In the contemporary era, 3D printing technology has become widely utilized across diverse fields, including biomedicine, industrial design, manufacturing, food processing, aerospace, and construction engineering. The inherent advantages of automation, precision, and speed associated with 3D printing have progressively led to its incorporation into road engineering. Asphalt, a temperature-responsive material that softens at high temperatures and solidifies as it cools, presents distinctive challenges and opportunities in this context. For the effective implementation of 3D printing technology in road engineering, 3D printed asphalt (3DPA) must exhibit favorable performance and printability. This requires attributes such as good fluidity, extrudability, and buildability. Furthermore, materials utilizing 3DPA for crack repair should possess high viscosity, elasticity, toughness, superior high-temperature stability, and resistance to low-temperature cracking. These characteristics ultimately contribute to enhancing pavement longevity and ensuring worker safety.

PURPOSES : This study uses deep learning image classification models and vehicle-mounted cameras to detect types of pavement distress — such as potholes, spalling, punch-outs, and patching damage — which require urgent maintenance. METHODS : For the automatic detection of pavement distress, the optimal mount location on a vehicle for a regular action camera was first determined. Using the orthogonal projection of obliquely captured surface images, morphological operations, and multi-blob image processing, candidate distressed pavement images were extracted from road surface images of a 16,036 km in-lane distance. Next, the distressed pavement images classified by experts were trained and tested for evaluation by three deep learning convolutional neural network (CNN) models: GoogLeNet, AlexNet, and VGGNet. The CNN models were image classification tools used to identify and extract the combined features of the target images via deep layers. Here, a data augmentation technique was applied to produce big distress data for training. Third, the dimensions of the detected distressed pavement patches were computed to estimate the quantity of repair materials needed. RESULTS : It was found that installing cameras 1.8 m above the ground on the exterior rear of the vehicle could provide clear pavement surface images with a resolution of 1 cm per pixel. The sensitivity analysis results of the trained GoogLeNet, AlexNet, and VGGNet models were 93 %, 86 %, and 72 %, respectively, compared to 62.7 % for the dimensional computation. Following readjustment of the image categories in the GoogLeNet model, distress detection sensitivity increased to 94.6 %. CONCLUSIONS : These findings support urgent maintenance by sending the detected distressed pavement images with the dimensions of the distressed patches and GPS coordinates to local maintenance offices in real-time.

PURPOSES: The objectives of this study are to analyze the current status of pothole during a rainy season and to suggest a future pavement maintenance method via pothole analysis. METHODS: Potholes are caused by moisture submerged in pavement. The pore pressure caused by traffic and environmental loads causes failure between the aggregate and asphalt binder. Thus, heavy rain is a primary pothole creator, especially in aged pavement. To prevent accidents on roadways, Gyeonggi-do has initiated a fast pothole repair program. However, the number of potholes increase every year. In this study, the current status of potholes and maintenance methods are analyzed. Based on these results, a future pavement maintenance method is suggested. RESULTS AND CONCLUSIONS : Gyeonggi-do’s pothole situation is worse than Seoul’s. Problems were founded, as follows. The amount of potholes was large, and the number increased annually. Pothole management is done at a basic level, because there is no long-term plan. Potholes occur frequently at the same site because of the poor quality of emergency repair. Finally, there is no systematic and comprehensive pavement management. Thus, pothole prevention measures are ill-prepared. Therefore, to reduce potholes and to manage high quality pavement, it is necessary to make a long-term pavement management plan.

PURPOSES : The objective of this study is to develop new pothole repair materials using polyurethane-modified asphalt binder, and to evaluate them relative to current pothole repair materials in order to improve the performance of repaired asphalt pavement. METHODS : In the laboratory, polyurethane-modified asphalt binder is developed, and then asphalt binder is added to produce pothole repair materials. In order to evaluate the properties of this new pothole repair material, both an indirect tension strength test and a direct tension strength test are performed to measure the material strength and bond strength, respectively. Additionally, the basic material properties are evaluated using the asphalt cold mix manual. The strength characteristics based on curing times are evaluated using a total of 7 types of materials (3 types of current materials, 2 types of new materials, and 2 types of moisture conditioned new materials). The indirect tension strength tests are conducted at 1, 2, 4, 8, 16, and 32 days of curing time. The bond strength between current HMA(Hot Mix Asphalt) and the new materials is evaluated by the direct tension strength test. RESULTS AND CONCLUSIONS : Overall, the new materials show better properties than current materials. Based on the test results, the new materials demonstrate less susceptibility to moisture, faster curing times, and an improved bond strength between HMA and the new materials. Therefore, the use of the new materials reported in this study may lead to enhanced performance of repairs made to asphalt pavement potholes.

PURPOSES: The purpose of this study was to break away from the workforce method using cold-mix asphalt mixtures and has a constant quality and has develop repair materials of pre-production asphalt-precast types. METHODS: The selection of the repair material was determined as the results obtained through physical properties of materials and the field applicability. In case of repair materials, values obtained through Marshall stability test & the dynamic stability test & retained stability test as well as the site conditions was considered. In case of adhesive, test results were obtained through examination of the bond strength(tensile, shear) and the field applicability of the adhesive was examined through combined specimens to simulate field applications. RESULTS : According to the results of laboratory tests, in the case of repair materials, Marshall stability and dynamic stability, retained stability of cold-mix reaction type asphalt mixture is the highest. In the case of adhesive, two-component epoxy-urea has a very high bonding strength(tensile, shear) was most excellent. According to the results of field tests, when epoxy-urea was excellent workability. Also, the repair body through actual mock-up test did not occur large deformation and fracture after 12 months. CONCLUSIONS : A suitable repair material is cold-mix reaction type mixture of asphalt-precast, a suitable adhesive is a two-component epoxy-urea.

Purpose of this study is investigates mechanical property of Chemically Bonded Phosphate Ceramic(CBPC). For the purpose of the investigation of mechanical property, compressive stress and length change ratio were evaluated. Evaluated results of compressive stress was shown that compressive stress increased depending on aging time. On the other hand, length change ratio decrease depending on aging time.

아스팔트 콘크리트 포장 파손 중 40cm-50cm 지름과 5cm-10cm 깊이를 갖는 움푹 파이는 형태의 포장 파손을 포트홀(pothole)이라고 한다. 포트홀 파손 발생 메커니즘은 아스팔트 혼합물에 수분이 침투하고, 아스팔트 바인더와 골재의 점착력이 침투한 수분에 의하여 약화되어 발생한다. 따라서 아스팔트 콘크리트 포장의 포트홀은 주로 장마 기간에 많이 발생하지만 최근 들어 지구 온난화의 영향으로 겨울철 강우 또는 강설의 증가와 제설제의 영향으로 겨울과 봄에도 많이 발생하고 있다. 본 연구에서는 아스팔트 콘크리트 포장에 발생한 포트홀 파손을 효율적으로 상온에서 보수할 수 있는 보수 재료에 대하여 25℃에서 간접인장강도시험을 수행하고, 5회 동결융해 반복 후 간접인장강도시험을 수행하여 인장강도비(TSR, Tensile Strength Ratio)를 산정하였다. 이때 사용된 우레탄 개질 아스팔트 포트홀 보수재는 목표 공극률 4%대의 혼합물을 사용하였으며, 비교대상 상온 보수재는 사전 혼합된 형태로 사용되고 있는 기성 제품 2종류를 선정하였다. 각각의 포트홀 보수재는 양면 50회 다짐을 수행하여 공시체를 제작하였다. 동결융해 조건은 KS F 2398에 따라서 영하 18℃에서 16시간 방치한 후 60℃ 항온수조에서 24시간 담그는 것을 동결융해 1회로 보고 5회 반복한 후 간접인장강도시험을 수행하였다. 5회 동결융해 반복시험 후 인장강도비가 우레탄 개질 아스팔트 포트홀 보수재의 경우 35%이며, 비교 대상 상온 포트홀 보수재는 각각 67%와 66%로 나타났다. 우레탄 개질 아스팔트 보수재의 인장강도비가 다른 두 혼합물보다 50%정도 인장강도비가 작은 것으로 나타났지만 5회 동결융해 반복 시험 후 25℃의 인장강도값의 경우 비교 대상인 상온포트홀 보수재가 개발중인 상온 포트홀 보수재보다 각각 36%와 12%로 매우 작은 것으로 나타났다.

In recent years, many potholes in asphalt pavement occurred. In order to facilitate the repair, in this study, repair materials with high durability and excellent productivity appropriate for asphalt pre-cast materials was developed. Physical properties test and durability test of various repair materials(SMA, PMA, guss mixtures, water-reactive mixtures) were performed. In order to evaluate the workability at pre-production time of samples using repair materials were made in different shapes and sizes. Finally, after comparing mixtures, water-reactive mixture was selected as repair material. This was verified through several testing.

Asphalt overlay on top of concrete pavement is commonly used in Korea. But water and deicing chemical can penetrate asphalt layer and stay at the boundary of asphalt and concrete layer, which cause accelerated degradation of concrete. Theoretically asphalt mixture is impermeable, but water can penetrate where improper compaction applied area or boundary area. Accordingly, optimum asphalt contents in existing mix design were modified in order to increase impermeability and test road was constructed with the modified method. The testing field site was monitored for 17 months and the performance of the test road was similar to the road used conventional mix design, although modified mix design used for the test road has 30% less air void. Thus, reduced pavement deterioration is expected on the concrete pavement rehabilitation with asphalt overlay