Effect of Recycled Shell Waste as a Modifier on the High- and Low-Temperature Rheological Properties of Asphalt

Abstract

The deteriorating ecological environment and the concept of sustainable development have highlighted the importance of waste reuse. This article investigates the performance changes resulting from the incorporation of shellac into asphalt binders. Seashell powder-modified asphalt was prepared with 5%, 10%, and 15% admixture using the high-speed shear method. The microstructure of the seashell powder was observed by scanning electron microscope test (SEM); the physical-phase analysis of the seashell powder was carried out using an X-ray diffraction (XRD) test; the surface characteristics and pore structure of shellac were analyzed by the specific surface area Brunauer-Emmett-Teller (BET) test; and Fourier infrared spectroscopy (FTIR) qualitatively analyzed the composition and changes of functional groups of seashell powder-modified asphalt. The conventional performance index of seashell powder asphalt was analyzed by penetration, softening point, and ductility (5 °C) tests; the effect of seashell powder on asphalt binder was studied using a dynamic shear rheometer (DSR) and bending beam rheometer (BBR) at high and low temperatures, respectively. The results indicate the following: seashell powder is a coarse, porous, and angular CaCO3 bio-material; seashell powder and the asphalt binder represent a stable physical mixture of modified properties; seashell powder improves the consistency, hardness, and high-temperature performance of the asphalt binder but weakens the low-temperature performance of it; seashell powder enhances the elasticity, recovery performance, and permanent deformation resistance of asphalt binders and improves high-temperature rheological properties; finally, seashell powder has a minimal effect on the crack resistance of asphalt binders at very low temperatures. In summary, the use of waste seashells for recycling as bio-modifiers for asphalt binders is a practical approach.

Analysis of the Influence of Waste Seashell as Modified Materials on Asphalt Pavement Performance

“…It is indicated that SPMA has better low-temperature crack resistance than SCESPMA. Previous studies have found that adding other seashell materials to asphalt will generally reduce its low-temperature crack resistance [ 20 , 21 ], which is consistent with the results of this study. However, this study finds that the stratum corneum of seashell has better low-temperature crack resistance than other structural layers.…”

“…There have been studies on the use of biological materials to prepare modified asphalt. Generally, 5~30% of biological materials are used to prepare modified asphalt to study the road performance of modified asphalt [ 20 , 26 ]. The preparation of the seashell powder-modified asphalt sample in this study refers to the relevant existing research methods [ 20 ].…”

“…Generally, 5~30% of biological materials are used to prepare modified asphalt to study the road performance of modified asphalt [ 20 , 26 ]. The preparation of the seashell powder-modified asphalt sample in this study refers to the relevant existing research methods [ 20 ]. The sample preparation process is as follows: pour 2100 g neat asphalt into 7 sample cups evenly; heat the asphalt in the sample cup to 150 °C until it becomes complete flow; mix SP and SCESP into 6 sample cups, and stir the mixture for 30 min at 2500–3000 r/min under the high-speed shear instrument, as shown in Table 5 .…”

“…When eggshell powder is mixed into asphalt, it makes asphalt hard and increases moisture susceptibility [ 19 ]. Laurel scallop, goby scallop and pectin scallop powders can significantly improve the elasticity of asphalt, reduce its low-temperature crack resistance, and keep the types of functional groups inside it unchanged [ 20 ]. The medium and low content of oyster powder can improve the low-temperature, rutting and fatigue properties of asphalt.…”