mechanical characters of Shanghai soft soil under freezing and thawing action. This paper tests three kinds of soils from the location ofShanghai Metro line 4 constructions in different state, i.e. original state, freeze-thaw state and secondary freeze-thaw state, and obtains the changing rules of soil characters under secondary freeze-thaw action. © (2013) Trans Tech Publications, Switzerland.
作者关键字: Artificial ground freezing; Freeze-thaw cycle; Frozen soil; Laboratory test; Uniaxial compressive strength
5.Wang, X.-D., Li, X.-W., Xiong, Z.-Q., Liang, L.
Antarctic ice-sheet freeze-thaw detection based on XPGR combined with wavelet transform
结合XPGR与小波变换检测南极的冰盖融化
(2014) Dongbei Daxue Xuebao/Journal of Northeastern University, 35 (5), pp. 650-654.
摘要: In view of the problem of XPGR (cross-polarized gradient ratio) algorithm existed in the ice-sheet freeze-thaw detection, an XPGR combined with wavelet transform algorithm was proposed, which did not depend on the field observations. The proposed algorithm was used in the Antarctic ice-sheet freeze-thaw detection by microwave radiometer. That was the processing for the long time series data of XPGR algorithm by the use of wavelet transform model to automatically get the distribution of Antarctic ice-sheet melting onset date, melting duration and melting end date. The computational efficiency, usability and operability of detecting were improved in the ice-sheet freeze-thaw detection because many samples could be automatically selected by the algorithm with certain denoising effect. To some extent, the accuracy of detecting ice-sheet freezing and thawing was also improved and the goal of Antarctic ice-sheet monitoring system construction was better achieved.
作者关键字: Accuracy; Ice-sheet freeze-thaw detection; Microwave radiometer; Wavelet transform; XPGR
6.Lv, Q., Wang, S., Zhao, Y.
Permeability characteristics of modified loess under freeze-thaw cycles
冻融循环作用下改性黄土的渗透特征
(2014) WIT Transactions on Ecology and the Environment, 189, pp. 537-544.
摘要: Loess roadbed in seasonal frozen soil areas often suffers frequent freeze-thaw cycles which bring negative effects to loess structure and its permeability characteristics. This paper investigated permeability properties and microstructures of modified loess in different ratios of cement, lime and fly ash under the condition of freezing and thawing cycles and gave an optimal proportion of the three additives based on permeability properties. Permeability test results of modified loess are optimistic (around 10-7 cm/s order of magnitudes or lower) even the loess has been through repeated freeze-thaw cycles. The paper then provides a comprehensive suggestion for loess modification: cement of 4%-5% of loess weight, lime of 6% and fly ash of 10%. © 2013 WIT Press.
作者关键字: Freeze-thaw cycles; Microstructure; Modified loess; Permeability coefficient
7.Yan, H., Liu, J., Wang, T.
Static properties of silty soil subjected to repeated freezing and thawing
反复冻融作用下粉砂土的静态属性
(2013) Advanced Materials Research, 639-640 (1), pp. 925-929.
摘要: In order to deeply comprehend the static properties of silty soil subjected to repeated freezing and thawing in deep seasonal frozen area, the static properties were studied on silty soil under different freeze-thaw cycles, coefficient of consolidation, water content and confining pressure. The results showed that stress-strain relationship of silty soil was work-hardening, and mainly in a ductile failure state. Correlation analysis results showed that there were good relationships between static properties, such as static modulus and static strength, and freeze-thaw cycles, coefficient of consolidation, water content and confining pressure. The cohesion decreased with in creasing of the number of freeze-thaw cycles, but there was no changing law for the internal friction angle. © (2013) Trans Tech Publications, Switzerland.
作者关键字: Confining pressure; Elastic modulus; Freeze-thaw cycles; Silty soil; Static strength
8. Yun, H.-D.
Flexural behavior and crack-damagemitigation of plain concrete beam with a strain-hardening cement composite (SHCC) layer at tensile region
受拉区应变强化水泥复合层无钢混凝土梁的抗弯性能和裂隙损伤分析
(2013) Composites Part B: Engineering, 45 (1), pp. 377-387. 被引用 1 次。
摘要: The paper deals with the flexural and cracking behavior experimentally observed in the plain concrete beam with a hybrid polyvinyl alcohol (PVA) and polyethylene (PE) fiber reinforced strain-hardening cement composite (SHCC) layer before and after repeated freeze-thaw exposure. The influences of the SHCC layer thickness, SHCC type, and freezing-thawing cycles on the overall flexural performance of SHCC-layered concrete beams are investigated. Concrete beams, which had 100 × 100 mm rectangular cross section and 300 mm span length, were tested in four-point bending. Two kinds of SHCCs were used as layer materials for the tension zone of concrete beam. Beam specimens with two different SHCC layer thicknesses (30 mm and 50 mm) were prepared. Freezing and thawing tests of SHCC materials and SHCC-layered concrete beams followed ASTM C 666 Procedure B and continued until the specimen achieved 300 freeze-thaw cycles. Experimental study shows that when subject to monotonic flexural loading, the SHCC-layered repair system showed 2.5-3.5 times increased load carrying capacity, and mitigated cracking damage of plain concrete beam with a SHCC layer compared with plain concrete beam. The enhancement in the flexural strength and ductility is found to increase with the SHCC's tensile strain capacity and layer thickness. While the freezing and thawing exposure decreased the deflection at the ultimate flexural strength of SHCC-layered concrete beam, flexural strength of SHCC-layered beam after 300 cycles of freezing and thawing increased up to average 15% compared to that of virgin SHCC-layered concrete beam. © 2012 Elsevier Ltd. All rights reserved.
作者关键字: A. Fibers; A. Hybrid; B. Damage tolerance; B. Mechanical properties; D. Mechanical testing
9.Yan, H., Liu, J., Wang, T.
Experimental research of influences of freeze-thaw on the mechanical properties of silty soil
冻融作用对粉砂土力学性能影响的实验研究
(2013) Beijing Jiaotong Daxue Xuebao/Journal of Beijing Jiaotong University, 37 (4), pp. 73-77.
摘要: In order to deeply comprehend the static properties of silty soil subjected to repeated freezing and thawing in deep seasonal frost area, the static properties of silty soil under different freezethaw cycles, coefficient of consolidation, water content and confining pressure were studied. The results show that stress-strain relationship of silty soil is work-hardening, and mainly in a plastic failure state after repeated freezing and thawing. The influence of freeze-thaw on the static strength and elastic modulus is obvious. The mechanical index of silty soil happens to stabilize even after 20 cycles of freezing and thawing. There are good relationships between static properties and water content, compactness, and confining pressure. The cohesion decreases with the number of freeze-thaw cycles increments, but there is no changing law for the internal friction angle.
作者关键字: Confining pressure; Elastic modulus; Freeze-thaw cycles; Silty soil; Static strength
10.Barker, J., Thomas, H.
Geotechnical engineering in cold regions
寒冷地区的岩土工程
(2013) ISCORD 2013: Planning for Sustainable Cold Regions - Proceedings of the 10th International Symposium on Cold Regions Development, pp. 204-214.
摘要: What is unique about geotechnical engineering in cold regions? Principles of soil mechanics for temperate climates have been largely well-understood and practiced for decades. However, these are based on soil temperatures above freezing. In cold regions, heat flow becomes important in relation to freezing and thawing (seasonal frost), but also in relation to permafrost and its resistance to thawing and consequences of thawing. Soil moisture experiences a change of phase and this can cause a dramatic change in physical properties of the soil. In addition, porewater migrates in certain soils during freezing and this can cause dramatic heaving, well in excess of that which would be caused by phase change alone. Based on an illustrated «white paper» recently prepared for colleagues practicing geotechnical engineering in temperate areas, the authors summarize these fundamental phenomena, providing examples of practical design approaches which have been successfully used for building foundations and for roads in seasonal frost and permafrost areas. The paper concludes with a list of relevant references for readers interested in geotechnical design criteria and more-specialized cold regions engineering topics. © 2013 American Society of Civil Engineers.
作者关键字: cold regions; foundations; freeze-thaw, porewater; Geotechnical engineering; heat flow; soil mechanics
11. Agarwal, A., Foster, S.J., Hamed, E., Ng, T.S.
Influence of freeze-thaw cycling on the bond strength of steel-FRP lap joints
冻融循环对钢管混凝土组合搭接粘结强度的影响
(2014) Composites Part B: Engineering, 60, pp. 178-185. 被引用 1 次。
摘要: The long term durability of FRP strengthened steel structures under freeze thaw cycles is a key parameter in their design. This paper presents an experimental investigation of the effect of freeze-thaw exposure on the bond strength and the mode of failure of steel-CFRP lap joints. A total of 48 single lap shear specimens were prepared and exposed to varying numbers of freeze-thaw cycles before being tested to failure at room temperature. The results show that the freeze-thaw cycling decreases the bond strength by about 28% and leads to variations in the mode of failure. A separate set of tests was also conducted on adhesive tensile specimens under similar conditions as those of the steel-CFRP joints, which showed a reduction in the initial elastic modulus after exposure to freeze-thaw cycling. A simple shear stress-slip model is used to predict the failure load of the specimens, which reveals a good correlation with the experimental results. © 2013 Elsevier Ltd. All rights reserved.
作者关键字: A. Polymer-matrix composites (PMCs); B. Debonding; B. Environmental degradation; D. Mechanical testing; Steel-FRP joints
12.Makusa, G.P., Mattsson, H., Knutsson, S.
Investigation of increased hydraulic conductivityof silty till subjected to freeze-thaw cycles
冻融循环作用下增大粉质沙渗透系数的研究
(2013) ASTM Special Technical Publication, 1568 STP, pp. 33-46.
摘要: The hydraulic conductivity of silty till increases when the till is subjected to freeze-thaw cycles. A dramatic increase normally occurs after the first freeze-thaw cycle, and the magnitude generally depends on the initial or molding water content. Freezing of silty till causes aggregations of clods and the formation of macrostructure. The initial or molding water content determines the number of freeze-thaw cycles required to complete the agglomeration of clods and the formation of stable macrostructures, which in turn controls the hydraulic conductivity of compacted specimens frozen and thawed in the laboratory. The findings of this study show that for specimens compacted wet of the optimum water content, a significant increase in the hydraulic conductivity was measured after the first freeze-thaw cycle. When specimens were compacted at the optimum water content, a number of freeze-thaw cycles were required in order to obtain the corresponding significant increase in the hydraulic conductivity. Copyright © 2013 by ASTM International.
作者关键字: Clods; Dry cover; Freeze-thaw; Hydraulic conductivity; Macrostructure; Microstructure; Silty till
13.Zhou, L., Hou, X.L., Wang, Z.P.
The effect of the freeze-thaw cycles in nanometer pores on the cement structure
冻融循环对水泥纳米孔结构的影响
(2014) Applied Mechanics and Materials, 488, pp. 620-624.
摘要: The pore structure of cement-based materials is closely related to the freeze-thaw resistance durability. And this paper focused on nanometer pores to verify the connection of freeze-thaw cycles in the nanometer pores with the structure deterioration and to explore the stress in the pore wall during the freeze-thaw process. And BET method was adopted to analyze the pore structure of the cement and results indicated the changing trends of parameters such as the pore volume, average pore size and surface area of specimens. Moreover, pore size distribution presented prominent fluctuations of pore sizes in the range of 0 ~ 20 nm, while the changes on the scale of 20 ~ 100 nm were limited. © (2014) Trans Tech Publications, Switzerland.
作者关键字: BET method; Freeze-thaw cycles; Nanometer pores; Pore size; Structure deterioration
14.Hashimoto, K., Yokota, H., Sugiyama, T., Kikkawa, T.
Pore structure analysis of mortar under freeze-thaw cycles using x-ray computed tomography
利用x射线计算机断层成像分析冻融循环条件下砂浆的孔隙结构
(2013) Zairyo/Journal of the Society of Materials Science, Japan, 62 (8), pp. 492-497.
摘要: Frost damage due to freeze thaw action of pore water in concrete is an important issue on durability of concrete structures in cold regions. It is generally known that different temperature histories in freeze-thaw cycles affect scaling of concrete, in which the pore structure might be changed due to propagation of micro cracks. In previous research, 3D images from X-ray computed tomography have been used to analyze the pore structure of concrete. This study aimed to evaluate the pore structure of mortar under freeze-thaw cycles with different temperature histories by using X-ray computed tomography. As the results, 1) the temperature histories gave different progress of residual strain and void distributions, in which decrease of toutuosity and spacing factor were shown with more residual strain due to frost damage; 2) propagation of micro cracks due to frost damage probably increases spacing factors and tortuosity calculated from information obtained in analysis using X-ray computed tomography; and 3) tortuosity and spacing factor linearly correlated with diffusion coefficient although void ratio did not correlated with diffusion coefficient Thus, this study showed that pore connectivity informed from tortuosity and spacing factor evaluated by X-ray computed tomography, in addition to pore structural indicators such as total pore volume, were reasonably discussed with progress of frost damage and alteration of diffusion coefficient. © 2013 The Society of Materials Science, Japan.
作者关键字: Air-void spacing factor; Diffusion coefficient; Freeze-thaw cycles; Pore structure; Tortuosity; X-ray CT
15.Kim, K., Kim, Y., Jang, B.-A., Park, Y.M.
Geomechanical characteristics of gneiss in Antarctica due to freeze-thaw tests
南极洲片麻岩地质特征的冻融测试
(2013) Proceedings of the International Offshore and Polar Engineering Conference, pp. 8-13.
摘要: Freeze-thaw tests were performed on gneiss samples collected from Terra Nova, Antarctica, in order to examine and compare the properties of rocks which were slightly weathered (SW) and moderately weathered (MW). The tests were conducted under temperatures ranging from -20±2°C to 20±2°C. A cycle of testing consisted of 5 h of freezing followed by another 5 h of thawing under full saturation with water. In this paper, a total of 200 cycles of the freeze-thaw test were performed, and were followed by measurements of porosity, absorption, ultrasonic velocity, and shore hardness per each 20 cycles, uniaxial compressive strength (UCS) determined every 50 cycle. The strength of the SW rocks decreased by approximately 0.07 MPa per a single cycle, while that of MW rocks decreased around 0.19 MPa per a single cycle. During the 200 cycles of SW rocks, the absorption increased from 0.23% to 0.39% and the P-wave velocity decreased from 4,227 m/s to 3,596 m/s. Similarly, those of MW rocks changed from 0.65% to 1.6%, and from 3,751 m/s to 2,877 m/s. In conclusion, it was inferred that the properties of SW rocks experienced approximately 200-300 cycles of freeze-thaw became close to those of MW rocks. Copyright © 2013 by the International Society of Offshore and Polar Engineers (ISOPE).
作者关键字: Engineering property; Freeze-thaw; Gneiss; Terra nova bay; Weathering
16. Martínez-Martínez, J., Benavente, D., Gomez-Heras, M., Marco-Castaño, L., García-Del-Cura, M.Á.
Non-linear decayof building stones during freeze-thaw weathering processes
岩石冻融风化过程中的非线性衰减
(2013) Construction and Building Materials, 38, pp. 443-454. 被引用 8 次.
摘要: This paper studies the resistance of rocks to freeze-thaw and their petrophysical evolution during weathering. Moreover, the accuracy of existing standards regarding frost durability is discussed. A long-term test was established with these purposes, in which 102 samples of six different dimension stone types were tested (carbonates). Samples were divided into five groups and each group was tested after 0, 12, 24, 48 and 96 freeze-thaw cycles. At the end of the cycles several properties were measured: volume loss, open porosity variation, visual damage, mechanical properties evolution (measuring strength and elastic modulus) and ultrasonic propagation (quantifying both P-wave velocity and spatial attenuation). The micro-textural evolution was also studied using SEM in polished samples. Results display that the rocks with the highest open porosity values (>10%) are the least durable. These rocks show a non-linear decay pattern, with long periods of apparent stability followed by rapid and catastrophic decay. Microscopic observation reveals that during the stable period, isolated microcracks appear from where new ones nucleate and grow as the test progresses. When a critical threshold is exceeded, microcracks turn into cracks and grow rapidly, causing rock breakdown after a low number of cycles. Most of the measured petrophysical parameters do not predict the ultimate breakdown of rocks. However, spatial attenuation of ultrasonic waves reveals as the most sensitive parameter, detecting the critical decay threshold of rocks and their imminent breakdown. Results suggest an important review of standardized durability tests since they do not reflect the reality of frost weathering of rocks: to increase the number of freeze-thaw cycles and to monitoring the weathering process of samples by means ultrasonic measurements. © 2012 Elsevier Ltd. All rights reserved.
作者关键字: Catastrophic stone decay; Elastic modulus; Frost durability; Limestone; Porosity; Strength; Ultrasounds
17.Kodama, J.-I., Azehara, T., Fukuda, D., Fujii, Y.
Deformation and fracture processes of argillaceous schist and granite subjected to Freeze-Thaw Cycles
冻融循环作用下泥质片岩和花岗岩的变形和断裂过程
(2014) Zairyo/Journal of the Society of Materials Science, Japan, 63 (3), pp. 219-226.
摘要: Fracture processes of argillaceous schist and granite subjected to freeze-thaw cycles were investigated based on their deformation behaviors. It was found that argillaceous schist showed apparent anisotropy in deformation. Significant extensile strain was observed in the direction perpendicular to the cleavage plane around -3°C in freezing process on the water-saturated specimen, followed by extensile plastic strain at the end of the cycle. No apparent extension and anisotropy were found on the water-saturated specimen of granite, but decrease in contraction rate was seen at -3°C in freezing process with AE activity. The extensile plastic strain of both rocks gradually increased with the number of freeze-thaw cycles, but magnitude of the plastic strain on argillaceous schist was much greater than that of granite. These results indicate that there might be common mechanism in fracture process between both rocks, but significant differences in deterioration rate. Deterioration of argillaceous schist is much faster because fracture mainly develops by extension of well-developed cleavage in the rock. It was concluded that weak plane such as cleavage strongly affected deterioration of rocks by freeze-thaw cycle. © 2014 The Society of Materials Science, Japan.
作者关键字: Anisotropy; Deformation; Fracture; Freeze-thaw cycles; Rock; Strain measurement; Weak plane
