scholarly journals Chloride Ion Corrosion Pattern and Mathematical Model for C60 High-Strength Concrete after Freeze-Thawing Cycles

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yan Li ◽  
Bing Li ◽  
Lian-ying Zhang ◽  
Chao Ma ◽  
Jiong Zhu ◽  
...  
Keyword(s):  
Mathematical Model ◽  
High Strength Concrete ◽  
Chloride Ion ◽  
High Strength ◽  
Chloride Ions ◽  
Diffusion Method ◽  
Freeze Thaw ◽  
Strength Concrete ◽  
Artificial Environment ◽  
Transport Control

In this study, the porosities of C60 high-strength concrete after 0, 30, 60, and 90 freeze-thaw cycles determined via the water retention method are 1.30%, 3.65%, 5.14%, and 7.34%, respectively. Furthermore, a mathematical model of porosity varying with the number of freeze-thaw cycles is established. Using an artificial environment simulation experimental system and the natural diffusion method, the chloride diffusion law of C60 high-strength concrete after 0, 30, 60, and 90 freeze-thaw cycles is obtained. The corresponding diffusion coefficients are calculated based on the experimental results and Fick’s law, where 0.3431 × 10−12, 0.5288 × 10−12, and 0.6712 × 10−12, and 0.8930 × 10−12 m2/s are obtained, respectively, and a mathematical model of diffusion coefficient with freeze-thawing is established. Transport control equations comprising solution flow and solute migration control equations are established for chloride ions in concrete after freeze-thawing cycles. The equations consider the effects of freeze-thawing, solution pressure, solution concentration, solution density, convection, mechanical dispersion, and chemisorption on chloride ion transport in concrete. Using COMSOL numerical software, the transport control equations for chloride ions are solved using a real concrete numerical model, and the chloride ion corrosion process in concrete after freeze-thaw cycles is simulated. The simulation results are consistent with the experimental values.

scholarly journals Mechanical Properties of High Strength Concrete Containing Nano SiO2 Made from Rice Husk Ash in Southern Vietnam

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 932
Author(s):  
Huu-Bang Tran ◽  
Van-Bach Le ◽  
Vu To-Anh Phan
Keyword(s):  
Compressive Strength ◽  
Rice Husk ◽  
High Strength Concrete ◽  
Rice Husk Ash ◽  
Chloride Ion ◽  
High Strength ◽  
Ion Permeability ◽  
Strength Concrete ◽  
Nano Sio2 ◽  
Southern Vietnam

This paper presents the experimental results of the production of Nano-SiO2 (NS) from rice husk ash (RHA) and the engineering properties of High Strength Concrete (HSC) containing various NS contents. Firstly, the mesoporous silica nanoparticles were effectively modulated from RHA using NaOH solution, and subsequently precipitated with HCl solution until the pH value reached 3. The optimum synthesis for the manufacture of SiO2 nanoparticles in the weight ratio of RHA/NaOH was 1:2.4, and the product was calcined at 550 °C for 2 h. The EDX, XRD, SEM, TEM, FT-IR, and BET techniques were used to characterize the NS products. Results revealed that the characteristics of the obtained NS were satisfactory for civil engineering materials. Secondly, the HSC was manufactured with the aforementioned NS contents. NS particles were added to HSC at various replacements of 0, 0.5, 1.0, 1.5, 2.0, and 2.5% by the mass of the binder. The water-to-binder ratio was remained at 0.3 for all mixes. The specimens were cured for 3, 7, 28, 25 days under 25 ± 2 °C and a relative humidity of 95% before testing compressive and flexural strengths. Chloride ion permeability was investigated at 28 and 56 days. Results indicated that the addition of NS dramatically enhanced compressive strength, flexural strength, chloride ion resistance, and reduced chloride ion permeability compared to control concrete. The optimal NS content was found at 1.5%, which yielded the highest strength and lowest chloride ion permeability. Next, the development of flexural and compressive strengths with an age curing of 3–28 days can be analytically described by a logarithmic equation with R2 ≥ 0.74. The ACI code was used, and the compressive strength at t-day was determined based on 28 days with R2 ≥ 0.95. The study is expected to solve the redundancy of waste RHA in southern Vietnam by making RHA a helpful additive when producing high-strength concrete and contributing meaningfully to a sustainable environment.

Performance Deterioration of High Strength Concrete under Mixed Erosion and Freeze-Thaw Cycling

2010 ◽  
Vol 163-167 ◽  
pp. 1655-1660
Author(s):  
Jian Zhang ◽  
Bo Diao ◽  
Xiao Ning Zheng ◽  
Yan Dong Li
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Mass Loss ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
High Strength Concrete ◽  
High Strength ◽  
Freeze Thaw ◽  
Strength Concrete ◽  
Dynamic Modulus Of Elasticity

The mechanical properties of high strength concrete(HSC) were experimentally investigated under mixed erosion and freeze-thaw cycling according to ASTM C666(Procedure B), the erosion solution was mixed by weight of 3% sodium chloride and 5% sodium sulfate. The mass loss, relative dynamic modulus of elasticity, compressive strength, elastic modulus and other relative data were measured. The results showed that with the increasing number of freeze-thaw cycles, the surface scaled more seriously; the mass loss, compressive strength and elastic modulus continued to decrease; the relative dynamic modulus of elasticity increased slightly in the first 225 freeze-thaw cycles, then decreased in the following 75 cycles; the corresponding strain to peak stress decreased with the increase of freeze-thaw cycles. After 200 cycles, the rate of deterioration of concrete accelerated obviously.

Rheological Property and Durability of High Strength Concrete Using Zeolite Powder and Microsphere

2014 ◽  
Vol 1030-1032 ◽  
pp. 1003-1009
Author(s):  
Yu Xin Gao ◽  
Jia Chao Lin ◽  
Bao Jun Cheng ◽  
Xiong Wu ◽  
Yuan Peng ◽  
...  
Keyword(s):  
Rheological Property ◽  
High Strength Concrete ◽  
Composite Powder ◽  
Chloride Ion ◽  
High Strength ◽  
The Self ◽  
Ion Permeability ◽  
Strength Concrete ◽  
Closest Packing ◽  
Electric Flux

The rheological property of fresh high-strength concrete (HSC) and mechanical properties, self-shrinkage and resistance to chloride ion permeability of hydrated HSC were studied on the basis of the closest packing theory. Results showed that the packing density of composite powder was the highest when the content of microsphere was 30.0%; when the content of zeolite powder added to concrete varied from 0.0% to 4.0%, the rheological and discontinuous property of concrete would be improved and its viscosity would be increased; meanwhile, compared to the standard concrete, the self-shrinkage of concrete with 2.0% zeolite powder at 1d, 3d, 7d and 28d was decreased by 77.1%, 49.6%, 44.0% and 38.1% respectively; finally, the resistance to chloride ion permeability of hydrated HSC with zeolite powder was improved with a result of 18.5% reduction of electric flux at 28d.

Compressive Strength, Chloride Diffusivity and Pore Structure of Non-Autoclaved Prestressed High-Strength Concrete with Metakaolin

2012 ◽  
Vol 450-451 ◽  
pp. 1409-1414 ◽  
Author(s):  
Jun Jie Zeng ◽  
Zhong He Shui ◽  
Wan Ru Zhang ◽  
Zheng Leng
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
High Strength Concrete ◽  
High Strength ◽  
Chloride Ions ◽  
Strength Concrete ◽  
Durability Properties ◽  
Chloride Diffusivity ◽  
Chloride Migration ◽  
Improvement Effect

The experimental study was performed on the relationship between the mechanical and durability properties of high-strength concrete with metakaolin (MK) and slag. The compressive strength, chloride penetrability and pore structure of the OPC and the concrete with MK and slag were measured. It is found that MK can significantly increase the compressive strength, decrease the chloride ions migration coefficient and improve the pore structure of the steam cured high-strength concrete. The chloride resistance is improved obviously by 5% MK and further increase of the MK dosage performs a little change of the chloride migration coefficient. Better improvement effect on the mechanical and durability properties is obtained with the incorporation of 10% MK and 10% slag. Linear relationship is found between the coarse pore porosity and the compressive strength, while the chloride migration coefficient correlates well with the capillary pore volume.

scholarly journals Thermal Properties of Conventional and High-strength Concrete

2018 ◽  
Vol 245 ◽  
pp. 06005 ◽  
Author(s):  
Tatiana Musorina ◽  
Alexsander Katcay ◽  
Mikhail Petrichenko ◽  
Anna Selezneva
Keyword(s):  
Thermal Properties ◽  
Thermophysical Properties ◽  
High Strength Concrete ◽  
High Strength ◽  
Temperature Fluctuations ◽  
Conventional Concrete ◽  
Freeze Thaw ◽  
Strength Concrete ◽  
Concrete Properties ◽  
Cold Chamber

Important characteristics for the Nordic countries: a freeze-thaw resistance and an ability of a material to keep heat inside the building. This paper aims to define the thermophysical properties of a high-strength concrete, compare the discovered performance with the conventional concrete properties. With this object in mind two experiments in cold chamber “CHALLENGE 250” have been conducted and followed by analysis. In these experiments, the insulation of facades is beyond the framework of the investigation. Only the thermophysical properties of concrete are taken into account. The samples were affected by temperature fluctuations. Results from the experiments show that strength characteristics of a material are in indirect ratio to accumulation properties of a structure. This conclusion is directly related to porosity of material and additives. During 70 minutes, with outside temperature being below zero, the temperature inside the concrete dropped to an average. As the outside temperature increases significantly to more than zero, the temperature inside the concrete has become below average (continued to decline) in 70 minutes. The more strength of material, the better thermophysical properties. High-strength concrete is less susceptible to temperature fluctuations, therefore more heat-resistant. As mentioned in the paper below, the material has one disadvantage: this is a large cost per cubic meter.

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