the second stage of the hydration reaction can be shortened by adding gypsum

The effect of gypsum on the hydration of alite–belite

gypsum can affect the hydration products and hydration rate of mineral, such as alite, C 3A and ferrite phase [3–10]. The chemical reaction between C 3A and different amounts of gypsum is of great relevance as it affects the early hydration products. According to the calorimetric curves obtained for the different gypsum additions, mechanism

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 ...

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 .

Gypsum hydration: A theoretical and experimental …

Ultrasonic results indicate gypsum hydration reaction consists of two stages: the dissolution of hemihydrate in the first st age …

Formation of α-Hemihydrate Inside of a Gypsum Crystal …

Gypsum (calcium sulfate dihydrate) is one of the most used inorganic binding materials in the world. During calcination, calcium sulfate subhydrates are formed and, for technical reasons, are mixed with water to form dihydrate again. Therefore, the dehydration process of gypsum and the rehydration of hemihydrate were investigated. This …

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 …

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.

(PDF) The effect of gypsum on the hydration of …

After the induction period, the behavior changes and gypsum enhance the C 3 S hydration [6,8,18,19,[51][52][53][54][55] [56] [57]; see Fig. 4. Yamashita et al. [58] have observed that increasing ...

Interactions Between Alite and C3A-Gypsum Hydrations in Model Cements

The second stage corresponds to the induction period, followed by the acceleration period corresponding to the alite peak (Figure 5a), which occurs at 4-4.5 h for all LC 3 systems, with higher ...

Investigations on the early hydration properties of …

Hydration of blended cement pastes with two types of freshly synthesized β-phase belites (β-C2S and β-Ca2SiO4), which leads to low-hydration cement, is analyzed by using thermal technique, namely isothermal conduction calorimetry. The reaction kinetics at early ages (up to 24 h) are studied for neat and belite blended cement pastes …

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 …

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 ...

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 ); …

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.

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 …

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 ...

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 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.

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 …

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

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 …

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 ...

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 …

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).

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 …

Investigation on the hydration and strength properties of …

Interestingly, the cumulative heat results of samples with 5–15% gypsum additive were similar after the early-stage hydration (72 h) (Table 2). This confirms that the reduced content of the clinker can be compensated by adding gypsum to maintain the same reaction degree of hydration or even slightly increase.

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 …

The effect of gypsum on the hydration of alite–belite–ferrite …

These heat evolution results show that the addition of gypsum could shorten the induction period and promote to a higher hydration rate in the acceleration …

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 …