T_85_aashtoB - SPECIFIC GRAVITY OF COARSE AGGREGATE AASHTO...

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1 SPECIFIC GRAVITY OF COARSE AGGREGATE AASHTO T 85 GLOSSARY Absorption: The increase in weight due to water contained in the pores of the material. Bulk Specific Gravity (also known as Bulk Dry Specific Gravity): The ratio of the weight in air of a unit volume of aggregate at a stated temperature to the weight in air of an equal volume of gas-free distilled water at the stated temperature. Bulk SSD Specific Gravity: The ratio of the weight in air of a unit volume of aggregate, including the weight of water within the voids filled to the extent achieved by submerging in water for approximately 15 hours, to the weight in air of an equal volume of gas-free distilled water at the stated temperature. Apparent Specific Gravity: The ratio of the weight in air of a unit volume of the impermeable portion of aggregate (does not include the permeable pores in aggregate) to the weight in air of an equal volume of gas-free distilled water at the stated temperature. SSD - Saturated, Surface Dry. The condition in which the aggregate has been soaked in water and has absorbed water into its pore spaces. The excess, free surface moisture has been removed so that the particles are still saturated, but the surface of the particle is essentially dry. SCOPE Specific Gravity is the ratio of the weight of a given volume of aggregate to the weight of an equal volume of water. Water, at a temperature of 73.4°F (23°C) has a specific gravity of 1. Specific Gravity is important for several reasons. Some deleterious particles are lighter than the good aggregates. Tracking specific gravity can sometimes indicate a change of material or possible contamination. Differences in specific gravity can be used during production to separate the bad particles from the good using a heavy media liquid. Specific gravity is critical information for the Hot Mix Asphalt Design Engineer. It is used in calculating air voids, voids in mineral aggregate (VMA), and voids filled by asphalt (VFA). All are critical to a well performing and durable asphalt mix. Water absorption can also be an indicator of asphalt absorption. A highly absorptive aggregate could lead to a low durability asphalt mix. In Portland Cement Concrete the specific gravity of the aggregate is employed in calculating the
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This note was uploaded on 07/23/2009 for the course CEE 353 taught by Professor Bari during the Spring '09 term at Universidad Nacional de Asuncion.

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T_85_aashtoB - SPECIFIC GRAVITY OF COARSE AGGREGATE AASHTO...

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