Study of the strength gain of fiber cement-modified soil in the logging road pavement

One of the key factors in the development of the Russian timber industry is the increase in available timber resources, which should be ensured by the constant expansion of the network and improvement of the quality of timber roads. Well forested areas, as a rule, are significantly removed from the places of extraction and production of traditionally used road-building materials: sand, crushed stone, gravel, crushed stone-sand mixtures, which leads to an increase in the cost of their transportation and the cost of constructing logging roads in general. In these conditions, it is effective to use the technology of strengthened local soils for the construction of logging roads, which ensures high quality and durability of road pavement while reducing the cost of construction and installation work. Considering the high transport loads and weak clay soils at the base of the roadbed that are common in the forest zone, it is advisable to use fiber cement-modified soil for constructing layers of road pavements. On account to the dispersed reinforcement of the cement-soil matrix of the material with fiber distributed throughout its volume, the fiber-cement soil has higher strength indicators, frost resistance and crack resistance of the road pavement structure compared to cement-modified soil. The process of structure formation of fiber cement soil occurs through the interaction of cement stone and fiber, so the study of the dynamics of this material strength gain is relevant. Laboratory studies of physical and mechanical parameters were conducted at 7, 28 and 56 days of strengthening of fiber cement soil. Also, pilot production studies were conducted on the dynamics of increasing the elasticity modulus of fiber cement soil pavement on a trial pavement section of a logging highway. Based on the results obtained from studies of compressive strength and tensile strength during splitting of fiber-cement soil samples, the influence of fiber admixture on the process of structure formation and on the dynamics of the material strength gain was established. During the construction of a trial pavement section of a logging highway, the technical and technological feasibility of fiber cement-soil layers establishment in logging highway pavement structures was proven. The dependence of the actual elastic modulus of the fiber cement-soil pavement on the time of material strength gain, as well as the minimum time period required to achieve the calculated elastic modulus of the road pavement structure of a timber highway, has been traced. The construction of fiber cement-soil layers of road pavements requires a minimum set of road construction equipment and the amount of imported road construction materials, thus significantly reducing the cost of construction and installation work, and also, due to the long service life of road pavements, the cost of logging roads maintenance.