Organosilane and lignosulfonate as innovative stabilization techniques for crushed rocks used in road unbound layers

Abstract

The tunnelling operations connected to the construction of the new Norwegian E39 highway generate a considerable amount of blasted rocks. The local use of these rocks as construction materials in the unbound layers of the highway represents a sustainable cost-benefit application. Two non-traditional stabilizing additives improve the mechanical properties of the aggregates not fulfilling the code strength requirements: one is based on organosilane, the other one is based on lignosulfonate. Laboratory investigations (thin-section microscopy, X-ray crystallography, X-ray fluorescence, repeated load triaxial test) characterize the rock materials and the effectiveness of the additives. The research further investigates the performance of three typical road base layer sections specifically built according to real practice and treated with water (no treatment), organosilane and lignosulfonate, respectively. They are exposed to climatic conditions only; no surface courses and no trafficking actions are applied. The developments of the layers’ stiffness and deformation are assessed by means of light weight deflectometer and dynamic cone penetrometer. The time span covered by the investigation is one year, both in the laboratory and in the field. The stabilizing additives can enhance the mechanical properties of the crushed rocks.