thousands of terms used in the concrete industry. Some can be vague and confusing. It's good to know the
language when you're working with concrete contractors. Here then are some of the terms you're most likely to
hear in the concrete world.
For a complete
listing of concrete terminology, click here.
rule of concrete that says, under many conditions using common concrete materials, concrete strength is
inversely related to the ratio of water to cement. This means low water-to-cement ratios tend to produce
higher concrete strengths.
(Not to be confused with L.A. Law, Law & Order, Burke's Law, or Abraham Lincoln.)
to affect air entrainment, curing time, and plasticity, admixtures are substances used sparingly to modify the
results of a mix or final concrete product. Admixtures are materials other than water, aggregate, and cement
(the basic components of concrete).
mixture of sand, rock, crushed stone, expanded materials, or particles, both enhances the structural performance
of concrete and improves cement pastes formation and flow. Aggregate usually constitutes about 75% of concrete
concrete contains minute air bubbles that are distributed uniformly throughout the cement paste. Entrained air
can be produced in concrete by use of an air-entraining cement, by introduction of air-entraining admixture, or
by a combination of both methods.Air-entraining admixtures are used to stabalize microscopic air bubbles in
concrete. Proper air-entrainment, with appropriate volume and
spacing factor, will dramatically improve the durability of concrete exposed to moisture during cycles of
freezing and thawing. Entrained air also improves concrete's
resistance to surface scaling causes by chemicals deicers.
American Concrete Institute
organization providing education and information about concrete.
American National Standards Institute
States representative in the International Organization for Standardization (ISO).
American Standard of Testing Materials
that serves as a standardized testing center to evaluate the performance of a variety of building materials.
A slab of
concrete, often at an entrance for vehicles, that extends beyond a buildings entrance.
self-generated release of mixing water from freshly placed concrete. Rapid evaporation of bleed water may lead
to plastic shrinkage cracking. (See Plastic Shrinkage Cracking.)
Cement is not
the same as concrete, but rather one component of concrete. Cement, a combination of finely ground materials,
hardens when mixed with water to become the "glue" in concrete. (It is acceptable to pronounce this word as
“See-Ment” in many parts of the country.)
someone refers to a “cement” driveway, floor, or patio you will know that they are not a concrete
Concrete is not
the same as cement. Concrete is a combination of cement as a binding agent, chemical additives, water and
mineral. This combination, when properly mixed and placed, hardens into an excellent building material for a
wide variety of uses.
saw cuts made on concrete surfaces. These lines form the boundaries or where the concrete can relieve tension as
it cures. (Not to be confused with a detention facility, although you will find control joints in prisons and
other detention facilities.)
that concrete will set to its design strength under favorable conditions, usually after 28 days. Curing is the
hardening of concrete through the controlled evaporation of water or a solvent, hydration, polymerization, or
chemical reactions of various types. Successful concrete curing requires the maintenance of satisfactory
temperature and moisture content.
chemicals used on concrete that prevent the coated surface from absorbing water while still permitting moisture
vapor to escape from the structure. Generally speaking, "dampproofing" applies to above grade surfaces while
"waterproofing" refers to below grade surfaces.
Dry shake (dry topping)
surface treatment where a dry material is shaken onto the surface to produce color, hardening, high-traction, or
anti-skid results. The dry shake is applied before the concrete sets, and is then troweled in.
contraction caused by the loss of moisture.
(compacting, leveling, smoothing, etc.) of recently placed or fresh concrete to ensure the planned-for
flat-surfaced concrete work, including sidewalks, driveways, basements and concrete floors.
A building site
(or buildings) existing or proposed ground level or elevation. Also used in categorizing building or
construction levels, e.g. above grade, on grade, or below grade.
reaction, often indicated by an increase in temperature, that results when water and cement are
introduction of the concrete mixture into the final location where it is to harden and cure. (Hint: If a
concrete contractor talks about “pouring” concrete, he hasn’t been around long.)
term used instead of “placing”. No self-respecting concrete professional will ever talk with you about “pouring
concrete”. (See “Placing”)
characteristic determining the resistance to deformation or ease of molding in cement paste, freshly mixed
concrete, or mortar. (Also see Plastic Shinkage
When water evaporates from the surface of freshly
placed concrete faster than it is replaced by bleed water, the surface concrete shrinks. Due to the restraint
provided by the concrete below the drying surface layer, tensile stresses develop in the weak, stiffening
plastic concrete, resulting in shallow cracks of varying depth. These cracks are often fairly wide at the
Cement made by
heating a limestone and clay mixture in a kiln and pulverizing the resulting material. Concrete made with
portland cement is believed to be more consistent and stronger than concrete made from natural
For more than you'll ever want to know about cement,
visit the Portland Cement Association.
away of a concrete surface. Contrast to spalling, the flaking or chipping of concrete.
A measurement of
concrete's workability. Slump is a test for the rigidity of uncured
concrete. Lower slump concrete is very stiff, and higher slump
concrete is more fluid. It's an indirect measurement of concrete's
The slump cone
is a right circular cone that is 12 inches high. The base of the
cone is 8 inches in diameter and the top of the cone is 4 inches in diameter. The cone is filled with fresh concrete in three layers of equal volume.
Each layer is stroked 25 times with a rod, the end of which is
bullet shaped. After the cone has been filled with concrete and the
concrete has been cut off with the top of the cone, the cone is raised vertically allowing the concrete to fall
or slump. The distance that the concrete falls or slumps from the
original height is the slump of the concrete. Slump is measured in
inches and is reported to the nearest inch.
caused by water entering concrete and forcing the surface to peel, pop out, or flake off. Concrete spalling is most likely to occur on exterior surfaces that are exposed
to freeze and thaw cycles. Causes include: high water cement ratio
in the concrete mix, lack of air entrainment, improper finishing, and inadequate curing.
The use of a
trowel (a flat steel tool that manipulates concrete) to smooth and compact the surface of fresh
Water Repellant Coating
treatment, usually a transparent coating or sealer, that repels water when applied.
For a complete listing of concrete terminology, click here.