Expression of Cementitious Pore Solution and the Analysis of Its Chemical Composition and Resistivity Using X-ray Fluorescence
September 23rd, 2018
This protocol describes the procedure to express fresh pore solution from cementitious systems and the measurement of its ionic composition using X-ray fluorescence. The ionic composition can be used to calculate pore solution electrical resistivity, which can be used, together with concrete electrical resistivity, to determine the formation factor.
The overall goal of this procedure is to describe a method to describe fresh pore solution from a plastic cementitious base system using a stainless steel pressurized nitrogen gas filter and to measure the pore solution chemical composition using an energy dispersive X-ray fluorescence benchtop spectrometer. The chemical ionic composition measured by the XRF can be used the calculate the electrical resistivity of the pore solution, which can then be used in conjunction with the electrical resistivity of concrete to determine the formation factor. Since XRF is a commonly used device in the cement industry, this method could potentially enable cement manufacturers to use a tool already at their disposal to provide more information about the cementitious pore solution such as the ionic composition and resistivity for numerous applications and a lower cost and testing time than conventional methods.
Essentially, this method could extend the applications for the use of an XRF for a variety of cement and concrete studies. To begin this procedure, check that the individual components of the pore solution extractor are clean and dry. Then, assemble the pore solution extractor according to the manufacturer's instructions.
Check that there are no visible deformities in the cellulose filter. Next, add the fresh paste into the main chamber. Make sure to leave at least one centimeter from the top free.
Then, connect the pore solution extractor to the nitrogen source and seal the main chamber. Use a clean canister to collect the pore solution. Open the valve of the nitrogen tank.
Use the pressure gage to regulate the pressure to 200 kilopascals. Maintain constant pressure for a period of five minutes. Transfer the pore solution to a five milliliter syringe.
Make sure to eject all air bubbles in the syringe. Seal the syringe with a needle cap. Test immediately or store inside a five degrees C chamber until testing.
Assemble the solution testing containers. Make sure that the plastic cylinders are clean and dry. Place the polypropylene film on top of the larger cylinder.
Insert the smaller cylinder on top of the larger cylinder. Push down on the smaller cylinder, pressing the film in between. Ensure that the film is smooth and has no tears or deformations.
The main ionic species present in pore solution needed to calculate the electrical resistivity of pore solution are sodium, potassium, calcium, sulfate, and hydroxide. The results from the XRF analysis will show the concentration of sodium, potassium, calcium, and sulfide ions. Inject at least two grams of the pore solution sample in the assembled testing container.
Seal the container with a lid. Leave the container with the solution on a paper towel for two minutes. Check that the film has no leak.
Place the sample inside the XRF sample holder and close the XRF. Analyze the sample for ionic composition. A series of calculations are then completed to obtain the concentration of the sulfate and hydroxide ions and the electrical resistivity of the pore solution.
First, use stoichiometry to calculate the concentration of the sulfate ions based on the concentration of the sulfide ions detected by the XRF. Then, use a charge balance to calculate the concentration of hydroxides in the pore solution. After obtaining all the ionic concentrations of the five ionic species considered, convert the ionic concentrations from parts per million to mole per liter assuming a density of 1, 000 gram per liter.
And finally, use the model developed by Snyder and others to calculate the electrical resistivity of the pore solution. A representative result for the expressed pore solution in the sealed syringe is shown for a cement paste with a water-to-cement ratio of 0.36 at 10 minutes of expression. A table with representative results for ionic composition and resistivity is shown for a cement paste with a water-to-cement ratio of 0.36 at 10 minutes of expression.
After watching this video, you should have a good understanding of how to express fresh pore solution from a plastic paste sample using a pressurized nitrogen gas filter and to measure the pore solution chemical composition using an energy dispersive X-ray fluorescence benchtop spectrometer. From the measured values of the XRF, you should able to obtain the ionic concentrations of the main ionic species present in the pore solution and to calculate the electrical resistivity of pore solution. This information can be ultimately used in conjunction with the electrical resistivity of concrete to calculate the formation factor and for other concrete durability applications and concrete studies.
If performed properly and safely, this procedure should take no longer than 20 minutes from start to finish.
Overview
This protocol outlines a method for expressing fresh pore solution from cementitious systems and measuring its ionic composition using X-ray fluorescence (XRF). The ionic composition is essential for calculating pore solution electrical resistivity, which, along with concrete electrical resistivity, helps determine the formation factor.
Key Study Components
Area of Science
- Cement Chemistry
- Concrete Durability
- Material Science
Background
- The method utilizes a stainless steel pressurized nitrogen gas filter.
- XRF is a widely used tool in the cement industry for chemical analysis.
- Understanding ionic composition aids in assessing concrete performance.
- This approach offers a cost-effective alternative to traditional testing methods.
Purpose of Study
- To provide a reliable method for extracting and analyzing pore solution from cementitious materials.
- To enable the calculation of electrical resistivity of pore solutions.
- To enhance the understanding of the relationship between pore solution properties and concrete durability.
Methods Used
- Assembly of a pore solution extractor following manufacturer instructions.
- Use of nitrogen gas to pressurize and extract the pore solution.
- Analysis of ionic composition using an energy dispersive X-ray fluorescence spectrometer.
- Calculation of electrical resistivity based on ionic concentrations.
Main Results
- Successful extraction of pore solution from a cement paste with a specific water-to-cement ratio.
- Measurement of key ionic species including sodium, potassium, calcium, sulfate, and hydroxide.
- Calculation of electrical resistivity based on measured ionic concentrations.
- Demonstration of the method's efficiency and applicability in concrete studies.
Conclusions
- The described method provides a quick and effective means to analyze pore solution properties.
- Results can inform concrete durability assessments and related applications.
- This protocol can be integrated into existing cement testing workflows.
Frequently Asked Questions
Executive Industry Relevance
Rapid and accurate determination of cementitious pore solution composition and resistivity is critical for material science teams optimizing concrete durability and performance. This method leverages X-ray fluorescence (XRF) to provide quantitative ionic profiles and resistivity data, supporting predictive modeling and mechanistic de-risking in construction materials R&D. Integrating these measurements enables more informed decisions at key inflection points in material development pipelines.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables quantitative assessment of ionic species relevant to material performance hypotheses.
- Supports mechanistic de-risking by clarifying the relationship between pore solution chemistry and concrete durability.
- Facilitates predictive confidence in material selection and formulation strategies.
Screening & Assay Development
- Provides standardized, reproducible measurement of ionic composition for comparative studies.
- Delivers rapid, quantitative outputs suitable for high-throughput screening of cement formulations.
- Enables reliable evaluation of material modifications and additives on pore solution properties.
Translational & Preclinical Research
- Aligns laboratory measurements with real-world durability metrics through resistivity and formation factor calculations.
- Supports continuity from early material discovery to preclinical validation of concrete performance.
- Reduces risk in advancing new formulations by providing mechanistic insight into ionic transport and durability.
Pipeline & Workflow Integration
This XRF-based workflow fits from early discovery through preclinical material validation, enabling iterative optimization and risk-adjusted advancement of cementitious systems.
- Discovery Biology: Quantitative ionic profiling supports hypothesis testing and mechanistic understanding of material behavior.
- Screening: Standardized XRF outputs enable reproducible comparison across formulations and batches.
- Analytics: Provides direct measurements and calculated resistivity values for robust data-driven decisions.
- Translational Research: Links laboratory ionic data to field-relevant durability outcomes via formation factor analysis.
- Enterprise Reuse: XRF instrumentation and protocols are broadly applicable across cement and concrete R&D programs.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces ambiguity in material performance assessment.
- Operational Value: Streamlines workflows with rapid, cost-effective, and reproducible measurements.
- Strategic Value: Enables better go/no-go decisions and capital allocation in material development pipelines.
- Portfolio Impact: Supports risk-adjusted prioritization and advancement of new cementitious formulations.
Implementation Considerations
- Requires expertise in XRF operation and ionic analysis.
- Needs access to calibrated XRF instrumentation and sample preparation infrastructure.
- Demands cross-team standardization of sample handling and data interpretation.
- Adaptable to various cementitious systems with appropriate calibration and validation.
- Sample integrity and rapid processing are critical to minimize evaporation and carbonation artifacts.
