Partial Replacement of Filler with Blending of Khat Ash and Eggshell Powder on Hot Mix Asphalt

Abstract

Asphalt concrete road construction is now an important aspect of Ethiopia's growth and transformation plan for developing a high-performance transportation network to support the country's economic development. Aggregate, asphalt binder, and filler make up flexible asphalt mixtures. One of the major issues in the construction of highway pavement is a lack of filler from crushed stone dust (CSD), as well as a scarcity of cement. The problem can be solved by substituting non-conventional filler material blending of khat ash and eggshell powder (BKE) for conventional filler material (CSD) replaced by 8, 16, 24, 32 and 40% weight of CSD filler. The aim of this research can be done for a variety of reasons, including the use of waste products to create a pollution-free and sustainable environment, waste materials have the potential to improve the strength and durability of the original materials, and these materials have the ability to lower construction costs. Waste Khat and Eggshell both easily obtainable waste products, for the purpose of to investigate the suitability of BKE as an equal proportion of mineral filler in hot mix asphalt (HMA).To achieve this objective prepared laboratory tests such as material quality, marshal properties and moisture susceptibility were done. All the laboratory test results satisfied standard specification criteria. The specific gravity of the fillers CSD, KA, ESP, and BKE, were 2.63, 2.38, 2.41, and 2.40 respectively and Marshall Mix design was carried out with bitumen content of 4.0, 4.5, 5.0, 5.5 and 6.0% by weight of total mix and filler content of 4.5, 5.5 and 6.5% by weight of aggregate. Based on this the optimum bitumen content (OBC) 5.5% and optimum filler content (OFC) 5.18% selected by using NAPA method and optimum replacement of BKE replaced with CSD filler is 24% on the mixture consisting of acceptable values of marshal stability, flow and volumetric properties. The tensile strength ratio at 0% BKE (100% CSD) filler and 24% BKE filler results were 82.08% and 82.56% respectively. Therefore, BKE are better resistance to moisture effects. In general, it can be concluded that the blending of Khat ash and eggshell powder can be used as filler materials instead of the most commonly used conventional fillers, such as crushed stone dust filler. Further studies recommended that partially replacing filler with 24% BKE filler content was the best when compared to other percentage replacement ratio values.