What’s a crack sealing?
Crack sealing is one of the asphalt maintenance methods and to prevent it from failure, which using this methods, contractors, road and transportation departments and municipality increases lifespan of the asphalt and save a tremendous amount of expense.
Streets’ cracks occur due to expansion and contraction caused by weather conditions. These cracks cause water to infiltrate asphalt’s base and ruin its unity, and if this action doesn’t come to an end, it will cause metamorphosis within asphalt structure and create bumps and puddles.
Crack sealing is a procedure for hindering water’s advance to lower levels of asphalt, and also in asphalts which due to inappropriate substructure are incapable of traffic’s pressure, crack sealing works as a buffer for new asphalt and prevents new cracks on its surface.
According to research, preventing asphalt damage with right timing could increase its lifespan to more than 10 years. Another one of crack sealing advantages is being more economical than renovation method which by comparing expenses analysis for 1-kilometer of asphalt construction with 10-meter width with same amount of surface with is attached, it could be deduced that crack sealing cost is about 0/043 of renovation cost and therefore it’s much more economical.
Keep in mind that crack sealing is a maintenance method, not a renovation one. So if Alligator cracks appear in one part, that part should be removed and then patched again.
Rahdarsanat Technical Co. has successfully started importing crack sealing devices and its technology since 1380 and was able to be the first in Iran to present itself as a pioneer in this industry.
Asphalt cracking types:
Cracks appear in different shapes and types which we’ll discuss in following:
- Transverse Cracking:
This crack type begins at one side of the asphalt to another or at the middle to both sides. Reason for this appearance is insufficient consistency for bearing loads which are applied on the surface duo to different weather conditions.
2. Longitudinal Cracking:
This type of cracking occurs in road’s length axis which is usually parallel to its center. Reason for this type of cracking is insufficient consistency for pressures caused by temperature change.
3. Block Cracking:
They can be up to 1.5 meters large and usually have four sides and occur duo to heavy traffic load for asphalt base.
4. Alligator Cracking:
They have similarity with alligator skin or a map and can’t be repaired with crack sealing. They must be removed and then patched again.
Crack sealing steps:
Routers are equipped with a drum with discrete blades which can move over cracks with maneuverability and remove cracks with certain width and height.
Black Blower is proper device for cleaning asphalt cracks after scraping. High air pressure rid asphalt of particles. Present pollutant within cracks can causes material adhesion to crusts be insufficient. Particles remained from scraping must be cleaned to crack’s bottom and have a completely clean surface.
3. Heating phase
In this phase, very warm air is combined with compact air and is utilized for cleaning crusts and removing moisture and warming up crusts for better material integration and adhesion.
Factors which causes negative adhesion are cold weather, pollution and moisture.
4. Insertion phase:
In this phase which is crack sealing’s last step, first after polymer materials (mastics) are warmed up with special devices, using insertion tube, mastics are placed on cracks and move afterwards.
Warning: If polymer material (mastic) aren’t warmed using special device manually, material could lose its mastic characteristic after a short period of time break and cause crack sealer failure.