CRITICAL EVALUATION OF ASPHALT CONCRETE MIXES CONTAINING GRANULAR VOLCANIC ASH MATERIAL

Abstract

Granular volcanic ash material is spread over considerable parts of Yemen, including urban and suburban areas. Due to the inferior properties of this material in its natural state, it can not be used as a foundation layer either for roads or buildings. However, when improved it can be used in different applications. A recent study by the author has indicated that using granular volcanic ash as a partial replacement of conventional basalt aggregate in hot asphalt concrete mixes is technically feasible. All conventional criteria requirements suggested by Marshal Mix Design Method for hot asphalt concrete mix design were achieved with samples at different levels of granular volcanic ash content. In this paper, further evaluation was performed to provide critical evaluation of some important mix characteristics. Samples, at different volcanic ash content, were prepared at optimum asphalt content and subjected to different advanced tests. These include dynamic creep, modulus of resilient, fatigue and permanent deformation tests. Results indicated that mixes containing volcanic ash aggregate had performed well in terms of creep and permanent deformation. However, improvements in fatigue life and in modulus of resilience were observed at volcanic ash contents up to 10% and 20%, respectively. Further investigation is recommended to find ways for improving the properties of volcanic ash material so that the negative trends in fatigue life and modulus of resilience can be dealt with at higher volcanic ash content.