Evaluation of the Performance of Sawdust Ash in Bituminous Concrete against Moisture Damage

In tropical regions, lack of moisture-damage-resistant fillers in flexible pavements poses significant challenges for infrastructure development and maintenance. Hence, this study examined sawdust ash (SDA) for such purposes. SDA is abundant as agricultural waste in rice-producing countries like India and China. Durability assessment of SDA-enriched bituminous concrete (BC) against moisture damage is considered as state-of-art in this investigation. To implement this study, numerous laboratory tests were carried out. First, the Marshall test was carried out to estimate the optimal bitumen content (OBC) and several Marshall properties, including Marshall volumetric properties. After that, a modified Marshall immersion test, energy loss ratio test, ultrasonic pulse velocity (UPV) test, indirect tensile strength test (ITS), resilient modulus ratio test, and rutting resistance test were done to execute this investigation. Furthermore, the morphological characteristics of the studied filler were investigated by atomic force microscopy (AFM). The experimental result shows that the 8% SDA-enriched BC mix may be applied in low-volume roads in tropical regions like India with 86.94% structural integrity for the presence of ample amounts of calcium oxide (CaO), silicon oxide (SiO2), ferric oxide (Fe2O3), and higher loss on ignition value in that ash. Moreover, the results have shown that the mixes containing 8% SDA perform exceptionally well against moisture damage with the highest energy loss ratio (63.27%) and dynamic modulus (12.1 MPa) after 14 days of immersion. Similarly, this type of mix delivers the highest tensile strength ratio (96.27%) and resilient modulus ratio (89.21%), with minimum rutting depth (9.55 mm), and performs not only in terms of moisture resistance but also in its ability to withstand rutting deformation significantly. These results make it a promising choice for asphalt pavements, to mitigate the detrimental effects of both rutting and moisture on the overall durability and longevity of the road.