Simulation of the exothermic hydration process …

The hydration reaction of each major mineral compound found in Portland cement, C3S, C2S, C3A and C4AF, is considered. ... the curing temperature increasing from 5 °C to 30 °C is helpful to ...

Study of the hydration of Portland cement blended with …

The hydration of the cement minerals C 3 S (3CaO·SiO 2), C 2 S (2CaO·SiO 2), C 3 A (3CaO·Al 2 O 3) and C 4 AF (4CaO·Al 2 O 3 ·Fe 2 O 3) is an exothermal chemical process.At early ages, the generated heat can be monitored by isothermal (conduction) calorimetry and five stages can be distinguished, as mentioned …

Hydration of C3A–gypsum systems

Hydration of C 3 A–gypsum systems with different gypsum additions was investigated in terms of the phase assemblage, kinetics and microstructural …

Mechanisms and Parameters Controlling the Tricalcium Aluminate

Generally, the temporal evolution of C 3 A hydration in the presence of gypsum can be divided into three main stages. Stage 1 is the initial rapid reaction and subsequent slow reaction; Stage 2 is ...

Interaction of silicate and aluminate reaction in a synthetic …

The addition of gypsum also enhances the reaction of C3S independently of the interaction with the aluminates. ... and Na2SO4 addition on the early‐stage hydration kinetics are investigated for ...

Influence of free calcium sulfate levels on the early hydration …

All samples were equilibrated at 20 °C for a 12-h period prior to adding water and mixing. ... These findings suggest that anhydrite facilitates the hydration heat release during the second and third hydration stages of BSA clinkers more effectively than gypsum, which appears to delay the second stage while only promoting the third stage ...

New insights into the effect of gypsum on hydration and …

The primary function of gypsum is to control the reaction of tricalcium aluminate (C 3 A) [11]. Without adding gypsum, the direct reaction of C 3 A with water …

A quantitative study of the C3A hydration

The reaction of C 3 A in the presence of gypsum can be divided into three stages, as depicted in Fig. 1 by the rate of heat evolution as function of hydration time. Stage 1 corresponds to the reaction between C 3 A and gypsum and in calorimetric measurements, it results in an initial dissolution peak followed by a stage of low heat …

Dehydration Pathways of Gypsum and the Rehydration …

In the high-temperature and low water vapor pressure region, gypsum dehydrates to form γ-CaSO 4 in a single-step process (CaSO 4 ·2H 2 O → γ-CaSO 4 ); …

New insights into the effect of gypsum on hydration and …

The second stage is propelled by the strengthening of CSH bridges, while the third stage involves reinforced CSH bridges and increased particle packing. It should …

Soil stabilization with gypsum: A review

In addition to the cation exchange, the formation of cementitious hydration products such as (CSH) and (CAH) has also been reported in gypsum-treated clays (Latifi et al., 2018; Zha et al., 2021).The CSH and CAH can be produced through the pozzolanic reaction if the calcium from gypsum reacts with soluble alumina and silica from clay in …

Effects of various gypsum on early-age hydration behavior …

It can be seen that gypsum does not participate in the hydration reaction in the early-ages and reduces the content of hydration products, which obviously inhibits the reaction progress of MOCP. On the other hand, for gypsum-modified MOCP, the main reason for its strength reduction is the reduction in hydration product (5-phase).

Influence of cellulose ethers chemistry and

In this stage, reactions including Eq. (1), Eq. (3) and Eq. (4) may take place. It may also include the transformation of AFt that is achieved from early stage hydration to AFm as in Eq. (6) [10]. This stage is highly correlated with the setting and hardening of CSA cement [5]. The heat flow slows down thereafter after 150 min.

The influence of low temperature rise polymer on early cement hydration

Fig. 1 displays the concrete samples' evolution rate and cumulative heat of hydration over the first 10 days of ageing. Fig. 1 illustrates how each sample's hydration heat may be broken down into five stages: diffusion, induction, acceleration, deceleration, and dissolution. These findings are in line with earlier studies' findings [31], [32].The cement …

A quantitative study of the C3A hydration | Request PDF

In the presence of calcium sulfates, a rapid reaction of C 3 A, C$, and H 2 O to ettringite as the only stable hydration product during this stage of C 3 A hydration occurs initially [19, 29 ...

Effects of Fluorogypsum and Flue-Gas Desulfurization Gypsum …

The second endothermic peak appeared at about 450 °C, which was formed by the loss of combined water by Ca(OH) 2 crystals. With the increase in the content of FG, the rate of the loss of mass of the paste at 110 °C gradually increased. ... The activation of waste gypsum and the hydration reaction process in cement-based …

Effect of Gypsum on Hydration and Hardening Properties of …

The effects of different dosages of gypsum on the hydration and hardening properties of AMCSA, such as setting time, hydration rate, compressive strength and hydration products, were studied. The results show that the mineral content of ye'elimite, C 2 S, C 3 S and iron phase in the calcined AMCSA clinker are 48.5 wt.%, 32.6 wt.%, 11.7 …

Advances of alkanolamine in hydration of Portland cement

C 3 A is the fastest hydrated mineral in ordinary Portland cement. Fig. 2 shows the hydration heat of Portland cement slurry with and without alkanolamine. It can be seen that in the first few minutes, alkanolamine accelerated the hydration of C 3 A (peak 1). Yaphary et al. [37] attributed the enhanced hydration of C 3 A to the chelation …

The setting of gypsum plaster

H 2 O) has two water molecules, it allows the soil to absorb water without altering the soil's chemical composition. However, owing to a change in its chemical composition, gypsum will turn into a ...

Influence of Polycarboxylate Superplasticizers with Different

It was seen that PCs mainly shortened the induction stage of C₃A-gypsum hydration, and the amount of remaining gypsum was related to the duration of the induction stage. The second heat flow peak of the sample with PCs was higher than that of the blank. Moreover, PC intercalation occurred during the hydration.

Preparation of high-performance building gypsum by calcining FGD gypsum

The XRD patterns of FGD gypsum with different CaO addition calcined at 140 °C and 200 °C are respectively presented in Fig. 2 (a) and (b). It can be seen from Fig. 2 that the patterns containing CaO addition are very similar, and their main diffraction peaks can be attributed to orthorhombic bassanite (CaSO 4 ·0.5H 2 O, JCPDS: 33-0310), …

Hydration of C3A–gypsum systems

Hydration of C 3 A–gypsum systems with different gypsum additions was investigated in terms of the phase assemblage, kinetics and microstructural development. The second stage of the reaction, which begins after the depletion of gypsum, was of particular interest. From in-situ X-ray diffraction results, it was seen that the dissolution …

Materials | Free Full-Text | Influence of Polycarboxylate

Influence of polycarboxylate superplasticizers (PCs) with different functional units on the hydration heat and hydration products of C3A-gypsum was investigated. Three kinds of PCs with different monomers were discussed. It was seen that PCs mainly shortened the induction stage of C3A-gypsum hydration, and the amount of …

Early C3A hydration in the presence of different kinds of …

Hydration reactions of C 3 A with various amounts of calcium sulfate hemihydrate, gypsum or a mixture of the two, were investigated by isothermal microcalorimetry, and a monitoring of the ionic concentrations of diluted suspensions. This study shows that sulfate type used modifies the early C 3 A–CaSO 4 hydration …

Effect of curing temperature on the reaction kinetics of …

The reaction time of each stage was shortened at elevated curing temperatures, thereby increasing the compressive strength of the material more quickly. ... Through the analysis of properties, SS contains dicalcium silicate (C 2 S) and tricalcium silicate (C 3 S) that can undergo hydration reaction, which makes it have a certain self …

Role of Gypsum in Cement and its Effects – …

The mixture then sent to final grinding process. For ordinary Portland cement it remains between 3 to 4% and in case of Quick setting cement it can be reduced up to 2.5%. Role of Gypsum in Cement The main purpose of adding gypsum in the cement is to slow down the hydration process of cement once it is mixed with water.

Hydration kinetics of a calcination activated bauxite tailings-lime

Section snippets Kinetics model for hydration. To study the hydration kinetics of a calcination activated tailings-lime-gypsum ternary system, the hydration kinetics equation, which was used in the study related to the hydration reaction of the pozzolanic reaction of metakaolin [22],can be borrowed, as shown in Eq.

Enhancing the hydration and micromechanical properties of C3A-gypsum

2.2. Characterization methods2.2.1. Hydration heat. A TAM IV isothermal micro-calorimeter was used to measure the hydration kinetics of C 3 A with setting at a constant temperature of 20 ± 0.1 °C. A water/C 3 A ratio of 3 was adopted for this study. The deionized water or 0.5 % TA solution was mixed within the ampule for 1 min, following by sealed and then …

Dehydration Pathways of Gypsum and the Rehydration …

Their experimental results reveal that gypsum dehydration proceeds through only a single CaSO 4 ·2H 2 O → γ-CaSO 4 step when the ambient water vapor pressure …

Stages of Hydration

Heat and rate of hydration are often reduced, and the duration of hydration is extended. • Cold weather construction may increase these effects. In mixtures using PLC, note the following: • Setting time may slightly increase. • The heat of hydration may be higher in the early stages of hydration but equal or lower at later stages of ...

The role of sulfate ions in tricalcium aluminate hydration: New

It corresponds to the reaction between C3A and gypsum, yielding a pour crystalline AFm-phase that coats the C3A particles that are quickly masked by needle-like ettringite precipitates (Geng et al ...

Gypsum hydration: a theoretical and experimental study

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Understanding gypsum in 3 diagrams

WEBLearn how gypsum, hemihydrate and anhydrite react with water and change their crystal structure and solubility. See thermal analysis, dilatometry and …

Insight into the role of early C3A hydration in structural …

(a) First stage (green) and second stage (blue) of structural build-up of C 3 A-10%G paste (the division of two stages is rough), (b) Evolution of static yield stress of C 3 A-gypsum-CaCO 3 pastes (solid lines) and fitting result of the Roussel's linear model (dash lines), (c) Comparison of storage modulus evolution between CaCO 3 in water ...

The hydration kinetics of cement pastes with …

In the acceleration stage, the first exothermic peak is primarily C 3 S hydration and the appearance of the second peak may be due to that the C 3 A continues to react with the ettringite to form monosulphoaluminate (AFm) after the gypsum is consumed in the hydration reaction system .

Hydration Reaction

This indicates that the water released slowly by the biochar makes the hydration reaction more complete. The pre-soaked saturated biochar mortar has less water evaporation …

Dual role of gypsum: Set retarder and strength accelerator …

Gypsum plays a crucial role in cement. Though it is used in a small quantity, in the range of 2.5-3.0 percent in terms of SO3, gypsum's role in cement is significant, more predominantly at early ages.