Laboratory characterization of a cement grouted bituminous macadam made with Portland slag cement

Abstract

Cement grouted bituminous macadam (CGBM) consists of porous asphalt skeleton with a void content of 25% to 35%, which is filled with a cementitious grout. It is usually considered as a semi-flexible layer as it incorporates both the flexibility of bituminous layer and the stiffness of the grout content. In this study, a porous asphalt skeleton with 28% voids was filled with a cement grout made with Portland slag cement (PSC). To achieve high fluidity of the grout at low water to cement ratio, a poly carboxylic ether based superplasticizer was added and the minimum dosage of superplasticizer required to fill all the voids of the porous mix under gravity was determined. Strength and stiffness properties of the CGBM were evaluated by carrying out various tests in the laboratory such as Marshall stability, indirect tensile strength, moisture susceptibility, flexural strength, rut resistance, shrinkage strain and flexural modulus. This paper presents results of all these tests and analysis of the same, which will help the engineers in rational analysis and design of pavements with CGBM layer.