Inner Damage and Anti-Chloride Penetration of High-Performance Concrete under Axial Tensile Load

2011 ◽  
Vol 261-263 ◽  
pp. 1210-1214
Author(s):  
Fu Xiang Jiang ◽  
Lei Xin ◽  
Tie Jun Zhao ◽  
Xiao Mei Wan
Keyword(s):  
Diffusion Coefficient ◽  
High Performance ◽  
High Performance Concrete ◽  
Tensile Load ◽  
Total Porosity ◽  
Tensile Loading ◽  
Chloride Penetration ◽  
Chloride Diffusion ◽  
Uniaxial Tensile ◽  
Chloride Diffusion Coefficient

The total porosity of high performance concrete specimens after different level uniaxial tensile loading were measured to reflect the damage degree of mechanical load to the microstructure of the concrete. Meanwhile, considering the environmental characteristics of the ocean tidal zone, chloride penetration tests of the concrete were carried out with salt solution capillary absorption method. Based on the profile of chloride measured from specimens, chloride diffusion coefficients of the concrete under uniaxial tensile load with different levels are determined further by Fick’s second law. Results show that both of total porosity and chloride diffusion coefficient of the concrete are increased significantly after short-term tensile loading. And the evolutions of the porosity and chloride diffusion coefficient are similar with the development of micro-cracks under uniaxial tensile load.

scholarly journals Investigation on Durability Performance in Early Aged High-Performance Concrete Containing GGBFS and FA

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Seung-Yup Jang ◽  
Subbiah Karthick ◽  
Seung-Jun Kwon
Keyword(s):  
Diffusion Coefficient ◽  
High Performance ◽  
High Performance Concrete ◽  
Steel Corrosion ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Structural Safety ◽  
Concrete Durability ◽  
Chloride Diffusion Coefficient ◽  
Rc Structures

The significance of concrete durability increases since RC (Reinforced Concrete) structures undergo degradation due to aggressive environmental conditions, which affects structural safety and serviceability. Steel corrosion is the major cause for the unexpected failure of RC structures. The main cause for the corrosion initiation is the ingress of chloride ions prevailing in the environment. Hence quantitative evaluation of chloride diffusion becomes very important to obtain a chloride diffusion coefficient and resistance to chloride ion intrusion. In the present investigation, 15 mix proportions with 3 water-to-binder ratios (0.37, 0.42, and 0.47) and 3 replacement ratios (0, 30, and 50%) were prepared for HPC (high-performance concrete) with fly-ash and ground granulated blast furnace slag. Chloride diffusion coefficient was measured under nonstationary condition. In order to evaluate the microstructure characteristics, porosity through MIP was also measured. The results of compressive strength, chloride diffusion, and porosity are compared with electrical charges. This paper deals with the results of the concrete samples exposed for only 2 months, but it is a part of the total test plan for 100 years. From the work, time-dependent diffusion coefficients in HPC and the key parameters for durability design are proposed.

On the Time Dependency of the Chloride Diffusion in High Performance Concrete

2013 ◽  
Vol 721 ◽  
pp. 148-152
Author(s):  
Zheng Chen ◽  
Xi Bin Zhao ◽  
Yan Hua Yuan ◽  
Zhong Hua Wang ◽  
Lu Feng Yang ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
High Performance ◽  
High Performance Concrete ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Time Dependency ◽  
Long Period ◽  
Age Factor ◽  
Astm C1202

The chloride diffusion coefficient of concrete is time dependent. The high performance concrete (HPC) was prepared and the specimens were tested by ASTM C1202 and the durability of HPC in long period is analyzed with the time dependency of diffusion in this paper. The results show that the chloride diffusion coefficients of the HPC with only fly ash are large than those of the HPC with multi-admixtures, but the attenuation of the chloride diffusion coefficients of the formers are faster than the latters. The analysis results show that the chloride concentrations in concrete is over estimated when time-dependence of chloride diffusion is not considered, and the durability of concrete in long period is determined by both chloride diffusion coefficient and age factor.

Influence of Uniaxial Tensile Cyclic Load on the Porosity of High Performance Concrete

2011 ◽  
Vol 94-96 ◽  
pp. 1500-1504
Author(s):  
Fu Xiang Jiang ◽  
Tie Jun Zhao ◽  
Ming Lei Hao
Keyword(s):  
Cyclic Loading ◽  
High Performance ◽  
Cyclic Load ◽  
High Performance Concrete ◽  
Tensile Load ◽  
Total Porosity ◽  
Load Level ◽  
Uniaxial Tensile ◽  
Cycle Number ◽  
Axial Tensile

The total porosity of the high performance concrete under cyclic loading was measured in this present paper. Results show that finite cycles of cyclic axial tensile load causes permanent damage to concrete, which can be measured after unloading. The higher the applied upper load level or the more the cycle number is, the more obvious will be the connection and development of micro cracks. Then the higher will be the total porosity. Especially, with the increase of cyclic load number, the total porosity of the concrete shows obvious stage characteristics. And there is a linear relationship between the total porosity and cyclic loading cycles in the second developing stage of fatigue strain.

scholarly journals Influence of Pore Structure on Chloride Penetration in Cement Pastes Subject to Wetting-Drying Cycles

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Honglei Chang ◽  
Zhiwu Zuo ◽  
Mingyue Qu ◽  
Fei Wang ◽  
Zhi Ge ◽  
...  
Keyword(s):  
Pore Structure ◽  
Penetration Rate ◽  
Error Function ◽  
Chloride Concentration ◽  
Total Porosity ◽  
Chloride Penetration ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Cement Pastes ◽  
The Matrix

Copious studies have discovered a phenomenon that a chloride concentration peak appears on the surface of concrete under cyclic drying-wetting environments. In such cases, the chloride diffusion coefficient (D) obtained through directly fitting the standard error function of Fick’s second law is no longer accurate. The more reliable D obtained by the method proposed by Andrade is employed in this research to investigate the influence of pore structure on chloride penetration rate of pastes. The results show that both the effective coefficient (Deff) and the apparent coefficient (Dapp) increase with total porosity, the most probable pore size, and water absorption porosity, suggesting that the increase of the three pore structure parameters accelerates chloride penetration rate under cyclic wetting-drying condition. The increase of the three parameters makes more room available and eases the difficulty for salt solution to enter the matrix and thus leads to the augmentation of chloride transporting in matrix.

Boundary Element Analysis of Accelerated Chloride Diffusion in High Performance Concrete

2013 ◽  
Vol 842 ◽  
pp. 151-155
Author(s):  
Yi Wang ◽  
Wo Cheng Hang ◽  
Lu Feng Yang ◽  
Zheng Chen
Keyword(s):  
Diffusion Coefficient ◽  
Boundary Element ◽  
High Performance ◽  
Numerical Solutions ◽  
High Performance Concrete ◽  
Chloride Concentration ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Chloride Diffusion ◽  
Chloride Permeability

This paper aims to analyze accelerated chloride diffusion in high performance concrete (HPC) blended with mineral admixture by using boundary element method (BEM). Rapid chloride permeability test (RCPT) was employed and executed. The experiment proves that the highest resistance to chloride permeability can be acquired in the quaternary-blended concretes (ordinary portland cement + fly ash + blast furnace slag + silica fume). A chloride diffusion BEM model was established according to the diffusion coefficient calculated from the charge passed. The numerical solutions agree with experiments well. It can be inferred that the acceleration degree of RCPT is not the same in different mix proportion. Besides, the results also suggest that the low chloride permeability of the concretes with mineral admixtures may be attributed to the lower diffusion coefficient and the lower surface chloride concentration.

Influence of Stone Dust in Manufactured Sand on Resisting Chloride Penetration in Marine Concretes

2012 ◽  
Vol 174-177 ◽  
pp. 1419-1423
Author(s):  
Jian Bo Xiong ◽  
Peng Ping Li ◽  
Sheng Nian Wang
Keyword(s):  
Diffusion Coefficient ◽  
Pore Structure ◽  
Binding Capacity ◽  
Chloride Penetration ◽  
Dust Content ◽  
Chloride Diffusion ◽  
Fine Aggregate ◽  
Chloride Diffusion Coefficient ◽  
Manufactured Sand ◽  
Stone Dust

In China, manufactured sand has been widely used as fine aggregate in concrete. Therefore, it is necessary to investigate the effect of manufactured sand on durability of concrete. This research studies the influence of stone dust content in manufactured sand on resisting chloride penetration in marine concrete by strength and other physical mechanical tests, XRD, TGA and pore structure analysis. Test results have shown that the chloride diffusion coefficient increased with increasing the stone dust content in manufactured sand when the stone dust content increasing from 3% to 13%. The stone dust in fine aggregate was participated in hydration procedure of cementitious, which will promote the hydration degree of cementitious and increase the chloride binding capacity of hydration product. The influence of stone dust in fine aggregate on chloride diffusion coefficient were the combined effects of concrete pore structure and cementitious hydration products, and the porosity and pore size distribution were the main factors that influence the changes of diffusion coefficient.

Comparison of chloride penetration into surface-treated concrete in artificial and natural environments

2016 ◽  
Vol 20 (9) ◽  
pp. 1315-1324 ◽  
Author(s):  
Jianfeng Dong ◽  
Yuxi Zhao ◽  
Yueliang Gan ◽  
Chaomei Ding ◽  
Qiming He
Keyword(s):  
Diffusion Coefficients ◽  
High Performance ◽  
High Performance Concrete ◽  
Chloride Penetration ◽  
Chloride Diffusion ◽  
Natural Environments ◽  
Nacl Solution ◽  
Normal Concrete ◽  
Wetting And Drying

This study investigated the penetration of chloride into surface-treated high-performance concrete and normal concrete in natural and accelerated environments. Both high-performance concrete and normal concrete were applied in a real port. Concrete specimens that were cast together with the concrete port were transported to the laboratory and subjected to wetting and drying cycles with NaCl solution. The chloride contents of the specimens in the laboratory and the in situ components were tested. The chloride diffusion coefficients and surface chloride contents were calculated based on Fick’s second law. The results show that high-performance concrete and surface treatment clearly slow the chloride penetration into the concrete both in the laboratory and in situ. The chloride contents on the surface and in the concrete in the components of the concrete port are higher during the summer than during the winter. The chloride penetration performance in the concrete of real structures cannot be inferred from its performance in specimens under artificial environments in the laboratory.

Water Transport Properties and Depth of Chloride Penetration in Ultra High Performance Concrete

2016 ◽  
Vol 711 ◽  
pp. 137-142 ◽  
Author(s):  
Daniel Dobias ◽  
Radka Pernicova ◽  
Tomas Mandlik
Keyword(s):  
Water Transport ◽  
High Performance ◽  
Moisture Absorption ◽  
High Performance Concrete ◽  
Chloride Transport ◽  
Chloride Ions ◽  
Chloride Penetration ◽  
Chloride Diffusion ◽  
Ultra High Performance Concrete ◽  
Depth Of Penetration

Properties of water transport and depth of chloride penetration into the Ultra High Performance Concrete (hereafter as UHPC) with mild steel fibres are presented in this paper. The main aim of this experimental part of work is to obtain sufficiently accurate input data for the evaluation of long-term durability of architectural concrete which are connected with water transport and its accompanying effects such as biological degradation or chloride transport. The article also presents the one dimensional chloride diffusion into UHPC which can be potentially dangerous particularly for durability of reinforced concrete structures. For the simulation of aggressive environments the concrete samples were exposed to chloride solution for one year. Measured data were examined in relation to the depth of penetration of chloride ions into the UHPC structure. Comparative measurements with normal strength concrete (hereafter as NSC) are done as well. An about five-time lower value of moisture absorption of UHPC compared to the NSC was observed and further the curve of chloride penetration into the structure is significantly steeper for UHPC samples.

Effect of Stone Dust Content in Manufactured Sand on Chloride Diffusion Coefficient of Various Strength Grade Concretes

2011 ◽  
Vol 399-401 ◽  
pp. 1276-1281
Author(s):  
Peng Ping Li ◽  
Jian Bo Xiong ◽  
Zhi Hong Fan
Keyword(s):  
Diffusion Coefficient ◽  
Total Porosity ◽  
Immersion Test ◽  
Dust Content ◽  
Chloride Diffusion ◽  
Fine Aggregate ◽  
Chloride Diffusion Coefficient ◽  
Manufactured Sand ◽  
Stone Dust ◽  
Main Factor

The influence of stone dust content on chloride diffusion coefficient in C30, C40 and C50 grade concretes were investigated by means of the natural immersion test, XRD test, MIP test, SEM and TGA test, respectively. The experimental results showed that the chloride diffusion coefficient in C30 grade concretes decreased with increasing the stone dust content, but it decreased first and then increased with increasing the stone dust content in C40 and C50 grade concretes. The hydration degree for cementitious and compressive strength for concrete was slightly promoted by using stone dust replacing cementitious at a low level. For C30 grade concretes, the porosity decreased with increasing the stone dust content in fine aggregate, but for C40 and C50 grade concretes, the total porosity decreased first then increased with increasing the stone dust content. And the concrete pore structure was the main factor that influences the changes of chloride diffusion coefficient in concrete.

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