6.6
Prueba del factor de compactación
El ensayo del factor de compactación es un método utilizado para evaluar la trabajabilidad del hormigón. Es especialmente adecuado para mezclas de hor…
La prueba del factor de compactación determina la trabajabilidad del concreto con tamaños de agregados de hasta un máximo de una pulgada y media.
El equipo de prueba consta de dos tolvas truncadas en forma de cono con puertas batientes en la parte inferior y un cilindro, todo apilado secuencialmente, con superficies interiores pulidas para reducir la fricción.
El hormigón se coloca en la tolva superior sin compactar, y la puerta inferior se abre, permitiendo que el hormigón fluya hacia la tolva inferior.
A continuación, se abre la puerta inferior de la tolva inferior, permitiendo que el hormigón caiga en el cilindro de abajo, y se elimina el exceso de hormigón.
Se utiliza una varilla de acero para empujar y desalojar suavemente el hormigón que se atasca en una o ambas tolvas durante la prueba.
Se determina el peso final del hormigón en el volumen establecido del cilindro y se calcula la densidad para este parcialmente compactado.
La densidad completamente compactada se determina llenando el cilindro con concreto en cuatro capas y apisonando cada capa.
Por último, el factor de compactación se calcula como la relación entre la densidad del hormigón parcialmente compactado y la densidad del hormigón totalmente compactado, lo que indica la trabajabilidad de la mezcla.
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Q1: What is the compacting factor test used for in concrete testing?
The compacting factor test assesses the workability of concrete, indicating how easily concrete flows and compacts. It measures the ratio of partially compacted concrete density to fully compacted density, providing a numerical value that reflects the concrete's ability to be placed and consolidated in molds during construction projects.
Q2: What equipment is needed to perform a compacting factor test?
The test requires two truncated cone-shaped hoppers with hinged bottom doors, a cylinder for collection, and a steel rod. All equipment has polished interior surfaces to minimize friction and allow concrete to flow freely between components during the test procedure.
Q3: How is the compacting factor value calculated?
The compacting factor is calculated as the ratio of the density of partially compacted concrete to the density of fully compacted concrete. Partially compacted density is obtained from concrete falling through hoppers into a cylinder, while fully compacted density is determined by filling the cylinder in four layers and tamping each layer thoroughly.
Q4: What concrete aggregate sizes are suitable for the compacting factor test?
The compacting factor test is suitable for concrete mixes containing aggregates with a maximum size of one and a half inches. This size limitation ensures the concrete flows properly through the hopper system and provides reliable workability measurements for the specified aggregate range.
Q5: What steps are involved in performing the compacting factor test procedure?
Concrete is placed in the upper hopper without compaction. The bottom door opens, allowing concrete to flow into the lower hopper. The lower hopper door then opens, letting concrete fall into the cylinder below. Excess concrete is struck off, and a steel rod dislodges any stuck material. The cylinder weight is recorded to calculate partially compacted density.
Q6: Why are polished interior surfaces important in compacting factor test equipment?
Polished interior surfaces reduce friction between the concrete and equipment, allowing the concrete to flow freely and naturally through the hoppers and into the cylinder. This minimizes artificial resistance and ensures the test accurately reflects the concrete's true workability characteristics without equipment interference.
Q7: How does the compacting factor test differ from determining fully compacted concrete density?
The compacting factor test measures partially compacted density by allowing concrete to fall freely through hoppers, simulating natural placement conditions. Fully compacted density is determined separately by deliberately filling the cylinder in four layers and tamping each layer to achieve maximum compaction, providing a baseline for comparison.