Experimental Research on Mechanical Properties and Microstructure Characteristics of Silty Clay Subgrade Filler With Red Pisha Sandstone and Carbide Slag in Seasonal Frozen Regions

Abstract As the foundation structure of highway engineering, the quality of the subgrade determines the service life of highway engineering. Under this condition, the filling soils are frequently improved for raising the stability of the subgrade. Proper utilization of lower-cost waste materials will reduce demand for natural materials and the cost of construction. In this study, the red Pisha sandstone (RPS) and carbide slag (CS) as green and sustainable materials to reinforce the silty clay. The improvement effect was evaluated through freeze-thaw cycles test, triaxial compression strength test, particle-size distribution test, X-ray diffraction test, and scanning electron microscopy test. The results indicated that the addition of 15wt.% RPS and 15wt.% CS increased about 136% of the triaxial compressive strength of silty clay. With the increase of freeze-thaw cycles, the strength loss ratio and the deformation change slightly. It also has the excellent function of freezing and thawing resistance and shear strength. The key factors for the superior mechanical performance of RPS-CS stabilized silty clay are that more sand-size particles are beneficial to the hydration reactions of RPS and CS during the entire curing time, adequate flocculation and agglomeration of soil particles occurred. Many small-sized rounded and plate-like CSH gels filled most of the soils pores and isolated pores fractures became fewer in the samples, which produced a denser and less permeable material. The outcomes of this research will contribute to the utilization of red Pisha sandstone and carbide slag as a sustainable stabilizer in highway subgrade applications in seasonal frozen regions.

Download Full-text

Experimental Study on the Additive Effects of Cyclic Freezing-Thawing on the Durability of Cement Soil

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.507.363 ◽

2014 ◽

Vol 507 ◽

pp. 363-367 ◽

Cited By ~ 2

Author(s):

Yong Qin Wen ◽

Chao Cui

Keyword(s):

Mechanical Performance ◽

Cement Content ◽

Cement Composite ◽

Strength Loss ◽

Unconfined Compression ◽

Freezing And Thawing ◽

Composite Cement ◽

Before And After ◽

Cement Soil ◽

Compression Resistance

With pumice as the additive agent used in cement composite soil . In order to test the mechanical performance of the composite cement soil, the unconfined compression resistance and freezing and thawing cycle test were done in the lab with different additive quantity(2%,4%,6%,8%,10%), different cement content(4%,8%,12%,16%,20%), different number of freezing and thawing(5,10,15,20,25), The results show that the strength of the composite cement soil are significantly increase with increasing cement content, before and after freezing-thawing the strength loss and mass loss are increase with increasing freezing-thawing number and cement content.

Download Full-text

Influence of NaCl Freeze Thaw Cycles and Cyclic Loading on the Mechanical Performance and Permeability of Sulphoaluminate Cement Reactive Powder Concrete

Coatings ◽

10.3390/coatings10121227 ◽

2020 ◽

Vol 10 (12) ◽

pp. 1227

Author(s):

Xinghua Hong ◽

Hui Wang ◽

Feiting Shi

Keyword(s):

Cyclic Loading ◽

Mechanical Performance ◽

Strength Loss ◽

Steel Fibers ◽

Freeze Thaw ◽

Sulphoaluminate Cement ◽

Compressive And Flexural Strengths ◽

Reactive Powder ◽

Mechanical Strengths ◽

Curing Age

This paper aimed to investigate the coupling effects of NaCl freeze–thaw cycles and cyclic loading on the mechanical performance and permeability of sulphoaluminate cement reactive powder concrete (RPC). Firstly, the compressive and flexural strengths of sulphoaluminate cement RPC were investigated. Then, the chloride ion permeability, mechanical strengths (compressive and flexural strengths) and mass loss were determined. Results indicated that the increased steel fibers content and curing age played positive roles in the mechanical strengths. The threshold values of steel fibers and curing age were 3.0% and 14 days. Sulphoaluminate cement RPC with early curing age (5 h) showed relatively high mechanical strengths: flexural strength (8.69~17.51 MPa), and compressive strength (34.1~38.5 MPa). The mass loss, the chloride migration coefficient, and the compressive strength loss increased linearly with NaCl freeze–thaw cycles. Meanwhile, the flexural strength loss increased with the exponential function. The relative dynamic modulus of elasticity of specimens decreased linearly with the increased freeze–thaw cycles. Finally, it was observed from this paper, cyclic loading demonstrated negative roles on the mechanical strengths and resistance to chloride penetration.

Download Full-text

The Influence of Regional Freeze–Thaw Cycles on Loess Landslides: Analysis of Strength Deterioration of Loess with Changes in Pore Structure

Water ◽

10.3390/w12113047 ◽

2020 ◽

Vol 12 (11) ◽

pp. 3047

Author(s):

Zuyong Li ◽

Gengshe Yang ◽

Hui Liu

Keyword(s):

Pore Structure ◽

Triaxial Compression ◽

Strength Loss ◽

Loess Landslide ◽

Strength Deterioration ◽

Freeze Thaw ◽

Thaw Cycle ◽

Freeze Thaw Cycle ◽

Loess Landslides ◽

The Stability

The loess landslide in Gaoling District of Xi’an, Shaanxi in China is closely related to the seasonal freeze–thaw cycle, which is manifested by the destruction of pore structure and strength deterioration of the loess body under freeze–thaw conditions. In order to study the relationship between macro-strength damage and pore structure deterioration of saturated loess under freeze–thaw conditions and its influence on the stability of landslides, this paper explores the effect of freeze–thaw cycles on the strength of saturated undisturbed loess through triaxial compression test, and explores the micro-microstructure changes of saturated undisturbed loess through scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR). This is to analyze the evolution of the pore structure and strength loss evolution of saturated loess during the freeze–thaw process, and to describe the freeze–thaw damage of saturated undisturbed loess through the change of porosity and strength deterioration. Then, the internal correlation expression between the porosity change and the strength degradation is established to realize the verification analysis of the test data based on the correlation model. The research results show that: (1) As the number of freeze–thaw cycles increases, the peak strength loss rate gradually increases, and the strength deterioration of saturated loess becomes more and more obvious. (2) The freeze–thaw cycle will lead to the development of pores and cracks in the sample, accompanied by the generation of new cracks, which will cause the deterioration of the pore structure of the sample as a whole. (3) The response of strength damage and porosity deterioration of saturated undisturbed loess is roughly similar under the freeze–thaw cycle. The change in porosity can be measured to better reflect the strength deterioration of saturated loess. Therefore, the change of pore structure of undisturbed loess under freeze–thaw cycle conditions is tested by field sampling and indoor tests to reflect the phenomenon of strength deterioration, thereby analyzing the stability of loess slopes.

Download Full-text

Rates and intensity of freeze–thaw cycles affect nitrous oxide and carbon dioxide emissions from agricultural soils

Canadian Journal of Soil Science ◽

10.1139/cjss-2019-0058 ◽

2019 ◽

Vol 99 (4) ◽

pp. 472-484 ◽

Cited By ~ 2

Author(s):

David E. Pelster ◽

Martin H. Chantigny ◽

Philippe Rochette ◽

Normand Bertrand ◽

Denis A. Angers ◽

...

Keyword(s):

Carbon Dioxide ◽

Nitrous Oxide ◽

Carbon Dioxide Emissions ◽

Slow Freezing ◽

Control Treatment ◽

Rapid Freezing ◽

Silty Clay ◽

Freezing And Thawing ◽

Freeze Thaw ◽

Freezing And Thawing Rates

In cool temperate regions, large emissions of nitrous oxide (N2O), an important greenhouse and ozone-depleting gas, have been observed during freeze–thaw (FT) cycles. However, it is unclear how freezing and thawing rates, freezing intensity, and freezing duration influence N2O emissions. We used a laboratory incubation to measure N2O emissions from two soils (sandy loam, silty clay) undergoing a single FT cycle of various freezing and thawing rates [rapid (0.5 °C h−1) vs. slow (0.017 °C h−1)], freezing intensity (−1 vs. −3 °C), and freezing duration (24 vs. 48 freezing degree-days). In general, soil carbon dioxide fluxes during freezing were highest when soils were frozen slowly at −1 °C, whereas fluxes after thawing were highest from the soils frozen and thawed rapidly at −3 °C. Soil N2O emissions during both the freezing and thawing periods were greatest in the soils exposed to rapid freezing to −3 °C, intermediate under rapid freezing to −1 °C and slow freezing to −3 °C, and smallest under slow freezing to −1 °C and the control treatment (constant +1 °C). The similar N2O emissions between the unfrozen control and the slowly frozen −1 °C treatment was unexpected as previous field studies with similar freezing rates and temperatures still experienced high N2O emissions during thaw. This suggests that the physical disruptions caused by freezing and thawing of the surface soil are not the primary driver of FT-induced N2O emissions under field conditions.

Download Full-text

Performance Evaluation of the Polyurethane-Based Composites Prepared with Recycled Polymer Concrete Aggregate

Materials ◽

10.3390/ma13030616 ◽

2020 ◽

Vol 13 (3) ◽

pp. 616

Author(s):

Wenbo Ma ◽

Zenggang Zhao ◽

Shuaicheng Guo ◽

Yanbing Zhao ◽

Zhiren Wu ◽

...

Keyword(s):

Compressive Strength ◽

Mechanical Performance ◽

Strength Loss ◽

Polymer Concrete ◽

Concrete Aggregate ◽

Test Results ◽

Freeze Thaw ◽

Polyurethane Composites ◽

Durability Performance ◽

Recycled Polymer

Currently the investigation on recycled cement concrete aggregate has been widely conducted, while the understanding of the recycled polymer concrete aggregate is still limited. This study aims to fill this knowledge gap through the experimental investigation on mechanical and durability performance. Specifically, the remolded polyurethane stabilized Pisha sandstone was collected as the recycled polymer concrete aggregate. The remolded Pisha sandstone was then applied to re-prepare the polyurethane-based composites. After that, the mechanical performance of the prepared composites was first examined with unconfined and triaxial compressive tests. The results indicated that the Pisha sandstone reduces the composite’s compressive strength. The reduction is caused by the remained polyurethane material on the surface of the remolded aggregate, which reduces its bond strength with the new polyurethane material. Aiming at this issue, this study applied the ethylene-vinyl acetate (EVA) to enhance the bond performance between the polyurethane and remolded sandstone. The test results indicated both the unconfined and triaxle compressive strength of the polyurethane composites were enhanced with the added EVA content. Furthermore, the durability performance of the EVA-modified composites were examined through freeze-thaw and wet-dry cycle tests. The test results indicated the EVA could enhance the polyurethane composites’ resistance to both wet-dry and freeze-thaw cycles. Overall, the modification with EVA can compensate for the strength loss of polyurethane composites because of the applied remolded aggregate and enhance its sustainability.

Download Full-text

Effects of Long-Term Freeze–Thaw Cycles on the Properties of Stabilized/Solidified Lead-Zinc-Cadmium Composite-Contaminated Soil

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18116114 ◽

2021 ◽

Vol 18 (11) ◽

pp. 6114

Author(s):

Zhongping Yang ◽

Jiazhuo Chang ◽

Yao Wang ◽

Xuyong Li ◽

Shu Li

Keyword(s):

Compressive Strength ◽

Contaminated Soil ◽

Triaxial Compression ◽

Soil Column ◽

Column Leaching ◽

Freeze Thaw ◽

Triaxial Compressive Strength ◽

Zinc Cadmium ◽

Lead Zinc

Lead, zinc, and cadmium were used to prepare a composite-contaminated soil to replicate common situations, in which soil is usually simultaneously contaminated by multiple metals. To examine the long-term durability of stabilized/solidified (S/S) contaminated soil, specimens were subjected to a series of freeze–thaw (F-T) cycles, up to ninety times (one day per cycle), prior to testing. Triaxial compression tests, soil column leaching tests, and X-ray diffraction analysis were then employed to study the mechanical properties, environmental influences, and micro-mechanisms of the S/S lead-zinc-cadmium composite-contaminated soils after long-term F-T. The results showed that triaxial compressive strength increases within three F-T cycles, then decreases before slightly increasing or stabilizing after thirty F-T cycles. The stage of decreased cohesion thus occurs between three and fourteen F-T cycles, with variation in other factors similar to that of the triaxial compressive strength. The cohesion mainly increases between three and seven cycles. The soil column leaching test showed that the permeability of soil is more than four times higher than that of soil not subject to freeze–thaw cycles after ninety F-T cycles. XRD tests further revealed that the chemical composition of S/S contaminated soil and the occurrence of each heavy metal (HM) remained unchanged under F-T treatment.

Download Full-text

Study on the variation of physical and mechanical characteristics under freeze-thaw condition

E3S Web of Conferences ◽

10.1051/e3sconf/202016503021 ◽

2020 ◽

Vol 165 ◽

pp. 03021

Author(s):

Tian Yanzhe

Keyword(s):

Compressive Strength ◽

Elastic Modulus ◽

Axial Strain ◽

Triaxial Compression ◽

Physical And Mechanical Properties ◽

Peak Stress ◽

Friction Angle ◽

Confining Pressure ◽

Freeze Thaw ◽

Triaxial Compressive Strength

Subjected to freeze-thaw cycles, the deformation of physical and mechanical properties is the main cause of engineering disasters. Based on the analysis of the results of triaxial compression test after different freeze-thaw cycles, conclusions are drawn that: under the certain freeze-thaw cycles conditions, with the increase of confining pressure, the triaxial compressive strength, elastic modulus and the axial strain increase gradually, indicating that the failure of rock changes from brittle failure to plastic failure; in the case of same confining pressure, with the increase of the number of freeze-thaw cycles, the triaxial compressive strength,elastic modulus of rock decreases and the axial strain corresponding to peak stress gradually increase. With the increase of the number of freeze-thaw cycles, the cohesion of grit is in the form of exponentially decays to reduce,the internal friction angle changes very little.

Download Full-text

Mechanical and Failure Criteria of Air-Entrained Concrete under Triaxial Compression Load after Rapid Freeze-Thaw Cycles

Advances in Materials Science and Engineering ◽

10.1155/2017/6786270 ◽

2017 ◽

Vol 2017 ◽

pp. 1-8 ◽

Cited By ~ 4

Author(s):

Feng-kun Cui ◽

Huai-shuai Shang ◽

Tie-jun Zhao ◽

Guo-xi Fan ◽

Guo-sheng Ren

Keyword(s):

Compressive Strength ◽

Uniaxial Compressive Strength ◽

Stress Ratio ◽

Triaxial Compression ◽

Complex Stress State ◽

Experimental Results ◽

Testing System ◽

Freeze Thaw ◽

Triaxial Compressive Strength ◽

Air Entrained Concrete

The experiment study on the air-entrained concrete of 100 mm cubes under triaxial compression with different intermediate stress ratioα2=σ2D : σ3Dwas carried out using a hydraulic-servo testing system. The influence of rapid freeze-thaw cycles and intermediate stress ratio on the triaxial compressive strengthσ3Dwas analyzed according to the experimental results, respectively. The experimental results of air-entrained concrete obtained from the study in this paper and the triaxial compression experimental results of plain concrete got through the same triaxial-testing-system were compared and analyzed. The conclusion was that the triaxial compressive strength is greater than the biaxial and uniaxial compressive strength after the same rapid freeze-thaw cycles, and the increased percentage of triaxial compressive strength over biaxial compressive strength or uniaxial compressive strength is dependent on the middle stress. The experimental data is useful for precise analysis of concrete member or concrete structure under the action complex stress state.

Download Full-text

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

Scientific Reports ◽

10.1038/s41598-021-91842-8 ◽

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.

Download Full-text

Strength and Microscopic Damage Mechanism of Yellow Sandstone with Holes under Freezing and Thawing

Advances in Civil Engineering ◽

10.1155/2020/5921901 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13 ◽

Cited By ~ 1

Author(s):

Huren Rong ◽

Jingyu Gu ◽

Miren Rong ◽

Hong Liu ◽

Jiayao Zhang ◽

...

Keyword(s):

Mechanical Properties ◽

Pore Size ◽

Power Function ◽

Damage Mechanism ◽

Uniaxial Compression Test ◽

Freezing And Thawing ◽

Freeze Thaw ◽

Thaw Cycle ◽

Freeze Thaw Cycle ◽

Microscopic Damage

In order to study the damage characteristics of the yellow sandstone containing pores under the freeze-thaw cycle, the uniaxial compression test of saturated water-stained yellow sandstones with different freeze-thaw cycles was carried out by rock servo press, the microstructure was qualitatively analyzed by Zeiss 508 stereo microscope, and the microdamage mechanism was quantitatively studied by using specific surface area and pore size analyzer. The mechanism of weakening mechanical properties of single-hole yellow sandstone was expounded from the perspective of microstructure. The results show the following. (1) The number of freeze-thaw cycles and single-pore diameter have significant effects on the strength and elastic modulus of the yellow sandstone; the more the freeze-thaw cycles and the larger the pore size, the lower the strength of the yellow sandstone. (2) The damage modes of the yellow sandstone containing pores under the freeze-thaw cycle are divided into five types, and the yellow sandstone with pores is divided into two areas: the periphery of the hole and the distance from the hole; as the number of freeze-thaw cycles increases, different regions show different microscopic damage patterns. (3) The damage degree of yellow sandstone is different with freeze-thaw cycle and pore size. Freeze-thaw not only affects the mechanical properties of yellow sandstone but also accelerates the damage process of pores. (4) The damage of the yellow sandstone by freeze-thaw is logarithmic function, and the damage of the yellow sandstone is a power function. The damage equation of the yellow sandstone with pores under the freezing and thawing is a log-power function nonlinear change law and presents a good correlation.

Download Full-text