Article No: 73

2006-05-01 13:02:03
Tech Talk
By: Ed Sauter


Editor's note: As part of our partnership with the Concrete Foundations Association (CFA), the following article is the first in a year-long series on the basics of concrete foundation construction. For more information, visit www.cfawalls.org or call 319-895-6940.

Positive Drainage Curing Compound Fluid Pressure? What were those words the foundation contractor used during our meeting yesterday? Construction projects, like so many other business endeavors, are not without communication problems between parties. Many of the problems are associated with terminology that is common to the contractor, yet distinctly foreign to the customer or owner.

Although the following list of frequently used terms is not exclusive to the foundation construction industry, these terms are certainly used often in that arena. Understanding them will increase your ability to communicate with the foundation contractor and allow for a more satisfying project. By taking the time to learn some of the basic terms, you ensure that your needs are met.

Admixture: Concrete is composed of water, aggregates and cement. Materials other than these, generally liquid and not considered reinforcing, that are added to the mix before or during mixing are considered admixtures.

Backfill: Material that is placed in an excavated space, generally around a foundation or retaining wall.

Bulkhead: A partition in formwork blocking fresh concrete from a section of the form, such as at a construction joint or wall end.

Concrete, reinforced: Concrete that contains deformed steel reinforcement and is designed on the assumption that the two materials act together in resisting forces.

Concrete, unreinforced: Concrete that does not contain reinforcement for structural purposes. It is also referred to as "plain" structural concrete. Such concrete may include horizontal reinforcement that is placed to reduce temperature and shrinkage cracks.
Curing compound: A liquid applied as a coating to the surface of newly placed concrete to retard the loss of water or to reflect heat, providing an opportunity for the concrete to develop its properties in a favorable temperature and moisture environment.

Dampproofing: A treatment of concrete to retard the passage or absorption of water or water vapor. Examples include tar or polyethylene sheeting.

Equivalent fluid pressure: The pressure applied to a construction from granular-like materials, such as soils, expressed as a fluid-like force. The applicable equivalent fluid pressure varies for each type of soil.

Expansive soil: A soil that changes in volume due to variation in moisture content.

Flat wall: A conventionally formed concrete wall with flat surfaces.

Footing: A structural element that transmits loads directly to the soil.

Foundation: The structural elements through which the load of a structure is transmitted to the earth.

Foundation wall: The structural element of a foundation that transmits the load of a structure to the footing or soil. A foundation wall includes basement and stem walls.

Hydrostatic pressure: The force expressed as a live load, applied by water acting on a surface.

Joint: A physical separation in concrete, including cracks, intentionally made or forced to occur at specified locations.

Joint, contraction: A groove in a concrete structure, either formed, sawed, or tooled, to create a weakened place to regulate the location of cracking resulting from the dimensional change of different parts of the structure. (Also known as a control joint).
Joint, isolation: A separation between two individual components of a concrete structure, usually a vertical plane, designed to interfere with the performance of the structure, yet allow movement in three directions and avoid the formation of cracks elsewhere in concrete.

Keyway: A recess or groove in one placement of concrete, which is filled with concrete of the next placement giving shear strength to the joint.

Lateral pressure: The force exerted in a horizontal direction on a structural member.

Positive drainage: Grading used to control and direct the flow of water around and away from a structure.

Slab-on-ground: A slab which is unreinforced or reinforced and continuously supported by ground, and whose total loading, when uniformly distributed, would impart a pressure to the grade or soil that is less than 50 percent of the allowable bearing capacity thereof.

Slump: A measure of consistency for freshly mixed concrete determined by measuring the amount of drop in a molded specimen of concrete immediately after removal of the slump cone.

Subgrade: Soil prepared and compacted to support a structure or a pavement system.

Unbalanced fill: The difference in height between the exterior and interior finish ground levels. Where an interior concrete slab is provided, the unbalanced backfill should be measured from the exterior finish ground level to the top of the interior concrete slab.

Waterproofing Material: A long-term protection treatment to prevent hydrostatic water intrusion. Examples include elastomeric membrane or drainage with a bonded, crack-bridging coating or sheet; or an unbonded, elastic or semi-rigid sheet system.

Final Thought
Too often, miscommunication occurs between homeowners and foundation professionals because of a misunderstanding of terms. With a clear understanding of each other's‚ language, everyone will clearly comprehend the project's goal and objectives. By taking the time to learn this language from the project onset, you are creating a vehicle for clear communication. Open lines of communication begin when everyone is speaking the same language. And, open communication is the first step to ensuring a successful project.

Established in 1974 for the purpose of improving the quality and acceptance of cast-in-place concrete foundations, the CFA has a variety of resources on this topic. In addition to providing promotional materials, educational seminars, opportunities for networking and a telephone network that places members in one-on-one contact with an experienced contractor for assistance in resolving a variety of issues, the CFA represents the interests of its members and the industry on several code and regulatory bodies, such as the American Concrete Institute's committee responsible for the creation of the "Residential Concrete Standard." Once complete, this standard will likely be adopted by the UBC, CABO and other building codes. The CFA has several of its members on the ACI committee responsible for this document and will endeavor to ensure that the interests of the foundation contractors are considered. For more information about CFA, see www.cfawalls.org or call 319-895-6940.

Ed Sauter is executive director of the Concrete Foundations Association.