• Construction Knowledge Home
• Construction Knowledge Database
• Ned's Blog
• Best Phone Apps
• Our Construction Phone Apps
• About Us

CONSTRUCTION KNOWLEDGE  >> SITE WORK >>

CURBS & PAVING
 

1. What Should I Know About Curb?
2. What are the Basics of Bituminous Paving?
3. What are the Basics of Concrete Paving?
4. What Public Domain Documents are Available for Further Study?
5. Tricks of the Trade & Rules of Thumb for Curbs and Paving:
 

What Should I Know about Curb?

Curb runs storm water where you want it and keeps idiot drivers off the grass. So the local codes or the Civil Engineer will probably dictate if curb needs to be installed for the stormwater part. Often the Owner chooses whether to invest in curb to keep the cars off the grass or landscaping, making a decision about future maintenance costs and the look of the project.

Curbing options include 18" concrete vertical curb, concrete rolled curb, granite curb, bituminous concrete curb and quite a few other types. In the geographic area you work, there is probably a normal curb style and standard details for installation. The Construction Supervisor should verify that the type of curb and installation details are clear to all involved parties.

The schedule of the curb work should greatly interest the Construction Supervisor. Sometimes it's best to get the curb in early (and try to protect it from damage) and sometimes it's better to wait (risking bad weather and chaos at the project completion). So you should think about the curb scheduling on each project and make a determination on when to install.

Curbs shout quality...or lack there of, when a visitor comes to a new building. So you should pay attention to the line, grade and overall quality of the curb. As in many areas, the Construction Supervisor can not check every detail of a subcontractor's work. I think, however, the Construction Supervisor should visually review the quality (line and grade and finish) every day for the first few days of curb work. A level of approved quality can be set for the project in this manner. It is better for all involved parties for unacceptable work to be removed immediately and replaced, rather then debating the issue for days while backfill and stone sub-grade may be placed. Telling someone to replace a section of curb because there is a visually obvious dip is not an enjoyable task. The Construction Supervisor, though, must always be responsible for cost, schedule and performance; poor quality is inadequate performance. If the construction industry is to improve itself, the Construction Supervisor can not leave the guarding of quality to an Inspector.

What are the Basics of Bituminous Paving?

Bituminous concrete is a mixture of asphalt cement and well-graded aggregate, compacted when hot into a densemass. On very small jobs bituminous concrete can be placed by hand and compacted. Typically, though, a self propelled paving machine places the mix, controlling paving depth, width and surface. Paving machines can be rubber tire or track, the rubber tire machines have a tendency to spin tires in soft sub-base and sometimes get stuck. The hot mix is delivered to the project in covered dump trucks. Some paving machines have the hot mix dumped directly into a hopper, which is then augured back to the screen for placement. Other paving machines pick-up bituminous concrete dumped onto the sub-base like a self-loading scraper. The hopper paving machines are more common than the self loading paving machines.

The Paving Contractor must determine the paving widths and joint locations. This decision will be based on available equipment and manpower and must include any specific requirements from the contract specifications. The paving width and joint locations should be approved by the Inspector or Design Professional. The Construction Supervisor should be confident the Paving Foremen and crew can produce quality work and are prepared for problem conditions. It is appropriate for the Construction Supervisor to question the Paving Foreman about his plans for rainstorms, equipment breakdown, etc. The Paving Foreman should have well thorough responses to these queries.

I've learned that the secret to bituminous paving longevity: make sure the sub-grade drains. If that sub-grade holds water, the freeze-thaw cycle or just the water making the soil mushy and weak will end up destroying the paving. Before stone gets placed over the sub-grade, a grader should really smooth the sub-grade and it should be smooth rolled as well. Sub-grading with a track loader will leave soil indentations that will hold pockets of water and destroy the paving.

What are the Basics of Concrete Paving?

Concrete paving is known as a rigid pavement while bituminous paving is considered flexible paving. The structural value of concrete paving is far superior to bituminous paving. The decision about which type paving to us is made by the Owner or Design Professional.  Concrete paving machines are sometimes used on large projects and they function similar to asphalt paving machines. It is more common to see concrete pavement formed on both edges, delivered in ready-mix trucks, and final placed with a vibrating screed. The concrete mix design, type of finish, method of moisture retainage, reinforcing, and type of joints must be show in the contract documents.

What Public Domain Documents are Available for Further Study?

The US Army Field Manual for Paving and Surfacing Operations is an detailed introduction to paving equipment and processes. This 217 page handbook is officially called FM 5-436.

Another resource, more useful in the paving design than in construction, but that may be helpful, is the US Dept of Defense Pavement Design for Roads, Streets, Walks, and Open Storage Areas. It has 121 pages of information and some excellent nomographs for determining paving thickness. The official name of this document is UFC 3-250-01FA 16 January 2004.

Another resource is the US Dept of Defense Standard Practice for Concrete Pavements. It has 58 pages of information and the official name of this document is UFC 3-250-04FA 16 January 2004.
 

Tricks of the Trade & Rules of Thumb for Curbs and Paving:
 

1. Plan the time of curb installation carefully for each project.
2. Visually check the line, grade and finish of the first days of curb work (set a standard of acceptable quality at the onset).
3. The secret to long lasting bituminous paving is a smooth sub-grade that drains.