Performance Evaluation of Asphalt Concrete Mixes Containing Granular Volcanic Ash

Granular volcanic ash material is spread over considerable areas of Yemen including urban and suburban areas. Due to the inferior properties of this material in its natural state, it cannot be used in base and subbase layers. It is common practice, when faced with such material, to replace it with superior properties filling material. Excavated volcanic ash is disposed off by transporting it to landfill sites. Such practice is becoming increasingly costly and continuously necessitates allocation of scares and valuable new landfill sites. The problem in some urban areas is becoming an environmental issue due to the massive buildup of disposed volcanic ash material. The main objectives of this study are twofold: one to investigate the merits of utilizing waste volcanic ash as a cheap alternative to aggregate for road construction and consequently this contributes toward an efficient waste management of this undesirable material and reduces its environmental impact. The effects of using granular volcanic ash material, as a partial replacement of conventional aggregate on the properties of hot-mix asphalt (HMA), were studied. Four different aggregate replacement proportions were used specifically at 0, 10, 20, and 30% of total weight of dry aggregate. The 0% volcanic ash content mix was used as the reference mix. Experimental results indicated that the mechanical properties of all mixes containing volcanic ash aggregate, up to 20%, were within the specification limits of the Marshall mix design method. In addition, it was found that the use of volcanic ash aggregate improved the HMA creep resistance properties. HMA with a 10% volcanic ash aggregate replacement gave optimum results in terms of stripping resistance, creep resistance, fatigue, and resilient modulus.