International Journal of Scientific & Engineering Research, Volume 11, Issue 11, Novermber-2020 ISSN 2229-5518 IJSER © 2020 http://www.ijser.org Fatigue Performance of Asphalt Pavement Wearing Course in Submerged Condition Modified with Shredded Tyre Chips Otto, C. G, Igwe, E. A, and Ekwulo, E. O Abstract— Improving the fatigue performance of flexible pavement wearing course subjected to submergence has been one of the major concerns of civil engineering professionals in Nigeria especially among the Niger Delta people due to flooding. Pavement have been observed to be submerged in water perpetually causing rapid failure which has made the government to spend huge amount of money on road rehabilitation and construction yearly. Based on this, the current study was aimed at assessing the fatigue performance and life span of flexible pavement using shredded tyre chips modified asphalt pavement in submerged conditions. This was achieved by modifying the hot mix asphalt at 1%, 2%, 3%, 4% and 5% and also carrying out a traffic study along Port Harcourt Aba Expressway to determine the Design Equivalent Single Axial Load (ESAL) which was used as a base to check the fatigue performance. The modified asphalt concrete was submerged in water for 0 day to 5days. From the findings made in this study, the fatigue performance was enhanced with an extension of life span ranging from 21 to 33years at 5% modification as the number of soaking days and frequencies increases. Keywords—Shredded Tyre Chips (STC), Hot Mix Asphalt (HMA) and Fatigue Performance. —————————— ◆ —————————— 1 INTRODUCTION here are various factors that tend to affect the de- sign life of asphalt concrete pavements and to name but a few are; poor design, poor construction, inadequate maintenance plan, improper usage and lots more. Damages resulting from moisture can easily be associated with any of the following listed above. In a study carried out by [10], moisture and traffic fre- quency has been established as one of the factors af- fecting pavement performance. Moisture in recent studies carried out within the Niger Delta region of Nigeria has been revealed to contribute heavily to- wards pavement deterioration [7][6][5]. According [11], the progressive deterioration of asphalt mixes in the presences of moisture causes loss of adhesion be- tween the asphalt binder and aggregate surface or loss of cohesion within the binder due to the solvent prop- erties of water. This process described is known as stripping. Since moisture is ever present as a result of rainfall and the absence of a functioning drainage sys- tem to eliminate water, the pavement is submerged for hours, days and even weeks. Hence, drastically reduc- ing the pavement performance and therefore hindering it from being serviceable through its design life which ideally should span between 15-30 years and 5-20 years for overlays. In the quest to improve the performance and lifespan of the flexible pavement in submerged conditions, var- ious research works have been carried out using addi- tives/modifiers. [8] used waste polythene bags in melted form as modifier in asphalt concrete pavement. The study revealed that the modifier can act as a wa- terproofing agent at 3% addition resisting the effect of moisture in terms of the Index of Retained Stability. A further study by [9] revealed that waste polythene bags are economical when used to modify asphalt. Over the years, some modifiers or additives have been incorporated into the asphalt concrete mixtures to im- prove the fatigue life under normal conditions not con- sidering submergence as it is in the Niger Delta region of Nigeria. Some of the additives or modifiers used, include polymers, recycled plastics such as polyeth- ylene, blast furnace slags, municipal waste combustion ash, and scrap tires. In a study carried out by [4], shredded tyre chips were used as filler materials to improve the dynamic modulus of asphalt concrete pavement. The study revealed that the dynamic modu- lus increases linearly with increase in amount of shredded tyre chips addition considering the frequen- cies of 0.1 -25Hz. The objective of this present study is to improve the performance of flexible pavement submerged in water using shredded tyre chips knowing that it can improve dynamic modulus as revealed in [4] and that dynamic modulus has direct effect on fatigue performance us- ing Port Harcourt-Aba Expressway as a case study. In this study, the foundation of the complete findings is based on the objective stated above with a well- defined assumption which could be viewed as the lim- iting conditions of the study. These assumptions include; i. That the pavement life span is 20 years. ii. That only vehicular loads ≥ 80kN can cause pave- ment failure. iii. Passenger cars do not contribute to pavement val- ue. T 167 IJSER