During the hydration of cement, tricalcium aluminate (C3A) reacts with gypsum and forms ettringite (AFt). Once all gypsum is consumed, ettringite can further react with remaining C3A and form monosulfate (AFm) at 1–2 days. Normally, at early ages, ettringite all transfers to AFm phase. After several months or years, ettringite can form again if a new source of sulfate becomes available in the p...

Microbes in Haughton Crater Sulfates: Impact craters are of high interest in planetary exploration because they are viewed as possible sites for evidence of life [1]. Hydrothermal systems in craters are particularly regarded as sites where primitive life could evolve. Evidence from the Miocene Haughton impact structure shows that crater hydrothermal deposits may also be a preferred site for sub...

The power of the state-of-the-art neutron powder diffractometer suite at the Institut Laue–Langevin for investigating the structure of nondeuterated materials is presented using gypsum, CaSO4 2H2O, as a reference material. It is shown that flexible modern neutron powder diffraction instruments at reactorbased sources can yield data with sufficient counting statistics above the incoherent scatte...

ABSTRACT: Extreme swelling pressures (in excess of 5 MPa) were measured against the invert of a tunnel excavated by drill and blast method in a hard claystone containing variable proportions of anhydrite and gypsum dispersed in the clay matrix. When the invert was not present, floor heave reached displacements in excess of 60 cm in some cross sections. Displacements and pressures developed at a...

With the rapid development of economic, gypsum is widely used in casting and other industry areas. In this paper, the result is obtained that the performance of plaster mold is better when gypsum-water ratio is 0.5. If the composition of gypsum slurry mixture ( -hemihydrate, mullite powder, zirconium powder, reinforcing fibers) is mullite powder: zircon flour: enhancing fiber = 1:0.25:0.2:0.02-...

Revised version 29 November 2006 Abstract— We have performed holographic interferometry measurements of the dissolution of the (010) plane of a cleaved gypsum single crystal in pure water. These experiments have provided the value of the dissolution rate constant k of gypsum in water and the value of the interdiffusion coefficient D of its aqueous species in water. D is 1.0×10−9 m s, a value cl...

Gypsum soils are among the most restrictive and widespread substrates for plant life. Plants living on gypsum are classified as gypsophiles (exclusive to gypsum) and gypsovags (non-exclusive to gypsum). The former have been separated into wide and narrow gypsophiles, each with a putative different ecological strategy. Mechanisms displayed by gypsum plants to compete and survive on gypsum are st...

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...

BACKGROUND AND AIMS Plants from gypsum habitats are classified as gypsophiles and gypsovags. The former include both narrow endemics limited to small gypsum areas and regionally dominant gypsophiles growing in gypsum areas of large regions, whereas gypsovags are plants that can grow both in gypsum and non-gypsum soils. Factors controlling the distribution of gypsum plants are still not fully un...