The Effect of Different Additives on the Swelling Process of Heavy Clays

In areas where heavy clays predominate (clays with plasticity index of more than 27), engineers always face the problem of replacing soils when constructing a roadbed for railroads and highways. Transportation of suitable construction material, as a rule, is very expensive. Construction of the roadbed of railroads and highways, especially in the cold regions of the Russian Federation, is almost always accompanied by a shortage of soils with good physical and mechanical properties. As a rule, these areas are characterized by clay deposits with unfavorable properties: high degree of swelling, low hydration strength, poor compaction, etc. Such properties are also characteristic of heavy clays which are widespread not only in Russia but also abroad. These features of heavy clays do not allow them to be used in the construction of the roadbed of railroads and highways without taking measures to improve their properties. The same problem has been faced by the engineers involved in the construction of the railroad track on the Taman Peninsula. Heavy swelling clays are common for this area. In the summer of 2017, soil samples were taken from the Taman Peninsula and tested in the laboratories of St. Petersburg State Transport University (PGUPS). Physical and mechanical properties of heavy clays were studied as well as properties of reinforced clays. The research shows that the optimal method for improving physical and mechanical properties of heavy clays (swelling, deformability) is the creation of a composite material consisting of heavy clay with the addition of dust filled sand (10% of the mass) and grade M400 cement (3% of the weight). This technique is applicable to all areas where heavy clays are common.