Engineering Properties of Diatomaceous Fill

It is common for fill that has a low dry density and high moisture content to have poor engineering properties, such as high compressibility and low shear strength. For the tested diatomaceous fill, the range in dry density varied from about 1.0 to 1.2 Mg/m 3 with a moisture content of 38–53%. The low dry density and high moisture content are due to the diatoms, which are essentially outer shells of silica that can contain water. Even though diatomaceous fill has a low dry density and high moisture content, it behaves as a dense granular material below an effective stress of 50 kPa. This is due to the diatoms, which can resist shear and compression because of their interlocking and rough surface features. At a higher effective stress the diatoms can be crushed, which significantly increases the compressibility of the fill.