A brief look at a few liquid bituminous asphalts
Emulsified asphalts are emulsions made up of very small asphalt cement particles or globules held suspended in water with the use of an emulsifying agent. Emulsified asphalts come in various grades such as rapid, medium, and slow setting for different uses. These grades are developed through the use of emulsifying agents and the addition of some solvents. The asphalt particles are either anionic a.k.a. negatively charged, or cationic a.k.a. positively charged. Cut back asphalts once common for chip seals has declined considerably because of environmental restrictions on hydrocarbon emissions from evaporating solvents in specific regions around the country. The cover coat aggregate must match up with the road oils having either a positive or negative charge. Both are to be considered as a system so that adequate adhesion of the aggregate cover coat may be achieved for a quality chip seal application.
Bituminous Chip Seals are just one point on a spectrum of Surface Treatments
An existing asphalt pavement typically can be chip sealed only after the necessary evaluations/repairs are completed, as addressed in Salvage Old Asphalt Pavements. the asphalt emulsion road oil is applied by a bituminous asphalt distributor truck that meters the specified application rate and temperature.
The asphalt emulsion road oil is immediately covered with the specified cover coat aggregate, by a metered aggregate chip spreader, the aggregate is then compacted with powered rollers that are either rubber tired or steel wheeled which seats the aggregate into the road oil.
Multiple coats may be necessary depending on the existing conditions of the pavement/environment if so the procedures explained herein are repeated. A single coat chip seal is known as (A-1) a double coat=(A-2) a triple coat=(A-3) although typically an existing asphalt pavement can be chip sealed as (A-1) however, when chip sealing over an existing gravel base an (A-3) is highly recommended.
Bituminous Chip Sealing over a gravel base
The existing gravel base should be graded/leveled and compacted. Upon completion of preparations the initial chip seal application begins and a typical (A-3) is completed as stated in the above explanations. Also, a bituminous prime coat may be recommended prior to the initial bituminous chip seal application, additional cost will need to be considered for a prime coat as well as traffic accessibility.
After the bituminous prime coat is applied by the asphalt distributor truck, sanding is sometimes necessary/recommended in high vehicle traffic areas to help reduce the splashing of tar. The bituminous prime coat needs to set and soak into the gravel base for 24/48 hours, prime coats allow the asphalt emulsion road oil to lay on the top and does not soak into the gravel base.
As addressed in Gravel Base Preparations and Sub Base Preparations. Prior to any bituminous surface installation the existing gravel base should be inspected to determine an adequate depth of aggregate stone. Following is a simple guide to use. At 6" minimum for residential driveways, 8" to 12" deep for commercial parking lots and roadways. However, to determine the adequate depth of aggregate needed, consult your local codes/contractor, for your area and or region. Surface Treatments should be considered tools for the knowledgeable asphalt contractor/pavement manager.
As experienced bituminous asphalt paving contractors Jim George & Sons, LLC. can determine the correct surface treatment products for a particular project.
Gravel Base Preparations and Sub Base Preparations
Shown here is a brief explanation in this category. The gravel base and sub base, i.e. the foundation is one of the most important details of every driveway, parking lot, etc. Adequate amount of aggregate is needed to assure the bituminous asphalt surface will carry the weight bearing loads it was designed for.
Also, when constructing a new aggregate base, choosing the correct size and grades of clean crushed aggregates is essential so compaction equipment can stabilize the base, achieving the correct compaction values. To determine the adequate depth of aggregate needed, consult your local codes/contractor, for your area and/or region.
Coal Tar Sealers and Asphalt Base Sealer Materials
When properly mixed and applied these types of seal coat material products can be a great asset to the home owner and property manager. They enhance the overall appearance of the property at a economical cost.
A myth about applying seal coat materials claims that hand brushing/squeegee application does a better job versus spray application. This claim is not true, both work very well, in fact, in certain applications spraying is better. For example; if aggregates are incorporated into the seal coat materials, spray application does a much better job. With hand applicators and or squeegee machine applicators the aggregate can possibly roll and pile up on the pavement surface as its being applied. The end of each pass may result in workers having to clean up the messy pavement and upsetting the customer.
However, this does not occur with a spray application, because the material stays where it's sprayed. With the proper spraying equipment, aggregate sand loads can be applied efficiently and evenly with professional results. Also, if a seal coating contractor talks down the spray method it's usually because he may not own the necessary equipment. However, he is simply promoting his business and services to the customer with good intent.
The initial investment to purchase the proper seal coat equipment can be in the thousands of dollars. We do not promote a particular brand or product. Both coal tar seal coat materials, and asphalt base seal coat materials are excellent in asphalt pavement preservation, waterproofing, and chemical resistance. Prior to the application of a surface treatment, an existing asphalt pavement surface must be properly evaluated/repaired.