Shape Memory Alloy Microfiber Reinforced Concrete
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Solution Overview
Problem
The existing methods for producing microfiber-reinforced concrete with shape memory alloy fibers face challenges in achieving improved rheological properties and preventing agglomeration, leading to uneven fiber distribution and incomplete compaction, especially at higher fiber volumes.
Innovation Solution
The method involves training fiber elements at a temperature above their transition temperature to form a shape that allows interlocking with the cement matrix, followed by cooling and plastic deformation into an intermediate shape that prevents agglomeration, then reintroducing them into the cement matrix and heating to restore the original shape for enhanced reinforcement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fiber elements with diameters of less than 1 mm and adding less than 2 vol% are used, then the concrete can be processed, but the rheological properties are significantly impaired and hedgehog formation occurs
Solution Approach 1:
The patent changes the physical state parameter of the fiber elements by heating them to a temperature above the transition temperature of the shape memory alloy, causing the fibers to assume a trained shape that prevents agglomeration. This parameter change allows higher fiber content (more than 2 vol.%) to be incorporated while maintaining workability and preventing hedgehog formation.
2Strength
If fiber elements are added to improve tensile strength, then compressive strength is maintained, but rheological properties are impaired and uneven fiber distribution occurs
Solution Approach 1:
The patent applies preliminary action by pre-heating the fiber elements to a temperature above the transition temperature before incorporating them into the cement matrix. This preliminary thermal treatment ensures the fibers are in a state that prevents agglomeration during mixing and pouring, resulting in homogeneous distribution. The fibers are then cooled to room temperature before the concrete is subjected to compression, at which point the shape memory alloy returns to its trained shape to provide reinforcement.
3Strength
If fiber elements are heated to transition temperature to interlock and build prestress, then reinforcement is achieved, but agglomeration occurs during processing
Solution Approach 1:
The patent applies dynamics by utilizing the temperature-dependent shape transformation of the shape memory alloy fibers. The fibers dynamically change their shape based on temperature: at temperatures above the transition temperature, they assume a trained shape that prevents agglomeration and allows easy processing; when cooled to room temperature, they return to their reinforcement-oriented shape to provide strength. This dynamic behavior resolves the contradiction between processability and reinforcement effectiveness.
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
This approach allows for a higher fiber content in microfiber-reinforced concrete with improved castability, reduced agglomeration, and homogeneous distribution, enabling stronger concrete while maintaining ease of processing, even for complex structures.
Implementation Method 1
the fiber elements comprise a shape memory alloy. The shape memory effect of the shape memory alloy is utilized in such a way that the fiber elements interlock with one another and build up a prestress in the cement matrix when the fresh concrete is heated to the transition temperature of the shape memory alloy
Data Source
Figure 1
AI summary
The invention relates to a method for producing a microfiber-reinforced high-strength concrete (1), comprising a cement matrix (10) into which a microfiber addition consisting of fiber elements (11) is introduced. The fiber elements (11) have a shape-memory alloy. The method has at least the following steps: training a fiber shape (12) of the fiber elements (11) at a temperature (T1) above a transition temperature (T2), wherein the fiber shape (12) allows the fiber elements (11) to latch; cooling the trained fiber elements (11); plastically deforming the fiber elements (11) from the trained fiber shape into an intermediate form (13) by means of which the fiber elements (11) are prevented from latching; introducing the fiber elements (11) into the cement matrix (10) in order to form a fresh concrete (14); and casting the fresh concrete (14) and heating the fresh concrete (14) to the transition temperature (T2) such that the fiber elements (11) reform into the fiber shape (12), thereby latching the fiber elements (11). The invention additionally relates to a microfiber-reinforced concrete (1) which is produced using such a method.