ASSESSMENT OF THE HOT MIX ASPHALT PROPERTIES USING REED PLANT MODIFIED ASPHALT

ABSTRACT Many researchers’ attention was drawn by the process of improving the characteristics and the performance of hot mix asphalt. In this research, Reed Plant Ash (RPA) and Reed Plant Powder (RPP) were used as a substance to optimize the characteristics of asphalt at (5, 10, 15, and 20) % by asphalt weight. The laboratory work included two parts to get the requirements of the research: the first part is the physical properties for pure and modified asphalt. The second part is the prepared specimen of HMA with pure and the best percent of modified asphalt according to the Marshall criteria using limestone dust at 7% as a filler to the surface layer. The study found that the HMA with modified asphalt by 10% RPP has more effects on its performance by improving the Marshal Stability, volumetric properties, tensile strength ratio, and retained Marshall Stability rather than control mix and HMA with modified asphalt by 15% RPA.


INTRODUCTION
The reed plant was chosen in the purpose of preserving the environment and its sustainability, and it is a material where there is an abundance of it in Iraq, especially near drainage banks and sewage pipes as well as it is an inexpensive material.
NCHRP 459 (2001) indicated that modification of asphalt binders is helpful to reach the requirements of the performance of flexible pavement at high -and low temperature grades, or it can improve the binder's performance at severe-service condition, such as very high traffic volume or at a high percentage of slow-moving and heavy vehicles.
The replacement of a fine aggregate of asphalt mixture by recycled concrete aggregate and steel slag improves Marshall Stability and decreasing flow Arabani and Azarhoosh, (2012).Do and keun (2008) stated that using recycled waste lime (RWL) as a filler in asphalt concrete mixture improved the resistance to permanent deformation at high temperatures.
Many researchers studied how to improve hot mix asphalt concrete properties and performance, the resisting to moisture damage ability and reducing temperature sensitivity by modifying it using additives materials as a partial replacement of mineral filler or using the same materials to modify the asphalt cement with many methods.Table 1 summarizes some of the previous work using modified asphalt cement, as well as Table 2 summarizes studies to modified asphalt concrete mixture.

PREPARING OF USED MATERIALS
AL-Dura refinery Asphalt Cement (40-50) penetration grade is used in this study; Table 3 shows the physical properties of it.

PREPARATION OF MODIFIED ASPHALT
According to Sarsam S.I., 2015 Modified Asphalt was prepared as follows: 1. Heating asphalt cement up to160°C.
2. While the mixture was being stirred added gradually RPA and RPP separated from each other to make two different types of modified asphalt.Added RPA and RPP in four percentages which are 5%, 10%, 15% and 20% from the asphalt weights stayed in the stirring machine for about 45 min at the same heated temperature.

EXPERMINTAL WORK
1. Checking penetration, softening point, ductility before and after laboratory aging for pure and modified asphalt at each percent of modification by RPA and RPP.
2. Calculating Stiffness Modulus at 104 sec loading time and 25°C from the Shell Nomo graph.
3. Determining the optimum asphalt cement content for the mix with pure asphalt and with the best modification percent of RPA and RPP.
4. Check the Marshall properties at optimum asphalt cement content to each prepared specimen.
5. Testing the indirect tensile strength for the all prepared mixes according to (AASHTO T 283).
6. Finding the Marshall Retained Stability to each mix prepared.

FINDING RESULTS
Tables 7, Table 8 and Fig. 3 show the penetration, softening point, and ductility before and after aging for the pure and modified asphalt by RPA and RPP respectively and Stiffness Modulus after aging results.Optimum asphalt content for the best percent of the modified asphalt with RPA and RPP according to the stiffness modulus value is shown in

CONCLUSIONS
1. Adding RPA as a modifying material: penetration before and after aging decreased by 18.75% and 24.32%, respectively, softening point before and after aging increased by 29.27% and 46.51% respectively, ductility before and after aging decreased by 9.02% and 11.11%, respectively, and stiffness modulus increased by 24.00% when the percent of RPA increase to 15% then the value of it decrease by 4.72%.
2. Adding RPP as a modifying material: penetration before and after aging decreased by 31.25% and 32.43%, respectively, softening point before and after aging increased to 39.02% and 55.81% respectively, ductility before and after aging decreased by 6.77% and 19.44% respectively, and stiffness modulus increased to 27.00% when the percent of RPP increase up to 10% then the value of it decrease by 24.19%.
3. 15% of RPA and 10% of RPP was selected to check the Marshall Properties and indirect tensile strength because it meets the requirements of (SCRB, 2003/ R9) specification.
4. Optimum asphalt content to prepare the specimens using modified asphalt by 15% RPA 10% RPP was higher than with pure asphalt by 9.91% and 22.20%, respectively.

Table 2 . Summary of some Literature Review to Studies Modified Asphalt Concrete Mixtures.
Physical properties of coarse and fine aggregate crushed quartz from Al-Nibaie quarry are used according to the mid specification of (SCRB, 2003/ R9) requirements of surface course gradation type IIIA; as showed in Table4, also Table5shows the used gradation.Limestone dust is used as mineral filler from lime factory in Karbala governorate.Reed plant was collected, dried, scorched, and sieved by sieve #200 to prepare Reed Plant Ash as shown in Fig.1.Preparing Reed Plant Powder by drying it in an oven in 110 ± 10ᵒC then grinding and sieving it by sieve #200 as shown in Fig.2.Table6explains the physical properties of the filling materials used in this study.
4 indicate the Marshall, volumetric properties, and indirect tensile strength results for the prepared specimens.