Characterisation of development of cement hydration using chemical shrinkage

2015 ◽  
pp. 75-106 ◽  
Author(s):  
METTE GEIKER
Keyword(s):  
Cement Hydration ◽  
Chemical Shrinkage

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

Cement Chemical Shrinkage Prediction Model Research Based on the Mineral Composition Content of Each Phase at Early Age

2010 ◽  
Vol 168-170 ◽  
pp. 31-35
Author(s):  
Lang Wu ◽  
Gu Quan Song ◽  
Bin Lei
Keyword(s):  
Prediction Model ◽  
Cement Hydration ◽  
Early Period ◽  
Cementitious Materials ◽  
Early Age ◽  
Chemical Shrinkage ◽  
Hydration Degree ◽  
Model Research ◽  
Increasing Temperature ◽  
The Relationship

Based on the microstructure evolution of cement hydration, using the relationship between the hydration rate and hydration degree, chemical shrinkage prediction model of cementitious materials are proposed. This model can simulate chemical shrinkage curve of cement-based material well. In the early period, increasing water-cement ratio can increase chemical shrinkage. While in the middle period, its influence on chemical shrinkage is negligible. Increasing temperature accelerates the hydration process significantly, therefore, increases the chemical shrinkage.

Mechanism of Preferential Adsorption of Carboxylic-Vinyl Copolymer, Hydroxy Carboxylate and Sulfonation - Polyol in Cement Hydration Process

2011 ◽  
Vol 194-196 ◽  
pp. 1035-1040 ◽  
Author(s):  
Hong Bo Tan ◽  
Bao Guo Ma ◽  
Kai Ke ◽  
Jun Xiao
Keyword(s):  
Ternary System ◽  
Organic Compounds ◽  
Steric Hindrance ◽  
Cement Hydration ◽  
Xrd Analysis ◽  
Chemical Shrinkage ◽  
Hydration Products ◽  
Adsorption Model ◽  
Hydration Mechanism ◽  
Preferential Adsorption

In the ternary system of hydroxy carboxylate (HC), sulfonation-polyol (SP) and carboxylic-vinyl copolymer (PC), HC and SP preferentially adsorb on the surface of particles to shield the initial hydration. In this way, the ternary system has excellent dispersibility and holding dispersibility, and it has little effect on later hydration. By means of the chemical shrinkage, SEM and XRD analysis, the hydration mechanism of the hydroxy carboxylate (HC) and sulfonation-polyol (SP) has been discussed and the preferential adsorption model (PAM) has been established. The results show that HC delays the initial hydration of C3S and accelerates both the hydration of C3A and the formation of AFt; HC reduces the strength for 28 d with the addition of 0.2%; SP delays initial hydration of C3S and C3A; the ability of shielding hydration becomes weaker along with cement hydrating and the development of strength is normal. In the ternary system of HC, SP and PC, HC and SP with the electrostatic attraction of -SO3- and COO- and complexation of OH- preferentially adsorb on the surface of particles and active hydrating points. Then, reaction of active hydrating points was shielded and the growth of the hydration products slows. In this way, hydration of C3A and C3S are delayed, and the holding dispersibility of PC becomes better. The PC preferentially adsorbs on inert hydrating points and consumes slowly to provide dispersibility with steric hindrance. Along with hydrating going on, organic compounds are enwrapped by hydration products and the shielding ability becomes weaker and weaker. Then, the hydration becomes normal.

PRACTICAL PROCEDURES FOR INTENSIFYING CEMENT HYDRATION

2016 ◽  
Vol 15 (2) ◽  
pp. 307-314
Author(s):  
Vladimir Corobceanu ◽  
Ciprian Ilie Cozmanciuc ◽  
Razvan Giusca ◽  
Constantin Gavriloaia
Keyword(s):  
Cement Hydration

EFFECT OF VISCOSITY MODIFIER ADMIXTURE ON PORTLAND CEMENT HYDRATION

2018 ◽  
Author(s):  
Stefan C. Figueiredo ◽  
Oğuzhan Çopuroğlu ◽  
Erik Schlangen
Keyword(s):  
Portland Cement ◽  
Cement Hydration ◽  
Viscosity Modifier ◽  
Portland Cement Hydration

The Effect of Cassava Starch on the Durability Characteristics of Concrete

2020 ◽  
Vol 14 (1) ◽  
pp. 289-301
Author(s):  
Daniel Oni ◽  
John Mwero ◽  
Charles Kabubo
Keyword(s):  
Cement Hydration ◽  
Research Work ◽  
Cassava Starch ◽  
Chloride Penetration ◽  
Hardened Concrete ◽  
Sulphate Attack ◽  
Marine Structures ◽  
Durability Properties ◽  
Chloride Attack ◽  
Starch Gel

Background: Concrete is a common material used in the construction of marine structures, such as bridges, water treatment plants, jetties, etc. The use of concrete in these environment exposes it to attack from chemicals like sulphates, chlorides and alkaline, thereby causing it to deteriorate, and unable to perform satisfactorily within its service life. Hence, the need to investigate the durability properties of concrete has become necessary especially when admixtures are used to modify some of its properties. Objective: This research work investigates the effect of Cassava Starch (CS) on the durability characteristics of concrete. Methods: The durability properties investigated in this work are water absorption, sorptivity, resistance to sulphates, sodium hydroxides and chloride penetration. The specimens were prepared by adding CS by weight of cement at 0.4, 0.8, 1.2, 1.6 and 2.0% respectively. The concrete specimens were cured for 28 days, tested for compressive strength before ponding in ionic solutions of sodium hydroxide, sulphuric acid and sodium chloride. Six (6) concrete mixes were prepared, five of which were used to evaluate the effect of CS on the durability characteristics of concrete. Results: The slump values reduced with the increasing dosage of CS due to the viscous nature of the CS paste. Generally, the addition of CS in concrete tends to improve the resistance of concrete to sulphate and chloride attack due to the ability of the muddy-like starch gel to block the pore spaces of hardened concrete, hence, reduces the rate at which water and other aggressive chemicals penetrate the concrete. In addition, the retarding ability of CS impedes the formation of mono-sulphate aluminates during cement hydration, thereby making the concrete less susceptible to sulphate attack. Conclusion: The addition of CS to concrete by weight of cement generally improved the durability characteristics of concrete, while the relative performances of the concrete mixes showed that CS 2.0 gave a better resistance to chloride penetration and sulphate attack.

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