Polyurethane Micro-capsules for Self-repairing Concrete
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Solution Overview
Problem
Conventional concrete technologies fail to effectively self-diagnose and self-repair micro-cracks, as hollow fiber capsule methods are limited by uneven distribution, brittle material characteristics, and reduced concrete strength, making it difficult to address micro-crack repair efficiently and reliably.
Innovation Solution
The use of polyurethane polymer micro-capsules dispersed within the concrete, which are fabricated by mixing polyurethane micro-capsules with concrete and water in specific ratios, stirring, and allowing for curing to create a self-repairing concrete that can autonomously repair micro-cracks through capillary siphon effects and polymerization reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hollow fiber capsules are used for self-repairing concrete, then self-repairing function is achieved, but uniform distribution in concrete is difficult and concrete strength is reduced
Solution Approach 1:
The patent changes the material parameters by replacing hollow fiber capsules with polyurethane polymer micro-capsules of smaller size (10-100 μm diameter). This parameter change enables uniform distribution throughout the concrete matrix while the smaller size prevents significant strength reduction. The micro-capsules maintain self-repairing functionality through controlled rupture at micro-crack sites.
Solution Approach 2:
The patent employs disposable micro-capsules that are designed to rupture when needed. These polyurethane micro-capsules contain repair agents that are released upon capsule rupture at crack sites, performing their self-repairing function once and then being consumed. This disposable nature allows widespread distribution without long-term structural concerns.
2Reliability
If hollow fiber capsules are used for self-repairing, then repair capability is provided, but premature rupture occurs during construction due to vibration
Solution Approach 1:
The patent modifies the mechanical parameters by using polyurethane polymer material with appropriate elasticity and strength for micro-capsule walls. The smaller size (10-100 μm) and optimized wall thickness provide sufficient resistance to construction vibrations while maintaining sensitivity to micro-crack stresses. This parameter optimization prevents premature rupture during handling and construction.
3Reliability
If hollow fiber capsules are used, then self-repairing is achieved, but micro-crack repair is limited due to capsule size and strength
Solution Approach 1:
The patent applies segmentation by dividing the repair system into numerous tiny micro-capsules (10-100 μm) distributed throughout the concrete. This segmentation allows the capsules to target and respond to individual micro-cracks independently. The fine segmentation enables penetration into and repair of micro-crack networks that would be inaccessible to larger hollow fiber capsules.
Solution Approach 2:
The patent changes the size parameter from millimeter-scale hollow fibers to micrometer-scale polyurethane micro-capsules. This 100-fold size reduction enables the capsules to effectively address micro-cracks while maintaining sufficient wall strength through optimized polyurethane formulation and wall thickness control.
4Reliability
If hollow fiber capsules are used, then repair agents are introduced, but concrete strength is reduced due to introduced defects
Solution Approach 1:
The patent uses inexpensive polyurethane micro-capsules as temporary, disposable elements embedded in the concrete. These micro-capsules serve their purpose by rupturing at micro-cracks to release repair agents, then being consumed in the process. Their temporary presence and small size minimize negative impact on concrete strength compared to permanent inclusions.
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
The polyurethane polymer micro-capsule concrete achieves improved mechanical performance and effective self-repair of micro-cracks, enhancing the durability and service life of concrete structures by ensuring uniform distribution and repeated repair capabilities without compromising the concrete's strength.
Implementation Method 1
self-repairing concrete that can autonomously repair micro-cracks through capillary siphon effects and polymerization reactions
Implementation Method 2
self-repairing concrete that can autonomously repair micro-cracks through capillary siphon effects and polymerization reactions
Data Source
AI summary
A self-repairing concrete includes polyurethane polymer micro-capsules, in which the polyurethane polymer micro-capsules are mixed for a fixed function of micro-cracks. The quality mixture ratio is: concrete/micro capsules/water=100:1-15:15-50. The manufacturing method is weighing a full amount of water in a container, adding polyurethane polymer micro-capsules, stirring, until fully dispersed microcapsules; pouring the water into the mixing container, adding the corresponding quality of cement; stirring; adding sand and gravel filling materials, conducting worksite watering, ⅓ volume for each time, vibrating, and air exhausting; until the slurry filling mold.