scholarly journals Hydration Kinetics of Portland Cement–Silica Fume Binary System at Low Temperature

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3896 ◽  
Author(s):  
Yao Li ◽  
Yonggang Deng ◽  
Runqing Liu
Keyword(s):  
Binary System ◽  
Low Temperature ◽  
Portland Cement ◽  
Silica Fume ◽  
Rate Constant ◽  
Reaction Order ◽  
Cementitious Materials ◽  
Hydration Kinetics ◽  
K Value ◽  
Kinetics Of

Portland cement–silica fume binary cementitious materials are widely used in engineering construction and have been investigated from micro- to macroscopic aspects. However, the theoretical background on the hydration kinetics of the binary system has not been sufficiently covered in the literature. In this study, the hydration dynamic characteristics of the Portland cement–silica fume binary system curing at low temperature were investigated. Hydration kinetics equations were optimized and a hydration model followed by a computer program was developed to calculate the reaction rate constant K and the reaction order n. This model presented that the hydration process of the binary system at low temperature could be divided into three stages, namely, nucleation and growth (NG), interactions at phase boundaries (I), and diffusion (D). The n values for the binary system varied in the range of 1.2 to 1.6, indicating that the hydration of the binary system at low temperature was a complex elementary reaction. Silica fume can reduce the total heat at the later stage of the hydration and the reaction order n, but increase the heat flow at the accelerating stage and the hydration rate constant K. Low temperature prolonged the hydration induction period, decreased and delayed the secondary exothermic peak, as well as reduced the n and K value.

scholarly journals Study of Hydration and Microstructure of Mortar Containing Coral Sand Powder Blended with SCMs

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4248
Author(s):  
Xingxing Li ◽  
Ying Ma ◽  
Xiaodong Shen ◽  
Ya Zhong ◽  
Yuwei Li
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Silica Fume ◽  
Dilution Effect ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Limestone Powder ◽  
Chemical Effect ◽  
Granulated Blast Furnace Slag ◽  
Coral Sand

The utilization of coral waste is an economical way of using concrete in coastal and offshore constructions. Coral waste with more than 96% CaCO3 can be ground to fines and combined with supplementary cementitious materials (SCMs) such as fly ash, silica fume, granulated blast furnace slag in replacing Portland cement to promote the properties of cement concrete. The effects of coral sand powder (CSP) compared to limestone powder (LSP) blended with SCMs on hydration and microstructure of mortar were investigated. The result shows CSP has higher activity than LSP when participating in the chemical reaction. The chemical effect among CSP, SCMs, and ordinary Portland cement (OPC) results in the appearance of the third hydration peak, facilitating the production of carboaluminate. CSP-SCMs mortar has smaller interconnected pores on account of the porous character of CSP as well as the filler and chemical effect. The dilution effect of CSP leads to the reduction of compressive strength of OPC-CSP and OPC-CSP-SCMs mortars. The synergic effects of CSP with slag and silica fume facilitate the development of compressive strength and lead to a compacted isolation and transfer zone (ITZ) in mortar.

Hydration Process of Portland Cement Blended with Silica Fume

2013 ◽  
Vol 699 ◽  
pp. 578-583 ◽  
Author(s):  
Neven Ukrainczyk ◽  
Jure Zlopasa ◽  
Eduard Koenders
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
Isothermal Calorimetry ◽  
Construction Materials ◽  
Radical Change ◽  
Sustainable Construction ◽  
Hydration Kinetics ◽  
Replacement Ratio ◽  
Cement Production ◽  
Ultrasound Bath

The enormous carbon footprint associated with the global cement production (5-7%) asks for a radical change in the use of sustainable replacement materials in concrete. Replacement of cement by pozzolanic waste materials, being a by-product from industrial processes, has been widely recognized as the most promising route towards sustainable construction materials. This paper presents experimental study on hydration of commercial Portland cement blended with silica fume in replacement ratio of 15 mass %. Isothermal calorimetry was employed to monitor the hydration kinetics. Thermogravimetric analysis coupled by differential scanning calorimeter (TG/DSC) was used to investigate the formed hydration products at 1, 3, 7, and 28 days of hydration. Two different approaches for a dispersion of silica fume in cement paste were compared: ultrasound bath and addition of superplasticizer (polycarboxylic ether based).

scholarly journals Influence of Glass Powder on Hydration Kinetics of Composite Cementitious Materials

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Xiaolin Chang ◽  
Xinping Yang ◽  
Wei Zhou ◽  
Guoshuai Xie ◽  
Shuhua Liu
Keyword(s):  
Glass Powder ◽  
Isothermal Calorimetry ◽  
Cementitious Materials ◽  
Heat Emission ◽  
Hydration Heat ◽  
Hydration Kinetics ◽  
Period Increase ◽  
Acceleration Period ◽  
Boundary Reaction ◽  
Kinetics Of

The influence of glass powder (GP) on hydration kinetics of composite cementitious materials has been investigated by isothermal calorimetry test and hydration kinetics methods in this paper. The hydration heat emission rate and hydration heat decrease gradually while the induction and acceleration period increase with the increase of GP content. According to Krstulovic-Dabic model, the hydration process of composite cementitious materials containing GP is controlled by a variety of complicated reaction mechanisms, which can be divided into three periods: nucleation and crystal growth (NG), phase boundary reaction (I), and diffusion (D). The NG and I process are shortened after incorporating GP.

scholarly journals REACTION KINETICS OF Cu ELECTRO-DEPOSITION ON THE SURFACE OF TiO2/GRAPHITE

2015 ◽  
Vol 8 (2) ◽  
pp. 116
Author(s):  
Fitria Rahmawati ◽  
Wanodya Anggit Mawasthi ◽  
Patiha
Keyword(s):  
Equilibrium Constant ◽  
Rate Constant ◽  
Reaction Rate ◽  
Reaction Order ◽  
Electrode Reaction ◽  
Deposition Process ◽  
Anodic Reaction ◽  
Electro Deposition ◽  
First Order ◽  
Kinetics Of

Research on the kinetics of electrode reaction during copper electro-deposition on the surface of TiO2/graphite has been conducted. The aims of this research are to determine the ratio of anodic reaction rate to cathodic reaction rate , the ratio of anodic rate constant to cathodic rate constant , the equilibrium constant when the reaction reach equilibrium condition and to study the polarization in the electro-deposition reaction. Copper was deposited electrochemically from CuSO4 solution at various concentration i.e. 0.1 M; 0.2 M; 0.3 M; 0.4 M; 0.5 M. In every 5 minutes during electro-deposition process, the pH changes in anode cell was recorded and the change of Cu2+ concentration was also analyzed by spectrophotometric method. The result shows that the reaction order of Cu2+ reduction is first order and the oxidation of H2O in anodic cell is zero order. The ratio of anodic rate constant to cathodic rate constant, is 4.589´10-3 ± 0.071´10‑3. It indicates that the reaction rate  in cathode is larger than the reaction rate in anode and it allowed polarization.  The electrochemical cell reached equilibrium after 25 minutes with the equilibrium constant is 8.188´10-10 ± 1.628´10-10.

scholarly journals The influence of curing temperature, plastic additives and polypropylene fibers on the mechanical behaviour of cementitious materials

2020 ◽  
Vol 150 ◽  
pp. 02012
Author(s):  
Mohammed Aqil ◽  
Lahcen Bahi ◽  
Latifa Ouadif ◽  
Siham Belhaj ◽  
Raounak Edderkaoui
Keyword(s):  
Compressive Strength ◽  
Mechanical Behaviour ◽  
Mechanical Performance ◽  
Cementitious Materials ◽  
Curing Temperature ◽  
Polypropylene Fibers ◽  
Hydration Kinetics ◽  
Degree Of Hydration ◽  
History Of ◽  
Kinetics Of

An experimental company was carried out to better understand the influence of curing temperature on the mechanical behaviour of cementitious materials, particularly compressive strength, the study focused on two types of mortars, the first containing polypropylene fibers while the second contains a proportion of PVC-type plastic grains from industrial waste, the hydration kinetics of the different components of the formulated mortar has been characterized by the isothermal calorimetric test, thus a history of the hydration degrees has been established, Afterwards, an attempt was made to correlate the compressive strength with the evolution of the degree of hydration for the different formulations, based on the results obtained, it is clearly observable that the compressive strength evolves with the degree of hydration and that the specimen containing the polypropylene fibers has the best mechanical performance with respect to compression.

Analysis of the Rate Constant for Hydration Kinetics of the Cement and Ash Fly in the Solidified Residues System Based on the Measurement of Ca(OH)2

2013 ◽  
Vol 380-384 ◽  
pp. 4395-4399
Author(s):  
Qin Li ◽  
Xiao Jun Zhou ◽  
Ke Wei Sun
Keyword(s):  
Chemical Analysis ◽  
Rate Constant ◽  
Matrix Material ◽  
Order Reaction ◽  
First Order Reaction ◽  
Cement Matrix ◽  
Analysis Method ◽  
Hydration Kinetics ◽  
First Order ◽  
Kinetics Of

Based on the hydration kinetics of the cement matrix material, the paper presents a chemical analysis method by means of analyzing the contents of Ca(OH)2 in cement matrix material. The kinetics constant for the cement, ash fly in the residues system solidified by recycled cement, ash fly was determined at different temperature. The hydration kinetics characteristic of the residues system after being hydrated 7 days is first order reaction.

Crystallization Kinetics of CaOx in Artificial Urine and in Saline System

2014 ◽  
Vol 881-883 ◽  
pp. 708-711
Author(s):  
Lan Qing Deng ◽  
Jun Fa Xue ◽  
Li Kuan ◽  
Jian Ming Ouyang
Keyword(s):  
Reaction Time ◽  
Calcium Oxalate ◽  
Crystallization Kinetics ◽  
Rate Constant ◽  
Reaction Rate ◽  
Reaction Order ◽  
Reaction Rate Constant ◽  
Artificial Urine ◽  
Kinetics Of

The crystallization kinetics of calcium oxalate (CaOx) was comparatively studied by detecting the change of free Ca2+ ions concentration with the reaction time in artificial urine and in saline system. The dynamics equations of CaOx crystallization was r=kcα, and the average reaction order (α) was 3.3 regardless of the relative suprasaturation degree (RS) of CaOx in the range of RS=10.58~17.53. The average reaction rate constant (κ) was (0.97±0.1)×109 in artificial urine and κ=(3.1±1.8)×109 in saline system, due to the presence of inhibitors to CaOx crystallization in artificial urine.

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