InfraStructures - August 2005

Why Crackseal?

Cracksealing is one form of preventative pavement maintenance that ensures the consistent operation of our roadways. Contractors and municipalities extend the life of our motorways and car parks and save ratepayer money with cost-effective cracksealing materials and devices. For ideal sealant performance, crews must be educated on the proper use of cracksealing equipment and accessories and the correct sealant application.

Pavement cracks develop due to the expansion and contraction caused by temperature fluctuation. These cracks allow moisture to penetrate the pavement base and sub-base materials, causing elements to lose cohesion and structural integrity. If not repaired or prevented this cracking effect will grow, leading to deformation of the materials, potholes and ultimately the degradation of the asphalt or concrete surfaces.

Cracksealing is a preventative measure against water from further damaging the road surface and structure. The use of hot or cold applied sealant minimizes water penetration, frost and traffic erosion. Most importantly, cracksealing lengthens the life of roadways; car parks and other structures made with asphalt or concrete. According to most MoTs', with the timely application of sealant, the useful life of the road surface can be extended by as much as 10 years in comparison to other temporary surface treatments such as chip seals, micro-paving, thin overlays and slurry seals. As an added benefit, cracksealing is executed at 1/6th the cost of conventional pavement rehabilitation or reconstruction methods.

However, as any preventative measure, it needs to be engaged before a major failure occurs. Extensive damage, such as lizard/alligator cracks, potholes or base shifting and erosion are too late for any preventative procedures to be effective.

Surface cracking begins almost immediately after an asphalt or concrete surface begins to cure and cool. It is at this time that sealing is most effective and inexpensive. Within the first year of a road surface entering service a sealant plan should be enacted, regardless of how small or simple a procedure may be used. A pour pot and squeegee application of cold liquid sealant at this stage will significantly improve the wear life of the structure. As time and traffic begin to impact the vibrancy of the surface more technical methods need to be employed possibly including, routing, sawing, pumping and the use of thermoplastic materials. At this time the cracks are becoming more visible, they are also becoming more contaminated with dust and debris. This contaminant will affect the ability of the sealant to adhere to the asphalt or concrete and, unless adequately cleansed, shorten the effective life of the sealing job. It may be as simple as blowing the crack out with compressed air; it may require the use of a heat lance to ensure moisture is removed completely. Also, although possible throughout the dry weather, optimum sealant performance occurs in the spring as the surface begins to expand, opening the cracks for cleaning and material application.

So the fact remains that with a very simple procedure, tremendous savings can be realized through the preservation of the driving surface. It is important to think ahead and plan, before the damage is done. There are few municipalities or government agencies with the reconstruction funds that were once so plentiful to keep roadways in pristine condition. We need to consider the most innovative methodologies to create the same effect in a more cost conscious environment.

Source: Cimline Incorporated