Investigation of mechanical properties of hot mix asphalts under the traffic effect

Investigation of Mechanical Properties of Hot Mix Asphalts Under The Traffic Effect In this thesis study, the effect of using modified SBS in hot mix asphalts (HMAs) as an additive has been searched. Pure and SBS including HMAs have been designed according to Marshall method. The properties of aggregate used in HMAs, bitumen and HMAs design parameters that has been determined again experimentally with the aim of controlling and have been compared. In area which has local traffic and used for carrying out land and laboratory experiments, two different types of asphalt concrete pavement applied in order to make up application area granular base course. As a land experiment, pavement surface temperature and axle load related to vehicle numbers have been identified by traffic measuring devices in 1st, 4th, 8th and 12 th months in one year to specify behavour of HMAs under the effects of traffic load on the asphalt concrete pavement that is prepared in the application area. Moreover, whell tracking measurement with calliper, strength measurement with test hammer and compression measurement with nuclear test device have been done in order to specify mechanical properties. Compression rates in road side is lower than wheel zone, beside this, average compression rate of asphalt concrete pavement modified with SBS is higher than pure asphalt pavement in one year period. Mean value of whell tracking measurements in pure asphalt concrete pavement is bigger than asphalt concrete pavement modified with SBS about 50 percent. The maximum and close values of compression rate have been gathered in 8th and 12th months for both asphalt pavements, besides the maximum compression rate value have been obtained for pure asphalt pavement in 12th month for wheel zone in compression rate measurement using Schmith hammer. The laboratory experiments have been applied on properties of pure and SBS including HMAs and design parameters are provided from application area and cores test pieces that have been provided periodically. It has been seen that type II design of pure and SBS including HMAs asphalt pavements friction layer, physical properties and design parameters of bitumen and aggregate provide KGM scientific criteria. Modified and pure HMAs have a little sensibility to heat in terms of penetration index is determined. They exceed scientific criteria limits in terms of softening points besides providing all the others criteria limits. Experimental results about bitumen and aggregate and the results that gathered from experiments aimed to control are in criteria limits and accordant with each other. A rising in ratio of voids filled with asphalt, a decrease air space ratio in montly period and space percentage between agregates as volumetric parameters of core test pieces have been seen. As a result of Marshall experiments, SBS modified HMAs test pieces have a greater value of stability and Marshall ratio(MQ). Increasing in stability and Marshall ratio, decreasing in yield values have been determined. Maximum stability value have been gathered from 12th month road side zone SBS modified HMAs core test pieces. As a result of applying tension experiments to control and test pieces, tensile strength increases with SBS usage and increasing time periods. As a result of indirect tensile stiffness modulus experiments, the strength of mixture increases with SBS usage and inceasing time periods. As a result of indirect tensile fatigue experiments, fatigue life of SBS modified HMAs are greater than fatigue life of pure HMAs, additionally, it is determined that fatigue life increases with increasing month periods. Moreover, brittle fracture is observed due to decreasing deformation. Maximum indirect tensile strenght, indirect tensile stiffness modulus and fatigue strength is determined in road side zone SBS modified HMAs core test pieces. If experiments results is taken into consideration,strength and stability oppose plastic deformation and fatigue fracture enhance with increasing SBS content, in contrast with occurence of more brittle fracture has been determined. Keywords: Hot Mix Asphalt, Styrene-Butadiyne-Styren, Marshall Test, Indirect Tensile Stiffness Modulus, Indirect Tensile Stiffness Modulus, Fatigue.