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This study deals with the retardation of cement setting time and workability in hot weather such as in Sultanate of Oman. Combination of sugar and gypsum was used as retarders. The aim of this study was to investigate the effect of retarders on consistency, setting time of ordinary Portland cement (OPC) paste and compressive strength of concrete cubes after 7 days of curing. OPC paste with a water cement ratio 0.4 to 0.5 was prepared by mixing 500 grams of ordinary Portland cement, a fixed amount of sugar of 0.02% by weight of cement with a combination of different gypsum of 1, 2, 3, 4, and 5% by weight cement and water. Sugar has a strong retarding effect, and this effect, controlled by Gypsum, can shorten the long setting time caused by sugar. The setting time of cement paste was reduced from 5.5 hours to 3 hours with an increase in Gypsum at a fixed amount of sugar. At a constant sugar content, increasing the gypsum content reduced the compressive strength from 31.5 MPa to 30.92 MPa.

Gypsum is regarded as an environmentally friendly binding material and is widely used to enhance the engineering properties of soft fine-grained soils. However, the time-dependent strength and deformation characteristics of fine-grained soils stabilised with gypsum have not yet been thoroughly investigated and rational evaluation of these characteristics will assist in the formulation of cost-effective and reliable design approaches. In this study, the time-dependent mechanical behaviours of gypsum-mixed fine-grained soil (GMFS) specimens were investigated under unconfined monotonic loading conditions, considering ageing periods of 3–90 days and five different loading rates (LR = 0.0005–1.0%/min). The results revealed that the unconfined compressive strength and stiffness of the GMFS specimens initially decreased with ageing and finally became stable after 14 days and 28 days of ageing for water/gypsum ratios of 1.30 and 1.60, respectively. Furthermore, the strength and stiffness of the GMFS specimens increased with an increase in LR.

International audience; In recent decades, most of construction activities have been taking place in developing countries such as the Middle East and North Africa region. The expansion in infrastructure has great impact in the technological, social, economic and environmental transformation of this region. Construction sector contribution to Gross Domestic Product (GDP) varies throughout the region and ranges between 2-10%. Currently, sustainable construction requires integrated and comprehensive sustainable design including careful choice of materials and methods. Materials that are locally available and require less energy to produce and transport would pave the way to more sustainable practices. Many countries in the region have realised the benefits of using local building materials on the economy, society and environment. This paper outlines the key trends and opportunities of using sustainable and affordable local building materials in the region to respond to the global climate change crisis and to promote more sustainable and environmentally friendly practices. The current practice of using various building materials such as bio-based materials, treated municipal solid waste incineration bottom ash (MSWI-BA), construction and demolition waste, gypsum-containing by-products (phosphorgypsum, FGD gypsum, borogypsum and others) and rammed earth will be reviewed. It is concluded that the use of these local building materials in construction activities would foster the development of the society. However, some of these materials are already developed and reached the implementation stage while most of them are still at R&D stage. Therefore, there is an urgent need for a comprehensive local and regional strategies to enhance the utilization of these materials.

A phytosociological study on the gypsicolous bryophyte communities of Sicily was carried out. The surveyed communities are: Tortuletum revolventis, Trichostomo crispuli-Tortuletum revolventis, Crossidio squamiferi-Aloinetum aloidis of the order Barbuletalia unguiculatae, and Crossidio crassinervis-Tortuletum obtusatae of the order Tortulo brevissimae-Aloinetalia bifrontis. The associations were examined from a synecological, synhierarchical and chorological point of view. A life form and life strategy analysis of all communities reflect the response of plant functional types towards the environmental demands. Only one life strategy dominates the communities; acrocarpous, turf-forming colonists clearly prevail on gypsum outcrops, subject to drought stress. They provide the main functional type within pioneering communities and communities of first successional stages. The keystone characters outlined ensure a successful dispersal, establishment and habitat maintenance of the species and associations.

In this study, the performance of several binary and ternary mixtures containing high-calcium fly ash and other pozzolans, such as Class F fly ash and silica fume, were investigated for their sulfate resistance using different sodium sulfate solutions. The mortar bars were placed in a similar sulfate solution as per modified ASTM C 1012/1012M (33,800 ppm SO42−) with a less severe sulfate solution (6000 ppm SO42−) has been tested to resemble actual field performance for a duration of 18 months. The phase composition of the mortar samples was investigated using X-ray diffraction and scanning electron microscope coupled with energy dispersive spectroscopy (SEM/EDS). Results show that the mortar bars placed in the moderate sulfate concentration experience less expansion and deterioration than the same bars placed in the higher sulfate concentration. Storage in sodium sulfate solutions resulted in the formation of ettringite and gypsum in both sulfate concentrations. Replacement of cement by high-calcium fly ash showed significantly higher amounts of ettringite formation, especially for the mortar bars stored in the higher sulfate concentration. SEM analysis revealed ettringite to be the primary cause of disruption and deterioration observed in the mortar bars.

Triple-oxygen and hydrogen isotopes of water are critical to aid our understanding of the hydrological cycle on the modern and ancient Earth. As such, this thesis presents advancements in techniques and in the understanding of the isotopic behaviour of water that undergoes evaporation in different conditions. An application of these findings is made to palaeoclimate data, and an expansion of the use of water isotopes from hydrated minerals is applied to a novel mineral system. Of fundamental importance to the hydrological cycle is the process of evaporation. Yet, under- standing how water isotopes behave as they experience evaporation remains poorly quantified. One limitation is the ability to confirm theoretical models or palaoeclimatic data sets with accurate, precise, and controllable experiments. To overcome this, I developed a widely applicable experimental method that permits the measurement of the triple-oxygen and hydrogen isotope evolution of an evaporating fluid and its coincident vapour that is both highly accurate and with a precision and sampling rate previously unobtainable. Additionally, the methodology permits a wide range of variables to be controlled or manipulated, allowing future scholars to thoroughly explore the effect of differing climatic conditions on the full suite of water isotopes as they undergo evaporation. One such variable explored is the morphology of an evaporating basin. Whilst currently neglected in studies that examine lacustrine palaeoclimate records, I present experimental data for both idealised and real basin morphologies (generated by 3D printing) that highlights a significant effect on the rate of isotopic change as a function of basin morphology, despite constant environmental conditions. Experimental data suggest that unless the surface area to volume (SA:V) ratio of a lake is considered, palaeoclimatic data from two lakes with distinct morphologies but undergoing evaporation under identical climates could be misinterpreted. Similarly, the results from the real basin morphology experiments suggest that rapid changes in SA:V ratio could result in inflections in the isotopic record that are solely a response to morphology as opposed to changes in climate. Understanding from the evaporation experiments is then applied to gypsum hydration water (GHW) data obtained from Lake Petén Itzá, Guatemala. The lake is in the northern neo-tropics and provides a complete record of climate variability over the last 43 ka. Using the GHW isotopic data in combination with a Monte Carlo and combined hydrological-climate re-analysis models, I determine relative differences between the cooler, drier stadial periods that are recorded in the sediments. In addition, multiple proxies indicate that intra-stadial variability is recorded at Lake Petén Itzá and this mirrors variation observed in polar oxygen isotope records. This suggests a close climate teleconnection between the poles and the tropics during these periods. Finally, I explore the use of oxygen and hydrogen isotopes in sedimentary talc. This is achieved by experimentally determining the fractionation factors between amorphous Mg-silicate and the water from which it precipitates. This is followed by calculating the fractionation factors as these precipitates undergo synthetic metamorphism to true talc. Isotopic measurements from Neoproterozoic samples are measured and the isotopic composition of the ancient precipitating fluid is estimated using the uncertainty of these parameters and Monte Carlo modelling. This thesis provides a strong experimental backbone for future examination of evaporating water under a variety of palaeoclimatic conditions and contexts. It demonstrates how insights from evaporation experiments can be applied to interpreting palaeoclimate data and how hydrated minerals of various types, and from a range of geological settings and times, can be used to provide robust information about the climate and fluids from which they formed.

The composite behaviour of fixings acting in shear between gypsum board and thin steel sections depends on the effective properties of the board material in compression at the base of the fixing and the contribution of the head of the fixing as it rotates. An elastic method is presented to determine the stiffness of the fixings, which uses the effective elastic modulus of the gypsum board determined from a ‘dowel’ test in bearing based on the BS EN 383:2007 test. The deformation of the board in front of the fixing was determined by finite-element (FE) modelling as acting over a constant strain zone of approximately 1·5 times the fixing diameter. A plastic method is also presented to determine the shear resistance of fixings into gypsum board based on the compression resistance obtained from a dowel test on the BS EN 383:2007 test. The theory is compared with the results of FE models using Abaqus for 3·5 mm dia. fixings into 12·5 mm thick gypsum board and with tests on fixings in shear and dowel tests; the correlation is shown to be good. A small-scale push test is proposed to determine fixing properties in shear.

Thermoregulating composites were produced by using a thermoregulating slurry (NPCS) containing nanoencapsulated phase change material (NPCM) from poly(styrene-co-divinylbenzene) as shell and the commercial paraffin Rubitherm®RT27 as core material. These composites were synthesized by using the constitutive water of the slurry as setting water and changing the NPCM/Hemihydrate (NPCM/Hem) mass ratio within 0.0–0.41. It was found that nanoparticles were uniformly dispersed into the gypsum, and the gypsum crystal morphology was tuned by the addition of the slurry. Attending to the thermal properties, these materials can work either as insulating or thermal energy storage materials, decreasing the thermal conductivity up to ~ 50%, whereas the thermal energy storage (TES) capacity is enlarged in a ~ 140%, respect to the pure gypsum, when the maximum NPCM/Hem mass ratio was used. This composite had a latent heat of 30.2 J g−1 and a heat capacity of equivalent 3.5 J g−1 K−1. Composites from a NPCM/Hem mass ratio up to 0.15 satisfied European mechanical standard EN 13,279–1 for gypsum binders and gypsum plasters and all of them, presented a bulk density higher than 0.60 g cm−3. The addition of a 41% in mass of nanocapsules allowed to save 13.5 kWh m−3 and, reducing the CO2 emissions up to 3.4 kg of CO2 per operating cycle. The use of this new material would lead to significant energy and economic savings, as well as a considerable reduction in the emission of polluting gases into the atmosphere., Los compuestos termorreguladores se produjeron utilizando una suspensión termorreguladora (NPCS) que contenía material de cambio de fase nanoencapsulado (NPCM) de poli(estireno-co-divinilbenceno) como cubierta y la parafina comercial Rubitherm®RT27 como material central. Estos compuestos se sintetizaron usando el agua constitutiva de la suspensión como agua de fraguado y cambiando la relación de masa NPCM/Hemihidrato (NPCM/Hem) entre 0,0 y 0,41. Se encontró que las nanopartículas se dispersaron uniformemente en el yeso, y la morfología del cristal de yeso se ajustó mediante la adición de la suspensión. Atendiendo a las propiedades térmicas, estos materiales pueden funcionar como materiales aislantes o de almacenamiento de energía térmica, disminuyendo la conductividad térmica hasta ~ 50%, mientras que la capacidad de almacenamiento de energía térmica (TES) se amplía en un ~ 140%, respecto a la pura. yeso, cuando se utilizó la máxima relación de masa NPCM/Hem. Este material compuesto tenía un calor latente de 30,2 J g−1 y una capacidad calorífica equivalente a 3,5 J g−1 K−1. Los composites a partir de una relación másica NPCM/Hem hasta 0,15 cumplieron con la norma mecánica europea EN 13.279–1 para aglomerantes de yeso y revoques de yeso y todos ellos, presentaron una densidad aparente superior a 0,60 g cm−3. La adición de un 41% en masa de nanocápsulas permitió ahorrar 13,5 kWh m−3 y, reducir las emisiones de CO2 hasta 3,4 kg de CO2 por ciclo de operación. La utilización de este nuevo material supondría un importante ahorro energético y económico, así como una considerable reducción de la emisión de gases contaminantes a la atmósfera.

Compared with traditional sodium or calcification roasting process for vanadium extraction from raw vanadium slag(V-slag), ammonium sulfate (AS) roasting could reduce about 470 °C roasting temperature and avoid Cl2, HCl, sodium-containing waste-water and waste gypsum discharging. To reduce the amount of AS added in vanadium extraction process, an efficient AS two-stage cyclic roasting and acid leaching process was proposed. The result of TG analysis indicates V- slag could be decomposed in 275-380 °C using AS roasting process. Using 2.03:1 total mass ratio of AS to V-slag, 90.86% V and 80.54% Ti could be extracted after 380℃ roasting for 30 min and 8% initial concentration of H2SO4 leaching at 70 ℃ for 100 min. XRD analysis indicates V-containing spinel phase in the 1st stage leaching residue would be efficiently decomposed by the cyclic two-stage roasting and leaching process. Furthermore, the valence of V(III) in raw V-slag was not changed after the 1st AS roasting stage, but a part of V(III) in the 1st leaching residue was oxidized to V(V) after 2nd roasting process.

This paper presents an experimental study and micro-mechanism discussion on gypsum role in the mechanical improvements of cement-based stabilized clay (CBSC). A soft marine clay at two initial water contents (i.e. 50% and 70%) was treated by reconstituted cementitious binders with varying gypsum to clinker (G/C) ratios and added metakaolin to facilitate the formation of ettringite, followed by the measurements of final water contents, dry densities and strengths in accordance with ASTM standards as well as microstructure by mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). Results reveal that the gypsum fraction has a significant influence on the index and mechanical properties of the CBSC, and there exists a threshold of the G/C ratio, which is 10% and 15% for clays with 50% and 70% initial water contents, respectively. Beyond which adding excessive gypsum cannot improve the strength further, eliminating the beneficial role. At these thresholds of the G/C ratio, the unconfined compressive strength (UCS) values for clays with 50% and 70% initial water contents are 1.74 MPa and 1.53 MPa at 60 d of curing, respectively. Microstructure characterization shows that, besides the common cementation-induced strengthening, newly formed ettringite also acts as significant pore infills, and the associated remarkable volumetric expansion is responsible, and may be the primary factor, for the beneficial strength gain due to the added gypsum. Moreover, pore-filling ettringite also leads to the conversion of relatively large inter-aggregate to smaller intra-aggregate pores, thereby causing a more homogeneous matrix or solid skeleton with higher strength. Overall, added gypsum plays a vital beneficial role in the strength development of the CBSC, especially for very soft clays.

This study investigated the effects of changing the type and surface area per unit mass (Sa) of activated materials on the compressive strength of ground granulated blast-furnace slag (GGBS) cement (GGBS > 60%). This study is divided into two parts. The first part involved the selection of activated materials. Compressive strength results show that gypsum improves the early strength of GGBS cement more effectively than does sodium silicate or sodium hydroxide. The gypsum activators increase GGBS activity through sulfates, generating ettringites and C–S–H to increase compressive strength. Chemical analysis shows that the sulfite (SO3) in GGBS cement has more stable compressive strength at 6–8%. The second part of this study investigated the influence of Sa. Gypsum was used as a strength activator. The sulfite in GGBS cement was controlled at 6.5% ± 0.5%, and Sa was adjusted as the variable. Linear regression analysis shows that the change in GGBS cement Sa (Msa) is positively correlated with compressive strength. The value of Msa can be estimated according to the value of Sa and the quantity of ingredients used for the study results (cement, GGBS and gypsum). The compressive strengths of GGBS cement at various curing ages can be predicted using Msa.

Atom- and energy-efficient synthesis of a crystalline calcium urea sulfate ([Ca(urea)4]SO4) cocrystal was explored using thermally controlled mechanochemical methods with calcium sulfate compounds containing various amounts of crystalline water (CaSO4·xH2O, x = 0, 0.5, 2). Small-scale (200 mg) experiments in a shaker mill were first performed, and the progress was monitored by in situ Raman spectroscopy and in situ synchrotron powder X-ray diffraction. Time- resolved spectroscopy data revealed that the presence of water in the reagents’ crystalline structure was essential to the reaction and largely determined the observed reactivity of different calcium sulfate forms. Reactions at elevated temperatures were shown to proceed significantly faster on all synthetic scales, while changes in rheology caused by adding external water hindered the reaction progress. The average yield of a 21 mm horizontal twin-screw extruder experiment was ∼5.5 g/min of extrusion (∼330 g/h). Energy consumption during the milling reactions required to achieve complete conversion ranged from 7.6 W h/g at 70 °C for a mixer mill to 3.0 W h/g at a 50 g scale and 4.0 W h/g at a 100 g scale for a planetary mill or 4.0 W h/g at both 70 °C and RT for a twin-screw extruder, showing a significant improvement in energy efficiency at large-scale production. The obtained crystalline cocrystal exhibited a significantly lower solubility in aqueous solutions, nearly 20 times lower per molar basis compared to that of urea. Furthermore, reactive nitrogen emissions in air at 90% relative humidity, measured as NH3, showed slow and nearly linear nitrogen loss for the cocrystal over 90 days, while the same level of emissions was achieved with urea after 1–2 weeks, showing the potential of this cocrystal material as a large-scale nitrogen-efficient fertilizer.

The Dawenkou Basin is a Cenozoic terrestrial fault basin in Shandong Province, East China, containing abundant mineral resources, especially gypsum. Recently a borehole was drilled in this basin unearthing the upper and middle members of the Dawenkou Formation. From the upper member, well-preserved ostracodes were discovered, which are entirely non-marine taxa including species of Eucypris, Caspiolla, Candona and Candoniella. Based on the new material, a new species Candona dawenkouensis n. sp. was erected. The ostracode assemblage biostratigraphically indicates an age of middle Eocene to Oligocene of the upper member of the Dawenkou Formation and the strata bearing mineral resources (mainly gypsum) of the middle member of the Dawenkou Formation is likely early Eocene.

Hemihydrate calcium sulfate whiskers (HH-CSWs) were hydrothermally synthesized in a sulfuric acid solution at 120 °C for different holding times (20, 40, and 60 min). The phase structures and morphologies were characterized by XRD and SEM, respectively. The XRD pattern of the sample under 60 min was refined via the Rietveld fitting method. The structure models of the HH-CSW sample under a 60-min holding time was established based on Rietveld fitting results. No difference in the positions of diffraction peaks was determined. The as-prepared holding time increased the intensity and aspect ratio of the diffraction peaks of both samples. In the prepared HH-CSW structure, Ca–O polyhedron is a 12-sided polyhedron similar to that in the gypsum structure; the Ca atom is located in two positions in the one-unit cell; the H2O channel along the c-axis similar is O-shaped and bigger than that in hexagonal and monoclinic CaSO4·0.5H2O structures. Therefore, although the prepared HH-CSW crystals’ structure are similar to that of the reported hexagonal and monoclinic CaSO4·0.5H2O structures, they are not the same. The formation mechanism of HH-CSW from flue gas desulfurization (FGD) gypsum is discussed based on the analysis of gypsum structure.

In the present study, radiation shielding and protection ability of prepared Flyash-lime-Gypsum (FaLG) bricks has been studied in terms of energy exposure build up factors and dose parameters. The energy exposure build up factors of Flyash-lime-Gypsum (FaLG) bricks have been calculated for the energy range of 0.015 MeV–15 MeV and for penetration depth upto 40 mfp directly using a new and simplified Piecewise Linear Spline Interpolation Method (PLSIM). In this new method, the calculations of G.P fitting parameters are not required. The verification and accuracy of this new method has been checked by comparing the results of exposure build up factor for NBS concrete calculated using present method with the results obtained by using G.P fitting method. Further, the relative dose distribution and reduced exposure dose rate for various radioactive isotopes without any shielding material and with Flyash-lime-Gypsum (FaLG) bricks have been calculated in the energy range of 59.59–1332 keV. On the basis of the obtained results, it has been reported that the prepared Flyash-lime-Gypsum (FaLG) bricks possess satisfactory radiation shielding properties and can be used as environmentally safe storage facilities for low level nuclear waste.

The paleosalinity of water from which the gypsum precipitated during the Messinian salinity crisis is a controversial issue. Recent microthermometry studies on primary fluid inclusions in gypsum provided very low salinity values not compatible with precipitation from seawater, and suggested strong mixing between seawater and nonmarine waters enriched in calcium sulfate. We applied a new microthermometric protocol on gypsum crystals from nine Mediterranean sections that were experimentally stretched to measure a larger population of fluid inclusions. The results show salinities ranging from 9 to 238 wt‰ NaCl equivalent, largely falling within the evaporation path of normal seawater. The data from previous studies were obtained mostly from those fluid inclusions capable of nucleating a stable bubble after a weak stretching, which probably correspond to those having a lower salinity acquired through post-depositional crack-and-seal processes. Our data suggest instead that the primary gypsum precipitated from a marine brine, later modified by post-trapping processes during tectonics and exhumation.

A lot of CO2 is released into the atmosphere during the manufacturing process of cement, which causes a global warming problem. Calcined clay-limestone cement concrete (LC3) can be used to partially solve this problem. Limestone cement concrete is produced from calcined clay-limestone cement which is an advanced ternary mixed cement formed by the combination of 30 percent low-grade calcined clay, 15 percent limestone powder, and 5 percent gypsum and 50 percent cement clinkers. That means 50 percent of cement clinkers are to be replaced by additional cementitious materials which are beneficial for reducing CO2 emission at the time of production of cement. In the present study, calcined clay-limestone cement is used to prepared concrete and compare it with concrete using ordinary portland cement (OPC) of grade 53. The physical and chemical characteristics of prepared cement samples were carried out and compared with OPC. M30 grade of concrete was prepared by calcined clay-limestone cement; mechanical properties such as compressive strength (CS) test are carried out on prepared concrete. After the age of 28 days, M30 grade of concrete was exposed to 100 °C, 200 °C, 400 °C, 600 °C, and 800 °C temperature, surface texture, weight loss, compressive strength test were carried on the cubes of size 150 × 150 × 150 mm3. The SEM analyses were carried out over 100 °C and 600 °C temperature on OPC and calcined clay-limestone cement concrete. The result shows that the compressive strength reduces with an increase in exposed temperature. The compressive strength decreases after 200 °C and significant losses occur after 400 °C. When the temperature reached 400 °C, noticeable minute cracks started to appear on the surface of the cube specimens.

This article is focused on the investigation of the mechanical and thermal properties of composite material that could be used for the production of plaster or plasterboards. This composite material is made of gypsum and reinforcing natural fibers. The article verifies whether this natural reinforcement can improve the investigated properties compared to conventional plasters and gypsum plasterboards made of pure gypsum. From this composite material, high-strength plasterboards could then be produced, which meet the higher demands of users than conventional gypsum plasterboards. For their production, natural waste materials would be used efficiently. As part of the development of new building materials, it is necessary to specify essential characteristics for their later use in civil engineering. Crushed wheat straw and three gypsum classes with strengths G2 (2 MPa)-gypsum class I., G5 (5 MPa)-gypsum class II. and G16 (16 MPa)-gypsum class III. were used to create the test samples. Samples were made with different ratios of the two ingredients, with the percentages of straw being 0%, 2.5%, and 5% for each gypsum grade. The first part of the article describes how the increasing proportion of straw affects the composite's mechanical properties (flexural strength and compressive strength). The second part of the article focuses on the change of thermal properties (thermal conductivity and specific heat capacity). The last part of the article mentions the verification of the fire properties (single -flame source fire test and gross heat of combustion) of this composite material. The research has shown that the increasing proportion of straw reinforcement caused a deterioration in the flexural strength (up to 56.49% in the 3. series of gypsum class II.) and compressive strength (up to 80.27% in the 3. series of gypsum class III.) and an improvement in the specific heat capacity and thermal conductivity (up to 31.40% in the 3. series). This composite material is thus not suitable for the production of high-strength plasterboards, but its reduced mechanical properties do not prevent its use for interior plasters. Based on the performed fire tests, it can be said that this composite material can be classified as a non-flammable material of reaction to fire Classes A1 or A2. From an ecological point of view, it is advantageous to use a composite material with a higher straw content. Web of Science 10 7 1873 1859

The rapid retreat of the Dead Sea during the past four decades led to the exposure of unique structures of massive gypsum along the shores. Many of these structures (having the shape of mounds) are associated with the activity of Ein Qedem-type saline springs that currently discharge Ca-chloride brine to the lake. Field observations, radiocarbon dating of aragonite (within the gypsum mounds) that yield ancient ages, and the narrow range of δ34S and δ18O values ( δ 34 S gyp : 14.1–16.9‰; δ 18 O gyp : 14.4–16.5‰) indicates that the formation of the gypsum structures is related to the mixing of brines: the Dead Sea brine and ancient (last glacial) Ein Qedem type brine. These are Ca-chloride brines having different salinities and sulfur concentrations that satisfy conditions of an outsalting process whereby supersaturation of gypsum is attained by the mixing of these two brines in the offshore shallow water environment. Thermodynamic calculations (using the PHREEQC software) show that gypsum outsalting occurred when both brines were enriched with sulfate as compared to the present. The Ein-Qedem brine had higher sulfate when subjected to less intensive bacterial sulfate reduction. The Dead Sea was characterized by higher sulfate concentrations during intervals of low lake stands. The conditions of higher sulfate concentrations and enhanced discharge of the saline springs occurred repeatedly in the Dead Sea between ∼6.6 to 0.6 ka and were intermittent with periods of enhanced supply of sulfate to the lake by freshwaters.

Context The effect of long-term gypsum on nitrogen (N) responsiveness in black oat (Avena strigosa Schreb.) forage lacks information. Aims and methods This study evaluated interactions between different rates of N (0, 50 and 100 kg N ha−1) and gypsum (0, 3, 6, 9 and 12 Mg ha−1) on the yield, nutrition and bromatology of forage black oats in a long-term experiment using a no-till system (NTS) in a Ferralsol in southern Brazil. Key results There was an interaction between residual gypsum and N rate on biomass forage yield in 2015, but not for the 2016 growing season. In 2015, the rate of 100 kg N ha−1 increased yield by 10% in the absence of gypsum and by 30% at low-medium rates of residual-gypsum (3 and 6 Mg ha−1), but there was no response to high N rate under high gypsum rates (9 and 12 Mg ha−1). In 2016, a poor-growing season, a gypsum rate of 6 Mg ha−1 and N rate of 100 kg ha−1 independently improved forage yield by 5%. Gypsum application produced higher forage contents of N, P, K, Ca and S, and decreased Mg content. N-fertilisation increased the N, K, Ca, and Mg contents, but decreased P content and S concentration. Gypsum had no effect on forage bromatological quality, and even with equivalent forage yield between 50 and 100 kg N ha−1, only the high N rate improved some of the forage quality attributes in both years. Conclusions and implications Neither gypsum nor topdressing of N altered N use by black oat forage.

Previous studies have mainly focused on changes in soil physical and chemical properties to evaluate the reclamation of sodic soils using flue gas desulfurization (FGD) gypsum. However, information on the effects of this reclamation method on microbial-based indicators of soil quality is limited, particularly after many years of FGD gypsum application. This study aimed to investigate the long-term effects of FGD gypsum on soil organic carbon (SOC), nutrients, microbial biomass and enzyme activity. Data were collected from soils of three exchangeable sodium percentage (ESP) classes (i.e., low-, middle- and high-ESP classes of 6.1–20, 20–30 and 30–78.4%, respectively) 17 years after FGD gypsum treatment in Inner Mongolia, China. Averaged across the three ESP classes, FGD gypsum application increased the SOC contents at the 0–20 and 20–40-cm soil depths by 18 and 35%, respectively, and increased available potassium at the 0–20-cm soil depth by 51% compared with the no-gypsum controls. The microbial biomass carbon and microbial biomass nitrogen contents at the 20–40-cm soil depth increased by 69 and 194%, respectively, under FGD gypsum. Except in the high-ESP class, urease activities in the 0–40 cm soil profile were significantly higher in the FGD gypsum treatments than in the controls. A significant increase in alkaline phosphatase activity was concentrated in the 20–40 cm soil layer; few classes showed significant increases in catalase and invertase activities in the 0–20 cm soil layer. Pearson correlation analysis showed that increases in soil fertility and biological activity could be attributed to reductions in electrical conductivity, pH and ESP caused by FGD gypsum application. These results confirm that FGD gypsum application is a viable strategy for reclaiming sodic soils due to its positive effects on soil fertility and biochemistry and that it may contribute to soil ecosystem sustainability.

Recent research on dust emissions from eolian dunes seeks to improve regional and global emissions estimates and knowledge of dust sources, particularly with a changing climate. Dust emissions from dune fields can be more accurately estimated when considering the whole eolian system composed of active to stabilized dunes, interdunes, sand sheets, and playas. Each landform can emit different concentrations of dust depending on the supply of silt and clay, soil surface characteristics, and the degree to which the landforms are dynamic and interact. We used the Portable In Situ Wind Erosion Laboratory (PI-SWERL) to measure PM10 (particulate matter 300 t/km2/yr.

The present study aims to assess the effect of four inorganic soil amendments, such as lime (CaCO3), red mud consisting of 75% hematite (Fe2O3), gypsum (CaSO4·2H2O), and Al oxide (Al2O3), of an alkaline heavy metal-contaminated soil. For this purpose, a pot experiment was conducted by physically mixing individual six subsamples of a soil sample collected from Thessaly area with four inorganic soil amendments along with two leafy plants, spinach and lettuce. Al oxide causes the maximum reduction of the water-soluble Cu concentration, as its concentrations is no longer detectable. The Cu availability index decreases when aluminum oxide was used. The use of gypsum and red mud caused almost equal reduction while the smallest decrease was caused by the use of lime. The Zn availability index decreased equally when aluminum oxide and gypsum were mixed with the soil sample. The highest reduction of Cu and Zn transfer coefficient (TC) was observed when the Al2O3 was used. In spinach, Zn TC reduction was 39.8% and Cu TC reduction was 41.0%. In lettuce, the addition of Al2O3 led to Cu TC reduction of over 37.3% and Zn TC reduction of up to 38.7%. Generally, Al2O3 nanoparticles may function as suitable sorbents for the removal of Zn and Cu from soil samples, with an increasing effectiveness in spinach rather than lettuce. Liming materials seem to increase the soil alkalinity and promote the complexation of soluble heavy metals with hydroxide ions leading to immobilization of heavy metals in soil and reduce their amount in leafy vegetables. Remediation of contaminated soils is considered necessary to reduce environmental risks and to achieve the means available to increase agricultural production of safe and quality food.

The present research investigated bio-based construction material based on hemp shives and gypsum. Low-density material was developed with densities of 200, 300, and 400 kg/m3. Simple yet robust pr...

Prior mineral scaling investigations mainly studied the effects of membrane surface properties rather than on the mineral properties and their impact on membrane permeability. In our study, mass, crystal growth orientation, and crystallinity of mineral precipitates on membranes, as well as their effects on membrane permeability have been investigated. Gypsum scaling tests on bare and bovine serum albumin (BSA)-conditioned membranes were conducted under different saturation indices. Results show that a longer scaling period was required for BSA-conditioned membranes to reach the same membrane permeate flux decline as bare membranes. Though the final reduced permeability was the same for both two membranes, the masses of the mineral precipitates on BSA-conditioned membranes were around two times more than those on bare membranes. Further mineral characterizations confirmed that different permeability decay rates of both types of the membrane were attributed to the differences in growth orientations rather than amounts of gypsum precipitates. Moreover, BSA-conditioned layers with high carboxylic density and specific molecular structure could stabilize bassanite and disrupt the oriented growth to inhibit the formation of needle-like gypsum crystals as observed on bare membranes, thus resulting in lower surface coverage with scales on membranes and alleviating the detrimental scaling effect on membrane permeability.

The Portland cement industry is one of the strategic industries in any country. The basis of an industry success is the availability of raw materials and, the low extraction in addition to transportation costs. The Bahr Al-Najaf region is abundant with limestone rocks but lacks primary gypsum. An investigation had been carried out to identify the source of secondary gypsum as an alternative to primary gypsum. Twelve boreholes were drilled for a depth of 2 m, as the thickness of suitable secondary gypsum layer ranges from 1 to 1.5 m. The mineralogical study revealed the predominance of gypsum followed by quartz and calcite, with an average of 62.9%, 19.6% and 14.35%, respectively. The geochemical analysis revealed that the content of SO3 is appropriate and ranging from 41.92% to 32.89% with an average of 37.73%. The SO3 content is within an acceptable range. The mean abundance of the major oxides of the study area may be arranged as SO3 > CaO> SiO2> MgO> Al2O> Fe2O3. The insoluble residue was at an acceptable rate. The laboratory experiments for milling secondary gypsum with clinker has successfully proven the production of Portland cement that matches the limits of the Iraqi Quality Standard (IQS) No. 5 of 1984. Great care must be taken when using secondary gypsum; secondary gypsum must be mixed well to maintain the chemical properties before blending with clinker and utilizing in the cement mill in the cement plant.

This study proposes a model for the kinetics and hydrodynamics of gypsum scale deposition on surfaces of anhydrite, calcite, dolomite, and sandstone rocks while interacting with the brines of 3000 and 6000 mg/L [Ca2+] at 363 K and 1 atm. To do so, this study utilizes the surface energy characteristics of an interacting scale-brine-rock system as well as the geochemical interactions between brine-brine and brine-rock. The results showed that the deposition flux decreases steeply over time, followed by asymptotic propensity as time elapses. A higher degree of salinity in terms of [Ca2+] increases the deposition flux as much as 2.9-fold for the flowing velocity of 10-6 m/s and 2.4-fold for a velocity of 10-5 m/s. Moreover, higher flow velocity would lead to more deposition on sandstone followed by carbonate and anhydrite rocks: ∼2.6-fold for the salinity of 3000 mg/L and 2.2-fold for 6000 mg/L [Ca2+].

Gypseous soils are capable of presenting ground construction challenges to civil and geotechnical engineers due to their unpredictable deformation characteristics. These undesirable responses are sometimes caused by environmental changes in moisture content due to temperature variations, fluctuation of underground water table, surface water, and gypsum content. Hence, the adoption of effective and economical means of stabilising gypseous soils is imperative. This study’s focus is on the early age strength and microstructural characteristics of gypseous soils treated with lime and GGBS. Treated and untreated gypseous soils with 5%, 15%, and 25% gypsum content were subjected to wet–dry cycles while investigating unconfined compressive strength (UCS), water absorption, pH, microstructural changes, and swell. The analysis of the results shows that at zero cycle, the UCS of the untreated gypseous soils increases from 0.62 to 0.79 MPa and swell decreases from 69 to 23%, respectively, as gypsum content increases. However, upon subjection to wet–dry cycles, the UCS reduced from 0.16 to 0.08 MPa at the end of the sixth cycle due to dissolution of gypsum within the soil pores which reduced the strength. The result also shows that gypsum content increases water absorption and reduces the pH of the untreated gypseous soils because of the neutral pH of gypsum. Furthermore, lime-GGBS-treated gypseous soils maintained a higher pH after six wet–dry cycles compared to untreated gypseous soils due to the high pH of lime and the increase in calcium content which improved bonding. In addition, microstructural analysis using SEM indicated early age precipitation of cementitious compounds (CSH) for increasing strength of lime-GGBS-treated gypseous soils compared to untreated gypseous soils.

Several studies have shown the feasibility and thermal potential of gypsum plaster with microspheres of PCM, but very few of them investigated an approach with practical and standards concern. In this work, different characterizations are performed according to European standards on a standard gypsum plaster and two different gypsum plasters formulated with 20 wt.% of PCM microspheres. A material is experimentally made by mixing conventional gypsum and PCM microspheres, whereas the other is an already prepared commercial mix. For the laboratory material, the addition of PCM increases the consistency of the fresh paste of plaster. In order to reach a consistency in agreement with the standards more water is required. This higher amount of water causes further issues on the densification and cohesion properties. In contrary, the properties of the commercial mix are closer to a common plaster. It is therefore assumed that the commercial material incorporates thinner additives. In view of these results, it is assumed that most of the drawbacks due to the addition of PCM microspheres in gypsum plasters could effectively be encountered by adequate addition of additives in order to reduce the amount of water, and binding resins in order to improve the adhesion and mechanical properties.

High ferrite cement (HFC) has attracted widespread attention due to the low carbon footprint and energy consumption. Gypsum, one of the essential components in Portland cement, plays a crucial role...

To date, a variety of 3-D printing methods and materials have been utilized to replicate natural rocks, yet no study has compared their outputs. Such work can enable us to select the most appropriate printing technique and material combinations to ensure better results when natural rocks are substituted with replicas. The present study compares binder jetting and stereolithographic (SLA) 3-D printing methods in the manufacturing of a porous rock model. The materials employed are gypsum powder and silica sand for the binder jetting technique, and resin for the SLA method. First, a digital rock model based on Berea Sandstone was created with computed microtomography imaging, then the image was printed using the aforementioned methods and materials. The replicas were examined by computed nanotomography imaging to compare the resemblance of internal pore structures to the natural specimen. It was found that powder-based printing with gypsum created an output that was comparable only on the exterior portions to the reference model, silica sand failed in the interior boundaries because of loosely packed particles, and the resin-based model was the most similar to the reference in terms of pore shape and geometry. Ultimately, this study should help lay out general guidelines in selecting appropriate purpose-based printing techniques and materials to benefit the field of geosciences.

Stabilization is one of the efforts to improve the condition of the soil which has a poor index of properties. One of the soil stabilization that is usually done is by adding chemicals to the soil. Chemicals commonly used in the form of cement, lime, bitumen. In this study, the stabilization of clay was carried out by adding gypsum and volcanic ash. The purpose of this study was to determine the value of the index properties due to the addition of 2% gypsum and volcanic ash on the clay soil, then to determine the maximum compressive strength value due to the addition of variations in stabilizing materials by testing the Unconfined Compression Test (UCT) and testing the California Bearing Ratio (CBR). ) laboratory. From the research, it was found that the original soil sample had a moisture content of 12.42%; specific weight 2.65; liquid limit 46.82% and plasticity index 29.40%. The original soil classification according to USCS is classified as Clay – Low Plasticity (CL) and according to AASHTO it is classified as A-7-6 (10). Unconfined Compression Test (UCT) values ​​for native soil and native soil plus 2% gypsum were 1.40 kg/cm2 and 1.66 kg/cm2. The laboratory CBR values ​​for soaked and unsoaked for the original soil were 4.44% and 6.28%, respectively. While the laboratory CBR values ​​soaked and unsoaked for the original soil plus 2% gypsum were 6.74% and 8.02%, respectively.The most effective results were obtained from a mixture of 2% gypsum and 10% volcanic ash with a UCT value of 2.79 kg/cm2 (an increase of 99.28%). For laboratory CBR testing, the most effective mixture was on a mixed variation of 2% gypsum and 9% volcanic ash with laboratory CBR values ​​soaked and unsoaked of 9.07% (an increase of 104.27% from the original soil) and 10 ,29% (an increase of 63.85% from the original land). The soil that has been mixed with the most effective stabilizer material, namely 2% gypsum and 9% volcanic ash is classified as Clay - Low Plasticity (CL) based on the USCS classification and is classified as A-6 (4) based on the AASHTO classification.

This paper focuses on the role played by the clay minerals and microorganisms in the deterioration process of Coptic architecture units at the church of Virgin Mary, Wadi El-Natrun region. For this purpose building materials (mainly mortars and plasters) from the studied church were examined using X-ray diffraction (XRD), X-ray fluorescence (XRF) and scanning electron microscope with energy dispersive spectroscopy (SEM-EDS), in order to identify their composition and were investigated petro-graphically to determine the real response of the masonry structure to the deformation imposed at the endogenous factors. Wall gypsum mortars in the church contain halloysite as a dominant clay mineral while plaster is clay free, concerning microorganisms, the fungal flora Aspergillus glaucus represent the most dominant fungi constituting (22.22%), Aspergillus flavus, Aspergillus flavus, Aspergillus fumigatus, Aspergillus occhraceus, and Aspergillus caudidus were also isolated.

In this research, a geotechnical assessment was conducted for clay of the Gercus Formation to determine its suitability for embankment dams. The selected area is located in the north of Iraq. Six samples were collected from two sites in Dokan (Sulaimaniyah) and Haibat Sultan mountain (Koysinjaq), three samples each. Various geotechnical (physical, mechanical and chemical) tests were conducted based on standard specifications. The results of the grain size test of clay samples showed their conformity with Zone C curves and their suitability for the construction of embankment dams, according to the Iraqi standard for roads and bridges. The results of the plasticity limits test showed that the soil is made of fine, low plasticity silt (ML), and low plasticity clay (CL), according to the unified standard soil classification. The water content and plasticity limit tests (liquid limit, plastic limit, and plasticity index) demonstrated that these clays are conformable with the limits of the Iraqi standards. The results of the modified compaction test found a maximum dry density value of 1.962 g/cm3 with an optimum moisture content of 11.5%. The results of the permeability index (K) revealed low permeability according to the Das classification and, therefore, showed the suitability of the samples as raw filling materials in the construction of dams. Chemical tests (sulfate content, organic materials content, total dissolved salts, gypsum content, and pH value) showed compatibility with the requirements for the use in dams construction under the Iraqi standard (SoRB/ R5).

We describe herein a detailed study on the effect of molar ratio MR = n(OH−)/n(Ca2+) on the Phosphogypsum (PG) waste ammonia-carbonation process. The use of an aqueous NH3 solution/gaseous CO2 mixture as an alternative and environmental medium compared with other mediums [(NH4)2CO3 for example] is proposed for CO2 capture and PG recycling. The main purity, reaction time, and production efficiency of the obtained products were systematically studied for the different molar ratios using several physicochemical techniques: XRD, XRF, FTIR, SEM/EDX, pH, and electrical conductivity meters. For economic reasons, the molar ratio was varied to obtain values close to those of the stoichiometry, MR (2 ≤ MR ≤ 4). The obtained results show that the MR presents an important effect on the conversion process. In parallel, a comparative study between the conversion process of the synthetic gypsum (SG) and PG shows that the two samples are similar. All these findings revealed that PG waste could be used as a substituent to the SG in the general application of this last useful product.

The main results of the study of the influence of man-made products of the metallurgical industry on the properties and structure of gypsum binder are presented. It has been proved that the introduction of man-made modifiers, metallurgical dust, and slag leads to an increase in the strength properties and electric conductivity of the material, but, over time, the waste efficiency decreases. The use of Portland cement as an activator leads to the formation of amorphous hydration products based on calcium hydrosilicates, which bind calcium sulfate crystals and provide an increase in the physicomechanical characteristics and electric behavior of the gypsum composite.

A field experiment was carried out in Kharif 2016 on B-deficient sandy loam soil at College of Agriculture, VC Farm, Mandya to study the effect of graded levels borax (5, 10, 15 and 20 kg ha1) and gypsum (100 and 200 kg ha-1) on yield and soil chemical properties of irrigated finger millet (Eleusine corocana L.) in Southern Dry Zone of Karnataka. A significantly higher grain yield of 45.95 q ha-1 (17.56% higher than the control) and a B:C ratio of 3.06 were also recorded at T12 compared with RDF + FYM (T1). Due to application of borax and gypsum, the pH, EC, and organic carbon content in soil during flowering stage and at crop harvest were non-significant. However, at the flowering and harvest of the crop, the T4 treatment had the lowest pH (7.49 and 7.43, respectively), whereas the T12 (flowering stage) and T10 (after harvest) treatments had the highest pH (7.65 and 7.67, respectively). Higher soil NPK values were detected in all treatments at flowering stage compared to after the crop was harvested. Application of borax 10kg ha-1 + 100 kg gypsum ha-1 along with RDF and FYM had a significantly higher exchangeable calcium content after harvest (6.77 cmol kg-1) than T1 (5.23 cmol kg-1). Sulphur content in soil at flowering stage and after harvest of crop was found to be significant among the treatments due to application of different levels of gypsum. High levels of borax applied treatments, i. e. T5 (T1+20 kg borax ha-1) and T15 (T5 + 200 kg gypsum ha-1) recorded significantly higher content of B at flowering stage (4.18 and 4.09 mg kg-1, respectively) and at harvest of crop (3.88 and 3.68 mg kg-1, respectively) when compared to T1 (1.32 and 1.16 mg kg-1, respectively). Therefore finger millet absorption of boron may be reduced by using borax with a greater dosage of gypsum (200 kg ha-1). As a result, optimising the Ca/B ratio in the soil and plant is critical for increasing irrigated finger millet yields.

Sarissa is one of the most important cities of Hittite Empire in the range of 16th–twelfth century BCE. The city’s importance comes from being the Empire’s summer palace as well as castle formation is seen around the city which gives the Turkish name “Kusakli” means “Surrounded-Belted” in English. Sarissa is said to be destroyed by a fire/incendiary or battle and almost all mudbricks were given fire and their initial structures were deformed. The fired form of these ceramics could not be identified due to different degrees of fired ceramics and their identification may also favor the provenance analysis of the region’s soil structure that is suitable for the production of mudbricks. For the analysis of mudbricks, X-ray fluorescence (XRF) analysis was evaluated first to understand the principal, compound former, and trace oxides to compare with geological soil formation and rock types. By examining XRF, the oxides were characterized for compound formation even for mineral composition. As evaluated, main oxides are SiO2, CaO, Fe2O3, Al2O3, MgO, and K2O; compound former was the volatile SO3 that has the formation possibility of gypsum as Sivas’s most provenance soil type within illite-muscovite type clays. Besides, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX) analysis were briefly evaluated and the firing temperatures were estimated. From SEM images and EDX analysis, a very good match with XRF analysis was found by means of elemental distribution and especially Na amount was approached as glassifier by sintering of materials in the range of 800 and 1200 °C due to the glassification, vitrification, sulfate removal, and low viscosity bubble formation due to glass melting.

The Brazilian gypsum has one of the highest levels of recognized mineral qualities in the world. Companies that operate in this sector support major economy-driving industries such as civil construction, architecture, medicine, and agriculture and are an input for the manufacture of paints, phosphors, and insecticides, among others. Most of the companies that constitute this sector are small and medium-sized enterprises (SMEs), which require supply chain solutions to maintain competition in market share. Supply chain integration as a collaborative solution has become a necessary strategy for enhancing SMEs decision-making capability. This study proposes a conceptual model based on a normative multi-agent system approach that offers a dynamic view about supply chain integration for managers and other stakeholders. From this contribution, it is possible to obtain constant information flow among stakeholders and build an effective strategic context for SMEs in the Brazilian Gypsum Local Productive Arrangement (LPA).

This study presents the unconsolidated undrained (UU) and consolidated undrained (CU) behaviour of a compacted gypsum-rich sandy lean clay with a total soluble salt content of 35% and a gypsum content of 33%. The compaction curve of the soil exhibits a double peak indicating two maximum dry densities and two optimum moisture content (OMC) values for the standard American Association of State Highway and Transportation Officials (Aashto) compaction effort. For triaxial testing, soil specimens were compacted at the wet OMC. UU triaxial tests on both unsoaked and 120 d soaked specimens in fresh water indicate a significant decrease of soil cohesion and angle of internal friction due to long-term soaking. An increase of compaction effort from that of standard Aashto to that of modified Aashto improved both soil strength parameters. CU triaxial tests were carried out on specimens compacted at standard Aashto compaction in a manufactured mould to prepare the triaxial soil specimens. The test results revealed that the stress paths for the tested samples differ markedly from those displaying the behaviour of overconsolidated soils, as discussed in detail in this paper.

Physical, mechanical and some thermal properties of gypsum-wood mixture particleboards were analyzed for specimens which were prepared in different proportions previously conditioned at 23 ˚C and 65% relative humidity. Water absorbtion (WA) and thickness swelling (TS) properties were measured after soaked in water for 24 hours. Furthermore, the increment of wood particle was increased the water absobtion values around 28.5 % and 2.1% thickness swelling values, respectively. However, the reduction of gypsum ratio was negatively effected the mechanical resistance of the boards. The highest MOR, MOE and internal bond (IB) values were observed in the C1 code board with 4.73 MPa, 27.04 MPa and 0.97 N/mm2 respectively. The thermal conductivty of wood-gypsum boards were ranged from 0.7404-0.5021 W/mK. The highest density was found in C1 type board as 1.333 kg/m³ and also the highest thermal coductivity was observed at the same sample. Besides, the highest surface temprature which was passed to opposite side of flame source, was found in C5 as 141.7 oC after 300 seconds. However, the lowest value was observed in C1 type board as 93.3 ˚C after 300 seconds.

To understand the hydration inhibition mechanism of gypsum (CaSO4·2H2O) on tricalcium aluminate (C3A), the very early hydration process of C3A in the presence of CaSO4·2H2O was investigated by Reax...

Gypsum deposits are wide spread in Zurbatiyah area, Eastern of Iraq, especially in Fatha Formation. Gypsum deposits have been known as a suitable materials for gypsum plaster industry. Sawdust and Palm fibers powders have been added in different ratios to gypsum plaster material mixture to improve their industrial properties. Addition of 0 %,1 %, 5%, 10% and 15 % pass of 4.75 mm size of sawdust and palm fibers powder and 0 %, 1 %, 5%, 10% and 15 % pass of 5.60 mm size of sawdust and palm fibers powder to gypsum plaster material mixture. This ratios showed results of consistency (35-75 ml/gm), setting time (11-20 min) and compressive strength (2.2-4.4 N/mm2) for sawdust powders size 4.75 mm, whereas the results of consistency (35-63 ml/gm),setting time (11-21 min) and compressive strength (2.0-4.2 N/mm2) for palm fibers powders size pass of 4.75 mm. The addition of 1% and 5% pass of 4.75 mm sawdust and palm fibers powder to gypsum plaster material mixture showed an improvements in consistency(37-41ml/gm), (36-40ml/gm) setting time (13-14 min), (12-13 min) and compressive strength (4.2-4.4 N/mm2), and (4.1-4.2 N/mm2) for sawdust and palm fibers respectively. Also the addition of 1 % and 5 % pass of 5.60 mm sawdust and palm fibers powder showed consistency (40-45 ml/gm), (39-44 ml/gm), (14-15 min.), (12-13min.), (3.5-4.2 N/mm2), and (3.0-4.1 N/mm2), for sawdust and palm fibers respectively. In general, the results of current study conform the requirements of the Iraqi standard specification No. 28 (1988) and ASTM C28, C472 (2010) for ordinary gypsum plaster industry.

This study provides an overview of calcium rich industrial wastes usage in construction materials, their properties and different applications through marble waste and flue gas desulfurization (FGD) gypsum. Large quantities of industrial wastes are stockpiled and haphazardly disposed in increasing amounts causing serious environmental concerns. The extensive use of marble and gypsum products is increasing in construction industry and limited amount of natural sources are available, which requires alternative sources of calcium-rich raw materials. The aim of this study is to explore the recycling opportunities for calcium-rich industrial wastes which have good technical properties and can be used as raw materials for civil infrastructure. Utilization of these industrial wastes, leads to increase economical efficiency and it takes a positive step towards the conservation of natural materials, resource recovery and protecting the environment. The findings of the previous work done by different researchers affirm the need of further detailed scientific research for the effective utilization of marble waste and FGD gypsum. As per the present study, approximately 22 million tons of marble waste and 20 million tons of FGD gypsum are expected to be generated by the year 2040 in India. The results of physico-chemical analysis indicated that marble waste and FGD gypsum has potential as raw material for civil infrastructure. This research review focuses on the transformation of marble waste and FGD gypsum towards sustainable production of construction materials, work done so far, current best practices of its utilization and future possibilities.