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.

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.

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.

scholarly journals Surface Charge Properties of Marble Powder and its Effect on the Formation of Hydrates in Cement Paste

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 914
Author(s):  
Xiaowei Ouyang ◽  
Shida Xu ◽  
Liquan Wang ◽  
Jianzhang Huang
Keyword(s):  
Surface Charge ◽  
Co2 Emission ◽  
Electrostatic Force ◽  
Cement Particle ◽  
Hydration Products ◽  
Early Hydration ◽  
Cement Based Materials ◽  
Marble Powder ◽  
Formation Of Hydrates ◽  
Reducing Energy

Replacing part of cement with waste stone powder can reduce the use of cement, thus reducing energy consumption and CO2 emission. Different stone powders affect the properties of cement-based materials differently. It is important to clarify the effect of the surface properties of the stone powder on the properties of cement-based materials. In this paper, the charge properties of marble powder and its effect on the formation of hydrates were investigated. Zeta potential was used to study the charge properties of the marble surface. Parallelly, the morphology of hydrates on the surface of the cement and marble particles at a very early hydration age was observed by using SEM. Finally, the influence of the surface charge properties of the marble particles on the formation of hydration products of cement was discussed. The results showed that the marble particles have specific adsorption of Ca2+ (chemical adsorption). Therefore, the marble particles in the simulated solution can adsorb a large amount of Ca2+, thus achieving a high potential value and facilitating the formation of hydrates on their surface. However, the adsorption of Ca2+ towards the surface of the cement particle is driven by a relatively weak electrostatic force. Compared with the marble particles, less Ca2+ ions are adsorbed, and thus, fewer hydrates are formed on the surface of cement particles.

scholarly journals The Role of Various Powders during the Hydration Process of Cement-Based Materials

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Shuhua Liu ◽  
Hongling Wang ◽  
Jianpeng Wei
Keyword(s):  
Early Stage ◽  
Steel Slag ◽  
Pozzolanic Reaction ◽  
Hydration Process ◽  
Limestone Powder ◽  
Strength Development ◽  
Early Hydration ◽  
Cement Based Materials ◽  
Early Strength

The role of various powders including glass powder (GP), limestone powder (LP), and steel slag powder (SSP) during the hydration process of cement-based materials was investigated by using X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), and strength tests. GP has adverse impact on early strength, but the pozzolanic reaction at later stage enhances the strength development greatly. LP can significantly improve early strength. SSP has a good contribution to the early and later strength of the paste when its content is less than 15%. GP has little effect on the kind of hydration products but relatively large effects on the quantity. Calcium hydroxide (CH) content of GP paste decreases over curing age gradually, which is different from pure cement paste because its pozzolanic activity consumes more CH than that generated from the cement hydration. SSP and LP mainly play a role of filling effect at early stage. Nucleating effect of LP also promotes the early hydration of cement. The hydration of LP occurs at later stage and forms the calcium carboaluminate hydrates. The hydration of SSP is relatively slow, which generates CH at later stage and is effective in the strength development.

scholarly journals Effect of MXene (Nano-Ti3C2) on Early-Age Hydration of Cement Paste

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Haibin Yin ◽  
Jianping Zhu ◽  
Xuemao Guan ◽  
Zhengpeng Yang ◽  
Yu Zhu ◽  
...  
Keyword(s):  
Cement Paste ◽  
Cement Hydration ◽  
Hydration Process ◽  
Early Age ◽  
Main Role ◽  
Hydration Products ◽  
Hydration Properties ◽  
Network Connection ◽  
The Impact ◽  
Early Age Hydration

As a new two-dimensional material, MXene (nano-Ti3C2) has been widely applied in many fields, especially for reinforced composite materials. In this paper, mechanical testing, X-ray diffraction (XRD), hydration heat, scanning electron microscope (SEM), and EDS analysis were used to analyze the impact of MXene on cement hydration properties. The obtained results revealed that (a) MXene could greatly improve the early compressive strength of cement paste with 0.04 wt% concentration, (b) the phase type of early-age hydration products has not been changed after the addition of MXene, (c) hydration exothermic rate within 72 h has small difference at different amount of MXene, and (d) morphologies of hydration products were varied with the dosage of MXene, a lot of tufted ettringites appeared in 3 d hydration products when the content of MXene was 0.04 wt%, which will have a positive effect on improving the early mechanical properties of cement paste. MXene has inhibited the Portland cement hydration process; the main role of MXene in the cement hydration process is to promote the messy ettringite becoming regular distribution at a node and form network connection structure in the crystals growth process, making the mechanics performance of cement paste significantly improved.

scholarly journals Self-Desiccation of a Vernacular CSA Binder

2022 ◽  
Author(s):  
Natalia Pires Martins ◽  
Burhan Cicek ◽  
Coralie Brumaud ◽  
Guillaume Habert
Keyword(s):  
Citric Acid ◽  
Thermogravimetric Analysis ◽  
Setting Time ◽  
Bound Water ◽  
The Self ◽  
Early Age ◽  
Hydrated Cement ◽  
Hydration Products ◽  
Early Hydration ◽  
Setting Times

The fast precipitation of ettringite in conventional Calcium Sulfo Aluminate (CSA) cement causes rapid stiffening of the cement paste and is directly associated with short setting times and self-desiccation. To extend the time during which those types of cement remain workable, retarding admixtures can be used. However, retarders may affect the amounts and types of hydration products formed and as a consequence the ability of hydrated cement to chemically bind water. This work investigates the influence of two natural-based admixtures on the self-desiccation ability of a vernacular CSA ternary binder used as earth stabilization. Vicat measurements were used to study the efficiency of citric acid and sucrose as retarding admixtures on the setting time of stabilized earth. A quantitative study of the self-desiccation ability of the binder was performed on dried binder pastes using thermogravimetric analysis (TGA). Results show that both admixtures have a significant impact on the setting time of the binder. Furthermore, TGA showed that the self-desiccation ability of this vernacular CSA binder is significantly reduced when citric acid at high dosages is used, both at early hydration and after 14 days. On the contrary, the use of sucrose does not affect the water chemically bound at an early age but can maximize bound water after 14 days of hydration.

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