More D An increase in void content by these procedures indicates greater angularity, less sphericity, rougher surface texture, or combinations thereof. A decrease in void content results is associated with more rounded, spherical, or smooth-surfaced fine aggregate, or a combination thereof. This void content depends on grading as well as particle shape and texture. A sample consisting of single-size particles will have a higher void content than a graded sample. Therefore, use either one method or the other as a comparative measure of shape and texture, and identify which test method has been used to obtain the reported data.
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More C It is also expressed as the ratio of the density of the aggregate particles to the density of water. Relative density specific gravity SSD is used in the determination of surface moisture on fine aggregate by displacement of water in Test Method C Relative density specific gravity SSD is used if the aggregate is in a saturated surface-dry condition, that is, if its absorption has been satisfied.
Alternatively, the relative density specific gravity OD is used for computations when the aggregate is dry or assumed to be dry. This value is not widely used in construction aggregate technology. The laboratory standard for absorption is that obtained after submerging dry aggregate for a prescribed period of time. Aggregates mined from below the water table commonly have a moisture content greater than the absorption determined by this test method, if used without opportunity to dry prior to use.
Conversely, some aggregates that have not been continuously maintained in a moist condition until used are likely to contain an amount of absorbed moisture less than the h soaked condition.
For an aggregate that has been in contact with water and that has free moisture on the particle surfaces, the percentage of free moisture is determined by deducting the absorption from the total moisture content determined by Test Method C by drying.
The values obtained for absorption by other test methods will be different than the values obtained by the prescribed h soak, as will the relative density specific gravity SSD. Scope 1. The relative density specific gravity , a dimensionless quality, is expressed as oven-dry OD , saturated-surface-dry SSD , or as apparent relative density specific gravity. The OD relative density is determined after drying the aggregate.
The SSD relative density and absorption are determined after soaking the aggregate in water for a prescribed duration. No other units of measurement are included in this standard. These notes and footnotes excluding those in tables and figures shall not be considered as requirements of this test method.
It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Tushicage Aggregate testing Lab Services: In general, high void content suggests that the material could be improved by providing additional fines in the fine aggregate or more cementitious material may be needed to fill voids between particles. Standards Subscriptions from ANSI provides a money-saving, multi-user solution for accessing standards. Two use graded fine aggregate standard grading or as-received gradingand the other uses several individual size fractions for void content determinations:. Request Quote Client Login.
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