Electrochemical Sensor for Cement Mixture Passivation
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Solution Overview
Problem
Current methods for ensuring complete filling and passivation of tendons with a cement and water mixture in structural applications are inadequate, leading to potential corrosion due to incomplete filling or contamination, which can result in structural failures.
Innovation Solution
A method and sensor system using three electrically conductive electrodes to measure the passivation properties of the mixture in real-time during injection, verifying the pH and chloride content to ensure comprehensive corrosion protection by applying direct currents and measuring voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual inspection methods (drilling holes or transparent covers) are used to check filling, then filling quality can be assessed, but the process requires considerable time, effort and investment, and some locations are not accessible
Solution Approach 1:
The patent replaces mechanical/visual inspection methods (drilling holes, transparent covers) with an electrochemical sensor system that measures passivation properties electrically. This substitution eliminates the need for physical access holes or transparent covers, reducing device complexity while maintaining measurement precision through electrochemical potential measurements.
Solution Approach 2:
The patent introduces a sensor as an intermediary element that can be integrated into the anchorage system. This sensor acts as a mediator between the filling process and quality assessment, enabling indirect measurement of filling quality through passivation property detection without requiring direct visual access or complex inspection procedures.
2Reliability
If extensive measures are taken to eliminate uncertainty about filling errors, then filling quality can be ensured, but the time up to completion is severely limited by the incipient setting of the mixture
Solution Approach 1:
The patent implements preliminary quality control by measuring passivation properties during the injection operation itself, before the mixture fully sets. This allows early detection of filling deficiencies or contamination issues while there is still time to take corrective action, eliminating the need for extensive post-injection verification measures that would consume additional time.
Solution Approach 2:
The patent establishes a feedback mechanism where the sensor continuously monitors passivation properties during injection and provides real-time information about filling quality. This feedback allows operators to immediately adjust the injection process or take corrective measures while the mixture is still workable, ensuring reliability without extending the overall operation time.
3Reliability
If complete filling with mixture is achieved, then passivation and corrosion protection are ensured, but contamination with chloride or use of cement with minimal alkalinity can still compromise passivation properties
Solution Approach 1:
The patent uses a disposable sensor that is integrated into the anchorage system and used once during the injection process. This single-use sensor provides comprehensive quality verification of passivation properties, detecting both filling completeness and chemical suitability (alkalinity and chloride content). The low cost and simple integration of this disposable measurement tool enable thorough quality control without adding significant system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables direct and comprehensive quality control during injection, allowing for immediate corrections and long-term corrosion monitoring, thereby ensuring effective corrosion protection of steel strands.
Implementation Method 1
selecting the first electrode (2) and the third electrode (5) and applying between these two electrodes a direct current, referred to as first direct current, of predetermined polarity, referred to as first polarity, resulting in electrolytic reactions on the third electrode (5)
Implementation Method 2
measuring the voltage V between these two electrodes during said first predetermined duration D1
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A method for determining the passivating properties of a mixture (11) containing at least two components, which are cement and water, including the steps of: - taking three elements, each made up of an electrically conductive material, these elements being referred to as first electrode (2), second electrode (4) and third electrode (5), - fixing at least one these three electrodes on a support (3) in such a manner that they are electrically insulated reciprocally, and the mixture (11 ) is able to come in contact with at least one predetermined face situated on each electrode, these faces being referred to as first face (20), second face (40) and third face (50), - selecting the first electrode (2) and the third electrode (5) and applying between these two electrodes, a direct current, referred to as first direct current, of predetermined intensity value, referred to as first intensity value, and predetermined polarity, referred to as first polarity, resulting in electrolytic reactions on the third electrode (5), for a predetermined duration (D1 ), referred to as first duration, and then - selecting the second electrode (4) and the third electrode (5), and measuring the voltage (V) between these two electrodes during said first predetermined duration (D1 ), and storing the measurement for the variation of said voltage (V) during said first predetermined duration (D1 ), - comparing the variations in the voltage (V) between the second electrode (4) and the third electrode (5) during the first predetermined duration (D1 ), with predetermined data defining at least whether or not a mixture (11) has passivating properties, and - determining at least whether or not the mixture (11 ) has such passivating properties.