Common problems and solutions of hot-melt road marking coatings

The main function of highway markings is to implement separate driving, and environmentally friendly road marking coatings guide vehicles of different types and speeds along the designated route through traffic markings drawn on the highway, thereby improving highway transportation capacity and reducing traffic accidents; Instruct and warn drivers to anticipate road conditions through traffic markings, clarify their rights, obligations, and methods of using and passing through highways; Provide legal basis for law-abiding and law enforcement personnel.

There are mainly the following types: solvent based coatings, heating based coatings, hot melt coatings (also known as melt based coatings), two-component coatings, water-based coatings, etc. In the construction of highways, high performance requirements are placed on the coating materials used for road markings in transportation engineering. Firstly, it is required to have a short drying time and simple operation to reduce traffic interference; Secondly, strong anti reflection ability, vivid colors, and high reflectivity are required to ensure good visibility during both day and night; It has good skid resistance and wear resistance to ensure the safety of driving and the service life of markings. The characteristics of hot melt reflective coating are: it has quick drying and a drying time of 1-3 minutes. Synthetic resin combines coloring pigments, body pigments, reflective materials, etc. with road surfaces, and has the characteristics of strong adhesion, stable performance, long-lasting chromaticity,

brightness, and reflectivity. It also has good wear resistance and skid resistance. Therefore, in the construction of highways in China, hot melt reflective coatings and hot melt vibration coatings are mainly used as materials. Due to the vast territory of our country, with east tides and west dryness, south heat and north cold, the climate conditions and environment are diverse. In the construction of highway road markings, we often encounter various problems. Below are some common problems and solutions in construction that we will discuss with you:
1、 Color change issue
During the melting process, the temperature is too high or the bottom of the hot melt kettle is burnt. The solution is to strictly control the temperature and clean the bottom of the hot melt pot before operation.

2. If the product itself is of poor quality, it is likely due to the deterioration of the coating. Batch products should be tested by a professional inspection department before construction and can only be used after passing the inspection.
   2、 Poor reflection effect at night
   During construction, glass beads are blown away by strong winds; The uneven distribution of glass beads on the surface is caused by reasons such as shaking and tilting of the spreader. The solution is to install a windproof cover on the glass wave spreader and prepare for the coating operation, and control the construction speed well.
3. Excessive impurities, low roundness rate, poor particle size distribution, coating flowability that does not meet technical requirements, insufficient viscosity, and low softening point in the pre mixed surface can all cause poor night reflection effect. These are all considered as substandard product quality. Qualified products should be used during construction.
   During construction, the road surface is uneven. Construction techniques and adaptability should be improved, and experienced technicians should be allowed to carry out construction operations.
   3、 Crack problem
   During winter construction, the coating shrinks when exposed to cold, resulting in internal stress. When this stress is concentrated in one area, it is highly prone to cracking; Cracks caused by cold weather are related to the construction season and the performance of the coating, as well as the condition of the road surface. Especially for newly laid cement pavements with fragile mortar layers or maintenance films, cracks are prone to occur. To prevent cracks caused by cold weather, the first step is to choose a suitable construction season and try to avoid marking construction in the cold winter. At the same time, it is important to pay attention to reasonable use and choose coating ratios that are suitable for different seasons. The newly laid cement pavement should be maintained for more than 2 weeks, and the fragile mortar layer or maintenance film on the pavement should be cleaned before the road marking construction.
4. Reflection cracks caused by roadbed cracks. Cracks caused by the expansion or contraction of roadbed materials, or cracks caused by uneven settlement, resulting in cracks on road markings. In general, it is unavoidable and the construction quality of the roadbed can be strengthened.
5. Cracks caused by the softening of the road surface. In some places during summer, the temperature can reach over 40 ℃, and in the scorching sun, the high temperature of asphalt road surface can reach over 60 ℃. Asphalt becomes soft, while the coating is relatively hard, which may cause soft road surface cracks under wheel impact load. The direct cause of soft road surface cracks is the mismatch between the hardness of the coating and the road surface, which occurs under impact loads. The formula should be adjusted appropriately to alleviate this.
6. Surface cracks on the coating are irregular network cracks that appear on the surface after coating construction. These cracks are shallow in depth, but often further develop into aging cracks on this basis, causing damage to the coating. To prevent surface cracking of the coating, it is necessary to start with selecting compatible resins and additives, and pay attention to controlling the construction temperature.
7. Cracks appear due to aging of the markings. The degradation and natural weathering of the coating surface material cause cracks in the marking line. Aging cracks are also caused by the long-term exposure of the marking paint to the road surface, exposure to sunlight and rain, temperature differences between spring, summer, autumn, winter, day and night, and seasonal temperature changes, as well as exposure to ultraviolet radiation and periodic expansion and contraction. Cracks caused by aging can only be addressed by selecting appropriate coatings to prevent premature aging of the coating. During marking construction, strict temperature control is necessary to ensure the quality of road surface treatment before construction and prevent blistering.
8. Micro pores and bubbles are caused by the expansion or gasification of air, moisture, or undercoating agents in road voids under the high temperature of the coating. Bubbling is caused by the inflation gas lifting the coating, while micropores are the holes left by the inflation gas penetrating the coating, resulting in common defects in the coating. The probability of producing micropores and bubbles on damp road surfaces increases because the micropores are filled with moisture or moisture. High temperature coatings cause the residual moisture in the micropores to vaporize and expand, forming micropores and bubbles. The primer contains certain low boiling components that are not easy to dry. When the remaining primer in the micropores encounters high-temperature coatings, the active substance rapidly vaporizes and expands, forming micropores and bubbles in the primer. Micro pores and bubbles not only affect the appearance of the markings, but also reduce the actual bonding area between the coating and the road surface, thus seriously affecting the adhesion and service life of the coating. Therefore, it is necessary to choose coating varieties with good fluidity. Ensure that the road surface is dry, and construction should be carried out after sufficient sunlight after rain. Choose a fast drying primer, strictly control the construction temperature, and pay attention to the coordination of environmental temperature.

Our company is a professional manufacturer of road hot-melt coatings, road retroreflective measuring instruments, and road marking machines. If you are interested, please feel free to communicate with me via email at any time export@toproadtraffic.com