scholarly journals Diffusion Decay Coefficient for Chloride Ions of Concrete Containing Mineral Admixtures

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Jae-Im Park ◽  
Kwang-Myong Lee ◽  
Soon-Oh Kwon ◽  
Su-Ho Bae ◽  
Sang-Hwa Jung ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Concrete Structures ◽  
Blended Cement ◽  
Chloride Ions ◽  
Mineral Admixture ◽  
Curing Temperature ◽  
Mineral Admixtures ◽  
Exposure Condition ◽  
Diffusion Decay ◽  
Decay Coefficient

The diffusion coefficient for chloride ions and the diffusion decay coefficient for chloride ions are essential variables for a service life evaluation of concrete structures. They are influenced by water-binder ratio, exposure condition, curing temperature, cement type, and the type and use of mineral admixture. Mineral admixtures such as ground granulated blast furnace slag, fly ash, and silica fume have been increasingly used to improve resistance against chloride ions penetration in concrete structures built in an offshore environment. However, there is not enough measured data to identify the statistical properties of diffusion decay coefficient for chloride ions in concrete using mineral admixtures. This paper is aimed at evaluating the diffusion decay coefficient for chloride ions of concrete using ordinary Portland cement or blended cement. NT BUILD 492 method, an electrophoresis experiment, was used to measure the diffusion coefficient for chloride ions with ages. It was revealed from the test results that the diffusion decay coefficient for chloride ions was significantly influenced by W/B and the replacement ratio of mineral admixtures.

scholarly journals Performance Evaluation of Ordinary Portland Cement with GGBFS and Portland Slag Cement at Same GGBFS Replacement Level in Concrete

2018 ◽  
Vol 203 ◽  
pp. 06004
Author(s):  
Ramesh Babu Chokkalingam ◽  
Manikandan Rajakannu
Keyword(s):  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Concrete Structures ◽  
Blended Cement ◽  
Mineral Admixtures ◽  
Slag Cement ◽  
Control Practice ◽  
Cement Manufacturing ◽  
Portland Slag Cement ◽  
Durability Of Concrete

Literature review indicates that the usage of mineral admixtures (Fly ash, Ground Granulated Blast Furnace Slag, Silica Fume and Rice Husk ash) significantly improves the durability of concrete structures. Though it is reported as best alternative materials for improving durability of concrete structures, it was not very well received in government projects in India till 1990. However, for the past two decades, the usage of mineral admixtures directly or in the form of blended cement in concrete have significantly increased. Major concern of using mineral admixtures which was persisting among majority of the Ordinary Portland Cement (OPC) users are (i) delayed setting and strength gain, affecting the rate of construction, (ii) inconsistent in quality of mineral admixtures, mostly happened in site blending (iii) no established results pertains to Indian condition. In India, mostly the usage of mineral admixtures in concrete are used as a replacement for OPC, specifically in Ready Mix Concrete and site batching plant. However, few literature have reported that usage of mineral admixtures in the form of blended cement which is made at cement manufacturing plant by either intergrinding or blending will exhibits better concrete properties due to consistent quality and better quality control practice followed. Hence, the authors have undertaken this study to investigate the performance of mineral admixtures (only GGBFS) as direct replacement materials and as blended cement in concrete. In order to understand in detail, both as replacement of OPC and in the form of PSC, was undertaken on various cement content in concrete, i.e., 300, 320, 340, 360, 380 kg/m3. Results of compressive strength at various age of curing indicates that usage of GGBFS in the form of Portland Slag Cement (PSC) shows better performance than as a replacement of OPC in concrete.

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.

scholarly journals The Synergic Effects of Mineral Admixtures in Ternary Blended Cement: A Review

2021 ◽  
Vol 27 (2) ◽  
pp. 83-105
Author(s):  
Shubbar Jawad Al-obaidey
Keyword(s):  
Blended Cement ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Fresh Properties ◽  
Cement Concrete ◽  
Cement Production ◽  
Sustainable Concrete ◽  
Concrete Properties ◽  
Different Types ◽  
Efficiency Factors

In the last decades, using mineral admixture in concrete became very necessary to improve concrete properties and reduce CO2 emissions associated with the cement production process. Subsequently, more sustainable concrete can be obtained.  Ternary blended cement containing two different types of mineral admixture can achieve ambitious steps in this trend. In this research, the synergic effects of mineral admixtures in ternary blended cement and its effects on concrete fresh properties, strength, durability, and efficiency factors of mineral admixture in ternary blended cement, were reviewed. The main conclusion reached after reviewing many literature pieces is that the concrete with ternary blended cement, depending on types of mineral admixtures used, replacement percentages by weight of cement, and age of concrete, exhibited superior properties than with no mineral admixtures and corresponding binary blended cement concrete.

scholarly journals Degradation of Shotcrete Materials Subjected to Sulfate and Chloride Attack in Varying Exposure Regimes

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Ruiqiang Zhao ◽  
Lihao Xu ◽  
Jun Yang ◽  
Yang Zou ◽  
Zhongya Zhang
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Cementitious Materials ◽  
Sulfate Attack ◽  
Chloride Ions ◽  
Supplementary Cementitious Materials ◽  
Mineral Admixtures ◽  
Exposure Condition ◽  
Hydration Kinetics ◽  
Partial Immersion

Durability of in situ shotcrete under external sulfate attack was investigated, taking into consideration the addition of mineral admixtures, along with the presence of chloride ions. Three water-to-binder ratios (w/b), i.e., 0.35, 0.45, and 0.55, and two types of supplementary cementitious materials (SCMs), namely, fly ash (FA) and silica fume (SF), were considered in the current study. Two different laboratorial immersion regimes (continuously full immersion and partial immersion with cycling temperature and relative humidity) were carried out to induce chemical/physical sulfate attack. Results show that loss of strength was the typical feature of chemical sulfate attack on shotcrete, while surface spalling dominated in deterioration caused by physical sulfate attack. The presence of chloride ions can globally mitigate these deteriorations. Meanwhile, the lower w/b ratio proved to be efficient in increasing the resistance to both sulfate attacks. Adding fly ash (FA) in shotcrete mixtures enhanced the long-term performance but invited massive white efflorescence on surface layer under partial-immersion exposure condition. Silica fume (SF) admixture can compensate the undesired reduction of early-age strength caused by FA addition, but make these specimens more susceptible to sulfate attack. Mercury intrusion porosimetry (MIP) analysis, scanning electron microscopy (SEM), and X-ray diffraction (XRD) tests reveal that these consequences were strongly related to the refinement of microstructure resulted from pozzolanic reactions and hydration kinetics.

Relative Humidity of Blended Cement Pastes in Sealed during Hydration

2013 ◽  
Vol 539 ◽  
pp. 60-63
Author(s):  
Dan Jin ◽  
Wu Yao ◽  
Yi Chen
Keyword(s):  
Relative Humidity ◽  
Blended Cement ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Cement Pastes ◽  
Cement Ratio ◽  
Water To Cement Ratio ◽  
Cement Based Materials ◽  
Different Ages ◽  
Key Factor

As an important part of cement-based materials，water plays an important role during hydration and self-desiccation so the measurement of relative humidity or internal moisture in the research of cement-based materials is vital. In this paper, the measurement samples are blended cement pastes in sealed with different water to cement ratios and different kind of mineral admixtures. The measurement was taken at different ages during hydration to investigate the changes of relative humidity. The result showed that the water to cement ratio was the key factor of affecting the change of relative humidity, and the effect of mineral admixture kind was not very obvious in this experiment.

Effects of Mineral Admixtures on Carbonation and Chloride Ingress of Concrete

2012 ◽  
Vol 212-213 ◽  
pp. 878-882 ◽  
Author(s):  
Abuduhelili Haibier ◽  
Yong Xin Wu
Keyword(s):  
Concrete Structures ◽  
Steel Corrosion ◽  
Chloride Ion ◽  
Chloride Penetration ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Chloride Ingress ◽  
Test Results ◽  
Concrete Carbonation ◽  
Carbonation Process

Reinforcement corrosion is one important factor affecting the durability and safety of reinforced concrete structures. Concrete carbonation and chloride ion penetration is the main cause leading to steel corrosion, also important indicators affecting the service life of concrete structures. An accelerated carbonation experiment and Chloride penetration experiment was carried out on ordinary Portland cement (OPC) concrete and admixture concrete in various conditions. Eight concrete specimens of different mixture properties were tested in experiment. Resistance of OPC concrete system with and without mineral admixture (fly ash, slag) and air-entraining agent against carbonation was investigated. Besides, the influence of mineral admixture on the chloride penetration was also studied. The carbonation process and the factors affecting concrete carbonation are discussed according to test results. The test results were presented and they were in good agreement with the results of previous research.

scholarly journals Blended cement hydration assessment by thermogravimetric analysis and isothermal calorimetry

2018 ◽  
Vol 149 ◽  
pp. 01062
Author(s):  
Meriem Meziani ◽  
Nasser Chelouah ◽  
Ouali Amiri ◽  
Nordine Leklou
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermogravimetric Analysis ◽  
Isothermal Calorimetry ◽  
Blended Cement ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Hydration Kinetics ◽  
Scanning Calorimetry ◽  
Cement Pastes ◽  
Degree Of Hydration

In the present study, the hydration of Portland cement pastes containing 5%, 10%, 15% and 20% tuff, limestone filler and granodiorite was investigated by thermogravimetric analysis coupled with differential scanning calorimetry and microcalorimetry isotherm. The monitoring of the hydration kinetics by thermogravimetric analysis made it possible to quantify the quantity of water combined with the cement (nonevaporable water) and the degree of hydration. By coupling this technique to the differential scanning calorimetry, it was also possible to measure the energy absorbed or released by the material during its decomposition. The results showed that the non-evaporable water content and the degree of hydration of the mixtures containing various mineral admixtures were relatively lower with respect to the reference mixture when as the content of mineral admixture increased. The effect of the evolution of the hydration process on the mechanical properties of mortars was also monitored. The relative variation of the compressive strength to that of the flexural strength was evaluated at 7, 28 and 90 days. Results showed that all the mixtures have a greater contribution in flexion than in compression.

Diffusivity Resistance of Concrete Systems in Chloride Rich Environment for Corrosion Protection of Embedded Steel Bars

2013 ◽  
Vol 831 ◽  
pp. 3-8
Author(s):  
Suad Khalid Al-Bahar ◽  
Safaa M. Abdul Salam ◽  
Adel M. Husain
Keyword(s):  
Service Life ◽  
Concrete Structures ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Steel Reinforcement ◽  
Mineral Admixtures ◽  
Chloride Ingress ◽  
Corrosion Initiation ◽  
Chloride Ion Penetration ◽  
Ion Penetration

Improving concrete performance and minimizing corrosion-induced deterioration of reinforced concrete structures are mandated Building Codes Practices and Specifications in arid regions such as the Arabian Gulf. Concrete structures resist corrosion due to the passivating properties of the hydrated cement around the steel reinforcement created by the high alkaline environment within the composite structure (pH > 12). However, the presence of chloride ions in the pore structure of the concrete destroys this passivating layer, which makes the steel reinforcement vulnerable to chloride-induced corrosion attack that accelerates degradation and deterioration of concrete structures. Corrosion activities-related tests such as Time-to-Corrosion Initiation (Modified ASTM G-109)6, and Corrosion Rate Test (Lollipop Test), can be effectively used to monitor the behavior of corrosion development, while chloride ingress characteristics tests such as Electrical Indication of Concretes Ability to Resist Chloride Ion Penetration ASTM C-1202-91)7, and the Resistance of Concrete to Chloride Ion Penetration (AASHTO T 259-80)8, are applied to evaluate the rate at which chloride ions can diffuse through concrete to onset the time-to-corrosion initiation, which will impact the structure service life and compromise its sustainability. Efforts have been made by scientists to develop mathematical simulation models that predict the service life of the structure based on Ficks Second Law for semi-finite diffusion of chloride ions, concentrated at different concrete depths. The study concluded that mineral admixtures have contributed to the enhancement of concrete performance and its resistance to chloride diffusivity, as well when in combination with corrosion-inhibiting admixture such as calcium nitrite.

Effect of Mineral Admixtures on Chloride Binding Mechanism in Concrete

2012 ◽  
Vol 204-208 ◽  
pp. 3716-3719
Author(s):  
Qiao Zhu ◽  
Yi Chen ◽  
Lin Hua Jiang
Keyword(s):  
Fly Ash ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Chloride Binding ◽  
Stray Current ◽  
Total Chloride ◽  
Free Chloride ◽  
The Stability

The chloride binding mechanisms of different mineral admixtures under the condition of stray current and NaCl solute were researched. The electric potential titration was used to measure the content of total chloride ions and free chloride ions. The results show that using of mineral admixture could effectively inhibit the destructive action of the stray current to the stability of bound chloride ion in cement paste. Among all, the most effective mix proportion on chloride-induced corrosion is the mixture with only slag, then the double mixing of fly ash and slag, the last comes the mixture with only fly ash.

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