THE PERFORMANCE EVALUATION OF HOT ROLLED ASPHALT MIXED WITH SAWDUST ASH AS A FILLER1

Abstract

ABSTRACT There are two methods of mixing hot asphalt (Hotmix) applied in Indonesia; those are AAHSTO (American Method) using Asphalt Concrete (AC) system and British Standard (British Method) using Hot Rolled Asphalt (HRA) system. Some p;roblems appeared when both methods are implemented in Indonesia. The problems of Asphalt Concrete System are cracking and brittle while HRA system bleeding are often happened. HRA asphalting system is also often called as gap gradation asphalting which relies on the strength and adhesiveness of fine aggregate. Filler is one of the important fine aggregate components. The materials of filler can be cement, refined stone (ash of stone), slag etc. However, this kind of filler has higher economical value and is very limited in quantity. Therefore, innovations and research in needed to find the economical filler material. The research is aimed to study and evaluate the performance of mixture of HRA and sawdust filler and compare to the mixture with standard filler (stone ash). In this research, the composition of each filler used in the mixture are 100% of stone dust, 50% of stone dust – 50% of sawdust, and 100% of sawdust. The research indicated that the mixture of asphalt and filler of 100% sawdust really has the worst mixing characteristics value, while the mixture of asphalt and filler of stone dust and sawdust with the content of each 50% - 50% can give characteristics value approaching to the mixture of asphalt and 100% stone dust filler, even though it has more content of asphalt. Is is also indicated that in the optimum content of asphalt to all mixtures of asphalt is the same as the optimum asphalt content of 100% stone dust as much as 6.65%, so to the mixture of asphalt by using sawdust filler either part of it (50%) or the whole (100%), the characteristics with the one using 100% stone dust filler is still better. The mixture using 100% sawdust filler is not recommended for heavy traffic, because it may be bleeding will be experienced, while the mixture using filler of 50% stone dust – 50% sawdust have to be further studied to find the best composition, since its structural values obtained nearly approaches the standard mixture (filler of 100% stone dust). Further test have to be concerned and especially its durability and permeability