Validity of Limestone Aggregates for Using in Asphalt Concrete Mixtures for Surface Layer of Roads

Abstract

In this paper, limestone quarries in the Bazian region, west of Sulaymaniyah city, northern Iraq, were evaluated geotechnically to examine their suitability for developing asphalt concrete for the top layer of roadways. Two samples were collected to perform geotechnical testing, including physical, chemical, and permanence tests. From the physical results, it is evident that the coarse and fine aggregate grain sizes demonstrated conformity to the American Society for Testing and Materials ASTM-C136 as well as the requirements of the fine aggregate standards ASTM-C117, which fall within the coarse, fine, and filler areas. Moreover, the findings revealed that the flat granules are 22% and the longitudinal granules are 35%. Based on these results, it did not go over the limits set by British standards, so it meets the requirements for concrete work. Another promising finding of durability tests was 21.8%, which represented the highest weight loss. This is an important finding in the understanding of the suitability of the aggregate to American and Iraqi standards in concrete work. A further novel finding of stability tests demonstrated the cement's suitability with Iraqi standards and the American standard C131-C535-2003. Finally, the results of Marshall's test for density, creep, and stability reveals the conformity with the Iraqi specification for asphalt concrete works D2726-05, where the density value was 2.292 and the percentages of creep and stability were 12.2 kN and 2.9 mm, respectively. The results of examining the cement asphalt were in accordance with the specifications required for concrete works, where the optimum percentage of asphalt for the design of the asphalt mixture for the surface layer was 4.8. Also, the percentage of airspace was 4.1 according to the American standard D2041.