Aggregate Crushing Value Apparatus Specifications

Aggregate Crushing Value (ACV) Apparatus: Essential Specifications

The Aggregate Crushing Value (ACV) test is a fundamental procedure in civil engineering and construction materials testing. It provides a relative measure of the resistance of coarse aggregate to crushing under a gradually applied compressive load. This value is crucial for assessing the suitability of aggregates for use in various pavement layers, especially base courses, and other load-bearing applications where aggregate strength is paramount.

The accuracy and reliability of the ACV test result depend heavily on the apparatus conforming strictly to established standards, such as BS 812: Part 110, IS 2386 (Part 4), or ASTM C131/C131M. Below are the detailed specifications for a standard ACV test apparatus:

1. Steel Cylinder:

Internal Diameter: 150 mm nominal (Actual internal diameter typically 154 mm ± 0.5 mm to allow for liner thickness).
Internal Height: Minimum 125 mm.
Wall Thickness: Sufficient to prevent significant distortion under load (typically around 6-7 mm).
Material: Hardened steel.
Plunger Guide: The cylinder must incorporate a robust guide mechanism (e.g., lugs or a machined collar) to ensure the plunger moves vertically without binding or significant lateral movement.
Base Plate: A removable base plate of hardened steel, ground flat on both faces, fits securely into the bottom of the cylinder.

Liner: A removable hardened steel liner with an internal diameter of exactly 150.0 mm ± 0.5 mm and an internal height of at least 100 mm is fitted inside the cylinder. This liner ensures precise dimensions for the test sample and facilitates easy removal after compaction.

2. Plunger (Ram or Tamping Rod):

Diameter: A nominal diameter slightly less than the liner’s internal diameter to allow free vertical movement without binding. The working face must be circular and ground flat.
Common Specification: Diameter typically around 149.5 mm ± 0.5 mm, ensuring a clearance of approximately 0.25-0.5 mm per side within the liner.
Length: Sufficient to project adequately from the cylinder when positioned on the aggregate sample before loading commences.
Material: Hardened steel.
Weight: The plunger assembly (including any integral stem) must have a total mass of exactly 14