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.

Studies the Properties of Polyaspartic Polyurea Coated Concrete under Coaction of Salt Fog and Freeze-Thaw

2012 ◽  
Vol 455-456 ◽  
pp. 781-785
Author(s):  
Ping Lu ◽  
Xin Mao Li ◽  
Xue Qiang Ma ◽  
Wei Bo Huang
Keyword(s):  
Elastic Modulus ◽  
Frost Resistance ◽  
Dynamic Elastic Modulus ◽  
Freeze Thaw ◽  
Decrease Rate ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Salt Fog

. This paper mainly studied the properties of PAE polyurea coated concrete under coactions of salt fog and freeze-thaw. After exposed salt fog conditions for 200d, T3, B2, F2 and TM four coated concrete relative dynamic elastic modulus have small changes, but different coated concrete variation amplitude is different. T3 coated concrete after 100 times of freeze-thaw cycle the relative dynamic elastic modulus began to drop, 200 times freeze-thaw cycle ends, relative dynamic elastic modulus variation is the largest, decrease rate is 95%, TM concrete during 200 times freeze-thaw cycle, relative dynamic elastic modulus almost no change, B2 concrete and F2 concrete the extent of change between coating T3 and TM. After 300 times the freeze-thaw cycle coated concrete didn't appear freeze-thaw damage phenomenon. Four kinds of coating concrete relative dynamic elastic modulus variation by large to small order: T3 coated concrete > B2 coated concrete >F2 coated concrete > TM coated concrete, concrete with the same 200d rule. Frost resistance order, by contrast, TM coated concrete > B2 coated concrete > F2 coated concrete > T3 coated concrete.

Research of Steel Fiber Self-Compacting Concrete Frost Resistance

2012 ◽  
Vol 174-177 ◽  
pp. 721-725 ◽  
Author(s):  
Ming Bao Gao ◽  
Yan Ru Zhao ◽  
Xiao Yan He
Keyword(s):  
Elastic Modulus ◽  
Frost Resistance ◽  
Steel Fiber ◽  
Concrete Specimen ◽  
Test Method ◽  
Dynamic Elastic Modulus ◽  
Self Compacting Concrete ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

With the fast freeze-thaw test method, the c50 steel fiber self-compacting concrete was carried out 300 tests of freeze-thaw cycle. In the process of freeze-thaw cycles, it determined by the quality of the concrete specimen, dynamic elastic modulus and strength, and analyzed the steel fibers and their different contents on frost resistance of self-compacting concrete impact. The results showed that: steel fiber self-compacting concrete in freeze-thaw cycle can play constrained role in the quality loss, dynamic elastic modulus and intensity, and can significantly improve the self-compacting concrete frost resistance. Within a certain range, the more steel fiber, the stronger of frost resistance.

The Mechanics Performance of C30 Concrete with Manufactured-Sand under Condition of Freeze-Thaw Cycles

2011 ◽  
Vol 71-78 ◽  
pp. 1036-1039
Author(s):  
Gui Feng Liu ◽  
Zheng Fa Chen ◽  
Xue Xing Chen
Keyword(s):  
Elastic Modulus ◽  
Acid Corrosion ◽  
Experimental Studies ◽  
Raw Material ◽  
Dynamic Elastic Modulus ◽  
Manufactured Sand ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Mechanics Performance ◽  
Freeze Thaw Cycle

Although many people discussed the strength and durability of concrete with natural sand in severe environment, few people investigated the mechanics performance of concrete with manufactured-sand under condition of freeze-thaw cycle, at present. Experimental studies on C30 concrete with manufactured-sand were carried out under condition of freeze-thaw cycle, which based on the testing of raw material performance and concrete mix ration, in this paper. Comparative studies on the changing laws of the mass, strength and the relative dynamic elastic modulus of concrete were developed in three cases which were freeze-thaw cycle, freeze-thaw cycle and acid corrosion and freeze-thaw cycle and alkali corrosion. The test results showed that the mass, strength and the relative dynamic elastic modulus of concrete with manufactured-sand decreased evidently with the increasing of times of freeze-thaw cycle. The durability of acid and alkali-resistant of concrete with manufactured-sand was also remarkably weakened due to the action of freeze-thaw cycle. The capability of acid and alkali-resistant of the concrete was decreased with the increasing of times of freeze-thaw cycle and the anti-acid capability was decreased more seriously.

scholarly journals Study on Long-Term Dynamic Mechanical Properties and Degradation Law of Sandstone under Freeze-Thaw Cycle

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Qingsong Pu ◽  
Junhong Huang ◽  
Fuling Zeng ◽  
Yi Luo ◽  
Xinping Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Strain Rate ◽  
Air Pressure ◽  
Freeze Thaw ◽  
Dynamic Mechanical ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Dynamic Compressive Strength

This study is based on the tunnel-face slope engineering of Dongfeng tunnel in Shanxi section of China’s Shuozhou-Huanghua Railway. The sandstone specimens in the perennial freeze-thaw zone of the slope were collected to carry out freeze-thaw cycle static physical mechanics test and split Hopkinson pressure bar (SHPB) dynamic mechanical test. Thus, the damage process of sandstone under freeze-thaw cycle and impact load is studied. Also, the dynamic compressive strength and dynamic elastic modulus of sandstone are analysed under different loading strain rates and freeze-thaw cycle based on LS-DYNA, a dynamic finite element program. The results showed that the dynamic compressive strength of sandstone subjected to multiple freeze-thaw cycles under 0.04 MPa air pressure has a greater damage ratio than that under 0.055 MPa and 0.07 MPa air pressure, which was more likely to cause damage to slope sandstone than in actual engineering; the dynamic compressive strength and elastic modulus of sandstone decrease greatly within a certain range of freeze-thaw cycles and loading strain rate, leading to significant deterioration. When the freeze-thaw cycle exceeded 200 times and the strain rate was greater than 200 s−1, the physical and mechanical properties of sandstone gradually tended to be stable.

Experimental Study on Freeze-Thaw Resistance of Concrete with Proto-Machine-Made Sand

2011 ◽  
Vol 71-78 ◽  
pp. 4361-4364 ◽  
Author(s):  
Xiao Yan Zhang ◽  
Xin Xin Ding ◽  
Shun Bo Zhao ◽  
Zhan Fang Ge
Keyword(s):  
Experimental Study ◽  
Elastic Modulus ◽  
Mass Loss ◽  
Source Rock ◽  
Crushed Stone ◽  
Dynamic Elastic Modulus ◽  
Cycle Times ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

Experiments were conducted to study the effects of source rock state and stone powder on freeze-thaw resistance of concrete with proto-machine-made sand, the strength grade of concrete was C50, the source rock states were gravel and crushed stone, the contents of stone powder in sand were 5%, 9% and 13% respectively. The values of relative dynamic elastic modulus and mass of concrete at different freeze-thaw cycle times were measured, the reduction of relative dynamic elastic modulus and mass loss were calculated to evaluate the freeze-thaw resistance of concrete. The results show that freeze-thaw resistances are controlled by the reduction of relative dynamic elastic modulus of concrete, which are good of concrete with proto-machine-made sand of gravel and crushed stone, and increases with the increasing content of stone powder in sand made of gravel. The reasons leading to difference of freeze-thaw resistance of concrete with sand made of gravel and crushed stone are discussed.

scholarly journals Experimental Study on the Durability of Alkali-Activated Slag Concrete after Freeze-Thaw Cycle

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Bin Chen ◽  
Jun Wang
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Raw Material ◽  
Dynamic Elastic Modulus ◽  
Important Indicator ◽  
Alkali Activated Slag ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Activated Slag ◽  
Alkali Activated

A freeze-thaw resistance is an important indicator of the durability of alkali-activated slag concrete, which causes structural failure when the performance is low, especially in severely cold areas. In this study, solid sodium aluminate and sodium silicate were used as composite alkaline activators, while slag was used as the raw material to prepare alkali-activated slag concrete, whose freeze-thaw resistance, as well as that of ordinary cement concrete, was experimentally studied by varying the freeze-thaw cycles. The effects of the mass, compressive strength, and dynamic elastic modulus of the sample were investigated by considering the influence of different water-to-slag ratios and slag contents, while the damage variables and model were also analyzed. The results showed that alkali-activated slag concrete had an excellent freeze-thaw resistance, which was significantly affected by the water-to-slag ratio and compressive strength; specifically, the higher the water-to-slag ratio, the lower the freeze-thaw resistance, and the higher the compressive strength, the better the freeze-thaw resistance. The freeze-thaw durability, microstructure, and damage mechanism were studied via microscopic analysis. When analyzed via the microstructure test, crack pores and microcracks with narrow spaces and large surface areas were generated under freeze-thaw damage conditions, but the dense hydration structure and high-bonding-strength hydration products led to a better freeze-thaw resistance. The damage model was established using compressive strength and relative dynamic elastic modulus as damage variables, and the attenuation exponential and accumulative damage power function model had a high accuracy, which could better reflect the freeze-thaw damage law and damage degree and predict the lifetime of alkali-activated slag concrete.

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 Experimental Study on Freeze-Thaw Effects on Creep Characteristics of Rubber Concrete

2022 ◽  
Vol 2022 ◽  
pp. 1-14
Author(s):  
Qi Li ◽  
Fei Xu ◽  
Hemin Zheng ◽  
Junhao Shi ◽  
Jianyu Zhang
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Stress Level ◽  
Creep Behavior ◽  
Mass Loss Rate ◽  
Crumb Rubber ◽  
Dynamic Elastic Modulus ◽  
Freeze Thaw ◽  
Stress Levels ◽  
Rubber Concrete

Crumb Rubber Concrete (CRC) can exhibit high freeze-thaw resistance, but its long-term creep behavior under various freeze-thaw conditions remains unclear, which is essential for the safety of pavement engineering in the severe cold zone. In this study, the freeze-thaw effects on the creep behavior of CRC under different stress levels were systematically analyzed by testing the compressive strength, the uniaxial creep under different stress levels, and the dynamic elastic modulus. To simulate real conditions of the road environment in the cold area, the lowest temperature of −20°C, six freeze-thaw cycles of 0, 30, 60, 90, 120, and 150, and seven different stress levels of 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9 of the compressive strength were employed in this study. The test results showed that the mass loss rate was 6%–11.2% and the compressive strength decreased by 6.51%–47% after 30–150 freeze-thaw cycles. When the stress level reached its critical value, the relative dynamic elastic modulus decreased with the number of freeze-thaw cycles. After 150 freeze-thaw cycles, failure did not appear when the stress level was lower than 50%, above which the creep failure was determined by the stress level and the number of the freeze-thaw cycles. Meanwhile, it was found that the cracking and interfacial debonding between the matrix and the crumb rubber particle were the main reasons for the degradation of CRC creep performance. Finally, a Weibull distribution-based empirical creep damage model was established to predict the failure of CRC, which can enhance its application to related engineering.

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.

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