MaterialslabManual - EGM 3520L Material Testing Lab...

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1 EGM 3520L Material Testing Lab Specific Gravity and Absorption Tests of Coarse Aggregates (Ref. ASTM C 127) 1. Introduction Aggregates are a component of composite materials such as concrete and asphalt concrete; the aggregate serves as reinforcement to add strength to the overall composite material. 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. In Portland Cement Concrete the specific gravities of the aggregate is employed in calculating the percentage of voids and the solid volume of aggregates in computations of yield. The absorption is important in determining the net water-cement ratio in the concrete mix. Knowing the specific gravity of aggregates is also critical to the construction of water filtration systems, slope stabilization projects, railway bedding and many other applications. 2. Objectives To determine the values of aggregate mentioned below: Absorption: The increase in weight due to water contained in the pores of the material.
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2 Bulk Saturated Surface Dry (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. Figure 1: Saturated Surface Dry (SSD) condition of aggregates Bulk Specific Gravity (oven-dry): 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. Figure 2: Oven dry condition of aggregates
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3 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. 3. Equipment Wire basket of 3.35 mm (No.6) or finer mesh with about a liter capacity Suitable balance and apparatus for suspending sample in water Set of sieves where the nominal maximum sieve size is 37.5 mm (1 ½ in. .) or less and all material is retained on 4.75 mm (No.4) sieve.
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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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MaterialslabManual - EGM 3520L Material Testing Lab...

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