Junzhe Liu

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Evaluation of combined addition of nitrite and chloride on the corrosion behavior of steel bars in modified magnesium oxysulfate cement paste

Construction and Building Materials (2024)

Liang Wang Yujiao Li Kanze Mei Mingxu Chen Junzhe Liu

10.1016/j.conbuildmat.2024.135794

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Citations (1)

A review of carbonation in reinforced concrete(I): Mechanism of carbonation and evaluative methods

CONCRETE (2005)

Junzhe Liu

Based on the available literature,it reviews the recent progress of studies on carbonation of concrete.Concrete solution consist of sodium,potassium and hydroxide ion for electric balance mainly,less calcium ion.The pH value of the pore solution depends on the concentration of sodium and potassium mainly.The higher concentration of calcium ion,the lower pH values.The higher alkali content is,the better it will accelerate solution rate of portlandite,and accelerate the carbonation of concrete.Then the phenolphthalein indicator,X-ray diffraction method,thermo-analysis method and EPMA method were introduced for evaluating the carbonation depth of concrete.

Portlandite

Potassium hydroxide

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Citations (3)

Expansive deformation behavior of steam-cured cementitious materials and corresponding control measurement

Journal of Central South University(Science and Technology) (2012)

Junzhe Liu

For the sake of understanding expansive deformation behavior of cement-based materials under steam curing condition,a serial of experiments were carried out to investigate the linear expansive deformation of specimens with different water-binder ratios and binder compositions based on the typical steam-curing regime of railway precast concrete element production.X-ray diffraction analysis was used to determine the hydration products of samples.The relationship between expansive deformation value and free water content of sample before steam curing was also analyzed.The results indicate that specimens show different deformation characteristics in different stages of the whole steam curing process.The expansive deformations of specimens significantly increase in heating duration and subsequently decrease until to stable status.Expansive deformation of specimen is mainly influenced by the solid phase type and free water content before steam curing(or initial water content).Through choosing a water-binder ratio no more than 0.30 and partially replacing cement by mineral admixture,expansive deformation of cement-based materials during steam curing can be effectively reduced.

Expansive

Cementitious

Expansive clay

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Citations (6)

Coupling effect of salt freeze-thaw cycles and cyclic loading on performance degradation of carbon nanofiber mortar

Cold Regions Science and Technology (2018)

Hui Wang Xiaojian Gao Junzhe Liu

Degradation

10.1016/j.coldregions.2018.07.002

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Citations (31)

Detection and monitoring of seafloor methane bubbles using hydrophones

The Journal of the Acoustical Society of America (2022)

Shima Abadi Tor A. Bjorklund Junzhe Liu H. P. Johnson

Natural marine seeps of methane are important sources of greenhouse gas emissions that enter the global environment. Monitoring marine methane seeps will reveal important information about how they form, their source regions, and how much of the inventory is microbially consumed within the water column before the gas is released to the atmosphere. While active acoustics methods have been extensively used to detect and monitor methane emissions from the seafloor, there are only a few studies showing the use of passive acoustics for bubble sound detection and monitoring. In this presentation, we use passive acoustics data recorded in a methane seep field in Puget Sound to characterize the bubble sound and estimate the bubble radii from their sound frequency. We use the ratio of a short-term average from a bubble burst over the long-term average to automatically detect the bubble sounds. We also show the relationship between the number of bubble sound detections and the hydrostatics seafloor pressure fluctuations due to tidal changes in water height.

Seafloor Spreading

Petroleum seep

10.1121/10.0016312

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Designing Method of Anti-Neutralization for Vehicle Tunnel Lining Concrete

DEStech Transactions on Materials Science and Engineering (2017)

Mingfang Ba Yongqiang Li Chunxiang Qian Junzhe Liu

The neutral erosion of lining concrete in vehicle tunnel under the condition of load and composite acid gases is noticeable. The anti-neutral analysis and prediction of an under-river tunnel lining concrete were discussed, and the neutral level was analyzed by a numerical way based on the effect of load level and composite acid gases. It was proposed that the anti-neutral level affected by moisture content exists a high and low range and the neutral depth increase with the increase of capillary porosity. Then the design method for highly anti-neutral lining concrete of vehicle tunnel was put forward based on the corrected carbonation depth. Finally the micro-structural parameters of highly anti-neutral lining concrete, such as moisture content, content of Ca(OH)2 and capillary porosity in concrete, were analyzed. The content of Ca(OH)2 was determined to be greater than or equal to the solubility of Ca(OH)2 under the condition of environmental temperature. The critical maximum connected capillary porosity was 9.15%. The research provides basis for the design and preparation of anti-neutral lining concrete of vehicle tunnel.

10.12783/dtmse/ictim2017/9953

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Citations (4)

Study on long-term inhibiting effectiveness of nitrite ion in concrete mixed with anti-freezing admixtures

Concrete (2004)

Junzhe Liu

The measurements of contents of chloride and nitrite by accelerated corrosion method of the reinforcing bars embedded in concrete containing anti-freezing admixtures were conducted to determine the variations of molar ratio of NO~-_2/Cl~- that inhibits reinforcing bars from corrosion.This study confirmed that the anti-freezing admixtures containing nitrite salt and chloride salt in concrete results in higher ion concentrations at steel bottom than other measuring point because bleeding of water is caused.But NO~-_2/Cl~-ratios tend to be relatively constant after 28 days. So if the nitrite ion with abundant NO~-_2/Cl~- ratios supplied in concrete,the long-term effectiveness can be ensured conclusively.

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Study on the properties of sea sand concrete

Guoliang Zhang Junzhe Liu Jianbin Chen Zhimin He

Sea sand concrete is a kind of concrete in which mixed sea sand as fine aggregate, which is large-scale application in the coastal areas in recent years, especially in Ningbo area. The sea sand solves the problem of river sand shortage, coupled with cheaper price, most of the ready-mixed concrete companies are willing to use desalted sea sand instead of river sand. Many companies even are using sea sand without any treatments. The history of using sea sand in our country is very short, so the durability of the sea sand concrete need to be tested by many projects in the future, along with the development of science and technology and the invention of precision instruments, the durability of sea sand concrete will be adequate assurance. Ningbo area has a wide range usage of sea sand concrete. By measuring the strength of sea sand concrete with fly ash, finding out the law of strength for the sea sand concrete by the presence of fly ash.At the same time, we used electron scanner to analysis the sea sand concrete internal microstructure, researched the influence of chlorine salts on sea sand concrete micro-structural features.

Economic shortage

10.1109/mace.2011.5987768

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Citations (2)

Experiment on the bonding performance of the lightweight aggregate and normal weight concrete composite beams

Case Studies in Construction Materials (2021)

Jianmin Wang Ziqiang Xiao Chengfeng Zhu Chuxiang Feng Junzhe Liu

Aiming at the bonding performance of the casting interface in the composite ceramsite lightweight aggregate concrete (LWAC) and normal weight concrete (NWC), the experiment on the shear bonding blocks and bending composite beams were designed for progressive study. The Z-shaped composite blocks were first made by the LWAC and NWC with different strength grades considering the variation of the casting interval time and the interface preparing method. The bending composite beams were designed considering the variation of the casting interval time, the relative position between the casting interface and the calculated sectional neutral axis in the LWAC and NWC composite beam. The result indicates that, the bonding shear performance of the casting interface decreases most obviously within 2 days of the casting interval time. The shear strength of the casting interface with 14 days casting interval time for considered different interface preparing methods is higher than that calculated according to the specification. Although there is no bonding sliding failure happening on the casting interface in the composite beam during the experimental loading, a certain influence exists on the crack developing near the casting interface, the load-deflection curve developing, the strain developing of the mid-span section and the subtle damage variation considering the variation of the casting interval time, the relative position between the casting interface and the calculated neutral axis in the composite beam.

Neutral axis

10.1016/j.cscm.2021.e00565

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Citations (14)

EARLY DETERIORATION MECHANISM AND PREVENT PRACTICE OF THE DEICING SALT ON CONCRETE

Low Temperature Architecture Technology (2005)

LI Lian-zhi Junzhe Liu Li-Hua Lu

The paper present the techno-measure of resisting early deterioration of concrete,resorting to the discussion on early detrioration mechanism and influencing factors of the deicing salt on concrete in cold region.Mixing air entraining agents and reducing water cement ratio were the most effective solution to improve resistance deicing salt scaling of concrete.Blast furnace slag can suppress alkali aggreate reaction caused by deicing salt.Setting up a rational drainage system,compacting concrete and improving concrete cover thickness were effective measures to protect bars.

Air entrainment

Alkali–aggregate reaction

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Citations (1)