The Aggregate Crushing Value (ACV) Apparatus is used to determine the resistance of aggregate to crushing under a specified load. This test is important for assessing the quality of aggregates used in construction, particularly for road construction and concrete production. It provides an indication of the aggregate’s strength and its ability to withstand the stresses imposed during service.
- Crushing Machine:
- The apparatus includes a cylindrical steel container where the aggregate sample is placed. The machine applies a compressive load to the sample, typically using a hydraulic or mechanical system.
- Steel Cylindrical Container:
- A sturdy steel cylinder with a standard diameter (usually 150 mm) and height (typically 130 mm). It holds the aggregate sample during the crushing test.
- Plunger:
- A plunger or piston that is used to apply a compressive load to the aggregate sample. The plunger usually has a diameter of about 150 mm and is designed to fit precisely into the container.
- Load Measuring Device:
- Includes a load cell or similar device to measure the amount of force applied to the aggregate sample. This allows for accurate measurement of the crushing load.
- Graduated Cylinder:
- Used to measure the volume of the crushed aggregate to calculate the aggregate crushing value.
- Standard Weights:
- Standard weights or masses are used to apply a specific load to the aggregate sample during the test.
- Sample Preparation:
- Prepare a representative sample of aggregate, typically sieved to a specific size range (e.g., 10 mm to 12.5 mm). The sample should be dry and free from any contaminants.
- Filling the Container:
- Place the aggregate sample into the cylindrical container. The sample is usually compacted to a specified density, often with a tamper or similar device.
- Applying Load:
- Place the container with the aggregate sample under the crushing machine. Apply a standard load to the aggregate using the plunger. The load is typically applied in two stages: a preliminary load followed by the final load.
- Crushing the Aggregate:
- Apply the load gradually until the aggregate sample is crushed. The test usually involves applying a load at a rate of 4 kN/min until the sample reaches a predetermined load or until crushing is observed.
- Measuring Crushing Value:
- After crushing, remove the aggregate sample from the container and sieve it to separate the crushed material. Measure the mass of the crushed material and the original sample.
- Calculating the Aggregate Crushing Value:
- Calculate the aggregate crushing value using the following formula:
- Quality Control: Ensures that aggregates used in construction meet required strength and durability standards.
- Material Selection: Helps in selecting suitable aggregates for specific applications, such as road construction or concrete production.
- Performance Evaluation: Evaluates the performance of aggregates under load, providing insights into their suitability for various construction projects.
- Structural Integrity: Provides essential information on the strength of aggregates, which is crucial for the stability and longevity of construction projects.
- Durability: Helps assess the ability of aggregates to withstand crushing forces, which impacts the durability of roads and concrete structures.
- Consistency: Ensures that aggregates used in construction meet consistent quality standards, reducing the risk of failure or poor performance.
The Aggregate Crushing Value Apparatus is a critical tool in aggregate testing, offering valuable information about the strength and suitability of aggregates for construction applications.