Con
Prefix that means with or together. Alternately, slang that means a confidence scheme.

Concave
Hollow and curved such as the inside of a hollow sphere.

Concave Joint
Joint which is made in water-resistant mortar.

Concealed Hinges
Invisible hinges when the door is not open.

Concealed Nail
Installation of roll roofing method of roofing installation where each course of roll roofing covers the nails in the prior course by overlapping it. Roofing cement holds down the edges of the courses, bonding them to each other.

Concealed Wiring
Electric wiring that is inside the walls of a building.

Concentric
Having a center in common. A circle within a circle.

Concentric Zone Theory
Land development theory that an urban area expands, in rings. The inner ring being the business district; ring 2 has manufacturing, warehousing and some commercial activity; ring 3 is low social economic status housing; ring 4 has middle-income housing; ring 5 has new high social economic status housing.

Conceptual Design
Detailed design showing an object in question.

Concession
Benefits granted by a seller/lessor to induce a sale/lease. Alternately, right granted by a governmental body, to use property for a particular type of business in a specific area.

Conclusive Presumption
When evidence cannot be supported to disclaim an obvious claim such as water being wet.

Concrete
A mixture of cement, sand and aggregate which is mixed with the proper proportion of water allowing it to solidify into a structural material with good compressive strength.

Concrete, Aerated
Concrete that has been altered chemically, with an additive, to disperse air bubbles through the mix. A yard of air-entrained concrete may contain over three trillion bubbles. This mix is easier to work than standard concrete and stands up well in cold weather, resisting salts better than other concrete. While it is good for pouring in cold weather because the bubbles allow the concrete to expand and contract more readily, it is not as strong as regular concrete. Also referred to as Air-entrained Concrete.

Concrete Block
Hollow building blocks, which are used in the construction of foundations and outer walls to provide strength and durability. Dimensions are 8"x 8"x 16".

Concrete Block Segmental Retaining Wall Systems
Retaining wall, mortarless concrete block made to interlock and can be fastened with fiberglass pins. A wall can be up to 5 ½ feet and withstand being toppled by a combination of the weight of the block and the incline on which it is set. Higher walls need additional support or certain hardware to hold them steady. Heavier than regular block, they weigh about 70 pounds each and also come in varying colors. Walls may be straight or curved.

Concrete Block Wall
Wall of concrete blocks cemented with mortar.

Concrete Brick
Portland cement and aggregates like sand or cinders mixed into brick-sized, solid masonry blocks.

Concrete Brick, Solid
Block made of portland cement, water and various aggregates, they are referred to by the type of aggregate; cinder, concrete, etc.

Concrete Finishing
To achieve a final cured surface that is smooth and hard, the concrete must be subjected to screeding, which is the use of a rigid piece of metal or wood to level the concrete and remove excess material; floating, which is the smoothing, with a flat plate, of the new concrete surface; and troweling, which is the use of a hand tool with a flat rectangular metal surface which smoothes and finishes the concrete.

Concrete Forms
Molds that are structurally sound enough to hold and shape poured concrete while it sets.

Concrete, Insulating
To provide an R-factor, which is a measurement of resistance to temperature transmission, of about 1.1.per inch of thickness concrete must have an expanded mica aggregate of 6 to 1, aggregate to cement.

Concrete Machine
Machine used to pour, spread and smooth concrete.

Concrete Masonry
Concrete masonry units built into masonry structures.

Concrete Masonry Unit (CMU)
Differently shaped and sized concrete bricks.

Concrete Mix
Amounts of cement, aggregate and water in certain proportions for the amount of concrete necessary to do a job.

Concrete Mixer
Motorized drum, which mixes the components of concrete by use of internal paddles.

Concrete Nail
Nail used with set concrete, having a thick-shanked nail with a flat head.

Concrete Paving
Concrete used as paving for a road surface.

Concrete Pipe
Steel reinforced pipe made of concrete.

Concrete, Pre-cast Architectural
Factory manufactured concrete pieces, which can be used as part of structural framework or as siding for certain types of buildings. There are many different types of pre-cast units available with exterior units adding weather resistance as well as decoration.

Concrete Pumper
A concrete pumping unit is usually mounted on a truck and powered by an internal combustion engine, which directs the concrete from the mixer to its use location, by moving it from the mixer to the pump intake hopper.