Wu Hao, Yu Daoan, Wang Wentao, Yan Chuanqi, Xiao Rui, Chen Rong, Zhang Peng, Zhang Hengji
Shandong Provincial Road and Bridge Group Co., Ltd., Jinan 250014, China.
School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031, China.
Materials (Basel). 2025 Aug 4;18(15):3660. doi: 10.3390/ma18153660.
Asphalt plant reclaimed powder is a common solid waste in road engineering. Reusing reclaimed powder as filler holds significant importance for environmental protection and resource conservation. The key factors affecting the feasibility of reclaimed powder reuse are its acidity/alkalinity and cleanliness. Traditional evaluation methods, such as the methylene blue test and plasticity index, can assess reclaimed powder properties to guide its recycling. However, these methods suffer from inefficiency, strong empirical dependence, and high variability. To address these limitations, this study proposes a rapid and precise evaluation method for reclaimed powder properties based on Fourier transform infrared spectroscopy (FTIR). To do so, five field-collected reclaimed powder samples and four artificial samples were evaluated. Scanning electron microscopy (SEM), X-ray fluorescence spectroscopy (XRF), and X-ray diffraction (XRD) were employed to characterize their microphase morphology, chemical composition, and crystal structure, respectively. Subsequently, FTIR was used to establish correlations between key acidity/alkalinity, cleanliness, and multiple characteristic peak intensities. Representative infrared characteristic peaks were selected, and a quantitative functional group index (Is) was proposed to simultaneously evaluate acidity/alkalinity and cleanliness. The results indicate that reclaimed powder primarily consists of tiny, crushed stone particles and dust, with significant variations in crystal structure and chemical composition, including calcium carbonate, silicon oxide, iron oxide, and aluminum oxide. Some samples also contained clay, which critically influenced the reclaimed powder properties. Since both filler acidity/alkalinity and cleanliness are affected by clay (silicon/carbon ratio determining acidity/alkalinity and aluminosilicate content affecting cleanliness), this study calculated four functional group indices based on FTIR absorption peaks, namely the Si-O-Si stretching vibration (1000 cm) and the CO asymmetric stretching vibration (1400 cm). These indices were correlated with conventional testing results (XRF for acidity/alkalinity, methylene blue value, and pull-off strength for cleanliness). The results show that the Is index exhibited strong correlations (R = 0.89 with XRF, R = 0.80 with methylene blue value, and R = 0.96 with pull-off strength), demonstrating its effectiveness in predicting both acidity/alkalinity and cleanliness. The developed method enhances reclaimed powder detection efficiency and facilitates high-value recycling in road engineering applications.
沥青厂再生粉是道路工程中常见的固体废弃物。将再生粉用作填料对环境保护和资源节约具有重要意义。影响再生粉再利用可行性的关键因素是其酸碱度和洁净度。传统的评估方法，如亚甲蓝试验和塑性指数，可评估再生粉性能以指导其回收利用。然而，这些方法存在效率低、对经验依赖性强和变异性大的问题。为解决这些局限性，本研究提出一种基于傅里叶变换红外光谱（FTIR）的再生粉性能快速精确评估方法。为此，对五个现场采集的再生粉样品和四个人造样品进行了评估。分别采用扫描电子显微镜（SEM）、X射线荧光光谱（XRF）和X射线衍射（XRD）对其微相形态、化学成分和晶体结构进行表征。随后，利用FTIR建立关键酸碱度、洁净度与多个特征峰强度之间的相关性。选取代表性红外特征峰，提出定量官能团指数（Is）以同时评估酸碱度和洁净度。结果表明，再生粉主要由细小的碎石颗粒和粉尘组成，晶体结构和化学成分差异显著，包括碳酸钙、氧化硅、氧化铁和氧化铝。一些样品还含有粘土，这对再生粉性能有至关重要的影响。由于填料的酸碱度和洁净度均受粘土影响（硅/碳比决定酸碱度，铝硅酸盐含量影响洁净度），本研究基于FTIR吸收峰计算了四个官能团指数，即Si - O - Si伸缩振动（1000 cm）和CO不对称伸缩振动（1400 cm）。这些指数与传统测试结果相关（XRF用于酸碱度，亚甲蓝值，洁净度用拉拔强度）。结果表明，Is指数表现出很强的相关性（与XRF的R = 0.89，与亚甲蓝值的R = 0.80，与拉拔强度的R = 0.96），证明其在预测酸碱度和洁净度方面的有效性。所开发的方法提高了再生粉检测效率，便于道路工程应用中的高价值回收利用。
