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Plaster or gypsum (CaSO 4 ·2H 2 O) is obtained from a suspension of β calcium hemihydrate (CaSO 4 ·1/2H 2 O). The effect of two additives, known to retard setting, namely citric and malic acids, on the …
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The result shows that 1% by weight of the addition leads to a compressive strength of 46.9 N/mm 2 in the plaster; for its part, the author of used self-leveling mortars based on phosphoric gypsum (alpha-Hemihydrate gypsum, α-HH), analyzing the effect on the setting time of three retarders: Protein Salt, Citric Acid and Sodium Tripolyphosphate.
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The research recommends acid neutralization prior filtration, use of gypsum particles < 2 mm in size, and stirring speed of 50 rpm to reduce the economic and environmental impacts of the acid ...
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Citric acid increases the fluidity of recycled gypsum plaster. Retarding effects are higher with high content of the admixture. Mechanical properties are diminished with the …
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The specimens were cured for 90 days in a laboratory environment (23±3 ºC y 55±10% HR). Before carrying out the tests, the specimens were kept in an oven at a temperature of 40 ºC until the mass was constant. ... However, in the gypsum with added citric acid, more prismatic shapes and a degree of amorphization of the crystalline framework ...
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Previous research has reported internal disintegration of gypsum matrices caused by citric acid (Camarini et al., 2016), ... Environmental evaluation of gypsum plasterboard recycling. Minerals, 11 (2021), p. 101, 10.3390/min11020101. Google Scholar. Zaragoza-Benzal et al., 2024.
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The role of citric acid, a retarder additive used to prolong the workability and setting time of gypsum binders, was studied at concentrations of 0, 125, 250, 500, 1000, 1500 and 3000 ppm with a constant water/binder ratio.The hydration process (setting) was studied by the knife method, conductivity measurements and attenuated total reflectance infrared spectroscopy, …
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School of Metallurgy and Environment, Central South University, Changsha 410083, China; 2. Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, The University of Queensland, ... From the SEM examination, citric acid and gypsum treatments contributed to the reduction in IEP and redistribution of —OH groups on particle surfaces ...
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with water/gypsum ratio of 0.5 and 0.7, and citric acid contents of 0.0%, 0.010%, 0.020% and 0.030%. Therefore, it was possible to verify the influence of citric acid contents on gypsum paste and gypsum bamboo composites. The use of citric acid and triturated bamboo in gypsum matrix proved to be effective in this research. KEYWORDS
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However, citric acid promoted another reaction path to form monosulfate and gypsum as shown in Eq. (3) together with the formation of ettringite. In the presence of 1.8 mmol citric acid, monosulfate and gypsum formed 21.8 and 5.2 wt% of the binder, respectively, and ettringite constituting around 73.0 wt% via Q-XRD analysis.
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This study summarized industrial by-product gypsum into eight types (flue gas desulphurization gypsum (FGDG), phosphogypsum (PG), titanium gypsum (TG), salt gypsum (SG), fluorgypsum (FG), nitro gypsum (NG), citric acid gypsum (CAG) and borogypsum (BG)). Subsequently, the chemical, physical properties and annual productivity associated with ...
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The retardant effects of citric acid on the properties of ettringite binders are not yet fully understood. This investigation provides insights into the effects of citric acid on both the fresh and hardened state properties of the binder produced from …
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Upon the addition of succinic acid, malic acid, and L-aspartic acid, the aspect ratio of α-HH crystals decreases, and the crystal morphology transitions from a rod-like needle structure to a short and stout structure.Notably, Malic acid demonstrates the most effective results.The study further demonstrates that the flexural and compressive ...
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Environmental impacts of citric acid production in three scenarios are assessed using the life cycle assessment approach. Citric acid production with ion exchange recovery method is the most environment-friendly scenario. ... When 80% flue gas desulfurization gypsum and phosphogypsum (weight of magnesium oxide) were incorporated into MOCP, the ...
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Regulating the phase structure of Cr(VI)-host minerals could be considered as an effective approach to separate Cr(VI) from the minerals. For example, Liu et al. used hydrothermal mineralization to modulate the phase transition from CaSO 4 ·2 H 2 O to CaSO 4 in gypsum slag, resulting in a significant difference in the adsorption properties of Cr(VI) and SO 4 2-on …
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In order to minimize this effect, the present study makes use of retarding additives such as citric acid-0.03% (C6H8O7) and borax-0.7% (Na2B4O7.10H2O) in gypsum plaster with gypsum waste,...
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Construction is among the most energy-consuming human activities, and energy is a problem on a finite planet. There is a search for new technologies that bring improvements and solutions in the optimization of low energy incorporated materials and
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The effect of pH on the inhibiting efficiency of citric acid in the precipitation reaction of gypsum (CaCl 2 + Na 2 SO 4 + 2 H 2 O → 2 NaCl + CaSO 4 ·2H 2 O with 0.1 M initial reactant concentration, in the presence of 1.5 mM citric acid, average of three parallel measurements).
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ABSTRACT: To improve the workability in gypsum plasters, additives are sometimes used, including citric acid, which provides acceptable setting times for low w/g ratios, maximizing the …
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Citric acid increases the fluidity of recycled gypsum plaster. Retarding effects are higher with high content of the admixture. Mechanical properties are diminished with the increase on admixture addition. Crystal structure has changed significantly with citric acid addition.
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Reactive crystallization of calcium sulfate dihydrate (gypsum) was investigated at pH 3.5 and 65 °C in the presence of citric acid and Cr3+ ions. Concentrations of both additives varied between 0 and 4000 ppm. The combined effect of additives on crystal size distributions, filtration characteristics, and crystal morphology were investigated and discussed.
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Attack of sulfuric acid and citric acid on PC and CSA-based binders was evaluated with respect to mass loss, dimensional change, cumulative H⁺ ion neutralisation, strength loss, and changes in ...
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The main effect of citric acid is to hinder the growth of gypsum, by binding onto gypsum crystal faces [25]. Citric acid binding depends on the crystalline faces, which results in the same time in ...
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Contamination of the environment with various harmful chemicals is a widely spread global issues that can be traced to various industries and their poorly managed exhausts and wastes. ... In the presence of citric acid, replacing gypsum with portlandite eventually disrupted drastically the hardening of the binder, indicated by the increasing ...
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1 Sulfuric Acid and Citric Acid Attack of ... 12 potential to be used in concrete elements exposed to acidic environment such as sewage system. ... If gypsum is formed as in sulfuric acid attack ...
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three-dimensional representation of the two acids. Malic acid has two acid groups and one hydroxyl group. Citric acid shows three acid groups and one hydroxyl group. In the present pH range ( 7), the acid functions are ionised since the acid constants are equal to 10–2.8, 10–4.2, and 10–4.7 for citric acid, 10–3.1 and 10–4.46 for ...
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The utility model discloses a system for producing gypsum whiskers by using citric acid gypsum, which comprises the following steps of firstly, pretreating the citric acid gypsum by using an ozone sterilization treatment and dehydration washing method to form a citric acid gypsum filter cake; then, dissolving and crystallizing the citric acid gypsum filter cake by using a normal pressure ...
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The cycle of citric acid production with the formation of gypsum-containing waste was considered and options for processing and utilization of citrogypsum were proposed.
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A process for producing series of gypsum products with waste dregs from production of citric acid includes such technological steps as dewatering the waste dregs to obtain plaster, baking, grinding to obtain beta-type plaster, sieving by 1-8 cu.cm, high-pressure digestion, drying, grinding to obtain alpha-type gypsum, and low-temp drying (or natural drying) to obtain setting retarder, …
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Citric Acid is a water soluble organic solid with a melting point of approximately 153°C. The acidity of citric acid results from the three carboxylic groups. Having a pKa1 of 3.13 it is considered as …
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