The first question of the 50 common problems in marking construction is “cracks”

No one can really explain the problem of hot melt marking cracks, and most of them are the responsibility of the material factory. Little do you know, the reasons behind it are very complex. If you often encounter such problems, you can patiently read down. Believe me, as long as you look into it, it will definitely overturn your original understanding!

Beginning of the main text: 1. Regular horizontal and vertical cracks appear in the hot-melt marking coating of asphalt pavement

1. Asphalt pavement will experience thermal expansion and contraction with seasonal changes, and marking will also experience thermal expansion and contraction. When the temperature decreases, both will shrink. The shrinkage rate of hot-melt marking coatings is usually lower than that of asphalt. This inconsistent shrinkage can cause significant stress inside the coating. When the stress exceeds the tensile strength of the coating, cracks will form. Sometimes, only a small hole needs to be drilled in the coating, and the crack can extend from this hole and penetrate the marking. This is usually a transverse crack that runs through (along the width direction of the marked line). It usually occurs within a certain period of time after construction, especially when there is a large temperature difference. Conclusion: The paint is fine, and the road surface may also be fine. The problem is that you are unlucky! (Since you’ve seen it all here, hold on and scroll down!)
2. The softening of asphalt pavement occurs during high temperature weather, where the softening point of asphalt is relatively low. Asphalt pavement is very soft during high temperatures in summer. If you observe carefully, you will find that the road surface will experience slight sinking when the wheels pass over it. If a heavy truck passes over the road surface, the road surface will noticeably sink. If the marking is relatively hard compared to asphalt, it is easy to produce cracks under the load of vehicles, usually transverse cracks and occasionally longitudinal cracks. This situation rarely leads to a conclusion: avoid using coatings with excessively high softening points at high temperatures.
3. When the repeated load of the vehicle is crushed at low temperatures, the repeated load of the vehicle will cause non load temperature cracks in the road surface and paint. Usually it is a transverse crack.
   Conclusion: It is unavoidable
4. Natural aging of hot-melt markings A. Small molecule substances (plasticizers) in hot-melt coatings will precipitate from the surface of the markings over time. This will greatly increase the softening point and glass transition temperature of the marking, thereby greatly reducing the tensile strength and toughness of the coating. Cracks will appear under the action of self stress, usually transverse irregular cracks (appearing 12-24 months after marking). B. The marking is affected by ultraviolet radiation, causing the internal resin molecular chains to break and form cracks. Of course, adding antioxidants and UV absorbers to coatings will greatly prolong the cracking time. Conclusion: Due to the inherent characteristics of hot-melt marking coatings, the above cracks can only prolong their occurrence time and cannot be cured. 5. The settlement of asphalt pavement: Insufficient compactness of asphalt pavement can cause natural settlement, especially in high temperature conditions, leading to cracking of markings. Generally, it is a longitudinal crack (along the length direction of the marking). Conclusion: Road surface problem. The above 5 situations are often encountered in reality and are also the most easily confused. Due to the physical properties of hot-melt marking coatings and the current technological conditions, it is impossible to avoid the occurrence of the above cracking situations. However, the above cracks do not affect the service life and function of the marking line. If the engineering acceptance period is particularly long and the understanding of the cracks is unclear, it is necessary to inform the acceptance party in advance to avoid unnecessary losses.
   2、 Quality issues with hot-melt marking paint and cracks caused by improper construction
5. Conclusion of network cracks and fissures: caused by inferior coatings.
6. Conclusion: The cracking and detachment of the markings are caused by poor quality paint and improper construction.
7. Conclusion of powdering and detachment of the marking line in a short period of time: caused by inferior paint. The above three situations are caused by improper formulation of hot melt marking coatings or improper use of raw materials, especially the non weather resistance of film-forming resins or insufficient melting of coatings in hot melt kettles during construction. The final summary is that hot melt marking coatings have a fixed glass transition temperature due to the thermoplastic film-forming resin and resin softening points mostly concentrated around 100 degrees Celsius, generally in an elastic state between 20 ° C and 70 ° C. And it presents the characteristics of becoming softer as it gets hotter and harder as it gets colder. Of course, currently, in order to reduce costs and reduce the amount of resin used, material factories will add excessive plasticizers and various flow aids to the formula, which will greatly reduce the glass transition temperature of the coating. In summer construction, slow drying or even non drying may occur. Generally speaking, as long as the road surface temperature is not lower than 0 ℃ and not higher than 60 ℃, the hot-melt marking coating will be in a relatively elastic state, especially in summer (except for old markings). The cracking of the markings requires a specific analysis of the situation.

Choose suitable coatings based on climate temperature and environment. Engaging in road marking construction will definitely encounter situations where the marking paint cracks, which can seriously affect the acceptance and payment of the entire project. Material manufacturers and construction parties will argue with each other, resulting in damage to the interests of both parties. I hope this article can clarify the situation and avoid unnecessary losses. This article is for reference only.

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