In-Situ RCC Sampler Assembly for Direct Field Compaction Testing
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Solution Overview
Problem
Current methods for in-situ monitoring of Roller Compacted Concrete (RCC) moisture, density, and strength during construction are indirect and provide delayed, inconsistent results due to calibration issues with nuclear gauges and laboratory testing methods that do not accurately replicate field compaction conditions, especially with materials like fly ash and bottom ash.
Innovation Solution
An in-situ roller compacted concrete testing sampler assembly comprising a stationary tube and a pushing tube assembly that is embedded in the RCC lift and compacted simultaneously with the lift, allowing for direct measurement of moisture, density, and strength under actual field compaction conditions, using a geo-grid mesh to minimize shifting and a compressible-rebound ring to prevent damage during compaction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If indirect testing methods (nuclear gauge, laboratory testing) are used to monitor RCC moisture, density, and strength, then testing can be performed without disturbing the construction process, but the test results are delayed and inconsistent due to calibration issues and inability to replicate actual field compaction conditions
Solution Approach 1:
The testing system is segmented into two functional parts: a stationary tube that remains fixed in the RCC lift and a pushing tube assembly that moves during compaction. This segmentation allows the sampling mechanism to experience actual field compaction conditions while maintaining a stable reference frame for accurate measurement.
Solution Approach 2:
The pushing tube assembly creates a dynamic copy of the field compaction process within the laboratory testing device. By allowing the pushing tube to move relative to the stationary tube during compaction, the system replicates the actual stress and density conditions experienced by the RCC material in the field, enabling accurate measurement without removing material from the construction site.
2Ease of operation
If nuclear gauge is used for moisture and density measurement, then non-contact testing is achieved, but calibration is required for each aggregate type and readings are falsely high for materials containing hydrogen or bound hydrogen
Solution Approach 1:
The patent replaces the nuclear gauge's electromagnetic measurement method with a mechanical sampling and testing approach. The pushing tube assembly mechanically extracts and compacts RCC samples under controlled conditions, then measures moisture, density, and strength through direct physical testing rather than indirect radiation-based measurement, eliminating calibration requirements and false readings from hydrogen-containing materials.
3Measurement precision
If probes are driven into compacted RCC lift for testing, then direct in-situ measurement is achieved, but aggregate within the compacted RCC lift shifts and loosens, causing reduced density readings
Solution Approach 1:
The stationary tube is pre-installed in the RCC lift before compaction occurs. The pushing tube assembly is then inserted and moved during the compaction process itself, allowing the sample to be compacted in-situ within the tube rather than requiring post-compaction probe insertion. This preliminary positioning eliminates aggregate disturbance because the sampling mechanism is already in place and the RCC material is compacted around it rather than being disturbed by insertion after compaction.
4Manufacturing precision
If test cylinders are prepared in the field and compacted with hammers, then laboratory testing conditions are established, but compaction energy is operator-dependent and inconsistent with actual field compaction equipment
Solution Approach 1:
The pushing tube assembly is designed to be dynamic rather than static, allowing it to move relative to the stationary tube during compaction. This dynamic mechanism automatically adjusts to the compaction forces applied by field equipment, enabling the same compaction energy to be applied to both the RCC lift and the sample within the tube. The system adapts to different compaction equipment and conditions rather than requiring controlled laboratory hammer compaction, eliminating operator dependence while maintaining precision.
Data Source
AI summary
An in-situ roller compacted concrete testing sampler assembly is provided. The testing sampler assembly includes a first tube and a second tube. The second tube is configured to contain a roller compacted sample. The first tube and the second tube are configured to be placed in a loose roller compacted concrete lift for a construction site, and compacted simultaneously during the compaction of the loose roller compacted concrete lift. The second tube is configure to move with respect to the first tube to compact the roller compacted sample during compaction of the loose roller compacted concrete lift.