Rheology and microstructure effects of waste spent coffee grounds in modifying asphalt binder

Abstract

Herein the biowaste by-product spent coffee grounds (SCGs) from coffee industry were incorporated into asphalt binders for performance enhancement. From the analysis of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dynamic shear rheometer (DSR), and Brookfield viscosity rheometer, it is confirmed that SCGs have potential prospects as bio-waste modifiers in the application of sustainable pavements. Results demonstrated that the modification process was mainly based on physical reinforcement. Compared with that of the neat asphalt, the shearing stress-resistant ability and high-temperature performance of the SCGs modified binders with the appropriate addition presented a bit of improvement; whereas the binders with 1% and 3% SCGs exhibited remarkably enhanced low-temperature stability. However, notable weaknesses of practical performance were shown for the binder with excessive content of SCGs, indicating the necessity of proportion selecting before application.本文将咖啡萃取后得到的固体废弃物咖啡渣(Spent coffee grounds, SCGs)应用于沥青材料改性中，旨在实现生物基固废材料处理和沥青路面性能提升的双重目的。通过傅里叶红外光谱(FTIR)、差示扫描量热仪(DSC)、动态剪切流变仪(DSR)和布氏黏度计等技术，证实了咖啡渣在路面材料可持续化发展中具有潜在的应用与推广前景。试验结果表明，咖啡渣改性过程主要基于物理增强作用；与基质沥青相比，合理掺量的咖啡渣改性沥青具有理想的高温稳定性和良好的抗永久变形能力；同时1%和3%掺量的咖啡渣引入有利于增强基质沥青的低温性能。然而，过多咖啡渣的加入可能会对改性沥青的流变性能产生负面影响，这表明改性时应选择合理掺量的咖啡渣改性剂以满足实际性能提升需求。 Graphical Abstract