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

Crystals ◽  
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.

scholarly journals The Role of Titanium Dioxide on the Hydration of Portland Cement: A Combined NMR and Ultrasonic Study

Molecules ◽  
2020 ◽  
Vol 25 (22) ◽  
pp. 5364
Author(s):  
George Diamantopoulos ◽  
Marios Katsiotis ◽  
Michael Fardis ◽  
Ioannis Karatasios ◽  
Saeed Alhassan ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Hydration Process ◽  
Spin Lattice Relaxation ◽  
Hydration Reaction ◽  
Early Hydration ◽  
Cement Pastes ◽  
Spin Lattice ◽  
Pore Size Distributions

Titanium dioxide (TiO2) is an excellent photocatalytic material that imparts biocidal, self-cleaning and smog-abating functionalities when added to cement-based materials. The presence of TiO2 influences the hydration process of cement and the development of its internal structure. In this article, the hydration process and development of a pore network of cement pastes containing different ratios of TiO2 were studied using two noninvasive techniques (ultrasonic and NMR). Ultrasonic results show that the addition of TiO2 enhances the mechanical properties of cement paste during early-age hydration, while an opposite behavior is observed at later hydration stages. Calorimetry and NMR spin–lattice relaxation time T1 results indicated an enhancement of the early hydration reaction. Two pore size distributions were identified to evolve separately from each other during hydration: small gel pores exhibiting short T1 values and large capillary pores with long T1 values. During early hydration times, TiO2 is shown to accelerate the formation of cement gel and reduce capillary porosity. At late hydration times, TiO2 appears to hamper hydration, presumably by hindering the transfer of water molecules to access unhydrated cement grains. The percolation thresholds were calculated from both NMR and ultrasonic data with a good agreement between both results.

Effect of Calcined Red Mud Addition on the Hydration of Portland Cement

2012 ◽  
Vol 727-728 ◽  
pp. 1408-1411 ◽  
Author(s):  
Daniel Véras Ribeiro ◽  
João A. Labrincha ◽  
Márcio Raymundo Morelli
Keyword(s):  
Portland Cement ◽  
Red Mud ◽  
Setting Time ◽  
Cementitious Materials ◽  
Adiabatic Calorimeter ◽  
Hydration Process ◽  
Early Hydration ◽  
Bauxite Ore ◽  
Calorimetric Studies ◽  
Reference Mixture

The red mud (RM) is a solid waste derived from the processing of bauxite ore to produce alumina and it is considered a hazardous waste due to its high pH. This paper describes the use of mud untreated and after calcination at distinct temperatures (450, 650, and 1000°C) attempting to improve its reactivity. The Portland cement was replaced up to 30 wt% red mud, and its addition changed the hydration process, evaluated by calorimetric studies of early hydration and setting time. By comparing with the reference mixture (without red mud), the obtained results confirm the potential of the red mud to be used as pozzolanic additive to cementitious materials. Temperature of hydration was monitored by a quasi-adiabatic calorimeter (Langavant). The hydration temperature increases with RM addition, particularly if calcined in the same interval (450-650°C). In this condition, the hydration process is accelerated.

Research on the Application of Slipform Concrete of Well Tower in winter

2012 ◽  
Vol 204-208 ◽  
pp. 3703-3706
Author(s):  
Xiang Zong
Keyword(s):  
Mechanical Performance ◽  
Setting Time ◽  
Reducing Agents ◽  
Reducing Agent ◽  
Mix Proportion ◽  
Time Test ◽  
Early Strength ◽  
Blend Ratios

To meet the demand of performance of slipform concrete in a well tower in winter, different blend ratios of early strength water reducing agents were added to the concrete. Compared with reference concrete, their setting time test analyses, workability analyses and tests of mechanical performance and removal of forms were conducted in the laboratory. The results show that concrete with FS-A early strength water reducing agent can greatly improve early strength of concrete and meet the demand of relevant performance of slipform. This research may provide reference for design of mix proportion and construction in similar slipform project.

Effect of Carboxylmethyl Cellulose Sulfate (CMC-S) on the Hydration Process of Cement Paste

2013 ◽  
Vol 838-841 ◽  
pp. 123-126
Author(s):  
Feng Yuan Huang ◽  
Xiao Jie Wu ◽  
Wei Feng Ying ◽  
Yong Peng Yu ◽  
Hong Xun Chi
Keyword(s):  
Cement Paste ◽  
Differential Scanning Calorimeter ◽  
Setting Time ◽  
Reducing Agent ◽  
Hydration Heat ◽  
Hydration Process ◽  
Early Age ◽  
Cellulose Sulfate

The application of Carboxylmethyl Cellulose Sulfate (CMC-S) in cement paste was studied. The effect of CMC-S on the setting time of cement paste was investigated. Hydration heat of specimens with different cured age was measured via the Hydration Heat Tester (HHT), and hydration process was recorded via Differential Scanning Calorimeter (DSC). The results indicated that CMC-S was a kind of set-retarding and water-reducing agent; its retarding properties appeared at early age, but after three days, the hydration process of cement paste was even improved.

scholarly journals Setting Characteristics and High Compressive Strength of an Anti-washout, Injectable Calcium Phosphate Cement Combined with Thermosensitive Hydrogel

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5779
Author(s):  
Yao Xie ◽  
Jia Liu ◽  
Shu Cai ◽  
Xiaogang Bao ◽  
Qianqian Li ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Calcium Phosphate ◽  
Calcium Phosphate Cement ◽  
Photoelectron Spectroscopy ◽  
Setting Time ◽  
Volume Ratio ◽  
Hydration Product ◽  
Thermosensitive Hydrogel ◽  
Early Hydration ◽  
X Ray

In this work, a thermosensitive poly(D,L-lactide-co-glycolide)-poly(ethylene glycol)-poly(D,L-lactide-co-glycolide) (PLGA-PEG-PLGA) hydrogel was introduced into calcium phosphate cement (CPC) to enhance the anti-washout property of CPC. The effects of the hydrogel on the setting time, injectability, anti-washout property and compressive strength of CPC were thoroughly investigated. The results showed that the hydrogel significantly increased the injectability and anti-washout property of CPC, meanwhile maintained the setting time with an acceptable range. Moreover, the hydrogel improved the initial compressive strength of CPC. The composite cement with 20% v/v hydrogel in the liquid phase showed fine crystals of hydration product, a more compact microstructure and lower porosity compared with control CPC. The analysis of X-ray diffraction (XRD), infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) indicated that suitable volume ratio of hydrogel (20% v/v) in the setting liquid of CPC could promote the formation of hydroxyapatite in the early hydration period. The degradation behavior of the cement was characterized by immersion tests in simulated body fluid. The hydrogel had no adverse effect on the degradation rate of CPC over the immersion period of 23 days. This study indicated that incorporating PLGA-PEG-PLGA hydrogel could be a promising strategy to reinforce the handing properties and initial compressive strength of calcium phosphate cement.

scholarly journals Preparation of Self-leveling Mortar Based on Anhydrite-II Phosphogypsum

2021 ◽  
Vol 2076 (1) ◽  
pp. 012035
Author(s):  
Yu Zhang ◽  
Jiahao Yang ◽  
Yu Liu ◽  
Bin Liu ◽  
Fengqing Zhao
Keyword(s):  
Sulfuric Acid ◽  
Calcium Aluminate ◽  
Water Resistance ◽  
Construction Material ◽  
Setting Time ◽  
Steel Slag ◽  
Calcium Aluminate Cement ◽  
Hydration Rate ◽  
Softening Coefficient ◽  
Aluminate Cement

Abstract The construction material from anhydrite-II phosphogypsum is dense in structure and has good water resistance. But its disadvantages are low hydration activity and long setting time. In this work, anhydrite-II phosphogypsum is modified by adding a composite activator, which is made of sulfuric acid modified steel slag, β-hemihydrate gypsum and calcium aluminate cement. With this, the hydration rate of anhydrite-II phosphogypsum is clearly increased and setting time shortened. The performance of self leveling mortar prepared is as per JC/T 1023-2021, with softening coefficient of 0.8.

scholarly journals Mechanism of Degradation of the Properties of Recycled Plaster Mixed Aluminate Cement

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Zhixin Li ◽  
Kaidong Xu ◽  
Jina Wang ◽  
Jianwu Zhang ◽  
Xianwei Ma ◽  
...  
Keyword(s):  
Degradation Mechanism ◽  
Setting Time ◽  
Hydration Rate ◽  
Mechanism Of Degradation ◽  
Degradation Of Properties ◽  
Aluminate Cement

This manuscript investigates the degradation of the properties of recycled plaster-mixed aluminate cement (RAP) and analyzes its degradation mechanism by DSC/TG and SEM. The results showed that the setting time of RAP was shortened due to the fast formation of recycled ettringite (AFt) and its strength was decreased relative to the pure recycled plaster (RP) in the absence of aluminate cement. Different from the properties of RP and RAP, the hydration of commercial plaster was slowed down by the addition of aluminate cement for its low hydration rate, and its strength was increased with respect to the pure commercial plaster (CP) without aluminate cement. Therefore, the properties of RP and RAP could be seen to decrease in relation to CP and commercial plaster mixed aluminate cement (CAP). The SEM and DSC/TG analyses confirm the presence of cluster and fine crystals and noncementing AH3 in RAP, which demonstrates its degradation of properties.

scholarly journals Strength and microstructure properties of solidified sewage sludge with two types of cement-based binders

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yijun Chen ◽  
Xingxing He ◽  
Shaohua Zhang ◽  
Xun Tan ◽  
Yong Wan
Keyword(s):  
Organic Matter ◽  
Sewage Sludge ◽  
Soft Soil ◽  
Microscopic Analysis ◽  
Hydration Product ◽  
Hydration Products ◽  
Early Hydration ◽  
Cementitious Binder ◽  
Before And After ◽  
Aluminate Cement

AbstractSolidification treatment with cementitious binder is an effective way to reduce environmental hazards of sewage sludge. Two cementitious binders, i.e., ordinary Portland cement (OPC) and sulfo-aluminate cement (SAC), were compared in this study to treat the sewage sludge. The strength of solidified sewage sludge (SSS) and changes in microscopic characteristics before and after treatment were analyzed through microscopic analysis methods. The effect of organic matter in sludge on the strength of SSS were also discussed. The results showed that the strength of SSS were lower than that of the solidified clay with no organic matter, and the filtrate extracted from the sludge can also weaken the cementation of the two cements significantly. The solidification effect of the OPC on the sludge was lower than that of the SAC evidently. The organic matter in the sewage sludge caused the surface of the soil particles to carry a large negative potential, which interfered with the hydration of the binder and reduced the amount of cementation skeleton formed by the binder hydration products. This resulted in a porous structure with low mechanical strength. The amount of early hydration product formed in the SAC-based solidified samples was higher than that of the OPC-based samples. This was favorable for filling the pores of the solidified samples and increasing their density. SAC had a better compatibility with soft soil containing high organic matter than OPC, and the which provides an effective alternative binder for dealing with sewage sludge.

scholarly journals Effect of Functional Superplasticizers on Concrete Strength and Pore Structure

2020 ◽  
Vol 10 (10) ◽  
pp. 3496
Author(s):  
Wuju Xun ◽  
Changlong Wu ◽  
Xuefei Leng ◽  
Jiye Li ◽  
Desheng Xin ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
High Performance ◽  
Concrete Strength ◽  
Reducing Agents ◽  
Reducing Agent ◽  
Polycarboxylic Acid ◽  
X Ray Diffraction ◽  
Hydration Rate ◽  
Compressive Strength Of Concrete

The current work investigates the fluidity and the loss of the flow rate of cement paste and mortar over time, as well as the pore structure and compressive strength of concrete and mortar in the presence of functional polycarboxylic acid high-performance water-reducing agents. The hydration rate, hydration products, and pore structure of the concrete containing different functional polycarboxylic acid superplasticizers were analyzed by means of mercury intrusion test, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results show that water-reducing agent Z significantly improves the pore structure of concrete and further compacts the structure of concrete and mortar, thereby improving the compressive strength of concrete. Moreover, the shorter side chains and ester functional groups in the structure of water-reducing agent H can slow down cement hydration rate, which lowers the early strength of mortar; nevertheless, at later stages, the pore structure of the concrete and mortar including superplasticizer H is less different from that of the concrete and mortar containing polycarboxylic acid water-reducing agents. Water-reducing agent J performs best but has a weaker effect on the pore structure of concrete and mortar compared to superplasticizer Z; it is also better than naphthalene-based water-reducing agents.

Investigation on Hydration Characteristics of Zinc-Doped Portland Cement Pastes

2010 ◽  
Vol 168-170 ◽  
pp. 623-627 ◽  
Author(s):  
Xiang Guo Li ◽  
Xiao Bo Yin ◽  
Bao Guo Ma ◽  
Bei Wu ◽  
Quanbin Chen ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Setting Time ◽  
Hydration Product ◽  
Hydration Heat ◽  
Cement Pastes ◽  
Ion Concentrations ◽  
Zn Concentration ◽  
Zinc Salts ◽  
Hydration Characteristics

Compressive strength, setting time, hydration heat and hydration product were investigated to evaluate the effects of Zn2+ ion concentrations and the anion of zinc salts on the hydration characteristics of Portland cement paste. The results show that the hydration characteristics of zinc-doped cement pastes depend on Zn2+ ion concentrations and the anion of salts. With the incorporation of ZnCl2, the hydration heat, exothermic rate and the early-age strength of cement pastes were reduced, the arrival time of the highest temperature was delayed, and little negative influences on the compressive strength at 28 days were observed. The total hydration did not decrease incorporating ZnSO4; the hydration exothermic process was delayed. There were little negative influences on the compressive strength of the samples at 3 days and 28 days. Moreover, for the samples with the same Zn concentration, the retardation effect of ZnCl2 samples was stronger than that of ZnSO4 samples.

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