scholarly journals Effect of Fly Ash on Leaching Characteristics of Cement-Stabilized Macadam Base

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 5935
Author(s):  
Dian Lun ◽  
Taiping Yuan ◽  
Xiaolong Yang ◽  
Hongliu Rong ◽  
Junjie Shi ◽  
...  
Keyword(s):  
Fly Ash ◽  
Calcium Ions ◽  
Calcium Ion ◽  
Permeability Coefficient ◽  
Leaching Test ◽  
Leaching Rate ◽  
Calcium Leaching ◽  
Leaching Characteristics ◽  
Porosity And Permeability ◽  
Calcium Ion Leaching

To study the leaching characteristics of a cement-stabilized macadam base with fly ash, a calcium leaching test, using varying cement and fly ash dosages in an ammonium chloride solution, was designed to obtain the rate of calcium ion leaching, porosity, and permeability coefficient of cement-stabilized macadam with leaching time. The results showed that the number of leached calcium ions increased with the cement dosage in the leaching of cement-stabilized macadam. With an increase in the cement dosage, the leaching rate of calcium ions decreased, and the leaching process of the material was delayed. The incorporation of fly ash could effectively slow down the degree of calcium ion leaching. The permeability coefficient increased gradually with the extension of leaching time, and the increase in fly ash content had a more significant effect on the improvement of the permeability coefficient than the increase in cement dosage did.

scholarly journals Strength Time–Varying and Freeze–Thaw Durability of Sustainable Pervious Concrete Pavement Material Containing Waste Fly Ash

2018 ◽  
Vol 11 (1) ◽  
pp. 176 ◽  
Author(s):  
Hanbing Liu ◽  
Guobao Luo ◽  
Longhui Wang ◽  
Yafeng Gong
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Pervious Concrete ◽  
Early Age ◽  
Pavement Materials ◽  
Freeze Thaw ◽  
Replacement Method ◽  
Porosity And Permeability ◽  
Volume Method

Pervious concretes, as sustainable pavement materials, have great advantages in addressing a number of environmental issues. Fly ash, as the industrial by-product waste, is the most commonly used as cement substitute in concrete. The objective of this paper is to study the effects of waste fly ash on properties of pervious concrete. Fly ash was used to replace cement with equivalent volume method at different levels (3%, 6%, 9%, and 12%). The control pervious concrete and fly ash modified pervious concrete were prepared in the laboratory. The porosity, permeability, compressive strength, flexural strength, and freeze–thaw resistance of all mixtures were tested. The results indicated that the addition of fly ash decreased the early-age (28 d) compressive strength and flexural strength, but the long-term (150 d) compressive strength and flexural strength of fly ash modified pervious concrete were higher than that of the early-age. The adverse effect of fly ash on freeze–thaw resistance of pervious concrete was observed when the fly ash was added. The porosity and permeability of all pervious concrete mixtures changed little with the content of fly ash due to the use of equal volume replacement method. Although fly ash is not positive to the properties of pervious concrete, it is still feasible to apply fly ash as a substitute for cement in pervious concrete.

scholarly journals THE EFFECT OF LACTIC ACID AND ARTIFICIAL SALIVA SOLUTION IMMERSION TO THE RELEASE OF CALCIUM IONS ON BIOACTIVE RESIN

2021 ◽  
Vol 6 (2) ◽  
pp. 190
Author(s):  
Dewi Puspitasari ◽  
Nurah Tajjalia ◽  
Diana Wibowo ◽  
Agung Satria Wardhana
Keyword(s):  
Lactic Acid ◽  
Acid Solution ◽  
Calcium Ions ◽  
Calcium Ion ◽  
Artificial Saliva ◽  
Distilled Water ◽  
Acid Condition ◽  
Ion Release ◽  
Lactic Acid Solution ◽  
Solution Increase

Background: Bioactive resin can release calcium ions when contact with solution media, even in acid condition. In the oral cavity, pH may change into acid condition due to the metabolic results of Streptococcus mutans. The bacteria metabolize carbohydrates into organic acids, one of which is lactic acid. Purpose: Analyze the effect of lactic acid solution and artificial saliva on the number of the release of calcium ions of bioactive resin. Methods: Forty-two specimens (diameter 15 mm x thickness 1 mm; n= 7/group fabricated with Activa™ Bioactive Restorative (Pulpdent). The specimens that meet the criteria were divided into 6 groups. The specimen was immersed for 1 and 7 days in the incubator at 37oC. The number of calcium ion release is measured using titration method. Results: Two Way Anova test and Post Hoc Bonferonni test showed there were significant differences among all group for lactic acid 1 day (4.040 ± 0.360) µg, artificial saliva 1 day (0.640 ± 0.338) µg, distilled water 1 day (1.040 ± 0.504) µg, lactic acid 7 days (5.400 ± 0.312), artificial saliva 7 days (1.640 ± 0.215) µg, distilled water 7 days (3.520± 0.356 µg). Conclusion: There was an influence of lactic acid and artificial saliva on the number of calcium ion releases of bioactive resin. Immersion of bioactive resin in the lactic acid solution increase the calcium ion releases and artificial saliva decrease the calcium ion release compared to distilled water. Keywords: artificial saliva, bioactive resin, calcium ion release, lactic acid

A fluoride selective water-soluble anion receptor based on a 1,2-phenylenediacetic acid and calcium ion dimer

2019 ◽  
Vol 43 (34) ◽  
pp. 13690-13695
Author(s):  
Dae Hyup Sohn ◽  
Nayeon Kim ◽  
Soonmin Jang ◽  
Jongmin Kang
Keyword(s):  
Calcium Ions ◽  
Calcium Ion ◽  
Water Soluble ◽  
Anion Receptor ◽  
Fluoride Ions

The dimeric receptor 1 from 1,2-phenylenediacetic acid and calcium ions recognized fluoride ions almost exclusively in 100% water.

Assessment of strength and leaching characteristics of heavy metal–contaminated soils solidified/stabilized by cement/fly ash

2019 ◽  
Vol 26 (29) ◽  
pp. 30206-30219 ◽  
Author(s):  
Fusheng Zha ◽  
Chunjie Ji ◽  
Long Xu ◽  
Bo Kang ◽  
Chengbin Yang ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Fly Ash ◽  
Contaminated Soils ◽  
Leaching Characteristics

scholarly journals Experimental study on the properties of highperformance concrete made with class C fly ash

2019 ◽  
Vol 276 ◽  
pp. 01014
Author(s):  
I Made Alit Karyawan Salain ◽  
I Nyoman Sutarja ◽  
Teguh Arifmawan Sudhiarta
Keyword(s):  
Experimental Study ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Permeability Coefficient ◽  
Splitting Tensile Strength ◽  
Type I ◽  
Fine Aggregate ◽  
Hydration Time ◽  
Class C

This experimental study presents the properties of highperformance concrete (HPC) made by partially replacing type I Portland cement (OPC) with class C fly ash (CFA). The purpose of this study is to examine, with hydration time, the development of the compressive strength, the splitting tensile strength and the permeability of HPC utilizing different quantity of CFA. Four HPC mixtures, C1, C2, C3, and C4, were made by utilizing respectively 10%, 20%, 30% and 40% of CFA as replacement of OPC, by weight. One control mixture, C0, was made with 0% CFA. The mix proportion of HPC was 1.00 binder: 1.67 fine aggregate: 2.15 coarse aggregate with water to binder ratio 0.32. In each mixture, it was added 5% silica fume and 0.6% superplasticizer of the weight of the binder. Tests of HPC properties were realized at the age of 1, 3, 7, 28, and 90 days. The results indicate that CFA used to partially replace OPC in HPC shows adequate cementitious and pozzolanic properties. The compressive strength and the splitting tensile strength of HPC increase while the permeability coefficient decreases with increasing hydration time. It is found that the optimum replacement of OPC with CFA is 10%, however the replacement up to 20% is still acceptable to produce HPC having practically similar harden properties with control mixture. At this optimum replacement and after 90 days of hydration, the compressive strength, the splitting tensile strength and the permeability coefficient can reach 68.9 MPa, 8.3 MPa and 4.6 E-11 cm/sec respectively. These results are 109%, 101%, and 48% respectively of those of control mixture.

HIGH AFFINITY CALCIUM BINDING TO DOMAINES OF PROTEIN C THAT ARE HOMOLOGUS TO THE EPIDERMAL GROWTH FACTOR

1987 ◽  
Author(s):  
A KÖhlin ◽  
J Stenflo
Keyword(s):  
Calcium Ions ◽  
Calcium Ion ◽  
Calcium Binding ◽  
Plasma Proteins ◽  
Metal Ion ◽  
Protein C ◽  
Protein S ◽  
Protein Z ◽  
High Affinity ◽  
Epidermal Growth

In addition to γ-carboxyglutamic acid (Gla)-dependent calcium binding all of the vitamin K-dependent plasma proteins, except prothrombin, have one or two high affinity calcium binding sites that do not require the Gla residues. A common denominator among these proteins (factors IX, X, protein C, protein Z and protein S) is that they have domaines that are homologus to the epidermal growth factor (EGF) precursor. In factors VII,IX,X, protein C and in protein Z the aminoterminal of two EGF homology regions contain one residue of β-hydroxyaspartic acid (Hya) whereas in protein S the aminoterminal EGF homology region contains Hya and the three following contain one β-hydroxyasparagine residue each.In an attempt to elucidate the role of the EGF homology regions in the Gla independent calcium binding we have isolated a tryptic fragment (residue 44-138) from the light chain of human protein C. The fragment was isolated using a monoclonal antibody that recognizes a calcium ion stabilized epitope that is expressed both in intact protein C and in protein C lacking the Gla domaine.The antibody bound the isolated EGF homology region in the presence of calcium ions but not in EDTA containing buffer. A calcium ion titration showed half maximal binding at approximately 200 μM Ca2+. The metal ion induced conformational change in the isolated fragment was also studied with affinity purified rabbit antibodies against Gla domainless protein C. Antibodies that bound in the presence of calcium ions and that could be eluted with EDTA recognized the metal ion induced conformational change in the isolated EGF homology domain. Our results suggest that one or both of the EGF homology regions are involved in the Gla-independent high affinity calcium binding in the vitamin K-dependent plasma proteins.

scholarly journals Probing the Role of Divalent Metal Ions in a Bacterial Psychrophilic Metalloprotease: Binding Studies of an Enzyme in the Crystalline State by X-Ray Crystallography

2003 ◽  
Vol 185 (14) ◽  
pp. 4195-4203 ◽  
Author(s):  
Stephanie Ravaud ◽  
Patrice Gouet ◽  
Richard Haser ◽  
Nushin Aghajari
Keyword(s):  
Metal Ions ◽  
Calcium Ions ◽  
Calcium Ion ◽  
Crystalline State ◽  
Zinc Ion ◽  
Binding Studies ◽  
X Ray ◽  
X Ray Crystallography ◽  
Catalytic Zinc

ABSTRACT The psychrophilic alkaline metalloprotease (PAP) produced by a Pseudomonas bacterium isolated in Antarctica belongs to the clan of metzincins, for which a zinc ion is essential for catalytic activity. Binding studies in the crystalline state have been performed by X-ray crystallography in order to improve the understanding of the role of the zinc and calcium ions bound to this protease. Cocrystallization and soaking experiments with EDTA in a concentration range from 1 to 85 mM have resulted in five three-dimensional structures with a distinct number of metal ions occupying the ion-binding sites. Evolution of the structural changes observed in the vicinity of each cation-binding site has been studied as a function of the concentration of EDTA, as well as of time, in the presence of the chelator. Among others, we have found that the catalytic zinc ion was the first ion to be chelated, ahead of a weakly bound calcium ion (Ca 700) exclusive to the psychrophilic enzyme. Upon removal of the catalytic zinc ion, the side chains of the active-site residues His-173, His-179 and Tyr-209 shifted ∼4, 1.0, and 1.6 Å, respectively. Our studies confirm and also explain the sensitivity of PAP toward moderate EDTA concentrations and propose distinct roles for the calcium ions. A new crystal form of native PAP validates our previous predictions regarding the adaptation of this enzyme to cold environments as well as the proteolytic domain calcium ion being exclusive for PAP independent of crystallization conditions.

Prediction of the Deterioration Depth of Concrete by Accelerating Calcium Leaching Test

2011 ◽  
Vol 365 ◽  
pp. 3-7 ◽  
Author(s):  
An Cheng ◽  
Sao Jeng Chao ◽  
Wei Ting Lin ◽  
Jia Liang Chang
Keyword(s):  
Nitrate Solution ◽  
Leaching Behavior ◽  
Calcium Leaching ◽  
Ammonium Nitrate Solution ◽  
Binder Ratio ◽  
Two Stages ◽  
Strength And Durability ◽  
Calcium Ion Leaching ◽  
Water Binder Ratio

The concrete is a solid and porous composite materials, when the concrete exposure to moisture environment for a long-term, the pore water will penetrate into concrete cause hydration products leaching. Leaching of calcium ions increase in porosity and resulting in harmful ions ingress into concrete to reduce strength and durability of concrete. The purpose of this study is to evaluate the effect of water-binder ratio on calcium ion leaching behavior of cement-based material. The ammonium nitrate solution was used to accelerate leaching process. Leaching duration was 56 days, 91 days and 140 days, respectively. The leaching depth and compressive strength were measured. The results showed that leaching resistance increased with a decrease in water/binder ratio. The leaching depth showed that leaching behavior of the specimens without minerals admixtures can be divided into two stages, the first stage was leaching of calcium hydroxide and than the C-S-H gel were leaching.

Electrochemical Properties of Multi-Wall Carbon Nanotubes as a Novel Negative Electrode for Calcium Secondary Batteries

2016 ◽  
Vol 859 ◽  
pp. 75-78
Author(s):  
Chang Hee Lee ◽  
Chang Su Kim ◽  
Yun Taek Jeong ◽  
Jun Hwan Kim ◽  
Soon Ki Jeong ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electrochemical Performance ◽  
Calcium Ions ◽  
Calcium Ion ◽  
Ethylene Carbonate ◽  
Negative Electrode ◽  
X Ray Diffraction ◽  
X Ray ◽  
Multi Wall Carbon Nanotubes ◽  
Discharge Capacities

We investigated the electrochemical behavior and properties of multi-wall carbon nanotubes (MWCNTs) as a novel negative electrode for calcium ion batteries during charging and discharging. The second charge and discharge capacities were ~63 and ~43 mAh g–1 in propylene carbonate-based electrolyte and ~86 and ~60 mAh g–1 in ethylene carbonate-based electrolyte, respectively. X-ray diffraction analysis results showed that the inter-layer distance of the MWCNTs was increased after charging, indicating that calcium ions were intercalated into the MWCNT graphitic sheets during the charging. The electrochemical performance of the MWCNT electrode was improved by using ball milling to introduce defects.

scholarly journals Numerical Simulations of Heterogeneous Chemical Reactions Coupled to Fluid Flow in Varying Thermal Fields

1991 ◽  
Vol 257 ◽  
Author(s):  
C. L. Carnahan
Keyword(s):  
Fluid Flow ◽  
Silicic Acid ◽  
Calcium Ion ◽  
Acid System ◽  
Thermal Fields ◽  
Transient Heat Flow ◽  
Porosity And Permeability ◽  
Strong Gradient ◽  
Reactive Chemical Transport ◽  
Heterogeneous Chemical Reactions

ABSTRACTA numerical simulator of reactive chemical transport with coupling from precipitation-dissolution reactions to fluid flow, via changes of porosity and permeability, is applied to precipitation-dissolution of quartz and calcite in spatially and temporally variable fields of temperature. Significant effects on fluid flow are found in the quartz-silicic acid system in the presence of a persistent, strong gradient of temperature. Transient heat flow in the quartz-silicic acid system and in a calcite-calcium ion-carbonato species system produces vanishingly small effects on fluid flow.

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