Collaborative Effect of Fines on Changes in Grain Distribution in the Process of Improving the Geotechnical Properties of an Alluvial Gravel 0/14

Abstract

The technical and economic optimization of road projects has led to research into the use of materials obtained by mechanical stabilization for pavement construction. This research has enabled us to outline a solution capable of giving the sub-base layer the necessary and sufficient capacity to support the induced loads forecast for the traffic. This work evaluates the effect of adding fine silty clay (Cl) and clayey silt (Csp), two corrective materials to alluvial gravel (0/14), the main material, in the process of improving its cohesion and geotechnical properties. The results obtained show that the optimum mix is obtained with 10% by weight of Cl and 15% Csp. The granulometry of the mixes is spread out, but poorly calibrated. The Ag-Cl mixtures made at 10%, 15%, 20%, 25% 30% and Ag-Csp at 15%, 20%, 25%, 30%, and 35%, do not obey the law of mixtures. Mixing with 10% Cl reduces the sand equivalent of alluvial gravel by 60.23%, while mixing with 15% Cl reduces the sand equivalent by 6.82%. The addition of correctors increases the optimum water content and fine sand content of the mixes. Increasing the fine sand content reduces the optimum dry density, CBR index and static modulus. Mixes containing 10% Cl and 15% Csp have CBR values of CBRCl (96%) and CBRCsp (84%) and are not suitable for pavement base layers. In fact, the hardness of the grains has a Los Anges value of 41%, higher than the maximum permitted by the standard of 35%. The mixes obtained can be used as pavement base layers for traffic levels in a cumulative number of heavy goods vehicles 5 × 10 5 < T1-T3 < 4 × 10 6 for an approximate life of 15 years.