Experimental Study on Mix Design of Chloride Resistant Cementitious Spacers

2014 ◽  
Vol 629-630 ◽  
pp. 351-357
Author(s):  
Chen Huang ◽  
Wen Ying Guo ◽  
Yi Bo Yang ◽  
Hui Zhao ◽  
Zhen Jie Li ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Design Method ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Mix Design ◽  
Easy Access ◽  
Ion Diffusion ◽  
Electric Flux ◽  
Chloride Environment ◽  
Chloride Ion Diffusion

Chloride resistant HPC and protective cover are two basic measurements to improve the durability of concrete in chloride environment. Though it provides crucial cover for concrete to resist chloride ions, spacer has limited chloride resistant ability, which is overlooked by past researchers. Cementitious spacers are easy access for chloride ions to penetrate into concrete resulting in reduction of structural durability. To improve cementitious spacers’ performance, a systematic study was conducted. Test results showed that there was major difference between mortar and concrete in terms of chloride coulomb electric flux but minor difference in terms of chloride ion diffusion coefficient, which implied using chloride ion diffusion coefficient as spacer’s durability indicator was preferable; parameters of mix design had a similar influence on mortar and concrete and, with the same mixing parameters, the strength and chloride resistant ability of mortar were weaker than concrete’s; it was feasible to develop the mix design of chloride resistant cementitious spacers based on concrete’s design method with certain adjustments, such as using stricter mix proportion, adding small-size coarse aggregate, lowering water-binder ratio and optimizing the binder proportion, to achieve higher strength and durability.

scholarly journals Experimental Study on Chloride Ion Diffusion in Concrete under Uniaxial and Biaxial Sustained Stress

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5717
Author(s):  
Xiaokang Cheng ◽  
Jianxin Peng ◽  
C.S. Cai ◽  
Jianren Zhang
Keyword(s):  
Diffusion Coefficient ◽  
Compressive Stress ◽  
Stress Level ◽  
Chloride Concentration ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Ion Diffusion ◽  
Chloride Ion Diffusion

The existence of axial and lateral compressive stress affect the diffusion of chloride ions in concrete will lead to the performance degradation of concrete structure. This paper experimentally studied the chloride diffusivity properties of uniaxial and biaxial sustained compressive stress under one-dimensional chloride solution erosion. The influence of different sustained compressive stress states on chloride ion diffusivity is evaluated by testing chloride concentration in concrete. The experiment results show that the existence of sustained compressive stress does not always inhibit the diffusion of chloride ions in concrete, and the numerical value of sustained compressive stress level can affect the diffusion law of chloride ions in concrete. It is found that the chloride concentration decreases most when the lateral compressive stress level is close to 0.15 times the compressive strength of concrete. In addition, the sustained compressive stress has a significant effect on chloride ion diffusion of concrete with high water/cement ratio. Then, the chloride diffusion coefficient model under uniaxial and biaxial sustained compressive stress is established based on the apparent chloride diffusion coefficient. Finally, the results demonstrate that the chloride diffusion coefficient model is reasonable and feasible by comparing the experimental data in the opening literature with the calculated values from the developed model.

scholarly journals Influence of Pore Size and Fatigue Loading on NaCl Transport Properties in C-S-H Nanopores: A Molecular Dynamics Simulation

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 700 ◽  
Author(s):  
Qingyu Cao ◽  
Yidong Xu ◽  
Jianke Fang ◽  
Yufeng Song ◽  
Yao Wang ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Pore Size ◽  
Transport Properties ◽  
Diffusion Rate ◽  
Chloride Ion ◽  
Fatigue Loading ◽  
Chloride Ions ◽  
Water Molecules ◽  
Ion Diffusion ◽  
Chloride Ion Diffusion

The transport properties of chloride ions in cement-based materials are one of the major deterioration mechanisms for reinforced concrete (RC) structures. This paper investigates the influence of pore size and fatigue loading on the transport properties of NaCl in C-S-H nanopores using molecular dynamics (MD) simulations. Molecular models of C-S-H, NaCl solution, and C-S-H nanopores with different pore diameters are established on a microscopic scale. The distribution of the chloride ion diffusion rate and the diffusion coefficient of each particle are obtained by statistically calculating the variation of atomic displacement with time. The results indicate that the chloride ion diffusion rate perpendicular to C-S-H nanopores under fatigue loading is 4 times faster than that without fatigue loading. Moreover, the diffusion coefficient of water molecules and chloride ions in C-S-H nanopores increases under fatigue loading compared with those without fatigue loading. The diffusion coefficient of water molecules in C-S-H nanopores with a pore size of 3 nm obtained from the MD simulation is 1.794 × 10−9 m2/s, which is slightly lower than that obtained from the experiment.

The Mix Design of Low Strength High Flowing Concrete with Low Cement Content Prepared by Manufactured Sand

2011 ◽  
Vol 413 ◽  
pp. 201-206
Author(s):  
Zhan Ao Liu ◽  
Ming Kai Zhou ◽  
Xiao Chen
Keyword(s):  
Cement Content ◽  
Design Method ◽  
Chloride Ion ◽  
Mix Design ◽  
Ion Diffusion ◽  
Natural Sand ◽  
Manufactured Sand ◽  
Low Strength ◽  
Chloride Ion Diffusion ◽  
By Products

Aiming at the engineering status of the shortage of natural sand and the contradictory between workability and strength surplus emerging in the design of low strength high flowing concrete (LHC), this paper has proposed a mix design method of LHC with low cement content prepared by manufactured sand (MS).And then verifies the feasibility of the method through experiments. Tests on slump, compressive strength and chloride ion diffusion coefficient were carried out and the results indicate that LHC with low cement content prepared by MS can be successfully produced using this method. Concrete designed by this method has low cement consumption and has utilized MS to replace NS as well as made full use of the industrial by-products of stone fines and fly ash. As a result, it is economical and ecological.

Experimental Study and Numerical Analysis on Chloride Diffusion Coefficient of Concrete with Various Water-Cement Ratios

2017 ◽  
Vol 726 ◽  
pp. 547-552
Author(s):  
Zheng Ren ◽  
Lian Zhen Xiao ◽  
Wen Chong Shi
Keyword(s):  
Diffusion Coefficient ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Ion Diffusion ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Influence Of Water ◽  
Chloride Ion Diffusion

A rapid chloride ion diffusion coefficient measurement (RCM) was used in this study. The influence of water-cement ratios of 0.30, 0.35 and 0.40 at various ages (3, 7, 14, 28 and 56 days) on chloride ion diffusion coefficient of the concretes and pastes was studied and analyzed. The results show that, with the increase of curing ages, the chloride ion diffusion coefficient of different water-cement ratio of each specimen is decreased. In the early age, the chloride ion diffusion coefficient of the paste with the water-cement ratio of 0.40 is 2~3 times of the paste with water-cement ratio of 0.30 and 0.35, and with the increase of curing age, this difference is gradually decreased. Additionally, the chloride ion diffusion coefficient of the cement paste is 1~2 times of the concrete with same water-cement ratio at different ages. Based on the actual experiment boundary conditions, the process of chloride ions diffusion and permeability was simulated by COMSOL software, and the simulation result was analyzed to predict the permeability of concrete.

Research on Chloride Ion Diffusion of Concrete Water-Based Capillary Crystalline Waterproofer and its Penetration Depth by Using Electron Microscope

2013 ◽  
Vol 857 ◽  
pp. 27-34 ◽  
Author(s):  
Xin Xiao ◽  
Qi Sen Zhang ◽  
Xiao Ye Liang ◽  
Xiao Ning Zhang
Keyword(s):  
Diffusion Coefficient ◽  
Electron Microscope ◽  
Penetration Depth ◽  
Good Condition ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Ion Diffusion ◽  
Strength Concrete ◽  
Water Based ◽  
Chloride Ion Diffusion

In order to improve the durability of concrete structure, studying reduction effect that water-based capillary crystalline waterproofer has on chloride ion diffusion coefficient in the concrete; analyse the inner microstructure of concrete by using electron microscope, and observe the penetration depth of waterproof agent in concrete directly. Research shows that: the water permeable crystalline waterproof agent can significantly reduce the diffusion coefficient of chloride ions in concrete, after concrete forms, the earlier brush waterproof agent, the longer it cure and its improving effect is more prominent after brushing waterproof agent , reduction rate of chloride ion diffusion coefficient in low strength concrete is higher than high-strength concrete;in good condition of water percolation, by detecting of electron microscope, it proved waterproofing agent can penetrate into internal concrete 6cm at least , the gel produced can be filled with pore and micro crack of concrete, so it can significantly improve the compactness of the whole structure.

scholarly journals Evaluation of Chloride-Ion Diffusion Characteristics of Wave Power Marine Concrete Structures

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5675
Author(s):  
Changhyuck Lim ◽  
Gyuyong Kim ◽  
Gyeongtae Kim ◽  
Bokyeong Lee ◽  
Youngduck Kim ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Atmospheric Pressure ◽  
Concrete Structures ◽  
Chloride Ion ◽  
Wave Power ◽  
Ion Diffusion ◽  
Chloride Ion Penetration ◽  
Chloride Attack ◽  
Marine Concrete ◽  
Chloride Ion Diffusion

Wave power marine concrete structures generate electrical energy using waves. They are exposed to a multi-deterioration environment because of air and hydrostatic pressure and chloride attack. In this study, the effect of air pressure repeatedly generated by water level change of wave power marine concrete structures on the chloride-ion diffusion of marine concrete was analyzed. The chloride-ion diffusion of wave power marine concrete structures was evaluated. The results show that the air chamber and bypass room, which were subjected to repetitive air pressures caused by water level changes, showed a higher water-soluble chloride-ion content compared to the generator room and docking facility, which were subjected to atmospheric pressure. Field exposure tests and indoor chloride attack tests were performed using fabricated specimens to analyze the effect of pressure on chloride-ion penetration. It was confirmed that Portland blast furnace slag had a greater inhibitory effect on chloride-ion penetration than ordinary Portland cement. The concrete specimens subjected to pressure showed increased capillary pores and micro-cracks. We devised an equation for calculating the diffusion coefficient based on measured data and estimating the diffusion coefficient for the location receiving repeated air pressure by using the diffusion coefficient of the location receiving general atmospheric pressure.

Influence of Concrete with Lithium-Slag and Steel Slag by early Curing Conditions

2014 ◽  
Vol 599 ◽  
pp. 52-55 ◽  
Author(s):  
Fu Fei Wu ◽  
Ke Bin Shi ◽  
Shuang Kuai Dong
Keyword(s):  
Diffusion Coefficient ◽  
Water Conservation ◽  
Water Solution ◽  
Steel Slag ◽  
Chloride Ion ◽  
Ion Diffusion ◽  
Binder Ratio ◽  
Water To Binder Ratio ◽  
Lithium Slag ◽  
Chloride Ion Diffusion

Using industrial waste (lithium-slag and steel-slag) for the preparation of high-performance concrete, and the same mix proportion’s concrete are cured using six kinds method, which is cured to the required age later and tests its chloride ion diffusion coefficient by RCM method. The results show that: the chloride ion diffusion coefficient of 28d and 84d decreases with the lower water-binder ratio. It can achieve RCM-Ⅴ grade when the water to binder ratio is 0.27. The admixtures total of 275-350kg/m3 is appropriate when the water to binder ratio is constant.The diffusion of water conservation,water solution with 5% Nacl after 7d water conservation,water solution with 5% Nacl after 14d water conservation,water solution with 5% Nacl after 7d in water conservation and water solution with 5% Nacl after 14d in water conservation is 1.5, 3.1, 2.5, 2.8 and 2.3 times than standard conservation , so the effect of early different curing ways to HPC can not be ignored.

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