scholarly journals Durability Assessment of Concrete with Class-F Fly Ash by Chloride Ion Permeability

2019 ◽  
Vol 8 (4) ◽  
pp. 8831-8836
Keyword(s):  
Fly Ash ◽  
Chloride Ion ◽  
Pozzolanic Reaction ◽  
Chloride Ions ◽  
Permeability Test ◽  
Reaction Products ◽  
Chloride Permeability ◽  
Cement Pastes ◽  
Rapid Chloride Permeability ◽  
Class F Fly Ash

This paper discusses on Rapid Chloride Permeability Test investigations on penetration of chloride ions included with replacement of cement by flyash material. By weigth of cement, the fly ash content is replaced from 0% to 60%. Concrete mixes with different binder content varies from 350, 400 and 450 kg/m3 were proportioned with different water binder(w/b) ratios = 0.4, 0.45 and 0.50. Specimens were casted and tested for 28 days. For all the combinations, RCPT was carried out and the charge passed through the specimens was noted. Rapid Chloride Permeability Test value of concrete without fly ash was found to be more than the concrete with fly ash. The Rapid Chloride Permeability Test values are found to be decreased if the percentage of flyash increases. The reason could be the pozzolanic reaction products (CSH) fill the pores between the cement pastes and cause a denser concrete matrix, resulting in better durability. Hence, it can be suggested that the fly ash concrete up to 50% replacement can be used for variety of applications.

The Permeability of Chloride Ions in Fly Ash-Cement Pastes, Mortars and Concrete

1987 ◽  
Vol 114 ◽  
Author(s):  
R. I. A. Malek ◽  
D. M. Roy
Keyword(s):  
Fly Ash ◽  
Electrical Potential ◽  
Chloride Ion ◽  
Ionic Species ◽  
Cylindrical Sample ◽  
Chloride Ions ◽  
Test Scheme ◽  
Chloride Permeability ◽  
Experimental Conditions ◽  
Cement Pastes

ABSTRACTFly ash-cement pastes are known to develop fine pore structures that may retard the transport of ionic species. The rapid chloride permeability technique for studying the Cl− ion diffusion in hydrated fly ash/cement pastes, mortars and concrete was used. The technique applies an electrical potential across a cylindrical sample and measures the charge passed in a certain period of time. The results obtained on pastes and mortars cured for 28 days were reported previously and contrasted with those of neat cement pastes and mortars. The present paper reports more extensive studies made to examine the chloride permeabilities of pastes and mortars cured for up to 90 days. In addition, the effect of variable fly ash contents was examined. Concrete samples were included in the test scheme and the data were compared with pastes and mortars. Two important factors controlling the test results are discussed: first the mix design and curing conditions; second the experimental conditions during Cl− permeability measurements. In the second factor, the amount and rate of heat build up and the chloride ion concentrations are compared with the current passed. In addition, measuring current versus resistivity are critically discussed in terms of the voltage-current varistic characteristics of cement matrices.

The Permeability of Chloride Ions in Fly Ash-Cement Pastes, Mortars and Concrete

1987 ◽  
Vol 113 ◽  
Author(s):  
R. I. A. Malek ◽  
D. M. Roy
Keyword(s):  
Fly Ash ◽  
Electrical Potential ◽  
Chloride Ion ◽  
Ionic Species ◽  
Cylindrical Sample ◽  
Chloride Ions ◽  
Test Scheme ◽  
Chloride Permeability ◽  
Experimental Conditions ◽  
Cement Pastes

ABSTRACTFly ash-cement pastes are known to develop fine pore structures that may retard the transport of ionic species. The rapid chloride permeability technique for studying the Cl- ion diffusion in hydrated fly ash/cement pastes, mortars and concrete was used. The technique applies an electrical potential across a cylindrical sample and measures the charge passed in a certain period of time. The results obtained on pastes and mortars cured for 28 days were reported previously and contrasted with those of neat cement pastes and mortars. The present paper reports more extensive studies made to examine the chloride permeabilities of pastes and mortars cured for up to 90 days. In addition, the effect of variable fly ash contents was examined. Concrete samples were included in the test scheme and the data were compared with pastes and mortars. Two important factors controlling the test results are discussed: first the mix design and curing conditions; second the experimental conditions during Cl- permeability measurements. In the second factor, the amount and rate of heat build up and the chloride ion concentrations are compared with the current passed. In addition, measuring current versus resistivity are critically discussed in terms of the voltage-current varistic characteristics of cement matrices.

The Diffusion of Chloride Ions in Fly Ash/Cement Pastes and Mortars

1986 ◽  
Vol 85 ◽  
Author(s):  
R. I. A. Malek ◽  
D. M. Roy ◽  
P. H. Licastro
Keyword(s):  
Fly Ash ◽  
Water Permeability ◽  
Electrical Potential ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Basic Material ◽  
Fly Ashes ◽  
Cement Pastes ◽  
High Calcium ◽  
Class F

ABSTRACTFly ashes having three distinctly different levels of calcium, designated low-calcium (Class F), intermediate-calcium (Class F/C), and high-calcium (Class C), comprised the basic material for the present study. Pastes and mortars were made using cement and one of three types of fly ashes at various levels of replacement and water-solid ratios. Chloride ion diffusion was measured by applying an electrical potential across cured cylindrical samples and measuring the amount of current passed in a certain period of time (proportional to amount of CE” passed in this time). Other supportive measurements were made, e.g. porosity, pore size distribution, water permeability and surface area. The Cl− ion diffusivity was correlated with the chemical composition of fly ash, mix proportion, and water permeability of the hardened paste or mortar.

Effect of Mineral Admixtures and Water/Binder Ratios on the Resistance to the Chloride Ions Penetration into Concrete

2011 ◽  
Vol 99-100 ◽  
pp. 758-761
Author(s):  
Yan Jun Hu ◽  
Yan Liang Du
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Silica Fume ◽  
Blast Furnace Slag ◽  
Chloride Ion ◽  
Test Methods ◽  
Chloride Ions ◽  
Mineral Admixtures ◽  
Chloride Permeability ◽  
Furnace Slag

In this study, concrete prisms were made with three mineral admixtures: fly ash, blast furnace slag or silica fume and with three water-to-binder ratios(w/b). Chloride penetration was measured by the rapid chloride permeability test (RCPT)-ASTM C1202, 150-days ponding test and alternate wetting and drying test by cyclic loading with salt solution and oven drying, and the results by the three test methods were compared. This paper discussed the effects of mineral admixtures and w/b on the concrete chloride permeability. Blending concrete with blast furnace slag, fly ash or silica fume was beneficial with regard to the resistance against chloride ion penetration. Concrete specimens with lower w/b showed lower chloride permeability.

Trapping of Chloride Ions in Cement Pastes Containing Fly Ash

1985 ◽  
Vol 65 ◽  
Author(s):  
D. M. Roy ◽  
R. I. A. Malek ◽  
M. Rattanussorn ◽  
M. W. Grutzeck
Keyword(s):  
Fly Ash ◽  
Chloride Ion ◽  
Exchange Chromatography ◽  
Chloride Ions ◽  
Emission Spectrometry ◽  
Type I ◽  
Cement Pastes ◽  
Plasma Emission Spectrometry ◽  
Mechanisms Of Formation ◽  
Sufficient Concentration

ABSTRACTChloride ions, when present at sufficient concentration in the concrete pore fluid, may be associated with corrosion of the reinforcing steel even in normally passivative environments. The effectiveness of fly ash containing pastes in trapping chloride ions was studied. A paste was prepared containing 30% low-calcium fly ash and 70% type I cement, with mixing water (50% by weight) containing 0.4% C1− with respect to the solid. Samples were cured at 25°C and 38°lC at 95% R.H. At designated times extending over a six-month period, the pore fluids were expressed from the hardened pastes using a squeezing cell designed for this purpose. Special precautions were taken to avoid carbonation of the fluids; contact with the atmosphere was minimized. The expressed fluids were analyzed by DC plasma emission spectrometry for cations and by automated selective ion exchange chromatography for anions. Other studies (XRD, thermal analysis) were carried out to identify the compounds formed and determine their mechanisms of formation. Investigations indicated that the mechanism of trapping chloride ion is partly chemical and partly physical through adsorption on the surface of fly ash particles (initially physical and subsequently chemical).

Mechanical and Transport Properties of High Volume UFA Cement Composites

2019 ◽  
Vol 810 ◽  
pp. 143-148
Author(s):  
Xing Yang He ◽  
Jian Xiang Huang ◽  
Ying Su ◽  
Jin Yang ◽  
Zheng Qi Zheng ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Fly Ash ◽  
High Volume ◽  
Pozzolanic Reaction ◽  
Cement Composites ◽  
Reaction Products ◽  
Chloride Permeability ◽  
High Volume Fly Ash ◽  
Medium Particle ◽  
Different Content

In this study, mechanical activation is used to generate ultra-fine fly ash (UFA) for high volume fly ash（FA）cement composites. The effects of different content and medium particle size of FA on mortar`s electrical resistivity, chloride penetration and mechanical properties are investigated. The results show that the compressive strength and resistance to chloride permeability of specimens with UFA have been enhanced, owing to higher pozzolanic reaction and higher dissolution rate of Si and Al units of UFA to accelerate the generate of reaction products. However, At the early ages, electrical resistivity of specimens increases with the increase of UFA; at later ages, specimens have a higher electrical resistivity with the increase of UFA.

The Diffusion of Chloride Ions in Fly Ash/Cement Pastes and Mortars

1986 ◽  
Vol 86 ◽  
Author(s):  
R. I. A. Malek ◽  
D. M. Roy ◽  
P. H. Licastro
Keyword(s):  
Fly Ash ◽  
Electrical Potential ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Basic Material ◽  
Type I ◽  
Fly Ashes ◽  
Cement Pastes ◽  
High Calcium ◽  
Class F

ABSTRACTFly ashes having three distinctly different levels of calcium, designated low-calcium (Class F), intermediate-calcium (Class F/C), and high-calcium (Class C) comprised the basic material for the present study. Pastes and mortars were made out of the three types of fly ashes and one type of cement (Type I) at various levels of replacement as well as different water/solid ratios (w/c). Chloride ion diffusion was measured by applying an electrical potential across cured cylindrical samples and measuring the amount of current passed in a certain period of time (proportional to amount of Cl− passed in this time). Other supportive measurements were made, e.g., porosity and pore size distribution, water permeability and surface area. The Cl− ion diffusivities were correlated with the chemical composition of fly ash (FA), mix proportioning, and water permeabilities of the tested hardened pastes or mortars.

Corrosion Resistance Performance of Ethylamines in Fly Ash Blended Cement Concrete

2014 ◽  
Vol 507 ◽  
pp. 286-290
Author(s):  
V. Rajkumar
Keyword(s):  
Corrosion Resistance ◽  
Fly Ash ◽  
Blended Cement ◽  
Impedance Measurement ◽  
Chloride Ions ◽  
Experimental Investigations ◽  
Optimal Dosage ◽  
Cement Concrete ◽  
Chloride Permeability ◽  
Resistance Performance

The main aim of this investigation is to study the influence of monoethylamine, diethylamine and triethylamine inhibitors on the corrosion resistance performance of 25% fly ash blended cement concrete. These inhibitors were added in dosages of 1%, 2%, 3% and 4% by weight of cement and experimental investigations have been carried out to compare the effectiveness of these three inhibitors with regard to strength and corrosion resistance. The mechanical strength properties studied were compressive, split tensile, flexural and bond strengths. The resistance to corrosion was evaluated based on the performance of the concrete for the penetration of chloride ions by means of impressed voltage technique, Rapid chloride permeability test (RCPT), AC impedance measurement, and weight loss measurement and ultimately the most effective of the three inhibitors and its optimal dosage has been determined.

scholarly journals Alkali-activated concretes based on fly ash and blast furnace slag: Compressive strength, water absorption and chloride permeability

2020 ◽  
Vol 40 (2) ◽  
Author(s):  
Daniela Eugenia Angulo-Ramírez ◽  
William Gustavo Valencia-Saavedra ◽  
Ruby Mejía de Gutiérrez
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Fly Ash ◽  
Water Absorption ◽  
Blast Furnace Slag ◽  
Construction Materials ◽  
Chloride Ion ◽  
Chloride Permeability ◽  
Alkaline Activator ◽  
Furnace Slag

Concretes based on alkaliactivated binders have attracted considerable attention as new alternative construction materials, which can substitute Portland Cement (OPC) in several applications. These binders are obtained through the chemical reaction between an alkaline activator and reactive aluminosilicate materials, also named precursors. Commonly used precursors are fly ash (FA), blast furnace slag (GBFS), and metakaolin. The present study evaluated properties such as compressive strength, rate of water absorption (sorptivity), and chloride permeability in two types of alkaliactivated concretes (AAC): FA/GBFS 80/20 and GBFS/OPC 80/20. OPC and GBFS/OPC* concretes without alkaliactivation were used as reference materials. The highest compressive strength was observed in the FA/GBFS concrete, which reported 26,1% greater strength compared to OPC concrete after 28 days of curing. The compressive strength of alkaliactivated FA/GBFS 80/20 and GBFS/OPC 80/20 was 61 MPa and 42 MPa at 360 days of curing, respectively. These AAC showed low permeability to the chloride ion and a reduced water absorption. It is concluded that these materials have suitable properties for various applications in the construction sector.

scholarly journals Influence of Fly Ash Additive on the Properties of Concrete with Slag Cement

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3265 ◽  
Author(s):  
Anna Szcześniak ◽  
Jacek Zychowicz ◽  
Adam Stolarski
Keyword(s):  
Fly Ash ◽  
Chloride Ion ◽  
High Strength ◽  
Experimental Tests ◽  
Chloride Ions ◽  
Strength Increase ◽  
Slag Cement ◽  
Initial Strength ◽  
Chloride Ion Penetration ◽  
The Impact

This paper presents research on the impact of fly ash addition on selected physical and mechanical parameters of concrete made with slag cement. Experimental tests were carried out to measure the migration of chloride ions in concrete, the tightness of concrete exposed to water under pressure, and the compressive strength and tensile strength of concrete during splitting. Six series of concrete mixes made with CEM IIIA 42.5 and 32.5 cement were tested. The base concrete mix was modified by adding fly ash as a partial cement substitute in the amounts of 25% and 33%. A comparative analysis of the obtained results indicates a significant improvement in tightness, especially in concrete based on CEM IIIA 32.5 cement and resistance to chloride ion penetration for the concretes containing fly ash additive. In the concretes containing fly ash additive, a slower rate of initial strength increase and high strength over a long period of maturation are shown. In accordance with the presented research results, it is suggested that changes to the European standardization system be considered, to allow the use of fly ash additive in concrete made with CEM IIIA 42.5 or 32.5 cement classes. Such a solution is not currently acceptable in standards in some European Countries.

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