U nless you hang drywall or travel in certain biogeochemical circles, the calcium sulfate mineral gypsum is probably not on your radar—nor is the amount of sulfate (SO4 2 ) dissolved in seawater, which determines how much gypsum is left behind when that seawater evaporates. All the same, sulfate is the second most abundant negatively charged ion dissolved in seawater today, and tracking its cha...

Gypsum Plaster is an important building materials, and because of the availabilty its raw materials. In this research effect various additives on properties plaster was studied , like Polyvinyl Acetate, Furfural, Fumed Silica at different rate addition two types fibers, Carbon Fiber Polypropylene to a volumetric rate. It found that after analysis results use Furfural as additive by 2.5% optimum...

This study includes the effect of lime addition on engineering properties gypseous soil taken from a part Najaf- Karbla plateau (52, 48, 72% gypsum). Also this shows increase in proportion gypsum northwest direction area. Maximum dry density and optimum moisture content (2.065, 2.025 2.003) at 15%, 14% 15% respectively for three samples. The maximum decrease while increases with increasing rati...

Constructed wetlands are increasingly used for water pollution treatment but may also be sources of the greenhouse gas CH(4). The effect of addition of two potential inhibitors of methanogenesis - iron ochre and gypsum - on net CH(4) emissions was investigated in a constructed wetland treating farm runoff in Scotland, UK. CH(4) fluxes from three 15-m(2) wetland plots were measured between Janua...

Fly ashes and gypsum are one of the main wastes produced in coal-fired power stations which may be sent to landfills for their disposal. In this work, leaching and speciation of mercury in fly ashes and gypsum from a modern co-combustion power plant equipped with a selective catalytic reduction (SCR) unit in the Netherlands were studied. The mercury leachable contents were checked against diffe...

This article focuses on the hydration, and associated microstructure development, of b-hemihydrate to dihydrate (gypsum). The sound velocity is used to quantify the composition of the fresh slurry as well as the hardening and hardened—porous—material. Furthermore, an overview of available hydration kinetic and volumetric models for gypsum is addressed. The presented models predict the sound vel...

We recently showed that the production of elemental sulphur and calcium carbonate (CaCO3) from gypsum waste by thermally reducing the waste into calcium sulphide (CaS) followed by its direct aqueous carbonation yielded low-grade carbonate products (i.e. <90 mass% as CaCO3). In this study, we used the insight gained from our previous work and developed an indirect aqueous CaS carbonation process...

The impacts of temperature on the surface thermal damage of rock salt, gypsum and mudstone from the Yingcheng salt mine, China were investigated by the surface crack growth and propagation tests at different temperatures. We found that: (a) high temperature could strengthen the rock salt molecular thermal motion and weaken the cohesion among the rock salt grains, so that the grain boundaries we...

AIM To compare and evaluate few physical properties of epoxy resin, resin-modified gypsum and conventional type-IV gypsum die material. MATERIALS AND METHODS In the present study, dimensional accuracy, surface detail reproduction and transverse strength of three die materials like epoxy resin (Diemet-E), resin-modified gypsum (Synarock) and conventional type-IV gypsum (Ultrarock) are analyzed...

This paper shows the microstructural differences and phase characterization of pure phases and hydrated products of the cubic and orthorhombic (Na-doped) polymorphs of tricalcium aluminate (C₃A), which are commonly found in traditional Portland cements. Pure, anhydrous samples were characterized using scanning transmission X-ray microscopy (STXM), X-ray photoelectron spectroscopy (XPS) and X-ra...