The authors conducted a study to find out what happens to the soil after several freeze-thaw cycles. To that end, they made a soil sample by mixing 400 grams of sulfur-alkaline waste and 1,000 grams of amorphous tripoli (a type of sedimentary rock), after which they subjected the sample to heat treatment at a temperature of 700 degrees Celsius, obtaining a silicate material which is safe for humans and the environment.
In the course of the experiment, the scientists kept the samples in a freezer at minus 20 degrees Celsius for three days, and then placed them in a refrigerator at plus 6 degrees Celsius for the same amount of time. These actions were repeated several times. Strength and deformation measurements were taken after the first, third and tenth cycles.
The study showed that freezing and thawing affects man-made soil in roughly the same way as natural soil, albeit more intensely: after the first cycle, specific adhesion is reduced by half, and then by another 15%. The degree of soil deformation is also initially reduced by half, although it rises by 70% from the third to the tenth cycle.
“It must be said that soil obtained from sulfur-alkaline waste resulting from oil production has its advantages: its density is 30% lower than that of natural soil, which reduces the load on the foundation, while its high hydrophilicity, i.e., the ability to absorb water, makes it possible for the underlying layers to dry quickly. This is why this material can be used in the construction of reliable road embankment structures on a weak saturated foundation,” Alla Grishina, candidate of technical sciences, is quoted as saying by Perm Polytechnic University.
Man-made soil can be used not only for the construction of public roads, but also for transport infrastructure at oil fields.
