Effect of seawater as mixing water on the hydration behaviour of tricalcium aluminate

2021 ◽  
Vol 149 ◽  
pp. 106565
Author(s):  
Yamei Cai ◽  
Dongxing Xuan ◽  
Pengkun Hou ◽  
Jie Shi ◽  
Chi Sun Poon
Keyword(s):  
Hydration Behaviour ◽  
Tricalcium Aluminate ◽  
Mixing Water

Impact of aging on the hydration of tricalcium aluminate (C3A)/gypsum blends and the effectiveness of retarding admixtures

2020 ◽  
Vol 75 (8) ◽  
pp. 739-753
Author(s):  
Florian Andreas Hartmann ◽  
Johann Plank
Keyword(s):  
Crystal Growth ◽  
Relative Humidity ◽  
Binary Mixtures ◽  
Calcium Ions ◽  
Hydration Reaction ◽  
Sodium Gluconate ◽  
Tricalcium Aluminate ◽  
Seeding Effect ◽  
Reaction Potential ◽  
Mixing Water

AbstractIn the production of concrete from cement powder and water, setting behavior of the slurry is determined by the formation of ettringite (Ca6Al2(OH)12 · (SO4)3 · 26 H2O) from tricalcium aluminate (Ca9Al6O18, abbreviated C3A) and gypsum (CaSO4 · 2 H2O). Due to the high reaction potential of cement and water, premature hydration can occur after unintentional exposure to moisture. Model binary mixtures of C3A and gypsum stored at 90% relative humidity and 35 °C produced ample amounts of ettringite, which subsequently reacted with atmospheric CO2 to CaCO3, Al(OH)3 and gypsum. Investigated were the two main polymorphs of tricalcium aluminate encountered in cement, pure, cubic C3A and orthorhombic C3A in which calcium is partially substituted by sodium or potassium. Alkali substituted C3A converted to ettringite faster and more completely than pure C3A. Ettringite from prehydration caused a seeding effect, which promotes crystal growth and accelerates bulk hydration of the C3A/gypsum mixtures. Set retarders commonly applied in cement were dissolved in the mixing water prior to hydration to investigate their ability to counteract this acceleration. Sodium gluconate merely delayed the crystal growth but does not prolong the hydration process overall. Potassium pyrophosphate retarded much more effectively by suppressing the seeding effect via removal of calcium ions from the hydration reaction.

Influence of chemical composition of mixing water on the gelation of inorganic polymer technology for improved oil recovery

2017 ◽  
Vol 3 (3) ◽  
pp. 33-38 ◽  
Author(s):  
А.V. Аntuseva ◽  
Е.F. Kudina ◽  
G.G. Pechersky ◽  
Y.R. Kuskildina ◽  
А.V., Melgui ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Oil Recovery ◽  
Inorganic Polymer ◽  
Improved Oil Recovery ◽  
Mixing Water

Corrosion of Rebar in Concrete Using Seawater as Mixing Water

2019 ◽  
Vol 68 (10) ◽  
pp. 284-287
Author(s):  
Toru Yamaji ◽  
Matsuho Miyasaka ◽  
Adel Husain
Keyword(s):  
Mixing Water

scholarly journals The use of mathematical modelling to analyse the process of mixing waters from different sources in water supply system

2018 ◽  
Vol 59 ◽  
pp. 00025
Author(s):  
Agnieszka Szuster – Janiaczyk ◽  
Rafał Brodziak ◽  
Jędrzej Bylka
Keyword(s):  
Mathematical Modeling ◽  
Water Quality ◽  
Quality Criteria ◽  
Supply System ◽  
Network Control ◽  
Quality Of Water ◽  
Water Mains ◽  
Different Sources ◽  
Mixing Water

One of the processes that significantly determines the quality of water to consumers is the process of mixing water from different sources in the water mains. Put to the network two or more chemically and biologically stable waters may result in the formation of water that will be deprived of these features. This article presents the german guidelines for analysing water quality for mixing waters from different sources, in various proportions. Then performed an analysis of utility the mathematical models,including quality criteria, for use in network control. An IT tool has been developed to manage selected water quality processes using mathematical modeling. The basis for implementing the tool was a network model created in Epanet integrated with the Matlab.

Investigation on a New Hydraulic Cementitious Binder Made from Phosphogypsum

2013 ◽  
Vol 864-867 ◽  
pp. 1923-1928
Author(s):  
Yue Xu ◽  
Jian Xi Li ◽  
Li Li Kan
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Active Carbon ◽  
High Strength ◽  
Tricalcium Silicate ◽  
Dicalcium Silicate ◽  
Cementitious Material ◽  
Saturation Ratio ◽  
Tricalcium Aluminate ◽  
Cementitious Binder

A new kind of high strength cementitious material is made from phosphogypsum (PG), active carbon and fly-ash. Through the orthogonal research, it was showed that the calcination temperature, retention time, dosage of active carbon and fly ash on the compressive strength of cementitious binder are the most important. The result also showed that, in the conditions of temperature 1200°C, time retention 30 min, dosage of active carbon 10%, dosage of fly ash 5%, the compressive strength of the cementitious material for 3d and 28d could reach to 46.35MPa and 92.70MPa, the content of sulfur trioxide was 11.60% accordingly. A lot of active mineral materials, such as dicalcium silicate, tricalcium silicate, tricalcium aluminate were formed in the calcination. The C-S-H gel, calcium hydroxide and ettringite were found in 3d and 28d hydrates. It is found that the lime saturation ratio and silica modulus need to be control between 0.40~0.65 and 4~8 in order to produce high strength cementitious material.

scholarly journals Effect of Aluminum Sulfate on the Hydration of Tricalcium Aluminate

2021 ◽  
Vol 719 (2) ◽  
pp. 022079
Author(s):  
Xiuyan Jing ◽  
Yan Zhang ◽  
Huaqing Liu ◽  
Jialong Liu ◽  
Sen Kong
Keyword(s):  
Aluminum Sulfate ◽  
Tricalcium Aluminate

scholarly journals Effect of a Nitrite/Nitrate-Based Accelerator on the Strength Development and Hydrate Formation in Cold-Weather Cementitious Materials

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1006
Author(s):  
Akira Yoneyama ◽  
Heesup Choi ◽  
Masumi Inoue ◽  
Jihoon Kim ◽  
Myungkwan Lim ◽  
...  
Keyword(s):  
Calcium Nitrate ◽  
Hydrate Formation ◽  
Frost Damage ◽  
Cementitious Materials ◽  
Heat Of Hydration ◽  
Cold Weather ◽  
Strength Development ◽  
Hardened Cement ◽  
Tricalcium Aluminate ◽  
Nitrite Nitrate

Recently, there has been increased use of calcium-nitrite and calcium-nitrate as the main components of chloride- and alkali-free anti-freezing agents to promote concrete hydration in cold weather concreting. As the amount of nitrite/nitrate-based accelerators increases, the hydration of tricalcium aluminate (C3A phase) and tricalcium silicate (C3S phase) in cement is accelerated, thereby improving the early strength of cement and effectively preventing initial frost damage. Nitrite/nitrate-based accelerators are used in larger amounts than usual in low temperature areas below −10 °C. However, the correlation between the hydration process and strength development in concrete containing considerable nitrite/nitrate-based accelerators remains to be clearly identified. In this study, the hydrate composition (via X-ray diffraction and nuclear magnetic resonance), pore structures (via mercury intrusion porosimetry), and crystal form (via scanning electron microscopy) were determined, and investigations were performed to elucidate the effect of nitrite/nitrate-based accelerators on the initial strength development and hydrate formation of cement. Nitrite/nitrate-AFm (aluminate-ferret-monosulfate; AFm) was produced in addition to ettringite at the initial stage of hydration of cement by adding a nitrite/nitrate-based accelerator. The amount of the hydrates was attributed to an increase in the absolute amounts of NO2− and NO3− ions reacting with Al2O3 in the tricalcium aluminate (C3A phase). Further, by effectively filling the pores, it greatly contributed to the enhancement of the strength of the hardened cement product, and the degree of the contribution tended to increase with the amount of addition. On the other hand, in addition to the occurrence of cracks due to the release of a large amount of heat of hydration, the amount of expansion and contraction may increase, and it is considered necessary to adjust the amount used for each concrete work.

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