Validity of the Lower Zab River Sediments for Road and Asphalt Works - Southwest of Kirkuk/Northern Iraq

Abstract

In this study, a geotechnical assessment of gravel and sand deposits were conducted on both sides of the Lower Zab River in the southwest of Kirkuk Governorate/Northern Iraq. geologically the sediment related to Quaternary age and tectonically located at the  unstable zone. 5 samples were collected from the study area for the purpose of conducting various geotechnical tests on them and their validity for road works to the sub-base layer and the base layer for asphalt works. The results of the physical tests were shown by grain size analysis of thes aggregates for the samples of the study area, and it was found that they are identical to class (A) According to the American Standard [1], and suitable for use in road works for the sub-base layer. The moisture ratio ranging between (1.95 - 4.26) %. The tests of flatness and elongation showed that the highest percentage of flat-shaped particles was (29%) and longitudinal-shaped particles (19%). The laboratory tests results showed the durability tests such as - Los Angeles test the highest percentage of weight loss was (20.06%), and thus it is valid according to the Iraqi Standard Specification [2] for use in road works. the highest result of test the aggregate impact value of samples is 7.8%, It conforms to the requirements of specifications that must be provided for road works for a sub base layer. Accordingly it is valid for road works. It was found from Proctor test for (5) samples from the study area that the values of the maximum dry density ranged between (2.14-2.28 gm/cm3), and the values of the optimum moisture content ranged between (3.1-2.41%). An asphalt typical mixture was designed for the base layer from the aggregate of the first station S1 as represent station consisting of coarse crushed aggregate 12%, medium crushed aggregate 22%, fine crushed aggregate 20%, river sand 40% and the proportion of filler 6%. The results of the asphalt tests for the ideal station S1 showed that the ideal percentage of asphalt from the weight of the mixture in the asphalt mixture is 4.1, which is within the limits of the specification Roads and Bridges [3]. The percentage of asphalt to the weight of the aggregate after adding the ideal percentage of asphalt showed that its value was 4.3%, As for the stability test result (Marshall), it reached 11.4 kN, and the result of the creep test (Marshall) reached 2.9 mm, and the density was 2.362