Assessing and Improving the Performance of Grouted Macadam

Abstract

There are many road defects appear in flexible pavement layers. Rutting, raveling and cracks are considered the main problems in Egypt. Using grouted macadam system as a surface asphaltic layer (or called Semi-Flexible Pavement (SFP)) has many advantages such as saving the natural asphalt and enhancing the performance against deteriorations. The main scope of this research is to evaluate and improve the performance of SFP using modified grout by additives as fine sand, Silica Fume (SF), Fly Ash (FA) and Super-Plasticizer (SP). Different mixing ratios for grout contents (cement: Fine sand: Additives: Water) were tried and tested using flow time (workability), flexural and compressive strength to achieve the optimal grout characteristics. Crushed siliceous-limestone was used in preparing open graded (porous) asphalt mixtures to obtain suitable permeability. After grouting the asphalt mixtures, Marshall and indirect tensile strength tests were performed. The results indicated that the use of equal amounts from cement and fine sand was preferred in grout. Silica fume was preferred as additive for improving the grout properties. The results obtained that the grouted macadam significantly improved the performance of pavement compared with traditional flexible pavement.