Feasibility of electrochemical chloride extraction from structural reinforced concrete using a sprayed conductive graphite powder–cement paste as anode

2013 ◽  
Vol 77 ◽  
pp. 128-134 ◽  
Author(s):  
A. Cañón ◽  
P. Garcés ◽  
M.A. Climent ◽  
J. Carmona ◽  
E. Zornoza
Keyword(s):  
Reinforced Concrete ◽  
Cement Paste ◽  
Graphite Powder ◽  
Electrochemical Chloride Extraction

scholarly journals Effects of Electrochemical Chloride Extraction on Hydrated Products of Various Cement Paste Systems

2015 ◽  
Vol 13 (12) ◽  
pp. 564-582 ◽  
Author(s):  
Hai Yen Nguyen Thi ◽  
Hiroshi Yokota ◽  
Katsufumi Hashimoto
Keyword(s):  
Cement Paste ◽  
Hydrated Products ◽  
Electrochemical Chloride Extraction

A novel multi-scale model for predicting the thermal damage of hybrid fiber-reinforced concrete

2019 ◽  
Vol 29 (1) ◽  
pp. 19-44 ◽  
Author(s):  
Yao Zhang ◽  
J Woody Ju ◽  
Hehua Zhu ◽  
Zhiguo Yan
Keyword(s):  
Reinforced Concrete ◽  
Cement Paste ◽  
Thermal Damage ◽  
Fiber Reinforced Concrete ◽  
Scale Model ◽  
Fiber Reinforced ◽  
Interfacial Damage ◽  
Hybrid Fiber ◽  
Multi Scale ◽  
Damage Degree

A multi-scale micromechanical model is proposed to predict the damage degree of hybrid fiber-reinforced concrete under or after high temperatures. The thermal degradation of hybrid fiber-reinforced concrete is generally composed of the damage of the cement paste caused by thermal decomposition and thermal incompatibility, the deterioration of aggregates and fibers, and the interfacial damage between aggregates and the matrix. In this multi-scale model, four levels of hybrid fiber-reinforced concrete structures are considered when the thermal damage degree is derived; namely, the equivalent calcium silicate hydrate (C–S–H) product level, the cement paste level, the concrete level, and the hybrid fiber-reinforced concrete level. At the cement paste level, thermal decompositions of C–S–H product and calcium hydroxide are taken into account. In addition, a dimensionless parameter of the crack density is introduced to represent the thermal cracking of the matrix. At the concrete level, the interfacial damage of aggregates is simulated by a spring–interface model, in which the interfacial parameters are assumed to be functions of temperature. Moreover, at the cement paste level and the hybrid fiber-reinforced concrete level, a sub-stepping homogenization method is proposed to determine the effective properties. Comparisons between previously published experimental data and predictions and discussions illustrate the feasibility of the proposed multi-scale model in predicting thermal damage of concrete and hybrid fiber-reinforced concrete.

scholarly journals Effect of Imidazoline Inhibitor on the Rehabilitation of Reinforced Concrete with Electromigration Method

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 398 ◽  
Author(s):  
Chonggen Pan ◽  
Jianghong Mao ◽  
Weiliang Jin
Keyword(s):  
Reinforced Concrete ◽  
Extraction Efficiency ◽  
Corrosion Potential ◽  
Steel Bar ◽  
Chloride Migration ◽  
Significant Difference ◽  
Steel Bars ◽  
Novel Method ◽  
Electrochemical Chloride Extraction ◽  
High Chloride

Steel bars embedded in reinforced concrete are vulnerable to corrosion in high chloride environments. Bidirectional electromigration rehabilitation (BIEM) is a novel method to enhance the durability of reinforced concrete by extracting chloride out of concrete and introducing an inhibitor to the surface of the steel bar under the action of an electric field. During the migration process, a higher ionization capacity of the inhibitor with a symmetrical molecular structure was introduced. A new imidazoline inhibitor was, therefore, employed in this study due to its great ionization capacity. The effect of imidazoline and triethylenetetramine inhibitor on chloride migration, corrosion potential, and strength of concrete were explored. The research results showed that the effect of chloride extraction and electrochemical chloride extraction made no significant difference on the surface of the concrete, where chloride extraction efficiency was more than 70%, and the chloride extraction efficiency was more than 90% around the location of the steel. while a dry-wet cycle test, the potential of concrete increased by about 200 mV by mixing imidazoline inhibitor. The imidazoline inhibitor was found to be effective at facilitating chloride migration and ameliorating corrosion, meanwhile, it had a negligible impact on the concrete’s strength.

scholarly journals Efficiency of ECE Applied on RC Slab using Locally Available Un-Galvanized Steel with Conductive Cement Paste Anode

2020 ◽  
Vol 9 (4) ◽  
pp. 1930-1936
Keyword(s):  
Reinforced Concrete ◽  
Cement Paste ◽  
Concrete Slab ◽  
Research Work ◽  
Chloride Content ◽  
Chloride Ions ◽  
Galvanized Steel ◽  
Current Intensity ◽  
Structural Element ◽  
Reinforced Concrete Slab

Electro-chemical Chloride Extraction (ECE) is considered one of the most effective technique used to extract chloride ions from reinforced concrete structures. Effectiveness of using ECE depends on some important factors such as anode type, current intensity, extraction duration, type of rebar and chemical properties of concrete. On the other hand, ECE may cause some detrimental effects on some mechanical properties of concrete and steel such as a reduction in bond and compressive strengths of concrete, and embrittlement (i.e. reduction in ductility) ductility of reinforcing steel. The major aim of this research work was to investigate the effectiveness of ECE using locally available un-galvanized steel mesh with conductive cement paste anode as a new type of anode on a reinforced concrete slab as a structural element. The slab behavior before and after ECE was studied by determining compressive strength, water absorption rate, concrete chloride content and steel corrosion potential. The slab behavior was studied taken into consideration the established steel arrangement with spacing 20 cm between re-bars. Another aim of this research work was to investigate the effect of initial chloride content on chloride extraction efficiency by applying optimum current intensity and duration (3 A/m2 and 6 weeks) on cylinders with pure chloride content 0.4% and 0.8% (by weight of cement). Effectiveness of ECE with small initial chloride content 0.4% and 0.8% was compared with that of high initial chloride content (2.5%) in order to know if the initial chloride content is an important factor on ECE effectiveness or not.

Effect of Interrupting Electricity Period on Electrochemical Chloride Extraction of Reinforced Concrete

2015 ◽  
Vol 754-755 ◽  
pp. 342-347
Author(s):  
Mien Van Tran ◽  
Dong Viet Phuong Tran ◽  
Mohd Mustafa Al Bakri Abdullah
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Rate ◽  
Current Density ◽  
Concrete Structure ◽  
Chloride Concentration ◽  
Steel Reinforcement ◽  
Reinforced Concrete Structure ◽  
Half Cell ◽  
Cell Potential ◽  
Electrochemical Chloride Extraction

Electrochemical chloride extraction – ECE is an effective method to rehabilitate reinforced concrete structure, which has been corroded. This study investigated concentration of chloride remained in concrete and half-cell potential of the steel reinforcement after ECE using interrupting period of electricity current. Efficiency of ECE using Ca (OH)2was surveyed with two current density of 0.5 and 1A/m2. In this study, ECE treatment was proceeded intermittently in approximately 8 weeks. Results pointed out that chloride concentration decreased to 30 – 60% significantly, especially at in the vicinity of reinforcing steel. Simultaneously, half-cell potential of the steel reinforcement after 4 weeks halted treatment stabilizes in low-corrosion rate.

Binary Superposition Mix Design Method for SFRC Part I: Principle and Evaluation

2010 ◽  
Vol 168-170 ◽  
pp. 2186-2190 ◽  
Author(s):  
Shun Bo Zhao ◽  
Hong Yuan Huo ◽  
Chen Xiao Song ◽  
Li Sha Song
Keyword(s):  
Tensile Strength ◽  
Reinforced Concrete ◽  
Cement Paste ◽  
Steel Fiber ◽  
Design Method ◽  
Splitting Tensile Strength ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Mix Design ◽  
Fiber Reinforced

The binary superposition mix design method is constructed to quantitatively calculate the compositions of steel fiber reinforced concrete (SFRC), which brings into sufficient cement paste wrapping steel fibers to strengthen the boundary surfaces of steel fibers with base concrete. The principle of the method is firstly introduced. The experiments were carried out to evaluate the validity of the method. In the experiment, the cubic and axial compressive strength as well as the splitting tensile strength of SFRC affected by the fraction of steel fiber by volume and the average thickness of cement paste wrapping steel fibers were tested. The results are analyzed on the basis of former studies specified in the current technical specification for fiber reinforced concrete structures, which show that the larger strengths especial the splitting tensile strength of SFRC in grade CF50 can be got by the method, but the less splitting tensile strength of SFRC in grade of CF40 should be further studied.

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