Civil Engineering Dept.  at U.O.T. granted  a master degree with distinction to the student Mays  (Mays Eyad Jaafar / majoring in roads, and her entitled thesis:

“Enhancement of Physical and Mechanical Properties of Rejuvenated RAP Mixtures with Nanoclay Powder “                        

One of the main objectives of this research is to enhance the performance and properties of hot recycled asphalt mixtures that contain a number of percentages of reclaimed asphalt paving materials (RAP) using modified asphalt cement with different percentages of nanopowdered clay. RAP was used in this work in three proportions (30, 40, and 50%) by weight of the total mixture, and they were replenished with gradient (85-100) asphalt,

The reason for choosing these ratios is to stay within the recommended limits for the use of RAP materials as recommended by previous researchers. The regenerated recycled mixture is modified using new asphalt cement blended and modified with montmorillonite nanoclay powder (MMT) in proportion (3.1 and 5%) by weight of asphalt cement. Previous research studied the effect of nanoscale MMT on the pristine binder and found that the viscosity of MMT-modified asphalt tends to rise with higher MMT as well as ductility point while penetration and ductility are reduced.

The Marshall Mix design was used to determine the Optimum Asphalt Percentage (O.B.C) content of the reference mix. All the basic materials used in this work are available locally, and they consist of: asphalt binder with a degree of penetration (40-50), aggregate grades for the surface layer with a maximum nominal size of 12.5 mm and Portland cement as a filler. After the recycled mixture was designed, it was evaluated with the reference mixture using Marshall stability, flow, indirect tensile strength, tensile strength ratio (TSR), compressive strength, residual strength index (IRS), and permanent deformation resistance.

In general, the test results indicated that the recycled mixture modified with the nano-clay was better than the recycled mixture without the nano-material.

It was observed that the recycled asphalt mixtures with 5% MMT of nano-clay enhance Marshall stability and reduce the flow by 53.4% ​​and 28.9% respectively for 50% RAP, while the indirect tensile strength ITS and compressive strength decrease compared to the original mixture. by 17.2% and 10.95% for the assays respectively for 50% RAP of the samples exposed to the conditions in the assay. However; Moisture resistance was enhanced  as indicated by the TSR tensile strength ratio and the IRS residual strength index, increasing by 16.13% and 0.42% in 50% RAP and 5% MMT. On the other hand, the rutting resistance was significantly increased in the same mixture as it was 83.2%.

The discussion committee consisted of:- 

1-  Prof. Dr. Muhammad Abbass Al-Jumaily,/Head

2- Asst. Prof. Dr. Miami Mohammed Helal / Member.

3-  Lect. Dr. Ammar Abbas Mohammed / Member.

4- Prof. Dr. Hussein Hamid Karim/ supervisor.