Methods for Stabilizing and Strengthening Yoldian Clays and Weak Clay Soils When Creating a Subgrade in the Far North Regions

Abstract

Purpose: Definition of the most effective methods and components for strengthening weak Yoldian clays used in the creation of transport routes in the North regions. Methods: The definition of the main physical-mechanical characteristics of clay soil was carried out in accordance with the requirements: of GOST (Russia State Standard) 12536—2014 “Soils. Methods for laboratory determination of granulometric (grain) and microaggregate composition”; GOST 25584—2016 “Methods for laboratory determination of the filtration coefficient”; GOST 22733—2016 “Soils. Method for laboratory determination of maximum density”; GOST 5180—2015 “Soils. Methods of laboratory determination of physical characteristics”; GOST 25100—2020 “Soils. Classification”. It is shown that the effective strengthening of weak clay soil is achieved as a result of its preliminary stabilization with the help of granulated blast-furnace slag or natural limestone of ≈2.5 mm fraction. The rational amount of granulated blast-furnace slag or limestone is 15 wt.% of the soil mass and at the same time, clay soil has the highest strength value — (2.25–2.45) MPa. The difference in strength indicators in favor of limestone constitutes 9.0%. It has been experimentally established that in order to increase reinforced clay soil strength it is effective to use granulated blast-furnace slag in combination with finely ground blast-furnace slag which rational amount of is 10 wt.% of soil mass which achieved strength of corresponds to M20–M25 grade. It has been defined that for comprehensive improvement of the indicators as strength, density, and frost resistance it is necessary to introduce additionally to clay soil, reinforced with blast-furnace metallurgical slag as reactive components which it’s effective to use Portland cement in amount of not more than 5 wt.% of soil mass in combination with dry complex chemical additive “PRA” which rational amount of constitutes 2.0 wt.% by weight of (Portland cement + finely ground blast-furnace slag). Practical significance: Stabilized and comprehensively strengthened weak clayey soil is characterized by the following actual indicators: M50 F35 K10 — 0.026 m/day which can be used as a base at construction of transport routes of local importance in the regions of the North.