STUDY OF CEMENT GROUTED BITUMINOUS MIX USING DIFFERENT GRADES OF BINDER

Abstract

Cement Grouted Bituminous macadam contains high void bituminous mix incorporating proper stone on stone contact for interconnectivity between voids, which eventually leads to 25% to 35% air voids in the bituminous skeleton. The bituminous mix will assure the flexibility, whereas, stiffness will be assured by grout, thus making it a semi-flexible layer. In this study, high void bituminous mix having volume of voids in between 30% to 35 %was prepared with different grades of paving bitumen such as VG 30, VG 40 and PMB 40 and likewise with emulsion at optimum content and then filled with grout (for full depth penetration) to make it a composite wearing course. The grout used was a high-strength good flow able grout. The grout was allowed to flow under the action of gravity to fill all the interconnected voids. The mechanical properties of the cement grouted composite course with different grades of paving bitumen and emulsion was incorporated by performing tests such as Marshall Stability, Compressive strength, indirect tensile strength and resilient modulus (ITSM). Whereas, performance was evaluated by performing Dynamic fracture energy, moisture induced susceptibility (MIST), and Abrasion. It was observed that CGBM prepared with PMB 40 bitumen possess remarkable properties as compared to other paving bitumen like VG 30 and VG 40. The results inferred from the mechanical and performance characteristics tests in case of Emulsion mix CGBM signifies the dominance of grout material in the composite mix and the findings from performance characteristics of Emulsion mix CGBM was not conclusive. It was also inferred from the results that this semi-flexible layer possesses superior properties as compared to conventional bituminous concrete (BC) course. Pavement design was done to check the suitability of CGBM as a wearing course in comparison with BC using IITPAVE. Pavement thickness for moderate traffic was estimated after structural analysis with IITPAVE. From the properties and specifications of CGBM, it can be expected that, incorporating this as a wearing course or overlay course as a replacement of BC in urban roads for moderate traffic can be great asset for sustainable road development.