Permeability of Anti-Chloride Ion of Fly Ash Recycled Concrete

2011 ◽  
Vol 317-319 ◽  
pp. 544-547
Author(s):  
Ai Jiu Chen ◽  
Jing Wang ◽  
Zhan Fang Ge ◽  
Ming Wu
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Coarse Aggregate ◽  
Chloride Ion ◽  
Reducing Agent ◽  
Polypropylene Fibre ◽  
Recycled Concrete ◽  
Ion Diffusion ◽  
The North ◽  
Chloride Ion Diffusion

Adding fly ash to recycled concrete with super-substitute technique, comparing the 28d strength of fly ash recycled concrete(FARC) with the 28d strength of ordinary recycled concrete(ORC), the compressive strength of fly ash recycled concrete slightly decreased with the increase of the fly ash and the admixture of renewable aggregate. Along with the increase of mixing amount of the air entraining and water-reducing agent, the compressive strength of fly ash recycled concrete tends to reduce. The order of the factors that affect the chloride ion diffusion coefficient of recycled concrete is fly ash admixture→mixing amount of the air entraining and water-reducing agent→admixture of recycled coarse aggregate→polypropylene fibre admixture, which provides a basis for the application of recycled concrete engineering in the environment which is affected by chlorine salt in the north frigid area .

scholarly journals Bentonite replacing part of cement concrete for resistance to chloride ion attack

2019 ◽  
Vol 136 ◽  
pp. 03011
Author(s):  
Jie Luo ◽  
Chuanchang Li ◽  
Yafei Ma ◽  
Lei Wang
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Chloride Ion ◽  
Cementitious Materials ◽  
Ion Diffusion ◽  
Natural Pozzolan ◽  
Cement Production ◽  
Chloride Ion Penetration ◽  
Chloride Migration ◽  
Chloride Ion Diffusion

Bentonite is known as a kind of natural pozzolan that can improve the mechanical properties of cementitious materials and reduce the overall CO2 output of cement production. This study is designed to evaluate the feasibility of using bentonite as a substitute for cement in concrete and analyze the effect of bentonite on resisting chloride ion penetration. The concrete was replaced by equal-quality bentonite for 0%, 5%, 10%, 15% and 20% cement respectively, and the water-cement ratio, fine and coarse aggregate content remained constant. The results indicated that as the bentonite content increased, the compressive strength of the mixes increased first and then decreased. The sample containing 10% bentonite got a higher compressive strength than the other samples. The rapid chloride migration (RCM) tests showed that the samples containing bentonite had better resistance to chloride ion attack than samples without bentonite against chloride, especially the sample containing 10% bentonite. It can be concluded that the concrete with 10% bentonite can improve the resistance to chloride ion diffusion with high compressive strength.

scholarly journals Carbonization Durability of Two Generations of Recycled Coarse Aggregate Concrete with Effect of Chloride Ion Corrosion

2020 ◽  
Vol 12 (24) ◽  
pp. 10544
Author(s):  
Chunhong Chen ◽  
Ronggui Liu ◽  
Pinghua Zhu ◽  
Hui Liu ◽  
Xinjie Wang
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Chloride Ion ◽  
Total Porosity ◽  
Recycled Concrete ◽  
Carbonation Depth ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Carbonation Resistance ◽  
Two Generations

Carbonation durability is an important subject for recycled coarse aggregate concrete (RAC) applied to structural concrete. Extensive studies were carried out on the carbonation resistance of RAC under general environmental conditions, but limited researches investigated carbonation resistance when exposed to chloride ion corrosion, which is an essential aspect for reinforced concrete materials to be adopted in real-world applications. This paper presents a study on the carbonation durability of two generations of 100% RAC with the effect of chloride ion corrosion. The quality evolution of recycled concrete coarse aggregate (RCA) with the increasing recycling cycles was analyzed, and carbonation depth, compressive strength and the porosity of RAC were measured before and after chloride ion corrosion. The results show that the effect of chloride ion corrosion negatively affected the carbonation resistance of RAC, and the negative effect was more severe with the increasing recycling cycles of RCA. Chloride ion corrosion led to a decrease in compressive strength, while an increase in carbonation depth and the porosity of RAC. The equation of concrete total porosity and carbonation depth was established, which could effectively judge the deterioration of carbonation resistance of RAC.

The Durability Life Prediction of Recycled Concrete under Chlorate Environment

2011 ◽  
Vol 314-316 ◽  
pp. 849-852
Author(s):  
Ai Jiu Chen ◽  
Jing Wang ◽  
Zhan Fang Ge ◽  
Ming Wu
Keyword(s):  
Life Prediction ◽  
Coarse Aggregate ◽  
Chloride Ion ◽  
Orthogonal Test ◽  
Polypropylene Fibre ◽  
Recycled Concrete ◽  
Second Law ◽  
Ion Permeation ◽  
Practical Application ◽  
Recycled Coarse Aggregate

Using orthogonal test, the influence of variable mixing proportions of recycled coarse aggregate, polypropylene fibre and air entraining and water-reducing admixture on the anti-penetration capability of chloride ion of recycled concrete is analyzed. And the mechanism of resistance to chloride ion permeation concerning different mixing proportions of the materials is figured out. After that, basing on the effects of these materials on the durability life of recycled concrete in chlorate surroundings, the sequence is worked out: first, air entraining and water reducing agent, then recycled coarse aggregate, last one, polypropylene fibre. Employing Fick’s second law, the durability life of recycled concrete applied in chlorate environment is estimated. As a result, evidences for the practical application of recycled concrete are provided for its use in the northern cold areas and the places along the coast.

The Effect of Superplasticizer on Strength and Chloride Permeability of Concrete Containing GGBFS

2013 ◽  
Vol 804 ◽  
pp. 12-16 ◽  
Author(s):  
Shi Yi Zhang ◽  
Ying Fang Fan ◽  
Ning Ning Li
Keyword(s):  
Mechanical Property ◽  
Compressive Strength ◽  
Diffusion Coefficients ◽  
Chloride Ion ◽  
Ion Diffusion ◽  
Chloride Permeability ◽  
Additive Content ◽  
Chloride Ion Penetration ◽  
Chloride Ion Diffusion

The effect of superplasticizer on the mechanical property and chloride permeability of concrete containing GGBFS is investigated in this paper. Compressive and rapid chloride-ion diffusion tests were conducted to determine the axial compressive and chloride-ion diffusion coefficients of GGBFS modified concrete. The tests result indicated that the compressive strength of GGBFS modified concrete with the addition of 2wt. % superplasticizer are further improved at 14 and 28 days. Superplasticizer can significantly enhance the resistance to chloride ion penetration of concrete containing GGBFS with a reasonable additive content at long-term age. The optimum content of superplasticizer is suggested to be 1wt. % to 2wt. % of the cementitous materials.

scholarly journals Evaluation of Relationship between Water Absorption and Durability of Concrete Materials

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
S. P. Zhang ◽  
L. Zong
Keyword(s):  
Compressive Strength ◽  
Surface Water ◽  
Water Absorption ◽  
Chloride Ion ◽  
Sulfate Attack ◽  
Ion Diffusion ◽  
Curing Conditions ◽  
Concrete Materials ◽  
Chloride Ion Diffusion ◽  
Durability Of Concrete

Environment has significant effects on the water absorption of concrete materials. This paper presents an experimental study of the influence of water absorption on the durability of concrete materials. A detailed analysis is also presented in order to establish useful relationship between them. Concrete specimens of different water absorption were prepared through different curing conditions, and results indicated that curing condition can significantly affect the surface water absorption. SEM photos also showed that different curing conditions caused different microstructure. After 28-days curing, compressive strength, permeability, sulfate attack, and chloride ion diffusion of concrete samples were investigated. As a result, both of surface sorptivity and internal sorptivity have no clear relationship with compressive strength. Results obtained also showed that only surface water absorption related to the performance of concrete including permeability, sulfate attack, and chloride ion diffusion. In addition, both impermeability and resistance to sulfate attack were linearly associated with surface sorptivity, and both correlation coefficients were not less than 0.9. Furthermore, chloride ion diffusion coefficient has exponent relation to surface water absorption with higher correlation coefficient. However, no apparent relationship was found between internal water absorption and durability like impermeability, resistance to sulfate attack, and chloride ion diffusion.

scholarly journals Correlation between diffusion coefficient values of chloride ions obtained through column and ion migration tests in cementitious matrices with varying contents of silica fume and mortar

2022 ◽  
Vol 15 (3) ◽  
Author(s):  
Silas de Andrade Pinto ◽  
Sandro Lemos Machado ◽  
Daniel Véras Ribeiro
Keyword(s):  
Silica Fume ◽  
Coarse Aggregate ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Transport Mechanisms ◽  
Ion Diffusion ◽  
Column Tests ◽  
Ion Migration ◽  
Chloride Migration ◽  
Chloride Ion Diffusion

Abstract Corrosion is one of the main phenomena that lead to pathological manifestations in reinforced concrete structures under aggressive environments. with the chloride ion being the most responsible for its occurrence. In this way, understanding the transport mechanisms of this ion through the microstructure of the concrete is of fundamental importance to prevent or delay the penetration of these aggressive agents to guarantee a durable structure. In the literature, there are extensive studies concerning the diffusion of chlorides in concrete and the influence of pozzolanic additions in this mechanism. However, only a few correlate the different methods of analysis. This work aims to determine the chloride ion diffusion coefficients in concrete containing various levels of silica fume (5%, 10%, and 15%) or varying the mortar content (54%, 80%, and 100%), and compares the results obtained through column tests and chloride migration tests. It was observed that, although the techniques used were quite distinct, the diffusion values obtained were similar, contributing to the validation of both techniques. Furthermore, the variation in the mortar ratio causes a reduction in the interfacial transition zone of coarse aggregate/mortars and an increase in the content of aluminates, which promotes a similar effect to the use of silica fume.

scholarly journals Effect of Curing Condition on Resistance to Chloride Ingress in Concrete Using Ground Granulated Blast Furnace Slag

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3233 ◽  
Author(s):  
JangHyun Park ◽  
Cheol Park ◽  
SungHyung Joh ◽  
HanSeung Lee
Keyword(s):  
Compressive Strength ◽  
Diffusion Coefficient ◽  
Blast Furnace Slag ◽  
Chloride Ion ◽  
Ion Diffusion ◽  
Concrete Compressive Strength ◽  
Replacement Ratio ◽  
Granulated Blast Furnace Slag ◽  
Chloride Ion Diffusion ◽  
Furnace Slag

Changes in the salt attack resistance of concrete using ground granulated blast furnace slag (GGBFS) were examined based on different curing conditions. These conditions were divided into air and underwater curing. Three concrete mixes with GGBFS replacement ratios of 0% (control group), 30% and 60% were fabricated. Then, evaluation of concrete compressive strength, evaluation of chloride ion diffusion coefficient and electrochemical impedance spectroscopy (EIS) were performed. As the GGBFS replacement ratio increased, the concrete compressive strength of the air cured specimens decreased compared to the underwater cured specimens. With respect to the chloride ion diffusion coefficient measurements, the coefficient decreased as the GGBFS replacement ratio increased. However, the diffusion coefficient of the air cured specimen relative to the underwater cured ones increased up to two times. The EIS results showed that as the GGBFS replacement ratio increased, |Z| increased in every frequency range. However, the |Z| of the air cured specimen was lower than the underwater cured one. This showed the same tendency as the evaluation results of the chloride ion diffusion coefficient.

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