Development of cementitious grout and semi-rigid asphalt mix to improve semi-rigid pavement characteristics

Abstract

This study is aimed at improving semi-rigid asphalt mix properties through development of suitable cementitious grout mix composition and appropriate porous asphalt mix skeleton impregnated with the developed grout. The methodology for the study involves carrying out mechanical tests to evaluate the influence and effects of fluidity and compressive strength of cementitious grout on semi-rigid asphalt mix. Four types of cement grout mixtures are experimented with varying mix proportions of cement, chemical admixtures, including accelerating and retarding agents. Laboratory tests are carried out to measure properties such as porosity, flexural strength, and Marshall stability for the semi-rigid pavement specimens. Trial mixes are also tested for their workability and compressive strength, with workability determined by measuring flowability. Additionally, a porous asphalt skeleton is developed to be impregnated with developed cementitious grout to improve the durability and strength of the asphalt mix, to be known as semi-rigid asphalt mix. The experimental investigation of Marshall Mix Design, volumetric and stability properties is carried out using Marshall samples and the same of flexural strength using rectangular section beam are conducted in the laboratory. The stability of Densely Graded (average 20 kN) and semi-rigid asphalt sample (average 35 kN) is explored; results indicating an increase in resistance to deformation with higher stability values for semi-rigid mix. Asphalt mix may be considered sound in moisture resistance with tensile strength ratios (TSR) value above 0.8; in present study, semi-rigid mix has shown higher TSR (93%), suggesting better moisture resistance and resilience while Densely Graded Asphalt has just meet 0.8 criteria. Semi-rigid mix exhibit higher flexural loads and modulus of rupture values compared to Densely Graded Asphalt mix (about 176% increase), indicating improved strength and rigidity. Results from present study show potential of suggested semi rigid asphalt mix to be used for pavements in tropical climate carrying high volume of heavy traffic as found in Bangladeshi highways’ condition.