Concrete Waterproofing Glossary

Macrofiber

a fiber with an equivalent diameter greater than or equal to 0.012 in. (0.3mm) for use in concrete.

intersecting cracks that extend below the surface of hardened concrete that vary in width from fine and barely visible to open and well-defined (also called pattern cracking). (See also checking and crazing.)

Mass

(1) the physical property of matter that causes it to have weight in agravitational field;
(2) the quantity of matter in a body.

Mass Concrete

any volume of concrete in which a combination of dimensions of the member being cast, the boundary conditions can lead to undesirable thermal stresses, cracking, deleterious chemical reactions, or reduction in the long-term strength as a result of elevate

Matrix

(1) the cement paste in which the fine aggregate particles in mortar are embedded;
(2) the mortar in which the coarse aggregate particles in concrete are embedded;
(3) the resin or binders that hold the fibers in fiber- reinforced polymer together, tran

Maturity Factor

a factor that is a function of the age of the concrete (hours or days) multiplied by the difference between the mean temperature of the concrete (degrees) during curing and a datum temperature below which hydration stops. (See also temperature-time factor

Maximum Size (of Aggregate)

in specifications for and in description of aggregate, the smallest sieve opening through which the entire amount of aggregate is required to pass. (See also nominal maximum size [of aggregate].)

Mean Stress

the average of the maximum and minimum stress in one cycle offluctuating loading.

Mechanical Anchorage

any mechanical device capable of developing the specified yield strengthof the reinforcement without damage to the concrete.

Mechanical Bond

interlock created when a fresh cementitious mixture is placed and hardens to conform to the surface texture of the existing solid material.

Melilite

a group of minerals ranging from the calcium magnesium silicate (akermanite) to the calcium aluminate silicate (gehlenite) that occur as crystals in blast-furnace slag. (See also gehlenite and merwinite.)

Melt

the molten portion of the raw material mass during the burning of cement clinker, firing of lightweight aggregates, or expanding of blast-furnace slags.

Membrane Curing

a process that involves the application of a liquid membrane-forming compound or covering with a protective sheet material, both of which function as a barrier to restrict evaporation of mixing water from concrete surfaces.

Membrane Theory

a theory of design for thin shells, based on the premise that a shell cannot resist bending because it deflects; the only stresses that exist, therefore, in any section are shear stress and direct compression or tension.

Merwinite

one of the principal crystalline phases found in blast-furnace slags. (See also gehlenite and melilite.)

Mesh Roller

a finishing tool consisting of a rolling drum attached to a handle of which the surface of the drum is made of mesh, sometimes used for rolling over the surface of fresh concrete to embed coarse aggregate.

Mesnager Hinge

a permanent semiarticulation or flexible joint in a reinforced-concrete archwherein the angles of rotation at the hinge are very small; by crossing steel reinforcing bars within the opening between the concrete structural segments, the resultant articulat

Metakaolin

a natural pozzolan produced by heating kaolin-containing clays.

Microconcrete

a mixture of portland cement, water, and suitably graded sand forsimulating concrete in small-scale structural models.

Microcracks

small, numerous cracks that develop in hardened concrete.

Microfiber

a fiber with an equivalent diameter less than 0.012 in. (0.3 mm) for use inconcrete.

Middle Strip

in flat-slab framing, the slab portion that occupies the middle half of thespan between columns. (See also column strip.)

Mineral Aggregate

aggregate consisting essentially of inorganic nonmetallic rock materials, either natural or crushed and graded.

Mineral Filler

a finely divided mineral product at least 65 percent of which passes the 75m m (No. 200) sieve. (See also silt.)

Mixer

a machine used for blending the constituents of concrete, grout, mortar, cement paste, or other mixture.

Mixer Efficiency

the adequacy of a mixer in rendering a homogeneous product within a stated period.

Mixing Cycle

the time taken for a complete cycle in a batch mixer, that is, the time elapsing between successive repetitions of the same operation (for example, successive discharges of the mixer).

Mixing Speed

rotation rate of a mixer drum or of the paddles in an open-top, pan, or trough mixer when mixing a batch, expressed in revolutions per minute (rpm) or in peripheral feet per minute (meters per minute) of a point on the circumference at maximum diameter.

Mixing Time

the period during which the constituents of a batch of concrete are mixed by a mixer; for a stationary mixer, time is given in minutes from the completion of mixer charging until the beginning of discharge; for atruck mixer, time is given in total minutes

Mixing Water

the water in freshly-mixed cementitious mixtures, exclusive of any previously absorbed by the aggregate (also called batch water or batched water.)
(See also water-cement ratio and surface moisture.)

Mixture

(1) the assembled, blended, commingled ingredients of mortar, concrete, or the like;
(2) the proportions for their assembly.

Mixture Proportion

the proportions of ingredients that make the most economical useof available materials to produce mortar or concrete of the required properties. (See also proportion.)

Mobile Placer

a small belt conveyor mounted on wheels or a truck that can be readily moved to the job site for conveying concrete from the concrete truck to the forms or slab.

Mobility

the ability of fresh concrete or mortar to flow.

Moderate Exposure Condition

an environment, normally in temperate climate regions, in which concrete will only occasionally be exposed to moisture and will not be saturated before freezing and where no deicing agents or other aggressive chemicals are used.

Moderate Sulfate-resisting Cement

a portland cement for use when either moderate sulfate resistance, moderate heat of hydration, or both is desired, now referred to as ASTM C150 Type II cement.

Modified Cement

(obsolete) a portland cement for use when either moderate heat ofhydration, moderate sulfate resistance, or both, is desired, now referred to as ASTM C150 Type II cement.

Modular Ratio

the ratio of modulus of elasticity of steel E s to that of concrete E c usually denoted by the symbol n .

Mohs Scale

relative scale of the hardness of minerals ranging from 1 through 10.

Moist Room

a room with controlled temperature and relative humidity for the purpose of curing and storing cementitious test specimens (also called a fog room).

Moisture Content of Aggregate

the ratio expressed as a percentage of the mass of water in a given quantity of aggregate to the dry mass of that quantity of aggregate.

Moisture-free

the condition of a material that has been dried in air until there is nofurther significant change in its mass. (See also mass.)

Mold

(1) a device containing a cavity into which neat cement, mortar, or concrete test specimens are cast;
(2) a form used in the fabrication of precast mortar or concrete units (for example, masonry units).

Monolithic Concrete

concrete cast with no joints other than construction joints.

Monolithic Topping

on flatwork, a higher quality, more serviceable topping course placedpromptly after the base course has lost all slump and bleed water.

Monomolecular

composed of single molecules; specifically, films that are one molecule thick; denotes a thickness equal to one molecule, for example, certain chemical compounds develop a monomolecular film over bleeding water at the surface of freshly placed concrete or

Montmorillonite

a swelling clay mineral of the smectite group; main constituent of bentonite. (See also smectite.)

Mortar

a mixture of cement paste and fine aggregate; in fresh concrete, the material occupying the interstices among particles of coarse aggregate; in masonry construction, joint mortar may contain masonry cement, or may contain hydraulic cement with lime (and p