اسراء رياض عبدالرضا الغرة

This study aims to ascertain the effects of polymer-modified bitumen (PMB) and to utilize mineral filler with micro-silica (MS) on various properties of hotmix asphalt (HMA). In this work, three specimens of an asphalt-concrete mixture were prepared. The first specimen represents a control mixture, the second specimen contains MS at rates 15, 30, and 45% by the total weight of the total aggregate as filler, and the third specimen contains MS and PMB with 4% novolac by the weight of bitumen and 15% hexamine by the weight of the novolac. The properties of designed mixes were evaluated using the indirect tensile strength test, tensile–strength ratio, and creep compliance. The test results showed an increase in the resistance of asphalt concrete to moisture damage, a reduction influence of water on asphalt concrete properties, creep compliance values indicating growing stiffness for asphalt mixture, and enhanced fatigue life. In conclusion, using 45% MS and PMB improved the properties of HMA and provided long-lasting mixtures for highway construction.

The use of waste materials in the construction process has become more popular during the last decades since that it reduces the initial cost and reduces the cost of solid waste disposal. Rice Husk Ash (RHA) is a waste material available in a huge quantity of Iraq and used as mineral filler in this study. The current research focuses on the investigation of the effect of three types of mineral filler on mechanical properties of Hot Mix Asphalt (HMA). In addition to RHA, the limestone and Ordinary Portland Cement (OPC) were used as mineral fillers (MF). The RHA was prepared by burning it in two stages, the first stage involves burning the RHA in a closed space and the second stage involves burning the RHA in an oven at 800 °C for two hours. Different percentages of these mineral fillers as (25%, 50%, 75% and 100%) RHA and OPC replacement with conventional mineral filler were used in produced HMA. The obtained mixes were tested to determine Marshall Stability, Marshall Flow, indirect tensile strength and tensile strength ratio. The results showed that the RHA can be used as mineral filler in HMA; however, the optimum ratio of mineral filler was 25 % RHA and 75 % limestone.

This research aims to assess the properties of Polymer Modified Bitumen (PMB) binder prepared with different types of additives such as (Waste low density polyethylene (W-LDPE) and crumb rubbers (CR)and Styrene Butadiene Styrene (SBS)). Most of these additives are sustainable materials since it is derived from old scrap materials. All the above-mentioned materials (W-LDPE, CR and SBS) were added with percentages of (2, 4, and 6 percentage) of the weight of pure asphalt binder. Several tests were conducted to evaluated the properties of improved asphalt binder such as penetration test, Ductility test, Softening point test, Rotational viscosity test as well as thin-film oven test. The results of investigation revealed that, the using of different types of PMB significantly improved the physical properties and performance of asphalt. The using of sustainable waste materials such as W-LDPE and CR significantly improve the properties of PMB and contribute in recycling great amount of waste materials. Also, the results showed that the using of high percentage of SBS (6%) significantly increase the viscosity of asphalt binder and that can affect workability of Hot Mix Asphalt (HMA) compared with same percentages of WLDPE and CR)

This research aims to test various types of fillers such as (limestone dust, rice husk ash and ordinary Portland cement) and examine their influence on the performance of the asphalt mixture containing Polymer Modified Bitumen (PMB) binder. The research includes designing a regular reference mix for the purposes of comparison and designing several asphalt mixtures with various percentage (25, 50, 75 and 100) % RHA & OPC as mineral filler and PMB. Several tests were conducted to evaluated the mechanical characteristics and performance of Hot Mix Asphalt (HMA) such as Marshall stability, Indirect Tensile Strength (ITS), creep compliance and wheel track test. The results of investigation revealed that, the using of PMB significantly improved the mechanical characteristics and performance of HMA. The results of creep compliance demonstrated that the replacement of conventional MF with 50% RHA or 50 % OPC leads to decrease creep compliance values of HMA contained PMB by 68% and 64 % respectively compared with control mix. Also, for the same percentages of replacement and PMB, the rut depth values decreased by 64% and 48 % respectively compared with the reference mixture.