Method for Integrating Fiber Optic Sensor Systems in Geopolymer Concrete for Real-Time Monitoring of Crack Propagation

Abstract

This invention introduces a method for integrating fiber optic sensor systems into geopolymer concrete to enable real-time monitoring of crack propagation and structural health. The method includes the preparation of fiber optic sensors with chemical-resistant coatings to endure the alkaline environment of geopolymer concrete, their strategic embedding in high-stress zones during casting, and the calibration of the sensors for accurate monitoring of strain, temperature changes, and crack development. The system enables continuous data collection and transmission to an optical interrogator, ensuring reliable and precise performance throughout the structure's lifespan. Geopolymer concrete, used as the primary material, is composed of industrial byproducts such as fly ash or ground granulated blast furnace slag, activated with alkali solutions like sodium silicate and sodium hydroxide. This composition reduces carbon emissions by up to 80% compared to traditional Portland cement. Additionally, recycled aggregates replace up to 50% of natural aggregates, promoting resource efficiency, while polypropylene fibers (0.1%-1% by weight) enhance crack resistance and tensile strength, ensuring long-term durability.This method is particularly suited for applications in critical infrastructure, including bridges, tunnels, high-rise buildings, dams, and marine structures, where structural safety and durability are paramount. By integrating sustainable geopolymer concrete with advanced structural health monitoring technology, this invention addresses modern construction challenges, ensuring safer, more resilient, and environmentally responsible infrastructure development.

Specification

Description:BACKGROUND
Field of the invention Title: Method for Integrating Fiber Optic Sensor Systems in Geopolymer Concrete for Real-Time Monitoring of Crack Propagation
DESCRIPTION:
Field of the Invention:
The present invention relates to sustainable construction materials and structural health monitoring technologies. It focuses on the integration of fiber optic sensor systems into geopolymer concrete to monitor crack propagation in real-time. This invention is applicable in civil engineering, material science, and structural engineering, addressing durability, sustainability, and safety challenges in modern infrastructure.
BACKGROUND:
Concrete is the most widely used construction material globally. However, traditional Portland cement-based concrete contributes significantly to global CO₂ emissions, accounting for approximately 8% of total emissions. The search for sustainable alternatives has led to the development of geopolymer concrete, which uses industrial byproducts like fly ash and slag to form a low-carbon binder.
Geopolymer concrete, with its lower environmental footprint, offers several advantages, including improved durability and resistance to chemical and thermal stress. Despite these benefits, geopolymer concrete remains vulnerable to micro-cracking, which can compromise the structural integrity of concrete over time. Early detection of these cracks is critical for ensuring structural safety, minimizing maintenance costs, and extending the lifespan of infrastructure Fiber optic sensors have emerged as an advanced solution for real-time structural health monitoring (SHM). These sensors can measure strain, temperature, and crack propagation with high accuracy. Unlike conventional sensors, fiber optic sensors are immune to electromagnetic interference, resistant to corrosion, and capable of operating in harsh environments. However, integrating these sensors into geopolymer concrete poses challenges, such as the risk of sensor damage during mixing and curing, signal attenuation, and long-term durability issues. The present invention addresses these challenges by introducing a method to securely integrate fiber optic sensor systems into geopolymer concrete during the mixing and curing phases, ensuring reliable performance throughout the lifecycle of the structure.
SUMMARY OF THE INVENTION
The invention provides a method for embedding fiber optic sensors into geopolymer concrete to enable real-time monitoring of crack propagation. The process involves:
1. Sensor Preparation: Encapsulating fiber optic sensors in protective coatings to shield them from the high alkalinity and mechanical stress of the geopolymer concrete matrix.
2. Sensor Placement: Strategically positioning the sensors within the concrete mold to monitor critical stress points and areas prone to cracking.
3. Mixing Optimization: Adjusting the geopolymer mix design to minimize mechanical stresses on the sensors during the mixing and curing phases.
4. Signal Integrity Assurance: Incorporating signal attenuation mitigation techniques to ensure reliable data transmission from embedded sensors. This method ensures that the fiber optic sensors remain functional and accurate throughout the structure's lifespan, enabling proactive maintenance and reducing long-term costs.
DETAILED DESCRIPTION:
Step 1: Preparation of Fiber Optic Sensors
Fiber optic sensors are coated with protective layers of polymer or epoxy materials to resist chemical attacks from the alkaline geopolymer matrix. Sensors are calibrated for strain, temperature, and crack detection.
Step 2: Geopolymer Concrete Composition
The geopolymer binder consists of industrial byproducts such as fly ash or slag, activated using an alkali solution (e.g., sodium hydroxide and sodium silicate). Recycled aggregates replace natural aggregates, reducing environmental impact. Polypropylene fibers may be added for additional crack resistance.
Step 3: Sensor Integration Process
1. Mold Setup: Sensors are positioned in the concrete mold at locations prone to stress, such as near reinforcement bars or along high-stress paths.
2. Mixing and Pouring: The geopolymer mix is carefully poured into the mold, ensuring minimal disturbance to sensor placement. Vibration is controlled to prevent damage to the sensors.
3. Curing: The concrete is cured under controlled conditions to maintain sensor alignment and prevent signal degradation.
Step 4: Signal Calibration and Monitoring
Post-curing, the sensors are connected to an optical interrogator for calibration and testing. The system is programmed to detect strain changes and crack propagation in real-time, enabling proactive maintenance and structural assessment.
ADVANTAGES OF THE INVENTION
1. Sustainability: Combines low-carbon geopolymer concrete with fiber optic technology, reducing the environmental impact of construction.
2. Durability: Enables early detection of micro-cracks, extending the lifespan of concrete structures.
3. Efficiency: Reduces maintenance costs by enabling proactive structural health monitoring.
4. Reliability: Protects sensors from chemical and mechanical stresses, ensuring long-term performance.
APPLICATIONS
The method has wide-ranging applications across various sectors, particularly in infrastructure and construction projects requiring enhanced durability, sustainability, and structural health monitoring. Some key applications include:
1. Bridges and Highways:
2. High-Rise Buildings:
3. Tunnels and Underground Structures:
4. Dams and Retaining Walls:
5. Precast Concrete Elements:


CONCLUSION
The invention provides an advanced method for integrating fiber optic sensor systems into geopolymer concrete to monitor crack propagation in real time. This innovation combines the benefits of low-carbon, sustainable geopolymer concrete with state-of-the-art structural health monitoring (SHM) technology, addressing critical challenges in modern construction. By embedding fiber optic sensors in geopolymer concrete, the method enables continuous and accurate monitoring of strain, temperature variations, and crack development, thus enhancing the safety, durability, and efficiency of concrete structures.
This method is particularly suited for critical infrastructure projects, ensuring early detection of structural damage and enabling timely maintenance, which reduces lifecycle costs and minimizes environmental impact. The integration of recycled aggregates and polypropylene fibers further promotes sustainability, making this a comprehensive solution for eco-friendly, durable, and smart construction.
, Claims:1. (Independent Claim): A method for integrating fiber optic sensor systems into geopolymer concrete, comprising:
o Preparing and protecting sensors with chemical-resistant coatings,
o Embedding sensors in a geopolymer mix containing recycled aggregates and polypropylene fibers,
o Curing the mix under controlled conditions,
o Enabling real-time monitoring of crack propagation through optical signal calibration.
2. (Dependent Claim): The method as claimed in Claim 1, wherein the geopolymer concrete binder comprises fly ash, slag, or metakaolin activated with an alkali solution.
3. (Dependent Claim): The method as claimed in Claim 1, wherein polypropylene fibers are incorporated at 0.1%-1% by weight to enhance tensile strength.
4. (Dependent Claim): The method as claimed in Claim 1, wherein fiber optic sensors detect strain, temperature, and crack formation in real-time.
5. (Dependent Claim): The method as claimed in Claim 1, wherein recycled concrete aggregates replace natural aggregates in proportions ranging from 30%-70% of the total aggregate.

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