FEASIBILITY OF USING RECYCLED ASPHALT MATERIAL AS SUBBASE MATERIAL IN PALESTINE
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Date
2023-07-18
Authors
Ala’ Hejazi Suleiman Gnuimat
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Abstract
Background: Road construction material is generally limited worldwide, including developing countries, in addition to their high prices and transportation cost. Previous studies on the use of recycled asphalt pavement (RAP) showed different percentages of the optimum RAP in the aggregate mix, which confirms the need for additional research in this field.
Problem Definition & Objectives: The lack of natural resources significantly impacts the construction sector. The need for aggregates will grow as pavement development increases and the aggregate requirements need to be met. To produce better materials that are consistent with the requirements for subbase material, the study aims to determine whether it is possible to use RAP materials in the subbase by examining the viability of reusing milling material and combining RAP with natural materials in specific proportions.
Methodology: The methodology included collecting three samples of milling material from each of three study streets in Ramallah and Al-Bireh Governorate, then mixing them with subbase materials in specific proportions. A mixture of the two materials was made in varying proportions (10-60%) and the number of mixed samples was a total of 11 samples; each sample was lab tested three times.
Results: The study's findings demonstrated that the quality of subbase materials can be improved by combining RAP materials with natural materials. It is also possible to improve these materials and address their deficiencies by blending them with RAP materials in proportions of (20–50%), resulting in a mixture with excellent properties and a cost reduction of more than a one third (33%). An optimum mixing ratio of 32.5% was attained in terms of the proctor test, sand equivalent, and California Bearing Ratio.
Conclusions: At the optimum mix percentage, the mechanical properties of the mixture significantly improve. It was also possible to obtain materials with better properties so that its specifications are met up to 50% mix proportion.
By using these materials, it is possible to save a one third of the cost as compared to the traditional cost when mixing by 30%, and to reduce the thickness of the subbase from 20 cm to 15 cm while maintaining the same efficiency.
Keywords: RAP, subbase, mixture, Palestine.