scholarly journals Research on Corrosion Damage and Bearing Characteristics of Bridge Pile Foundation Concrete under a Dry-Wet-Freeze-Thaw Cycle

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Zhongju Feng ◽  
Jianwei Huo ◽  
Haibo Hu ◽  
Ruixin Zhao ◽  
Fuchun Wang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Pile Foundation ◽  
Loss Rate ◽  
Corrosion Damage ◽  
In Situ Test ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

This study investigated the corrosion damage and bearing characteristics of bridge pile foundations under a dry-wet-freeze-thaw cycle of composite salt in an alpine salt marsh area using an in situ test, laboratory test, and numerical simulations. The in situ test showed that the dry-wet-freeze-thaw cycle has little effect on the quality of the concrete specimens and rebar. The area of the rebar at a depth of 0.25 m had the highest corrosion rate of 91%. The application of epoxy resin on the surface improved erosion resistance. After one year of outdoor dry-wet-freeze-thaw cycle test, due to the interaction of compound salts, the quality of specimens is reduced under the denudation of chloride ions, while the mass of specimens is increased by the corrosion products formed under the joint action of carbonate and sulfate, resulting in less obvious change of specimen quality, the antierosion coefficient of the specimens decreased, the maximum loss rate of compressive strength was 38.2%, and the pile foundation began to deteriorate. The laboratory test showed that expansive substances, such as Friedel salt, appeared in the concrete specimens of pile foundation during 225 cycles of dry-wet-freeze-thaw cycles, the relative dynamic elastic modulus was reduced by 60.9%, the antierosion coefficient was reduced to 0.51, and the compressive strength loss rate was 65.9%. As such, the pile foundation was seriously damaged. The numerical simulation shows that, with an increase of the peeling thickness and the corrosion depth, the bearing capacity of the pile foundation will gradually decrease after 8 years. Without maintenance, the bearing capacity of a pile foundation will decrease by 34.45% in the 20th year.

Experimental Research on a New-Type Concrete Antifreeze

2011 ◽  
Vol 148-149 ◽  
pp. 1209-1213
Author(s):  
Bao Min Wang ◽  
Kai Song ◽  
Ni Tu
Keyword(s):  
Compressive Strength ◽  
Loss Rate ◽  
Performance Test ◽  
Setting Time ◽  
Strength Loss ◽  
Freeze Thaw ◽  
Performance Indexes ◽  
Thaw Cycle ◽  
Basic Performance ◽  
Freeze Thaw Cycle

Basic performance test was performed on a newly-developed compound antifreeze and experiment was carried out to study the basic performance, mechanical property and durability of the concrete mixtures containing 0%, 4% and 5% antifreeze. The result shows the antifreeze may be used for the concrete construction at 20°C below zero and it has favorable performance for winter construction. When the amount to be added is 4% and 5%, the ratio of compressive strength of 28 days shall be 105% and 107% respectively; the ratio of compressive strength of 56 days shall be 114% and 112% respectively. In freeze-thaw cycle experiment, 50 times of freeze-thaw strength loss rate is 45.3% and 44.8% of the strength loss rate of the concrete without the antifreeze. The water-reducing ratio of the antifreeze, ratio of bleeding rate, air content, difference in setting time, strength ratio, ratio of shrinkage, permeated height ratio and other performance indexes all satisfy specification requirements.

scholarly journals Study on Strength Characteristics of Solidified Contaminated Soil under Freeze-Thaw Cycle Conditions

2018 ◽  
Vol 2018 ◽  
pp. 1-5 ◽  
Author(s):  
Qiang Wang ◽  
Jinyang Cui
Keyword(s):  
Electron Microscopy ◽  
Compressive Strength ◽  
Contaminated Soils ◽  
Unconfined Compressive Strength ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Strength Tests ◽  
Freeze Thaw Cycle ◽  
Microcosmic Mechanism ◽  
Scanning Electron

Cement solidification/stabilization is a commonly used method for the remediation of contaminated soils. The stability characteristics of solidified/stabilized contaminated soils under freeze-thaw cycle are very important. A series of tests, which include unconfined compressive strength tests, freeze-thaw cycle tests, and scanning electron microscopy (SEM) tests, are performed to study the variation law of strength characteristics and microstructure. It aims at revealing the microcosmic mechanism of solidified/stabilized Pb2+ contaminated soils with cement under freeze-thaw cycle. The results show that the unconfined compressive strength of the contaminated soils significantly improved with the increase of the cement content. The unconfined compressive strength of stabilized contaminated soils first increases with the increase of times of freeze-thaw cycle, and after reaching the peak, it decreases with the increase of times of freeze-thaw cycle. The results of the scanning electron microscopy tests are consistent with those of the unconfined compressive strength tests. This paper also reveals the microcosmic mechanism of the changes in engineering of the stabilized contaminated soils under freeze-thaw cycle.

scholarly journals Dynamic Mechanical Response and Dissipated Energy Analysis of Sandstone under Freeze-Thaw Cycles

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Ke Man ◽  
Zongxu Liu ◽  
Zhifei Song ◽  
Xiaoli Liu
Keyword(s):  
Compressive Strength ◽  
Strain Rate ◽  
Open Pit ◽  
Dissipated Energy ◽  
Freeze Thaw ◽  
Dynamic Mechanical ◽  
Thaw Cycle ◽  
Pore Evolution ◽  
Freeze Thaw Cycle ◽  
Dynamic Compressive Strength

Based on the sandstone from the slope of Baorixile open-pit mining area in Hulunbuir City, Inner Mongolia, the dynamic uniaxial compression test of sandstone with different freeze-thaw cycles has been carried out by Split Hopkinson Pressure Bar test (SHPB). The test results show that the crushing degree of sandstone becomes serious with the freeze-thaw cycle times and strain rate increases. The dynamic compressive strength increases with the raise of strain rate under the same freeze-thaw cycles, while it reduces with the increases of freeze-thaw cycles at the same strain rate. It is found that the 10 freeze-thaw cycles are an obvious inflection point. When it is less than 10 cycles, the dynamic compressive strength of sandstone specimens decreases rapidly, it is more than 10 cycles, and the strength decreases gradually. This is due to that the evolution progress of pores in sandstone is more uniform after a certain number of freeze-thaw cycles. Meantime, the effect of freezing and thawing is mostly restrained by the pore evolution. On the other hand, the dissipated energy required for sandstone failure grows up with the increase of the number of freeze-thaw cycles. It shows that more energy is needed for the engender of pores and fractures in sandstone caused by freeze-thaw cycle. This led to the deterioration of sandstone structural stability and the decrease of dynamic mechanical properties.

THE INFLUENCE OF FREEZE–THAW CYCLES ON UNCONFINED COMPRESSIVE STRENGTH OF CLAY SOILS TREATED WITH LIME

2015 ◽  
Vol 76 (1) ◽  
Author(s):  
Ali Akbar Firoozi ◽  
Mohd Raihan Taha ◽  
Ali Asghar Firoozi ◽  
Tanveer Ahmed Khan
Keyword(s):  
Compressive Strength ◽  
Unconfined Compressive Strength ◽  
Conventional Technique ◽  
Silica Sand ◽  
Clay Soils ◽  
Unit Weight ◽  
Freeze Thaw ◽  
Long Term Stability ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

There are several questions that are not well understood with respect to the long-term stability characteristics of lime-treated clay soils in spite of being used as a conventional technique to improve the properties of clay soils. This paper investigates the influence of freeze-thaw cycles on the unconfined compressive strength of kaolinite and illite mixed with silica sand. The results of this study show that an increase in the number of freeze-thaw cycles decreases the unconfined compressive strength. The role of lime increasing the soil strength is more significant in the case of samples exposed to freeze-thaw cycles compared to those not exposed to freeze-thaw cycles. The effect of freeze-thaw cycles on the dry unit weight and moisture content is insignificant compared to unexposed samples. The maximum volumetric changes occurred in the first freeze-thaw cycle, and afterward, the rate of volume change decreased with an increase in freeze—thaw cycles.

scholarly journals Study on Application Effect of Sand Consolidating Agent for the Slope of Highway Subgrade in Season Frozen Zone

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Dongliang Zhang ◽  
Guangqing Yang ◽  
Xiaodi Niu ◽  
Lu Zhang ◽  
Zhijie Wang
Keyword(s):  
Compressive Strength ◽  
Friction Angle ◽  
Freeze Thaw ◽  
Direct Shear Tests ◽  
Thaw Cycle ◽  
Sand Body ◽  
Before And After ◽  
Freeze Thaw Cycle ◽  
Sandy Slope ◽  
Sand Particles

In deep season frozen areas, the solidified layer is easy to be destroyed due to the influence of freeze-thaw cycles after the surface layer of the sandy slope is solidified by chemical methods. In order to study the application effect of the new sand consolidating agent after solidifying sand body, the mechanism of strength formation was analyzed by scanning electron microscopy (SEM). The freeze-thaw cycle tests were carried out on sand consolidating samples. The direct shear tests and unconfined compressive strength tests were carried out before and after freeze-thaw cycles to analyze the freeze-thaw resistance of sand consolidating samples. The sand consolidation agent was tested on-site, and its strength was tested to observe its effect. The results showed that the adhesive membranes on the surface of sand particles were formed by the sand consolidating agent, which increased the cohesion and strength of sand particles. After freeze-thaw cycle tests, the cohesion, internal friction angle, and compressive strength of the solidified sand gradually decreased with increasing freeze-thaw cycles. The decreasing rate reduced from fast to slow and then tends to be stable. The failure mode of samples changed from brittle failure to plastic failure. The sand consolidating layer can effectively prevent collapse of the sandy slope. Combining with the external-soil spray seeding, the sand consolidation layer is beneficial to the growth of plants.

Determining in-situ soil freeze–thaw cycle dynamics using an access tube-based dielectric sensor

Geoderma ◽  
2012 ◽  
Vol 189-190 ◽  
pp. 321-327 ◽  
Author(s):  
Y. Sun ◽  
Q. Cheng ◽  
X. Xue ◽  
L. Fu ◽  
J. Chai ◽  
...  
Keyword(s):  
Freeze Thaw ◽  
Thaw Cycle ◽  
Dielectric Sensor ◽  
Freeze Thaw Cycle

scholarly journals Mechanical Properties and Micro Structure of Cement Concrete in Freeze-Thaw Environment

2021 ◽  
Vol 233 ◽  
pp. 01011
Author(s):  
Xin jian Lv ◽  
Lei Yu ◽  
Ming ming Chai
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Pore Structure ◽  
Fresh Water ◽  
Pore Diameter ◽  
Dynamic Elastic Modulus ◽  
Freeze Thaw ◽  
Salty Water ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

In order to find the declay law of mechanical property and the performance difference after salty water and fresh water freeze-thaw cycle, freeze-thaw cycle environments under the salty water and fresh water are simulated. The compressive strength, dynamic elastic modulus and the mass lost are tested. The pore structure parameters are also tested by MIP. Plot the pore diameter distribution curve. The result shows that the compressive strength and dynamic elastic modulus are all decreased. The degree of these two properties decreasing under salty water freeze and thaw recycle is more than the one under fresh water. The parameters of porosity and critical pore diameter become larger. The amount of pores whose diameter is between 100nm and 1000nm increase. The amount of pores whose diameter is under 100nm decrease. The deteriorate degree of pore structure is deeper in salty water than in fresh water.

scholarly journals Mechanical Properties and Freeze–Thaw Durability of Basalt Fiber Reactive Powder Concrete

2020 ◽  
Vol 10 (16) ◽  
pp. 5682
Author(s):  
Wenjun Li ◽  
Hanbing Liu ◽  
Bing Zhu ◽  
Xiang Lyu ◽  
Xin Gao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Loss Rate ◽  
Steel Fiber ◽  
Basalt Fiber ◽  
Reactive Powder Concrete ◽  
Chloride Salt ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Reactive Powder

Basalt fiber has a great advantage on the mechanical properties and durability of reactive powder concrete (RPC) because of its superior mechanical properties and chemical corrosion resistance. In this paper, basalt fiber was adopted to modified RPC, and plain reactive powder concrete (PRPC), basalt fiber reactive powder concrete (BFRPC) and steel fiber reactive powder concrete (SFRPC) were prepared. The mechanical properties and freeze–thaw durability of BFRPC with different basalt fiber contents were tested and compared with PRPC and SFRPC to investigate the effects of basalt fiber contents and fiber type on the mechanical properties and freeze–thaw durability of RPC. Besides, the mass loss rate and compressive strength loss rate of RPC under two freeze–thaw conditions (fresh-water freeze–thaw and chloride-salt freeze–thaw) were tested to evaluate the effects of freeze–thaw conditions on the freeze–thaw durability of RPC. The experiment results showed that the mechanical properties and freeze–thaw resistance of RPC increased as the basalt fiber content increase. Compared with the fresh-water freeze–thaw cycle, the damage of the chloride-salt freeze–thaw cycle on RPC was great. Based on the freeze–thaw experiment results, it was found that SFRPC was sensitive to the corrosion of chloride salts and compared with the steel fiber, the improvement of basalt fiber on the freeze–thaw resistance of RPC was great.

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