Abstract:
Any improvement on the quality of bitumen is a great achievement as it is a major component in road construction material providing its ability to sustain traffic loading. Bituminous paved road fails or get damaged if it is no longer able to sustain traffic or other environmental loading. They fail through poor road maintenance, pot-hole development, overloading among other factors. Convectional bitumen can be modified using waste sugar cane ash (WSCA) and shredded waste plastic bags (SWPB) to improve its mechanical properties as well as solving their disposal problem
The main objective of this study was to understand the fundamental behavior of the modified bitumen, evaluate its mechanical property, and determine optimum mix proportion of the waste to modify conventional bitumen grade 80/100.
The physical properties of the material used in road construction were investigated to ascertain their suitability in road construction. The test carried out to assure the quality of aggregates with modified bitumen includes aggregates impact value, crushing test, Los Angeles Abrasion test, flakiness index, specific gravity and water absorption test. The results were found to be satisfactory. While the tests carried out on the bitumen samples included penetration test, softening point, ductility and bulk specific gravity to ensure its suitability to its grade for being used for wearing course. The procedure for Marshall Stability test was standardized by using America Society for Testing and Material (ASTM D-1559) to determine the optimum binder content of different mixes.
The results obtained from the tests carried out on modified bitumen and modeled briquettes were within the recommended standard specifications. The optimum bitumen content value was 5.5% and a stability value of 14,400N. Penetration index values were in the range of 61 to 68mm and softening point value in the range of 51.3 to 57.8oC. The other test results values were for the aggregates strength 20.6%, water absorption 0.69% while durability test was 2%. The conventional bitumen was modified using 3% SWPB and 2.5% WSCA by reducing the bitumen content in the mix with the same percentage.
From this study, modified bituminous mix has the ability to withstand high temperature, higher load compared to conventional mix and this will minimize the development of rutting and cracking of the wearing course reducing water seepage through the pavement surface. The construction cost of the wearing course can be reduced by approximately 3.0 and 2.5% when SWPB and WSCA is used respectively for modification. It is recommended that the convectional bitumen commonly used in Kenya 80/100 should be modified using WSCA or SWPB to make it a better binder for road construction.
