Department of Civil Engineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India.
PLoS One. 2021 Mar 15;16(3):e0248465. doi: 10.1371/journal.pone.0248465. eCollection 2021.
Pyrolysis has gained a strong interest in recent times for sustainable treatment and recovery of energy-rich products from different wastes including plastic. Waste plastic pyrolytic char (PPC) generated as a carbonaceous by-product in the pyrolysis process, is gaining attention as an asphalt binder modifier. Adequate thermal storage stability is an essential requirement for a modified asphalt binder to ensure that the composite offers integrity and homogeneous properties during its storage, handling and transportation in the field. The objective of this study was to evaluate and characterize the thermal storage stability properties of PPC modified binders. PPC modified asphalt binders were fabricated and evaluated at multiple dosages of sulfur as a cross-linking agent. In addition to the conventionally used softening point difference (SPD), characterization of thermal storage stability was attempted using rheology-based separation indices (SIs) derived through temperature sweep, frequency sweep, and multiple stress creep and recovery (MSCR) tests. These rheological SIs were based on complex modulus (G*), Superpave rutting parameter (G*/sin δ), Shenoy rutting parameter (SRP), zero shear viscosity (ZSV), and MSCR Jnr (at three stress levels 0.1, 3.2 and 10 kPa). Two formulations of each rheology-based separation index were studied: (1) ratio, and (2) maximum-average difference formulations. The temperature and frequency dependencies of rheological SIs were also evaluated. Further, the Fourier transform infrared spectroscopy (FTIR) was used to characterize storage stability by comparing the chemical functionalities of the PPC modified binders. A 0.3% dosage of sulfur was found to produce the best results considering all SPD, rheology-based SIs and FTIR. Principal component analysis showed that the ratio and maximum-average formulations had similar contributions to the first principal component accounting for more than 99% of the variability.
热解在最近一段时间受到了广泛关注，因为它可以从不同的废物（包括塑料）中可持续地处理和回收富含能量的产品。在热解过程中作为碳质副产物产生的废塑料热解焦（PPC）作为沥青粘合剂改性剂受到关注。足够的热储存稳定性是改性沥青粘合剂的基本要求，以确保在其储存、处理和运输过程中，复合材料在现场保持完整性和均匀性。本研究的目的是评估和表征 PPC 改性粘合剂的热储存稳定性特性。制备了 PPC 改性沥青粘合剂，并在多个硫剂量下作为交联剂进行了评估。除了常用的软化点差值（SPD）外，还尝试通过温度扫描、频率扫描和多重应力蠕变和恢复（MSCR）试验得出的基于流变学的分离指数（SI）来表征热储存稳定性。这些流变学 SI 基于复数模量（G*）、Superpave 车辙参数（G*/sin δ）、Shenoy 车辙参数（SRP）、零剪切粘度（ZSV）和 MSCR Jnr（在三个应力水平 0.1、3.2 和 10 kPa 下）。研究了两种流变学分离指数的配方：（1）比率和（2）最大-平均差异配方。还评估了流变学 SI 的温度和频率依赖性。此外，还使用傅里叶变换红外光谱（FTIR）通过比较 PPC 改性粘合剂的化学官能团来表征储存稳定性。考虑到所有 SPD、基于流变学的 SIs 和 FTIR，发现 0.3%的硫用量效果最佳。主成分分析表明，比率和最大-平均配方对第一主成分的贡献相似，占可变性的 99%以上。
