A discussion of the paper “early hydration of tricalcium silicate. I. Kinetics of the hydration process and the stiochiometry of the hydration products” by I. Odler and H. Dörr

An electrodeless resistivity measurement system developed recently can provide a reliable method for monitoring the hydration process of cement-based materials continuously and accurately. Phosphoaluminate cement (PAC) sets quickly and develops high early strength. In order to understand the mechanism, the hydration products and microstructure formation of PAC in early age need to be studied. In the study, early hydration process of PAC with different dosage of retarder was investigated by the electrodeless resistivity equipment. According to resistivity-time curve, resistivity of freshly mixed PAC paste decreases sharply and then rises slowly, some characteristic peaks appear at different hydration stages of PAC. Heat evolution of PAC was also measured. The hydration mechanism and structure formation were studied according to these results. Depending on the dosage of retarder, the hydration process of PAC includes four stages which are dissolution, induction, acceleration and deceleration.

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Research of Electrical and Hydration Behavior of Phosphoaluminate Cementitious Material

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.129-131.926 ◽

2010 ◽

Vol 129-131 ◽

pp. 926-930

Author(s):

Ming Zhang ◽

Zhu Ding ◽

Peng Liu ◽

Ming Ke Wang ◽

Feng Xing

Keyword(s):

Impedance Spectroscopy ◽

Cementitious Material ◽

Hydration Process ◽

Early Age ◽

Hydration Products ◽

Micro Structure ◽

Microstructure Formation ◽

Early Hydration ◽

Cement Based Materials ◽

Acceleration And Deceleration

Electrodeless resistivity and impedance spectroscopy measurement are reliable equipments of test online for monitoring the hydration process of cement-based materials continuously and accurately. Phosphoaluminate cement (PAC) sets quickly and develops high early strength. In order to understand the mechanism, the hydration products and microstructure formation of PAC in early age need to be studied. In the study, early hydration process and impedance spectroscopy characteristics of PAC with different dosage of retarder were investigated. According to the test, resistivity of freshly mixed PAC paste decreases sharply and then rises slowly, some characteristic peaks appear at different hydration stages of PAC, which indicates the hydration process of PAC includes four stages which are dissolution, induction, acceleration and deceleration. Impedance spectroscopy can reflect the change of micro-structure and ion concentribution of PAC matrix by resistance and capacitance.

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Influence of Surface Area Variation on the Kinetics of Hydration of Tricalcium Silicate

Canadian Journal of Chemistry ◽

10.1139/v72-107 ◽

1972 ◽

Vol 50 (5) ◽

pp. 701-706 ◽

Cited By ~ 3

Author(s):

K. G. McCurdy ◽

B. P. Erno

Keyword(s):

Surface Area ◽

Rate Constants ◽

Initial Step ◽

Total Surface Area ◽

Tricalcium Silicate ◽

Hydration Process ◽

Kinetic Investigation ◽

First Order ◽

Area Variation ◽

Kinetics Of

Tricalcium silicate reacts initially with aqueous solutions according to a rate law that is first order with respect to the mass of the solid. A kinetic investigation of the hydration of tricalcium silicate for fixed solid to solution, w/w, ratio has been conducted using samples of tricalcium silicate of different total surface area to volume ratios. Consideration of the pH independent rate constants indicates that the rate for the initial step in the hydration process is proportional to the surface area of the solid. Subsequent pH independent rate constants in the overall hydration process are surface area independent.

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The Influence of Water Reducing Agents on Early Hydration Property of Ferrite Aluminate Cement Paste

Crystals ◽

10.3390/cryst11070731 ◽

2021 ◽

Vol 11 (7) ◽

pp. 731

Author(s):

Chunlong Huang ◽

Zirui Cheng ◽

Jihui Zhao ◽

Yiren Wang ◽

Jie Pang

Keyword(s):

Setting Time ◽

Critical Role ◽

Hydration Product ◽

Reducing Agents ◽

Reducing Agent ◽

Hydration Process ◽

Early Hydration ◽

Cement Pastes ◽

Hydration Rate ◽

Aluminate Cement

The ferrite aluminate cement (FAC) could rapidly lose fluidity or workability due to its excessive hydration rate, and greatly reduce the construction performance. Chemical admixtures are commonly used to provide the workability of cement-based materials. In this study, to ensure required fluidity of FAC, chemically different water reducing agents are incorporated into the FAC pastes. The experiments are performed with aliphatic water reducing agent (AP), polycarboxylic acid water reducing agent (PC) and melamine water reducing agent (MA), respectively. Influence of the water reducing agents on fluidity, setting time, hydration process, hydration product and zeta potential of the fresh cement pastes is investigated. The results show that PC has a better dispersion capacity compared to AP and MA. Besides decreasing water dosage, PC also acts as a retarder, significantly increasing the setting times, delaying the hydration rate and leading to less ettringite in the hydration process of FAC particles. The water reducing agents molecules are adsorbed on the surface of positively charged minerals and hydration products, however, for PC, steric hindrance from the long side chain of PC plays a critical role in dispersing cement particles, whereas AP and MA acting through an electrostatic repulsion force.

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The kinetics of hydration of tricalcium silicate

Canadian Journal of Chemistry ◽

10.1139/v70-554 ◽

1970 ◽

Vol 48 (21) ◽

pp. 3291-3299 ◽

Cited By ~ 4

Author(s):

K. G. McCurdy ◽

B. P. Erno

Keyword(s):

Reaction Mechanism ◽

Intermediate Product ◽

Activation Energies ◽

Tricalcium Silicate ◽

Rate Data ◽

Large Excess ◽

First Order ◽

Kinetics Of ◽

Subsequent Decomposition

An investigation has been made of the kinetics of hydration of tricalcium silicate at several temperatures in a large excess of water in the presence of various added ions. The rate data have been interpreted by a reaction mechanism which involves: (a) the first order hydration of tricalcium silicate to form an intermediate product, 1.5CaO•SiO2, which can react by two pathways, (b) the direct first order decomposition of intermediate, 1.5CaO•SiO2, to form lime and silica or (b′) complexing of intermediate with silica and subsequent decomposition to form lime and silica. This reaction mechanism predicts the rate of production of base during the hydration. The effect of various added ions is interpreted in terms of the proposed mechanism.Rate constants and activation energies for the various steps in the proposed mechanism are reported.

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Research Progress on the Hydration of Portland Cement with Calcined Clay and Limestone

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1036.240 ◽

2021 ◽

Vol 1036 ◽

pp. 240-246

Author(s):

Jin Tang ◽

Su Hua Ma ◽

Wei Feng Li ◽

Hui Yang ◽

Xiao Dong Shen

Keyword(s):

Mechanical Properties ◽

Portland Cement ◽

Cementitious Materials ◽

Supplementary Cementitious Materials ◽

Research Progress ◽

Hydration Reaction ◽

Hydration Products ◽

Early Hydration ◽

Calcined Clay ◽

Dense Microstructure

The use of calcined clay and limestone as supplementary cementitious materials, can have a certain influence on the hydration of Portland cement. This paper reviewed the influence of limestone and calcined clay and the mixture of limestone and calcined clay on the hydration of cement. Both limestone and calcined clay accelerate the hydration reaction in the early hydration age and enhance the properties of cement. Limestone reacts with C3A to form carboaluminate, which indirectly stabilized the presence of ettringite, while calcined clay consumed portlandite to form C-(A)-S-H gel, additional hydration products promote the densification of pore structure and increase the mechanical properties. The synergistic effect of calcined clay and limestone stabilize the existence of ettringite and stimulate the further formation of carboaluminate, as well as the C-(A)-S-H gel, contributed to a dense microstructure.

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