Two-Axis Strain Gauge Sensor for Concrete Slump Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing concrete mixing technologies face challenges in accurately measuring the water-cement ratio, slump, and rheological properties due to factors like variable speed mixing, concrete buildup, and sensor wear, which affects the consistency and quality of the concrete mixture.
Innovation Solution
A sensor system with strain gauges mounted on two axes, one parallel and one perpendicular to the mixer's rotation, measures forces applied by the concrete mixture, and a dual-layer protective cover extends the sensor's lifespan, allowing for precise monitoring of slump, consistency, and water-cement ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-axis sensor measures force applied by concrete mixture, then the device complexity is reduced, but the measurement precision of slump and rheological properties deteriorates
Solution Approach 1:
The patent transitions from single-axis force measurement to two-axis force measurement. The sensor measures forces in both the axial direction (parallel to drum rotation) and radial direction (perpendicular to drum rotation), enabling comprehensive characterization of concrete mixture behavior during mixing. This dimensional expansion provides complete rheological data without excessive complexity.
2Device complexity
If the sensor operates without protective cover, then the device complexity is reduced, but the sensor lifespan deteriorates due to abrasion and corrosion
Solution Approach 1:
The patent implements a protective cover that shields the sensor from abrasive concrete aggregates and corrosive mixture components before damage can occur. The cover acts as a sacrificial barrier, protecting the sensitive sensor elements during the harsh mixing environment, thereby extending sensor operational life.
Solution Approach 2:
The protective cover is constructed from composite materials that combine wear resistance and corrosion resistance properties. This composite structure provides dual protection against the two primary degradation mechanisms (abrasion from aggregates and corrosion from concrete chemistry) without significantly increasing sensor complexity.
3Adaptability or versatility
If the sensor measures force at variable mixing speeds, then the adaptability to real mixing conditions is improved, but the measurement precision deteriorates due to noise interference
Solution Approach 1:
The patent incorporates feedback mechanisms that continuously monitor the mixing drum rotation speed and adjust the force measurement interpretation accordingly. By feeding back the actual mixing conditions to the measurement system, the sensor can distinguish between force variations caused by speed changes and those caused by concrete rheological properties, maintaining precision across variable speeds.
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 system provides improved accuracy in measuring concrete properties, reduces noise interference, and extends sensor lifespan by protecting against abrasion and corrosion, ensuring consistent mixing quality and reduced maintenance costs.
Implementation Method 1
The sensor includes a sensor body and strain gauges mounted on two axes, one parallel and one perpendicular to the direction of rotation of the mixer, that measure the force applied by a concrete mixture onto the sensor body
Data Source
Figure 1
Figure 2
Figure 3~6
AI summary
A sensor measures slump and rheological characteristics of the concrete and is connected to a system that adjusts the slump by monitoring the sensor within the interior surface of a concrete mixer and controlling liquid additions. Data is analyzed by a computer processing unit to determine the slump and rheological characteristics of the concrete, liquid required to meet the slump requirements. The measurement done by the sensor is more accurate then the existing methods because it brings into consideration the effect of the helix inside the mixer on the movement of the concrete mixture inside the mixer. Furthermore, this method also allows the operation of the sensor in "real" life situations where the rotation speed of the mixer can't be maintained at a fixed value. The fact that the sensor rotates with the drum and that the concrete mixture is pushed to the bottom of the mixing drum guaranties that all the concrete is "sampled" by comparing results collected from each revolution of the mixing drum.