ASTM C127 submerged weight and SSD weight?

In summary, the weight of SSD (saturated surface dry) aggregate is higher than the water submerged weight due to the presence of water in the pores of the rock. This is because when submerged, the specific gravity (SG) of the rock must have the SG of water subtracted to account for buoyancy. This is why when submerged, objects with a higher SG than water will weigh less. Additionally, our bodies have a density close to water, which is why we feel lighter when submerged due to the balance of our lungs (lighter) and bones (heavier). More fat can also contribute to better floating as it has a lower density than water.
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goldfish9776
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in ASTM C127 Aggregate test , why the weight of SSD is higher than water submerged weight?
 
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Specific gravity, SG, of rock must have the SG of water (= 1) subtracted when rock is submerged to account for buoyancy.
If rock SG=3 and weighs 3 tonne, then when submerged in water it will weigh 2 tonne.
The weight of any water in the aggregate dissapears when it is submerged as it becomes part of the water.
 
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  • #4
Baluncore said:
Specific gravity, SG, of rock must have the SG of water (= 1) subtracted when rock is submerged to account for buoyancy.
If rock SG=3 and weighs 3 tonne, then when submerged in water it will weigh 2 tonne.
The weight of any water in the aggregate dissapears when it is submerged as it becomes part of the water.
tas why we will always feel that we will be lighter when we are in the water ?
 
  • #5
goldfish9776 said:
will always feel that we will be lighter when we are in the water ?
Yes.
Our body is made mostly of water. But our lungs are lighter and our bones are heavier, so our bodies have a density very close to that of water.
When we breath in, with lungs full of air we float. When we breath out, the weight of our bones sinks us. More fat makes us float better because it has a density less than water.
 

1. What is ASTM C127 submerged weight and SSD weight?

ASTM C127 is a standard test method for determining the density (unit weight) of aggregates. It involves determining the weight of a specific volume of aggregate in both a submerged and saturated-surface-dry (SSD) state.

2. Why is it important to determine the submerged weight and SSD weight of aggregates?

Determining the submerged weight and SSD weight of aggregates is important because it helps to accurately measure the density of the aggregates. This information is crucial in construction and engineering projects, as it can affect the strength and stability of concrete and other building materials.

3. How is ASTM C127 submerged weight and SSD weight test performed?

The test involves immersing a known volume of aggregate in water to determine its submerged weight, and then drying the same aggregate to a SSD state and weighing it again to determine its SSD weight. The difference between the two weights is used to calculate the density of the aggregate.

4. What is the difference between submerged weight and SSD weight?

Submerged weight refers to the weight of an aggregate when it is fully immersed in water, while SSD weight refers to the weight of an aggregate when its pores are filled with water, but the surface is not submerged. The difference between these two weights is known as the absorption of the aggregate.

5. What factors can affect the results of ASTM C127 submerged weight and SSD weight test?

The results of the test can be affected by factors such as the type and size of the aggregate, the temperature and duration of submergence, and the accuracy of the measurement equipment. It is important to follow the standard test method closely and ensure proper calibration of equipment to obtain accurate results.

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