Treatment of Over Size Ratios Of Subbase Materials Used In Erbil Governorate Pavements, Kurdistan ,Iraq

Abstract

Coordination with the directorate of geological survey and mineral investigation in Erbil governorate to select the quarries and all subbase layer materials that  used in both flexible,  and rigid pavements , are taken from natural sources, According to their recommendation, the quarry locations are (Shamamek (E2), Qushtapa (E5), Ashty/Koya (E7), Salahadeen (E8) /Shaqlawa and Rawandouz (E9)) were chosen in this study in Erbil governorate..

            The correction method was conducted for MDD that had oversize practical’s on sieve (19 mm) less than 30%. Performing approach to obtain the correct and suitable procedure when retaining more than 30% of course aggregate for the types A or B Therefore, and  Thus, to have a practical procedure that is more appropriate to site conditions and to obtain equivalent high laboratory densities within the field, the implementers of the contractors are obliged to observe the specifications of the compaction ratios, avoid any settlement or failures for pavement structure in close future, and thus increase the safety factor.This study attempts to establish a useful practical treatment and recommends, based on the reality of actual work, to correct the modified density (according to ASTM, and AASHTO  specifications, less than 30%), when it is more than 30%, Using the method of multiplying the modified density by coefficient (1.0125) for every 1% greater than 30% and up to 35%, no more.