What soil has a smaller dry unit weight of 20-30 Ottawa sand?

* Dry Unit Weight Depends on Many Factors: The dry unit weight of a soil is influenced by:

* Particle Size Distribution: Ottawa sand has a specific gradation, but other sands can have finer or coarser particles, affecting the dry unit weight.

* Density of Soil Particles: The minerals composing the soil particles affect their density.

* Void Ratio: The amount of air spaces between the soil particles (void ratio) significantly impacts dry unit weight.

* Compaction Level: How tightly the soil particles are packed affects the dry unit weight.

* 20-30 Ottawa Sand: "20-30 Ottawa sand" refers to a specific type of sand with a particle size range of 0.25 to 0.85 millimeters.

To determine which soil has a smaller dry unit weight than 20-30 Ottawa sand, you need to consider these factors:

* What other soils are you comparing it to? Provide information about the specific soils you're interested in.

* What are the conditions of the soils? Are they loose, compacted, saturated? Knowing the conditions will help understand the void ratio and dry unit weight.

Example:

Let's say you're comparing 20-30 Ottawa sand to a silty clay. The silty clay could have a smaller dry unit weight if it's loose and has a high void ratio due to its smaller particle size and higher clay content, even though the clay particles themselves are denser.

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To give you a more accurate answer, please provide more details about the soils you're comparing.