Improving the detection efficiency and maintenance benefits is one of the greatest challenges in road testing and maintenance. To address this problem, this paper presents a method for combining the you only look once (YOLO) series with 3D ground-penetrating radar (GPR) images to recognize the internal defects in asphalt pavement and compares the effectiveness of traditional detection and GPR detection by evaluating the maintenance benefits. First, traditional detection is conducted to survey and summarize the surface conditions of tested roads, which are missing the internal information. Therefore, GPR detection is implemented to acquire the images of concealed defects. Then, the YOLOv5 model with the most even performance of the six selected models is applied to achieve the rapid identification of road defects. Finally, the benefits evaluation of maintenance programs based on these two detection methods is conducted from economic and environmental perspectives. The results demonstrate that the economic scores are improved and the maintenance cost is reduced by $49,398/km based on GPR detection; the energy consumption and carbon emissions are reduced by 792,106 MJ/km (16.94%) and 56,289 kg/km (16.91%), respectively, all of which indicates the effectiveness of 3D GPR in pavement detection and maintenance.

Accurately identifying and localizing concealed cracks in asphalt pavements through nondestructive ground-penetrating radar (GPR) testing has attracted much attention. However, various realistic factors restrict its detection accuracy. Therefore, this paper proposed a novel YOLOv3 model with a ResNet50vd-deformable convolution (DCN) backbone and a hyperparameter optimization (HPO) method using Bayesian search. First, a 3D-Radar system with multi-channel DXG $^{{TM}}$ ground-coupled antenna arrays was used to investigate concealed cracks in the asphalt pavement to establish a crack distress dataset with 366 images and 533 cracks. Then, owing to the small GPR image dataset, a simple semi-supervised label distillation (SSLD) method was employed to obtain the pretrained model. Subsequently, Bayesian searching based HPO was performed to find the maximum mean average precision (mAP) and corresponding hyperparameters in 20 searches. Finally, several mainstream detection models were used for comparisons. Experimental results showed that YOLOv3-ResNet50vd-DCN model converged faster and had a smaller loss value (approximately 0.05) in the training process, which illustrates the advantage of model pretraining with the SSLD method. Besides, the proposed model also achieved good detection results, with 92.6% accuracy, 92.3% F1 score, 92.1% mAP, and 0.923 area under the ROC curve (AUC) value, all 3% to 7% higher than that of the other models. After Bayesian searching for HPO, the detection results were further improved to 94.8% accuracy, 96.2% F1 score, 94.6% mAP, and 0.962 AUC value, validating the reliability and superiority of the proposed model and optimization method in detecting pavement concealed cracks of GPR images.

To realize the intelligent and accurate measurement of pavement surface potholes, an improved You Only Look Once version three (YOLOv3) object detection model combining data augmentation and structure optimization is proposed in this study. First, color adjustment was used to enhance the image contrast, and data augmentation was performed through geometric transformation. Pothole categories were subdivided into P1 and P2 on the basis of whether or not there was water. Then, the Residual Network (ResNet101) and complete IoU (CIoU) loss were used to optimize the structure of the YOLOv3 model, and the K-Means++ algorithm was used to cluster and modify the multiscale anchor sizes. Lastly, the robustness of the proposed model was assessed by generating adversarial examples. Experimental results demonstrated that the proposed model was significantly improved compared with the original YOLOv3 model; the detection mean average precision (mAP) was 89.3%, and the F1-score was 86.5%. On the attacked testing dataset, the overall mAP value reached 81.2% (−8.1%), which shows that this proposed model performed well on samples after random occlusion and adding noise interference, proving good robustness.

The effect of basalt fiber on asphalt binder and mastic at low temperatures is investigated in this study. Basalt fibers are dispersed into the asphalt binder and mastic specimens to prepare the fiber-reinforced binding materials. The fiber-reinforced specimens are tested using the direct tension test and a newly developed fatigue test procedure, which is able to directly apply cyclic tensile loading to the asphalt binder and mastic specimens. The reinforcement effects of basalt fiber to the fatigue resistance of asphalt binding materials are evaluated. The direct tension test results show that with an appropriate content, the tensile strength of the asphalt binder is improved with the use of basalt fiber. The basalt fiber also restrains the axial strain and increases the stiffness of both the asphalt binder and mastic specimens. The fatigue test results indicate that the fatigue life of both asphalt binder and mastic specimens is significantly improved by the basalt fibers. The effect of basalt f...