The table to the right provides a list of some of the differences between the two methods.Īs well as some procedural differences, ASTM D 854 also requires additional equipment that some laboratories do not have readily on hand. If you fall into this category, let me be the first to tell you that the differences between AASHTO T 100 and ASTM D 854 are quite significant. Many times the laboratory signs up for both methods (AASHTO and ASTM) assuming that, like most other tests, the two procedures are nearly identical. I have seen more things go wrong than right with this test in my time as a laboratory assessor.
With this number influencing others, it is important to be as accurate as possible when determining this soil property. Soil specific gravity is used to define the phase relationships of soil, define compactibility and density, and in conversions and calculations for other test procedures. This means that the metal block weighs 6.29 times the mass of a block of water that is the same volume. This may be difficult to visualize, but think of it this way: Let’s say that a block of metal has a specific gravity of 6.29. Specific gravity is the ratio of the mass of a certain volume of a material to the mass of the same volume of water.
In this article I will talk through the portions of the test that seem to cause the most confusion, explain reasons behind certain steps, and also offer helpful tips and suggestions. For example, does the technician know that there are significant differences between AASHTO T 100 and ASTM D 854? Have the calibrations been performed correctly? Or, is all of the right equipment available? ASTM D 854 can be a difficult test, and many people are not familiar with the intricacies involved with running it. Osmolality is normally used for more detailed analysis, but USG remains popular for its convenience.When planning an assessment for a laboratory that will be running ASTM D 854, many thoughts race through my mind. decreased concentration of solutes in urine) may be associated with renal failure, pyelonephritis, diabetes insipidus, acute tubular necrosis, interstitial nephritis, and excessive fluid intake (e.g., psychogenic polydipsia).
Hypovolemic patients usually have a specific gravity >1.015.ĭecreased specific gravity (hyposthenuria, i.e. In neonates, normal urine specific gravity is 1.003. A specific gravity greater than 1.035 is consistent with frank dehydration. increased concentration of solutes in the urine) may be associated with dehydration, diarrhea, emesis, excessive sweating, urinary tract/bladder infection, glucosuria, renal artery stenosis, hepatorenal syndrome, decreased blood flow to the kidney (especially as a result of heart failure), and an excess of antidiuretic hormone caused by the syndrome of inappropriate antidiuretic hormone secretion. Increases in specific gravity (hypersthenuria, i.e. In adult humans, normal specific gravity values range from 1.010 to 1.030.Īdults generally have a specific gravity in the range of 1.010 to 1.030.
The concentration of the excreted molecules determines the urine's specific gravity. The body excretes some of these waste molecules via urination, and the role of the kidney is to concentrate the urine, such that waste molecules can be excreted with minimal loss of water and nutrients. One of the main roles of the kidneys in humans and other mammals is to aid in the clearance of various water-soluble molecules, including toxins, toxicants, and metabolic waste. For background on kidney function, see Renal function.
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