Glossary of Terms and Definitions
| Term | Definition |
|---|---|
| AASHTO |
American Association of State Highway and Transportation Officials. |
| Abrasion |
Removal of material due to a frictional contact. |
| Abrasion And Scratch Resistance |
Ability of a material to resist the infliction of damage in the form of scratches, grooves and other minor imperfections. |
| ABS |
Acrylonitrile-Butadiene-Styrene; a form of thermoplastic. |
| AC |
Asbestos Cement; a composite material used in pipe construction. |
| Acceptance |
By the owner of the work as being fully complete in accordance with the contract documents. |
| Adapter Ring |
In microtunneling, a fabricated ring, usually made from steel, that serves to mate the microtunneling machine to the first pipe section. This ring is intended to create a waterproof seal between the machine and the spigot of the first joint. |
| Addenda |
Written or graphic instruments issued prior to the execution of the agreement, which modify or interpret the contract documents, drawings and specifications, by addition, deletions, clarifications or corrections. |
| Additive |
A substance added in a small amount, usually to a fluid, for a special purpose such as to reduce friction, corrosion, etc. |
| Admixture |
Ingredients added during mixing; often in construction to aid workability of concrete, mortar or grout. |
| Advance |
The motion of the machine in a direction toward the face wall of the entrance pit. |
| Advance rate |
Speed of advance of a pipe jack or other trenchless installation through the ground, generally expressed as either millimetres per minute or metres per day. |
| Aerial sewer |
An unburied sewer (generally sanitary type), supported on pedestals or bents to provide a suitable grade line. |
| Aerobic |
Presence of unreacted or free oxygen (02). |
| Aggressive |
A property of water which favors the corrosion of its conveying structure, |
| Aggressive Index (AI) |
Corrosion index established by the American Water Works Association (AWWA) Standard C-400; established as a criterion for determining the corrosive tendency of the water relative to asbestos-cement pipe; calculated from the pH, calcium hardness (H), and total alkalinity (A) by the formula AI = pH + log (A * H). |
| Agreement |
The written agreement between the owner and the contractor covering the work to be performed; the contract documents are attached to and made a part of the agreements. Also designated as the contract. |
| Alkalinity |
The capacity of a water to neutralize acids; a measure of the buffer capacity of a water. The major portion of alkalinity in natural waters is caused by (1) hydroxide, (2) carbonates, and (3) bicarbonates. |
| Alumina |
An oxide of aluminum present in clay. |
| AMP |
Asset Management Plan; a structured approach for utilities to achieve long term defined service standards – or – an external bearing used to isolate the final drive from the thrusting force of the machine. |
