Structural strength characteristics of fiber cement soil in road pavement of timber roads in the Sverdlovsk region

Abstract

The solution to the problem of increasing the efficiency of the technology for strengthening soils of logging highway structures can be dispersed reinforcement of the cement-soil matrix with fiber. The resulting composite material, fiber cement soil, in the forest zone has increased strength properties and crack resistance. In order to study the structural strength characteristics of fiber cement soil: the angle of internal friction and the specific coefficient of adhesion, laboratory studies were carried out using a single-plane cutting unit GT 0.2.1. Samples of fiber cement soil were made on the basis of natural soil from the subgrade of a logging road in the Sverdlovsk region containing 2 %, 4 %, 6 % Portland cement and 0 %, 0.75 %, 1.5 % fiber based on waste from the production of basalt thermal insulation boards. Structural strength characteristics were determined and it was found that the addition of basalt fiber in the composition of fiber cement soil affects the angle of internal friction at a significance level of p = 0.000026 and at p = 0.000016 the specific coefficient of adhesion depending on the content of Portland cement. With a content of 2 % Portland cement, the addition of 1.5 % basalt fiber reduces the specific coefficient of adhesion by 8 % (10 kPa) and the angle of internal friction by 1°, due to the insufficient development of the cement-soil matrix of the fiber-cement soil. With a content of 6% Portland cement, the addition of 1.5 % basalt fiber increases the adhesion coefficient by 43 % (258.7 kPa) and the angle of internal friction by 2°, due to retention in the cement-soil matrix and the perception of external loads by the fiber due to axial tension. It is advisable to use the obtained indicators of specific adhesion and angle of internal friction for modeling and calculating road pavement structures for logging roads made of fiber cement soil using the finite element method, taking into account loads from timber transport and difficult natural conditions of the forest zone.