Effect of Fine Recycled Asphalt Aggregates and Cement Additives on the Sandy Subgrade Performance

IIn different parts of the world, road pavements are on dune sandy subgrade, where road construction is not possible without amendments. In this regard, various methods, such as mixing soil with other materials like lime, cement, bitumen, geotextiles, chemical compounds, etc to improve the soil grading, have been considered. In this research, the simultaneous effect of incorporating fine reclaimed asphalt pavement aggregates (FRAPA) for improving grading and cement application as the binder of the dune sand was investigated to enhance subgrade strength properties. The soil was mixed and replaced by three different doses of crushed recycled asphalt FRAPA (5, 15, and 25 percent). Similarly, the soil was replaced by 2.5, 5, and 7.5 percent of cement; in each mixing step, samples were prepared using static compaction method. Specimens were tested in uniaxial compressive strength (UCS) after saturation at the temperature of 25°C for 3 and 7 days curing period. Some of the results of this study showed that the increase of cement itself does not have much effect on increasing the strength properties of the soil but the use of FRAPA can significantly improve its properties. The maximum compressive stress strength and soil elastic modulus were obtained in the ratio of mixing 7.5% cement and 15% FRAPA. In the next step, the experimental results were selected as inputs in the numerical models and from the results of the finite element analysis the optimal thickness for subgrade improvement was chosen; where the thickness of 20 cm was obtained accordingly.

کلیدواژه ها:

Fine Recycled Asphalt Pavement Aggregates (FRAPA) ، Dune Sand ، Cement Additives ، Pavement Subgrade ، Flexible Pavement Modeling