Mapping Temperature Zone Of Ethiopia For Binder Performance Grading System

Ethiopia is located near to the equator and climatic condition varies from hot-dry-arid regions torntropical rain forest. Seasonal temperature fluctuation is very high in some parts of the country.rnHence, temperature and loading time susceptible construction material such as asphalt binderrnshould assign by considering environmental temperature range and traffic condition. rnThe first challenge, concerning binder-assigning process in Ethiopia, is prediction of pavementrntemperature. In developed countries, pavement temperature is obtained from air temperature usingrnSHRP temperature conversion algorithm that accounts all heat-flow-balance in both fluids andrnsolid material. In Ethiopia, it is subjected to the engineer detailed knowledge of project locationrnand the parameters to be considered with. The second challenge is the test and specifications usedrnby highway agencies. The current conventional method is empirical and failed to predict how thernbinder perform under a wide range of temperature. Therefore, the aim of this study was to providerna temperature zone map based on predicted pavement temperature and evaluate currently utilizedrnasphalt binder by rheological test methods. rn20 years’ air temperature data for 27 locations are obtained from Ethiopian NationalrnMeteorological Agency to develop the temperature zone map while primary data of pen-gradern40/50, 60/70 and 80/100 binders are collected using conventional and rheological taste methods.rnThe samples are obtained from ECWC, CCCC and AACRA ongoing road project. Dynamic ShearrnRheometer and Elcometer-2300 rotational viscometer is available in Addis Ababa University. Thernfirst was used to conduct Amplitude and Frequency sweep test at intermediate temperature andrnPerformance grade determination and Multiple Stress Creep and Recovery test at highest pavementrntemperature; and the later was used to determine viscosity at 60rnornC, 135rnornC and 165rnornC. rn The performance Grade temperature zone map is developed by converting 20 years’ airrntemperature data to pavement temperature using SHRP temperature conversion model at 20mmrndepth of the pavement with 98% reliability. The map divided Ethiopian temperature zone into fivernmain PG-grade counties and most of the areas are dominated by PG58-YY and PG64-YY. On thernother hand, the result from rheological tests indicate that PG determination parameter G*/sinδ isrnfailed to provide clear distinction between penetration graded binders and categorize both 40/50rnand 60/70 as PG 64-YY. Hence, Multiple Stress Creep and Recovery test parameter, NonrecoverablernCompliancern(Jrnnrrn), are used to provide better ranking on the performance of the binders. Based on Jrnnrrnivrn rn rn values, the samples are graded with traffic load designation beside, indicating thernEquivalent Standard Axle Load it can support. Pen-grade 40/50 is designated as PG 52E-YY atrn52rnornC, PG 58V-YY at 58rnornC and PG 64S-YY at 64rnornC. rnEven though, penetration grade 40/50 have better stiffness and Jrnnrrn value , low-land areas such asrnAfar, Gambela and Benshanguil-Gumuz PG category indicate that road projects at these locations rnrequire modified binder; even for standard traffic load. Penetration grade 80/100 and 60/70 arerngraded as PG 58S-YY and PG 64S-YY respectively. However, pen-grade 60/70 Jrnnrrn value at 64rnornCrnis close to the margin 4kParn-1rn , indicating the risk of using the binder for potentially developingrncities and trade corridors such as Metehara and Metema.

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