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Updated: Jul 15, 2026
06:27
Expression of Cementitious Pore Solution and the Analysis of Its Chemical Composition and Resistivity Using X-ray Fluorescence
Published on: September 23, 2018
Two-dimensional correlation relaxation studies of cement pastes
Peter J McDonald1, Jonathan Mitchell, Michael Mulheron
1School of Electronics and Physical Sciences, University of Surrey, Guildford, GU2 7XH Surrey, UK. p.mcdonald@surrey.ac.uk
Magnetic Resonance Imaging
|May 1, 2007
Summary
Two-dimensional nuclear magnetic resonance relaxation studies reveal insights into cement hydration by tracking porosity changes. This technique provides characteristic relaxation time distributions for various cement types, aiding in understanding their development.
Area of Science:
- Materials Science
- Physical Chemistry
- Geotechnical Engineering
Background:
- Cement hydration is a complex process involving chemical reactions and physical changes.
- Understanding cement hydration is crucial for construction materials science and durability.
- Porosity evolution is a key indicator of cement hydration and strength development.
Purpose of the Study:
- To investigate cement hydration using two-dimensional nuclear magnetic resonance (2D NMR) relaxation correlation.
- To monitor the evolution of porosity during cement hydration.
- To analyze relaxation time distributions in different cement pastes.
Main Methods:
- Utilized a unilateral magnet, the Surface GARField, for 2D NMR relaxation correlation studies.
- Performed measurements on fresh white cement, prehydrated white cement, and ordinary Portland cement.
- Analyzed characteristic relaxation time distributions and T(1)/T(2) ratios.
Main Results:
- Observed distinct relaxation time distributions for different cement pastes.
- Successfully monitored porosity evolution indicative of the hydration process.
- The T(1)/T(2) ratio in the studied cements aligned with theoretical expectations from high-field NMR.
Conclusions:
- 2D NMR relaxation correlation is a viable method for observing cement hydration.
- Porosity evolution can be effectively tracked by monitoring NMR relaxation times.
- The study validates the use of low-field NMR for characterizing cementitious materials.
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The porosity of concrete is a measure of the void spaces within its structure. These spaces impact its strength and durability significantly. When water and cement interact, a chemical reaction called hydration creates a semi-solid paste. This paste includes combined water, making up approximately 23% of the cement's dry mass, and gel water, which fills minuscule voids known as gel pores, accounting for about 28% of the cement gel volume.
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01:20Strength of Cement
Strength tests for cement are not performed directly on neat cement paste due to difficulty in obtaining consistent, reliable specimens. Instead, cement is typically tested in the form of cement-sand mortar.
For compressive strength tests, ASTM C 109-05 standards prescribe a cement-sand mix ratio of 1:2.75 and a water/cement ratio of 0.485 for making 2-inch cubes. These cubes are mixed, cast, and cured in saturated lime water at 23°C until testing. Flexural strength testing, outlined in ASTM C...
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01:17Soundness of Cement
The soundness of cement refers to the ability of cement paste to retain its volume after setting. Unsound cement can lead to expansion and structural damage due to the presence of free lime, magnesia, and calcium sulfate. Free lime hydrates very slowly, expanding and causing unsoundness, which is difficult to detect because it intercrystallizes with other compounds. Magnesia also reacts with water, forming crystals that can disrupt the cement's structure. Calcium sulfate can create ettringite,...
01:15Fineness of Cement
The fineness of cement directly influences the rate of hydration, as the hydration begins at the surface of the cement particles. In addition to hydration, the fineness of cement is vital for various properties of concrete including workability, gypsum requirement, and long-term behavior. The fineness of cement is represented in terms of the specific surface of cement which is typically measured in square meters per kilogram, with several methods available for this determination.
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01:23Pore Size Distribution
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01:22Types of Cement II
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