Gypsum Particle Size Research Articles

Deterioration Process of Cementitious Material Properties under Internal Sulphate Attack

As one of the important factors affecting the structural durability of cementitious materials, sulphate erosion not only reduces the service life of the material but also poses a threat to the structural safety of the project. At present, scholars around the world have conducted extensive research on topics related to external sulphate attacks and have achieved fruitful results. However, the process and mechanism of attack degradation of the gelling material are not clear. In this paper, gypsum sand was introduced into the mortar. The effects of gypsum content, gypsum particle size and curing temperature on physical properties such as expansion and strength of specimens were investigated. X-ray diffraction (XRD), thermogravimetry (TG), differential scanning calorimetry (DSC), Scanning Electron Microscopy (SEM) and energy dispersive spectrometry (EDS) were used to analyse specimens’ phase composition and microstructure evolution at different attack ages. Finally, cementitious materials’ degradation process and mechanism under internal sulphate attack (ISA) were analysed. Through the above research, the following main conclusions are drawn: (1) The swelling rate of cement mortar specimens all increased with the increase of gypsum dosing; (2) The expansion of cement pastes and mortars does not increase with the increase in curing temperature; (3) The gypsum particle sizes are smaller, the expansion of mortar specimens is larger, and the loss of compressive and bending strength of mortar specimens is large; and (4) The main reaction product of ISA is Ettringite (AFt). The gypsum formed during the ISA process does not cause expansion, while AFt is the main reason for the destruction of the cementitious material.

Effectiveness of Gypsum Particle Size and Vermicompost in Reclaiming Salt Affected Soils and Faba Beans Productivity فاعلیة استخدام احجام مختلفة من الجبس،والفیرم کمبوست فى استصلاح الاراضى المتأثرة بالاملاح وانتاجیة محصول الفول البلدی

Soil salinity is one of the environmental factors limiting the plant growth and soil productivity. Field experiment was conducted during 2018/2019 and 2019/2020 seasons in El Hamoul district, Kafr El-Sheikh Governorate, Egypt. This study aimed to investigate the effect of soil amendments via. VC and gypsumparticle size on some soil physical and chemical properties and faba beans productivity in salt affected soil. The experiment was conducted in split plot design with three replicates. VC with four rates; VC0, VC1, VC2 and VC3 were placed in main plots, while gypsum particle size with three sizes; G1, G2 and G3 was placed in sub-plots. The results revealed that the application of VC3 combined with the G3 recorded the highest decreases in soil ECe and BD (18.97% and 8.87%, respectively) compared to the initial soil values. While RSE, total porosity, OM, CEC and soil nutrient contents were increased with the same combination by (27.62, 9.78%, 48.94%, 22.42%, 18.00, 20.91 and 19.09%) respectively compared to the initial soil values. Also, the application of VC3 combined with G3 achieved the highest values of 100-seed weight (69.20 and 78.36 g), plant height (81.03 and 84.93 cm), pods yield (6.23 and 6.60 Mg.ha-1) and seeds yield (4.02 and 4.39 Mg.ha-1) of faba bean in the 1st and 2nd seasons, respectively as compared to G1. Data also, revealed that the G3 were more effective than G1 on reclaiming the salt affected soil and faba beans yield.

The mechanical and photocatalytic properties of modified gypsum materials

Co-modified TiO2 photocatalysts (TiO2-N,C) were added to commercial gypsum to obtain self-cleaning building material. The gypsum/TiO2 composite were also studied towards their mechanical properties. The highest photocatalytic activity was obtained for gypsum samples containing TiO2/N,C photocatalyst treated at 100–300 °C, attributed to high anatase phase participation, relatively high nitrogen and carbon content and high BET surface area (ca. 170–270 m2/g). In this case (300 °C) the model pollutant (azo dye) degradation rate was 85% and 70% after 15 h of UV and vis irradiation, respectively. Higher compressive strength values was observed for gypsum sample loaded with photocatalysts treated at higher temperatures (600–800 °C), attributed to rutile phase presence and large crystallite size. The grinding operation during gypsum/TiO2 composite preparation can contribute towards the increase of compressive strength (even 40%) by reduction of gypsum particle size whereas photocatalyst particles act as the effective fillers of void spaces in gypsum material.

Influence of gypsum fineness in the first hours of cement paste: Hydration kinetics and rheological behaviour

During the cement production process, gypsum and other additives are input in the clinker grinding and each component present different breakage characteristics. The final particles size depends of the difference of the grindability of their constituent. Thus, it is difficult to know precisely the effect of gypsum fineness in the hydration kinetics or rheological behaviour of the cement paste. Therefore, three gypsum particle size were analysed, classified as fine, medium, and coarse, as well as one clinker collected before grinding. The primary tests included heat flow by calorimetry, X-ray diffraction, and rotational rheometer. It was possible to evaluate how gypsum fineness altered the hydration kinetics in the first few hours and promoted different rheological behaviours from the clinker analysed.

Effect of particle size on the transformation kinetics of flue gas desulfurization gypsum to α-calcium sulfate hemihydrate under hydrothermal conditions

The effect of particle size on the transformation kinetics of flue gas desulfurization (FGD) gypsum to α-calcium sulfate hemihydrate (α-HH) in calcium chloride (CaCl2) solutions was investigated to better guide value-added FGD gypsum use. Gypsum samples from different sources were sieved into several size groups, and their transformation rates were compared. The results showed that using FGD gypsum with a smaller particle size accelerated the transformation to α-HH. The size effect accelerated nucleation kinetics of α-HH rather than its crystal growth rate (that is, the thermodynamic driving force for the transformation changed little with particle size variation). Analysis using a kinetics model revealed that a smaller gypsum particle size lowered the overall activation energy barrier for the transformation. This is because the smaller gypsum particles had a larger relative specific surface area and thus provided more nucleation sites and crystalline defects to promote α-HH nucleation. A smaller particle size of FGD gypsum also gave a higher yield of fine α-HH particles because of the increased incidence of primary and secondary nucleation coupled with attrition. This paper indicates the transformation of FGD gypsum into α-HH could be effectively promoted by regulating FGD gypsum particle size.

Effects of Gypsum Particle Size on Reclaiming Saline-Sodic Soils in Egypt

In Egypt, improving salt-affected soils is important for ensuring secure agricultural productivity. Gypsum is commonly used for the reclamation of saline-sodic and sodic soils. Soil column experiments were conducted to investigate the effect of gypsum, ground to varying degrees of fineness, on the reclamation of clayey saline-sodic soils. The soil used was obtained from Gelbana Village in the Sahl El-Tina Plain, Sinai Governorate, Egypt. Three different degrees of gypsum fineness (<0.5, 0.5–1, and 1.0–2.0 mm) were tested, and the following treatments were included: control (leaching with no gypsum addition), fine particles (<0.5 mm), medium particles (0.5–1.0 mm), and coarse particles (1.0–2.0 mm). The gypsum requirement (GR) to reduce the initial ESP from 29.8 to 10 percent was calculated for the 30-cm soil matrix. The application of gypsum and the subsequent leaching enhanced the reclamation and decreased the salinity as well as the sodicity. With greater fineness of the gypsum particles, a greater decrease in salinity as well as sodicity was obtained. This study suggests that, for greater reclamation efficiency, the gypsum used in the reclamation of saline-sodic soils should be of fine particle size.

Direct carbonation of red gypsum to produce solid carbonates

This study focuses on direct mineral carbonation of waste gypsum, a by-product of titanium dioxide production industry and known as red gypsum. The red gypsum is a potential raw material for carbonation with carbon dioxide due to its high content of calcium. Before being used the red gypsum, it was characterized by MASTERSIZER 2000, XRD, and XRF analyses. The carbonation of red gypsum was carried out using a high pressure autoclave reactor. The reaction parameters such as CO2 pressure, reaction temperature and red gypsum particle size were optimized to achieve the maximum yield and purity of calcium carbonate. The purity of calcium carbonate produced and the carbonation efficiency at different temperatures have also been investigated. Both the purity of the product and the efficiency of the reaction were increased when elevated CO2 pressure and reduced particle size were used. They were increased initially with increasing temperature up to 200°C, but dropped with further increase of temperature. The mineral carbonation technology by using red gypsum can potentially contribute to both reduction of CO2 emission and remediation of environmental concern.

Impact of Gypsum Particle Size on Soil Physical Properties of a Saline-Sodic Soil from North Sinai, Egypt

WATER flow through structured soils can substantially affect …….. local water balance, contaminant transport, and plant-available water. Effect of different gypsum radius on hydraulic conductivity (HC) of saline-sodic soils was assessed. Saline-sodic clay soil from Gelbana Village, Sahl El-Tina plain, Sinai, was mixed with three treatment of gypsum (CaSO4.H2O) different in their particle size: T1"fine" (< 0.5 mm), T2"medium" (0.5-1 mm) and T3"coarse" (1-2 mm), and subjected to continuous leaching increments, and these treatments were compared to the control. Soil samples were packed in columns to make a 30-cm height with a bulk density of 1.36 Mg.m-3. Leaching was conducted by ponding with a constant head of 5 cm water. Leaching water was of EC 1.50 dSm-1 and SAR of 9.1. Six continuous water increments were performed for each column. To assess and simulate the water flow, to quantify improved management strategies, and to derive updated irrigation standards, the soil-water model HYDRUS-1D code was used. A considerable short-lived increase in HC following the addition of gypsum occurred to the soil. It quickly decreased in subsequent leaching increments. The increase amounted to 181, 126 and 117% due to the fine-particles, medium-particles and coarse-particles gypsum, respectively. The increase in HC persisted up to the 4th leachate, and was particularly marked with the fine-particle gypsum, and this increases up to 275% following the 5th leachate compared with the 1st leachate. In soils receiving medium-particle or coarse–particle, increased of the HC was less marked, being up to 56% following 5th leachate increment. The HYDRUS-1D provided reliable simulation results of infiltration rate and cumulative infiltration. Using the model to analyses management options proved an efficient tool for agro-ecosystem assessment.

Effect of trace metals on reactive crystallization of gypsum

AbstractThe effect of Fe2+, Fe3+, and Cr3+ ions on crystallization of calcium sulfate dihydrate (gypsum) produced by the reaction between calcium hydroxide suspension and sulphuric acid solution was investigated at 3.5 pH and 65°C in the absence and presence of 2500 ppm citric acid concentration. Crystal size distributions, filtration rates, and morphology of gypsum were determined and discussed as a function of ion concentration. Average particle size of gypsum was not affected significantly by the presence of Fe2+, Fe3+, and Cr3+ ions individually. Variation of gypsum morphology depending on ion concentration affected the filtration characteristics. The presence of Fe3+ or Cr3+ ions besides 2500 ppm citric acid influenced both average particle size and filtration characteristics. The effect of citric acid on gypsum morphology was suppressed at high Fe3+ and Cr3+ ion concentrations. The change of morphology is related to the complex formation between Fe3+ or Cr3+ ions and citric acid at high ion concentrations. (© 2007 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Influence of citric acid on calcium sulfate dihydrate crystallization in aqueous media

AbstractThe crystallization of Calcium sulfate dihydrate produced by the reaction between pure Ca(OH)2 suspension and H2SO4 solution was investigated at different pH values, temperatures and citric acid concentrations. Crystal size distributions, filtration rates and zeta potentials of gypsum were determined as a function of citric acid concentrations at pH 3.5 and 65°C. The influence of citric acid on the morphology of gypsum was also investigated and discussed. The average particle size of gypsum was reached to maximum in the presence of approximately 2500 ppm citric acid concentration, where the minimum cake resistance and maximum filtration rate were obtained. In the presence of citric acid, various crystal morphologies such as tabular, plate‐like, double‐taper leaf‐like and flower‐like, etc., were obtained. The change of morphology is related to the preferential adsorption of citric acid on different crystallographic faces. (© 2007 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

The use of gypsum for preventing soil sodification: effect of gypsum particle size and location in the profile

SummaryLaboratory studies were conducted on a mixture of surface soils from the Nile Delta (Egypt). Twenty‐two soil columns, initially saturated both with respect to their water‐holding capacity and to their base exchange capacity with calcium, contained 0.0, 0.25, 0.5, 1.0 and 2.0 per cent solid gypsum in the total weight of the solid material in the column. Three particle sizes of gypsum (&gt;0.5, 0.5–1 and 1–2 mm) were mixed either with the top layer or with the whole soil column. The result of leaching these columns with saline water (36 meq 1−1 NaCl+4 meq 1−1 CaCl2) at 0.1 cm h−1 was compared with a mathematical model based on thermodynamic equilibria.The three different particle sizes gave the same experimental results. Applying a given amount of gypsum to the surface soil was more effective in reducing the exchangeable sodium percentage (ESP) than mixing the same quantity through the soil. The mathematical model adequately predicted the changes in the soil column.

Calcium level in the peanut fruiting zone as influenced by gypsum particle size and application rate and time

Abstract The peanut requires a readily available source of Ca in the fruiting zone during fruit development. Field studies were conducted for three years on two soils to compare rates of fine and coarse gypsum material applied to peanuts shortly after planting and at early flowering in supplying Ca to the peanut fruit and its effect on yields. The fine and coarse gypsum was applied at three rates and at two different times in randomized complete block experiments. At approximately every four weeks, composite soil samples were collected at 0–5 and 5–10 cm depths and extracted with (0.05N HC1 + 0.025N H2 SO4) extractant. On the Lakeland soil fine gypsum applied at early flowering gave higher Ca levels at the 0–10 cm depth than coarse material applied shortly after planting or at early flowering. Yield data showed that at low rates coarse gypsum applied at planting was superior to early flowering application. In most instances on the Greenville soil, coarse gypsum applied at planting produced higher levels o...

Irrigation Water Requirement for Dissolution of Gypsum in Sodic Soil

AbstractLaboratory studies were conducted to determine the effect of exchangeable sodium content of the soil and the particle size of gypsum on the irrigation water needs for dissolving gypsum mixed in sodic soils. Gypsum dissolution increased with an increase in the exchangeable Na content of the soil. About 4 cm of water was sufficient to dissolve all the agricultural grade gypsum of &lt;0.26‐mm size. The amount of water required to dissolve the added gypsum and to reclaim a sodic soil did not increase with the amount of gypsum added, provided it equalled the gypsum requirement.The effect of particle size of gypsum on its dissolution and the applicability of the equal‐reduction hypothesis were examined. The dissolution of gypsum was approximately predicted by a dissolution equation based on particle surface area if the initial particle sizes were neither very coarse (&lt;0.5 mm) nor very fine (&gt;0.1 mm). The water required for complete dissolution of gypsum computed from a dissolution equation, increased from 2.8 cm to 15.9 cm as gypsum particle size increased from &lt; 0.1 mm to 0.5–2.0 mm.

The influence of gypsum particle size on pasture response on a sulphur deficient soil

The pasture response to four particle sizes of gypsum fertilizer was measured on a sulphur deficient basaltic soil over a three-year period. At a low rate of application, pasture response was inversely related to particle size ; at a higher rate, only the coarsest fraction differed from the other treatments. The reduction in plant sulphur content and uptake with this fraction suggests that particles &gt;5 mm may be approaching the upper limits of usefulness on this soil. In the first year, the negative interaction between particle size and level of gypsum applied showed that particle size may replace level of application in its effect on response. More efficient use of the sulphur in the fertilizer resulted from application of the finer fractions. Separation of particle size effects into those due to rate of solution of sulphur from the compound, and those due to placement through physical distribution over the soil surface, showed that rate of solution of sulphur was the more important variant. Recognition of its influence could lead to prescribing the correct particle size of gypsum for every sulphur deficient soil. The main effect of the applied sulphur was on the clover component of the pasture. The results suggest that a sulphur content of 0.07 per cent in mature plant tops may be a critical value indicating an adequate sulphur supply, and that 5 lb sulphur an acre in the plant tops may be all that is required for maximum clover production.

Leaching losses of sulphate from superphosphate and gypsum applied on a soil from rhyolitic pumice

Abstract In studies on Waipahihi sand, a yellow-brown pumice soil of the Taupo suite, 97% or more of sulphate applied as superphosphate or gypsum was leached out under an alternate leaching and drying procedure. Losses were proportional to the amounts applied. They were unaffected by particle size of gypsum over the ranges 16–30, 30–60, and 60–120 mesh (B.S.S.), except in the first leaching.