Resistivity Study on Early Hydration Process of Phosphoaluminate Cementitious Material

2009 ◽  
Vol 79-82 ◽  
pp. 95-98 ◽  
Author(s):  
Ming Zhang ◽  
Zhu Ding ◽  
Feng Xing ◽  
Peng Liu
Keyword(s):  
Resistivity Measurement ◽  
Heat Evolution ◽  
Hydration Process ◽  
Early Age ◽  
Hydration Products ◽  
Microstructure Formation ◽  
Time Curve ◽  
Early Hydration ◽  
Hydration Mechanism ◽  
Acceleration And Deceleration

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.

Research of Electrical and Hydration Behavior of Phosphoaluminate Cementitious Material

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.

Study on Hydration Mechanism of Phosphoaluminate Cement

2011 ◽  
Vol 675-677 ◽  
pp. 701-704
Author(s):  
Peng Liu ◽  
Zhi Wu Yu ◽  
Ling Kun Chen ◽  
Zhu Ding
Keyword(s):  
Portland Cement ◽  
Electrochemical Impedance ◽  
High Strength ◽  
Heat Evolution ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Scanning Microscope ◽  
Hydration Mechanism ◽  
Calcium Phosphorus ◽  
Electron Scanning Microscope

Phosphoaluminate cement (PAC) is a kind of new cementitious material which has many special properties compared to Portland cement (PC). PAC sets quickly and develops early-high strength. In order to investigate the hydration mechanism, the hydration products and microstructure of PAC were studied with x-ray diffraction (XRD), electron scanning microscope (SEM) and electrochemical impedance spectroscopy (EIS). Heat evolution of PAC was also measured. The results show that the hydration mechanism of PAC is different from Portland cement, which is caused by the special minerals including CxP, CA(P), phase L, and so on. The main hydration products of PAC are calcium phosphorus aluminates hydrate (C-A-P-H), calcium phosphate hydrate (C-P-H), aluminates hydrate (C-A-H), the corresponding hydration microcrystal as well as gels. Also, there is no calcium hydroxide produced during hydration. The hydration procedure of PAC is divided into four stages which are dissolution and induction, acceleration, deceleration, stabilization.

Research on the Hydration Mechanism of Portland Cement with Magnesium Slag

2014 ◽  
Vol 576 ◽  
pp. 57-62 ◽  
Author(s):  
Jun Ping Deng ◽  
Xiao Liang Wang ◽  
Yi Ping Guo
Keyword(s):  
Portland Cement ◽  
Industrial Waste ◽  
Activity Index ◽  
Early Period ◽  
Performance Testing ◽  
Hydration Process ◽  
Hydration Products ◽  
Hydration Mechanism ◽  
Products Analysis ◽  
Strength Improvement

Magnesium slag is a kind of industrial waste during the silicothermic process for magnesium reduction which has potential hydration activity. By adding 20% to 50% of magnesium slag into Portland cement, the influence principle of the additive amount of magnesium slag on the pozzolanic activity is investigated through performance testing and hydration products analysis. During the early period of hydration process, the strength of pozzolanic effectiveness ratio weakens with the increasing additive amount of magnesium slag, while during the later period of hydration process with the additive amount of magnesium slag less than 40%, the strength of pozzolanic effectiveness ratio increases with increasing additive amount of magnesium slag. The activity index of magnesium slag increases with the increase of period and additive amount, and the strength brought by hydration of magnesium slag is a key source of the strength improvement of Portland cement with magnesium slag.

scholarly journals Early Hydration Process and Kinetics of Concrete Based on Resistivity Measurement

2021 ◽  
Vol 19 (3) ◽  
pp. 196-206
Author(s):  
Yongming Tu ◽  
Dongyun Liu ◽  
Lei Yuan ◽  
Tongfang Wang
Keyword(s):  
Resistivity Measurement ◽  
Hydration Process ◽  
Early Hydration ◽  
Kinetics Of

Study on Optimization Proportioning Experiment and its Hydration Mechanism of Composite Cementing Material

2011 ◽  
Vol 121-126 ◽  
pp. 418-422
Author(s):  
Jin Xiao Liu ◽  
Zeng De Yin ◽  
Wen Bin Sun
Keyword(s):  
Portland Cement ◽  
Uniform Design ◽  
Material Strength ◽  
Filling Material ◽  
Hydration Products ◽  
Early Hydration ◽  
Hydration Mechanism ◽  
Cementing Material ◽  
Aluminate Cement

This article aims at the accelerating characteristic of coal filling material. We scientifically made a series of proportion on composite-cementing material through uniform design with Portland cement, sulpho-aluminate cement and gypsums. After having testing the capability of this, we found that some certain composite-cementing material strength has been improved, both early and later strength. Furthermore, we also continually analyzed the hydration products and microstructure of composite-cementing material, then determined that early hydration products were mostly ettringites and later were C-S-H-centered and CH-centered gel.

Effect of Admixture on Mechanical Behavior and Micro-Structure of Sulphoaluminate Composite Material

2010 ◽  
Vol 113-116 ◽  
pp. 2193-2196
Author(s):  
Ming Zhang ◽  
Feng Xing ◽  
De Cheng Zhang ◽  
Yun Fei Zhang
Keyword(s):  
Fly Ash ◽  
Mechanical Behavior ◽  
Early Period ◽  
Diffraction Peak ◽  
Strength Increase ◽  
Hydration Products ◽  
Micro Structure ◽  
Early Hydration ◽  
Hydration Mechanism ◽  
Calcium Sulphoaluminate

Mechanical behavior of sulphoaluminate cement (SAC) mortar mixed slag (SL), fly ash (FA) and combined admixture were studied in the study, at the same time, hydration products and micro-structure were analyzed with XRD and SEM for making clear hydration mechanism. Test results show that early period strength of SAC mortar decreased, and strength contribution rate of admixture is combined admixture (slag + fly ash) ＞ slag ＞ fly ash on the same content due to the combined admixture is more beneficial to accelerate hydration. Yet strength increase of SAC mortar mixed admixture after cured 60d is not obvious, which was not large different with pure SAC mortar. A large amount of ettringite and gel produced during 1d period of SAC paste, but with the hydration carrying on, diffraction peak of hydration products (ettringite and gel) and unhydrated calcium sulphoaluminate change little, which means hydration degree at 1d is higher. Diffraction peak of ettringite and gel at different curing period is lower when mixed admixture in matrix, the amount of ettringite and gel increased and unhydrated calcium sulphoaluminate decreased with hydration carrying on, which means early hydration speed slow down when introduction of admixture into SAC matrix.

Citric Acid on the Hydration Mechanism of Cement

2011 ◽  
Vol 413 ◽  
pp. 174-179
Author(s):  
Bao Guo Ma ◽  
Jun Xiao ◽  
Hong Bo Tan
Keyword(s):  
Citric Acid ◽  
Key Words ◽  
Cement Hydration ◽  
Hydration Heat ◽  
Hydration Process ◽  
Chemical Shrinkage ◽  
Early Hydration ◽  
Hydration Mechanism ◽  
Diffraction Peaks ◽  
Acid Dosage

This article reports on the study to evaluate the hydration process of cement by the addition of citric acid. Through the test of citric acid of cement paste, hydration heat performance, resistivity, chemical shrinkage, and combined with XRD, SEM, DSC-TG discusses the influence of citric acid on cement hydration process. The results thus obtained were compared to the hydration process of cement with the blank sample and vary of dosage of citric acid. The results show that: The early hydration about 1~2 h resistivity increases, dissolve balance stage was extended; The chemical shrinkage increased significantly, and increases with dosage; With the increase in citric acid dosage, AFt diffraction peaks increases, while the CH peak decreases, indicating that the citric acid accelerated the initial hydration of C3A, while inhibiting C3S hydration and promoting AFt generation. Key words: citric acid, mechanism ,hydration heat, resistivity

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