Current Rehabilitation Methods
Rehabilitation of highways plays a key role in how roads give users a comfortable and smooth ride. The U.S. highway system is the most expensive public works problem that has ever existed. Some states have repair and maintenance budgets that approach a billion dollars a year. In the 1980’s repair standards on roads were made by the U.S government. This article is concerned with the current rehabilitation methods that have been in practice for the roads of southeastern Michigan.
Usually an engineer goes out to the site and performs certain tests on the roads to make sure it should be rehabilitated. This could consist of inspecting the base and sub base of the surface. This is done by milling or taking a core sample of the road. One this is done the engineer can determine what type of rehabilitation method to be used. There are 4 basic rehabilitation methods that are used for concrete. They are categorized as “Type A Repairs” Joint and Crack Sealing, “Type B Repairs” Partial Depth Repairs, “Type C Repairs” Full Depth Repairs, and “Type D Repairs” Slab Replacement.
Type A(Joint and Crack Sealing)
The main practice of sealing cracks is to saw out the crack to ensure a smooth and geometric surface. Then a sand or air blaster is used to clean the inside of the crack to ensure that the sealant will adhere to the surface. The joint is then sealed with either silicone or hot pour sealant.
Type B (Partial Depth Repair)
This type of repair is for more deteriorated concrete. The area needed for milling is marked out and can be milled up to half the concrete slap above the top of the dowel bars. Then the surface area is cleaned by air or sand blasting. Then grout is applied to make the concrete adhere to the surface.
Type C (Full Depth Repair)
This procedure requires that the total slab be removed. A saw is used to cut out the portion of concrete and then is lifted out using pins. New dowels have to be put into the concrete and coated with grout. An important factor in having a successful repair is having the dowels aligned properly and straight.
Type D (Slab Replacement)
This repair is the same as type c but on a larger scale. The whole slab of concrete is removed. It follows the same steps as type c repairs. Sometimes it is recommended that a joint be placed in the middle of the repair to prevent a mid panel crack.
Cold Patch Asphalt
This is a short term rehabilitation method that is the cheapest to use and consequently the most used method. Cold patch asphalt does not need to be kept heated and can be placed in any large cracks or pot holes that need to be filled. It is very convenient because it does not need any large rolling machine. The only problem is that it only may last a year before the bonded material wears off and becomes rubble. To properly install it the hole has to be cleaned and then laid down in a hole preferably with vertical walls. This will ensure its maximum longevity.