Asphalt – From Conception to Completion
Everyone is familiar with the feeling of driving along and coming upon that stretch of brand new Asphalt; the sudden quiet, calm and smooth feeling in your car. Everyone feels a certain amount of appreciation at that moment, then usually never give it a second thought. It is unfortunate that a majority of the public does not have a clear understanding of the detailed process that goes into the construction of that smooth section of Asphalt, from conception to completion.
We would like to try to shed a little light on all the work that goes into the average paving process. It was said years ago by a well experienced individual in this industry, that the public, for the most part, will never know how much work goes into building a road; all they see is the finished product and how clean the site is left in a clean state. He went on to explain how those two factors are what builds the public’s perception of a company, whether good or bad. This is certainly a great point for every construction company to consider, however, the finish and cleanliness of a site are only two small parts of the whole process.
Before any Asphalt is laid or a bucket breaks ground, our company starts with the conception of a job. First we look at the job being evaluated and collect information to generate a quotation. On tendered projects, we generate a bid instead, meeting a designated deadline for submission. This process includes a package for multiple contractors to submit their pricing based on an exact scope of work. As a company we commit countless hours into project evaluation, for both third party designed projects, and those we design in-house. This early stage of conception involves talking with customers, site meetings, preparing quotations and budgets, and analyzing information to ensure we are providing the best value to the customer.
DESIGN / SPECIFICATIONS
Each job that is awarded or approved will at some point include an engineering phase. Tendered projects are typically designed by an engineering company hired as a third party, to create all the standards, specifications, and expectations before the bidding process even begins. This is done so all contractors bidding on a tender will have the same information, creating an even playing field for the scope of work being bid on. Projects awarded without a tender or an engineer involved will still require a certain amount of engineering expertise, if it is to be done properly.
At Fedorowich Construction, we firmly believe in accountability and quality control. We provide many civil engineering services that allow us to complete projects to the same standards that would be expected when administered by an engineering firm. To enhance the quality of our engineering services, we offer survey/design and G.P.S. services. These services are essential in the analyzing of existing surfaces, completing accurate estimates of excavation and materials required, as well as completing a final finish grade design. Fedorowich Construction’s quality control department also provides many soil testing services, including: sieve analysis, plasticity index, percent light weights, fracture count, sand equivalent testing, permeability and proctor testing. These tests are essential to keep all of the aggregate materials we produce in house within required specifications, and consistent with the highest standards of quality. We also provide full series Asphalt testing in our lab. These tests are required to ensure that the Asphalt being used meets the specifications required, such as granular size and make up, fracture count, oil content, and air voids. A smooth finish to asphalt is important for ride quality, but the quality control process is designed to ensure that the life and strength of the Asphalt is maximized. Lastly, we provide field density testing, which is an essential part of the compaction process. Quality control in a tendered project is often assigned to a separate third party testing firm.
Fedorowich Construction believes that quality control measures should be consistently used for all sizes of projects; whether paving a driveway or building a highway, paving contractors should always be knowledgeable and uphold industry standards in quality control.
The Asphalt surface is the aesthetics of a finished project. One very important factor to always remember is that without a proper base structure underneath the Asphalt, the money invested could very well be money lost. One of the largest contributing factors to the longevity of Asphalt is a properly designed and installed base structure.
A base structure often consists of three main layers: Existing Subgrade, Subbase and Base.
The first step in designing a good base structure is to determine the type of existing subgrade we are dealing with. Subgrade is defined as the natural material that exists in a certain area, which determines how it will react to bearing the load it needs to support. After excavating to design depth, the material that is exposed would be considered the subgrade. In the event that the subgrade is not sufficient to support the desired load, there are a few options. One option is over excavation and replacement of the excavated materials with a granular fill more suitable for compaction and bearing loads. When excessive saturation or overly silty materials exist, the amount of over excavation becomes costly and the assurance of success is hard to predict. Therefore, when dealing with conditions such as these, we suggest the implementation of structure enhancing materials like Geotextile Cloths and Geotextile Grids. These products consist of synthetic weaved cloth-like material that is laid over poor subgrade, designed to enhance strength and prevent the subgrade from pushing up and contaminating the sub base or base. If geotextile materials are not required, but you would like to ensure the stability of the subgrade, common practice is to perform a proof roll to identify any excessive deflection. This is often done with a heavy roller, grader or loaded tandem. Once you have ensured the subgrade is sufficient to handle the weight of its designed purpose, it is time for the installation of sub base and base.
Subbase is the main load bearing material in a designed base structure. Its role is to spread the load evenly over the subgrade. Sub base usually has a specific
specification for its makeup, load bearing capacity, and stability. Sub base is
installed in predetermined elevations and lift depths. This is key to achieve intended shape and proper compaction. The thickness of the layer of sub base also varies, depending on how much load the structure has to take. Cases of subbase being
omitted from a design are rare, but it does happen on some light duty structure jobs where the expected load can be handled by just a base material alone. The same expectation that was set for the subgrade is true for the subbase; it should not deform, and should not displace. Meeting compaction requirements is also crucial in the subbase, as this will eliminate the chances of the subbase structure sinking and consolidating over time. Subbase not compacted to its optimum compaction will eventually settle, and this will in turn cause settlement in the asphalt pavement.
Base is a manufactured granular layer that is placed underneath the pavement. It varies in size and gradation, depending on what is required in the specification of the job; however, the most common difference between the base and subbase material is the requirement of fractured rocks in the base. The fractured rock creates an interlocking matrix in the base lift which is key for a firm and sealed surface to lay Asphalt on. The base layer has to be as close and as true to the design grade as possible, as any imperfection in the base layer will be reflected in the asphalt pavement. Just as the subbase and subgrade, the base layer should not deform or displace, and it should be compacted to its optimum compaction to avoid settlement and consolidation over time.
Asphalt, or hot-mix, is the last layer of the structure, and is composed of durable aggregates mixed with asphalt oil. There are different types of aggregate gradation, as well as different types of asphalt oil for varying applications. The mix for the asphalt should be designed with enough gravel to sustain stability, and enough asphalt oil to bind the aggregates together without compromising load bearing capacity. Too much aggregate and not enough oil will lead to raveling prematurely, and too much oil and not enough gravel will cause rutting or displacement and deformation in the pavement. This is the reason why frequent testing of the mix, to ensure consistency, is essential. It is our belief that customer satisfaction should be the top priority of every company. Unfortunately, with the lack of awareness outside of the industry, many companies cut corners and sacrifice quality without the customer ever realizing it. Unfortunately, the industry standards we have discussed are not compulsory for every company to uphold. Fedorowich Construction believes that educating the public is as important as completing a high quality job. Asphalt and paving services affect everyone, whether it be individual driveways, parking lots for business, or roadways for communities. Our goal is to ensure, regardless of the company performing the job, that you, the customer, are aware of the quality you should expect in a well-done paving job. Hopefully, our information has shed some light on the paving process, and next time you travel over a section of fresh Asphalt, you may give it a second thought!