Gypsum hydration: a theoretical and experimental study
This article addresses the hydration of hemihydrate since it determines the properties of gypsum and it is influenced strongly by water and the properties of hemihydrate. …
Hydration and mechanical properties of FGD gypsum
1. Introduction. Flue gas desulfurization (FGD) gypsum is an industrial by-products, which primarily consists of dihydrate gypsum (CaSO 4 ⋅2H 2 O),and the treatment of 1 t of SO 2 in coal flue gas by limestone-gypsum wet desulfurization technology will produce about 2.7 t of FGD gypsum, and China emitted nearly 100 million t of FGD gypsum by 2020 [1].At …
Dehydration Pathways of Gypsum and the …
In this work, the dehydration pathways of gypsum and the rehydration mechanism of soluble anhydrite were mainly investigated by thermodynamic modeling and MC simulations. The dehydration pathways of …
Gypsum as a Building Material
Hydration of building gypsum technically requires that water requirements accounts for 18.6% of the weight of semi-hydrate gypsum. But in fact, water often accounts for 60%-80% in order to make the gypsum slurry have certain plasticity. ... Excess water gradually evaporates in the hardening process, which leads to a large number of pores left ...
(PDF) Effect of Using Sugar and Gypsum as a Retarder on …
The study was carried out to evaluate the suitability of organic admixture in concrete production. Six sets of concrete were made by partially replacing the fine aggregates (sand) and coarse ...
Drying time of plaster within in-fill plasterboard walls and
The experimental results show that the drying of gypsum is correlated with relative humidity and gypsum thickness: the higher the relative humidity, the lower the evaporation …
Highly efficient modified phosphogypsum building gypsum …
The high efficiency modified phosphogypsum process is a dehydration reaction process of gypsum dihydrate, which only generates water vapour, and there is no generation of the remaining greenhouse gases, so only energy consumption is considered when the process is analysed for its carbon footprint. ... The flexural strength reached 2.4 MPa ...
Comparative Analysis of Hydration Expansion Performance …
1 National Key Laboratory of Solid Waste Resource Utilization and Energy-saving Building Materials, Beijing Building Materials ... Gypsum has micro-expansion characteristic during the process of hydration and solidification, and there are certain differences in the hydration expansion characteristics of different types of hemihydrate gypsum ...
Enhancing the hydration and micromechanical properties of C3A-gypsum
This study investigates the influence of tannic acid (TA), a natural plant-based biomolecule, on the hydration of tricalcium aluminate (C 3 A)-gypsum systems, aiming to elucidate its potential as a novel concrete strength enhancer. To this end, detailed investigations were conducted into the hydration and nano-mechanical properties of C 3 A-gypsum system …
Improving the early-age properties of eco-binder with high …
The long setting times and low early-age mechanical properties resulting from the insufficient hydration products (especially ettringite at early age), limited the application of an eco-binder with minor clinker and without calcination, in which phosphogypsum was intensively reused (45 wt%) as raw material. The external addition of aluminate phase was proposed to …
US10815152B2
US10815152B2 US16/308,119 US201716308119A US10815152B2 US 10815152 B2 US10815152 B2 US 10815152B2 US 201716308119 A US201716308119 A US 201716308119A US 10815152 B2 US10815152 B2
Effect of gypsum on low-heat Portland cement early …
Alkanolamines are commonly used complexing agents in the cement industry. Due to its surface activation effect on cement clinker particles, it is commonly used as cement grinding aids [44], [45].When used as chemical admixtures, it can accelerate the early hydration process of cement by complexing with metal ions [46], [47].Among them, triisopropanolamine (TIPA), diethanol …
The influence of hydration and swelling properties of gypsum …
The composition of FGD gypsum is similar to natural gypsum and it is easy to obtain high purity. A hydration – re-crystallization process for preparing non-fired bricks involves hot-drying at 180 °C to dehydrate gypsum into semi-hydrated gypsum (CaSO 4 ·1/2 H 2 O) [22]. The industrial application of this method could help to significantly ...
Hydration reaction and microstructural characteristics of …
The hydration of hemihydrate phosphogypsum in the alkaline environment was investigated aiming to recycle phosphogypsum-a promising gypsum resource in gypsum …
Investigation of hydration mechanisms of alpha and beta …
The gypsum stone which was created from the hydration process out of α-HH is characterized by its higher compressive strength and slower reaction. 1 Introduction Calcium sulfate hemihydrate [CaCO 4 ∙ 0.5H 2 O(s)] can be found naturally in very dry climate regions in Egypt, Australia, Death valley and Kuwait as bassanite, but in the presence ...
Highly efficient modified phosphogypsum building gypsum …
The high efficiency modified phosphogypsum process is a dehydration reaction process of gypsum dihydrate, which only generates water vapour, and there is no generation …
Effect of citric acid on the process of hydration of building gypsum
The effect of compound retardant powder P on the hydration process, ion concentration in liquid and supersaturation degree, and crystal morphology of dehydrate of FGD building gypsum is investigated.
Study on retarding feature and retardation mechanism of …
Extremely rapid setting time of building gypsum severely limits its further processing and application. Gypsum retardation is an indispensable technology that provides a long period of plasticity for gypsum construction. Developing highly efficient gypsum retarders is of great significance for improving gypsum retardation technology. Many progressive …
Study on the Retarding Mechanism and Strength Loss of …
retarders, and this could make it an ideal building gypsum retarder. As shown in Fig. 4, the hydration exothermic process of building gypsum can be divided into three stages. Gypsum releases the heat of solution in the first stage when it comes into contact with water; the hydration heat began to increase slowly in this early stage. The second ...
Study on the Effect of Three Types of Calcium Sulfate on the …
The hydration process was slowed down by the addition of anhydrite and dihydrate gypsum. The addition of calcium sulfate led to a denser microstructure and decreased porosity in SCRM because anhydrite calcium sulfoaluminate had been more thoroughly hydrated.
A novel gypsum-based self-leveling mortar produced by …
At present, building gypsum resulted from natural gypsum has been more widely applied in construction fields, ... more S hydrates during the first 30 min of the hydration process of the sample so that the 30-min slump loss is the maximum, and OG, UA and UB replace S, causing less S hydrate during the first 30 min of the hydration process of the ...
[PDF] Microstructure and mechanical properties of β …
Semantic Scholar extracted view of "Microstructure and mechanical properties of β-hemihydrate produced gypsum: an insight from its hydration process" by Q. Yu et al. ... (CaSO4·2H2O or gypsum) is used widely as building material because of its excellent fire resistance, aesthetics, and low price. Hemihydrate occurs in two formations of α-…
Associated Effects of Sodium Chloride and Dihydrate Gypsum …
The results indicate that (1) when dihydrate gypsum is used alone, it combines with calcium aluminate hydrate (C-A-H) to form calcium sulfoaluminate hydrate (AFt), which encourages the hydration ...
Moisture transport, condensation and dehydration …
The one step process under open conditions is replaced by a two step dehydration under closed conditions, with a mass loss ratio of 3:1. (right) Measured NMR signal of dry gypsum during slow dehydration.
Gypsum dehydration process
The clinker formation process is initiated by the dehydration of gypsum to anhydrite at around 100-120°C, followed by a decomposition of clay minerals at around 300-600°C. The decaibonization of the calcium carbonate that is present starts at about 700°C, and is completed before the temperature reaches 900°C.
Improving the early-age properties of eco-binder with high …
Phosphogypsum (PG) is the major by-product in wet-production process of phosphoric acid, and its recycle and reuse efficiency is quite low and most is landfilled, stacked or discarded [6].The main chemical component in PG is gypsum (CaSO 4 ·2H 2 O) and a minor amount of impurities (e.g., fluorine, phosphorus, etc.), which has the potential to leach out and …
Construction and Building Materials
In order to track the hydration process in real time, the actual gypsum to water ratio was expanded to 20. The sample was prepared by 10.0 g α-HH, 200.0 g water, and 0.001 g PASP. In order to record the electrical conductivity change at the hydration process of α-HH, the electrical conductivity was measured manually.
Gypsum | PPT
Gypsum - Download as a PDF or view online for free. 6. Gypsum is a rock like mineral commonly found in the earth's crust, extracted, processed and used by Man in construction or decoration in the form of plaster and alabaster since 9000 B.C.. Plaster was discovered in Catal-Huyuk in Asia in an underground fr, and in Israel Gypsum floor …
Effect of GO nanosheets on shapes of cement hydration …
The results suggest that the GO nanosheets can promote to produce bar-like crystals from cement hydration reaction process, and control the shape of hydration crystals, leading to the formation of flower-like or dense polyhedral crystals that are not present in paste without GO nanosheets. ... C 4 AF and gypsum are involved in complex hydration ...
Optimization of strength and microstructural properties of building
1. Introduction. Hemihydrate gypsum is a typical air-hardening binder. The production of hemihydrate depends on thermal decomposition of calcium sulfate dihydrate, and the application of hemihydrate is based on the in-turn process from hemihydrate to calcium sulfate dihydrate [1], [2], so gypsum is acknowledged as a green sustainable …