The particle density of an aggregate is the ratio of its mass to the volume of its solid particles, excluding the voids between particles but including the voids within individual particles.
In simpler terms, imagine you have a pile of gravel. The particle density doesn't consider the empty spaces between the gravel pieces in the pile. However, it does consider any tiny air pockets or pores within each individual piece of gravel.
Here's a breakdown:
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Definition: Particle density (sometimes called "absolute specific gravity") focuses on the solid material itself.
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Calculation: Particle density is calculated as:
Particle Density = (Mass of Aggregate) / (Volume of Solid Aggregate Particles)
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Volume Considerations: The volume used in the calculation includes:
- The volume of the solid material.
- The volume of internal voids within the aggregate particles that are impermeable to water.
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Volume Exclusions: The volume excludes:
- The volume of the voids between aggregate particles.
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Significance: Particle density is a fundamental property of aggregates and is used in various calculations, including:
- Mix Design: Determining the correct proportions of aggregates, cement, and water in concrete mixes.
- Volume Calculations: Converting between mass and volume measurements of aggregates.
- Material Characterization: Understanding the physical properties of different types of aggregates.
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Difference from Bulk Density: It's important to distinguish particle density from bulk density. Bulk density does include the volume of voids between particles. Particle density is always higher than bulk density for the same aggregate material.
Therefore, particle density gives a measure of the density of the solid, impermeable portion of the aggregate material itself.
