Holland & Tucker, TheGardenArtForum.Com
Armature: A term used in "additive" sculpting to describe the framework or "skeleton" used to support and build up a shape upon. Whether used with Darjit, clay, plaster, cement or any other material, the armature must be constructed of a material compatible with the material to be applied and sturdy enough to support its weight.
Bonding Agents: Any of the family of adhesives employed to secure concrete or mortar to reinforcements or other surfaces. Commonly used to adhere new concrete to old or existing concrete when resurfacing or repairing. Can be used as a surface treatment, admix or both.
Cement: A building material manufactured by grinding calcined limestone and clay to a fine powder, which can be mixed with water and poured to set as a solid mass or used as an ingredient in making mortar or concrete.
Cement Paste: The colloidal (glue like) material which constitutes the majority of the porous mass of which hydrated cement paste is composed. The plastic combination of cement & water that supplies the cementing action in concrete.
Cement, Portland: (ASTM C150) A powdery substance produced by burning a mixture of clay and limestone at high temperatures. This results in lumps called “clinkers” which are then ground into a fine powder that consists of hydraulic calcium silicates.
Change of State: The alteration of physical properties as well as the processes themselves that materials go through when changing from gases to liquids, to solids or the reverse and inclusive of various "semi" states in between. Example: Water. When steam cools it condenses and moves from a gaseous state into a liquid state. Reduce the temperature further and it goes from the liquid state to a solid state...ice. Concrete & mortar go through a change of state that is generally considered as transitioning from a plastic (semi-liquid state) to a solid as a result of the chemical processes involved.
Cold Joint: The visible delineation that occurs when concrete placement is delayed and the concrete already in place hardens prior to the fresh placement of concrete against it.
Concrete: A mixture of cement (usually Portland), various aggregate fillers (sand, gravel, rock) and water which chemically hardens into an insoluble monolithic composite. The most common formulation is often referred to as a "standard 1-2-3 mix" and consists of One part Cement + Two parts Sand + Three parts Gravel (or Stone).
Concrete, Lightweight: Any concrete that incorporates any of a variety of weight reducing aggregates (such as perlite or vermiculite), or has been mixed or processed with components that generate controlled entrained air bubbles, specifically for the purpose of creating an end product whose weight is less than that of conventional concrete (approximately 150 pounds per cubic foot).
Concrete Mix Ratios: The numerical values of basic concrete mix components as expressed in relative parts. These relative values should always be expressed or stated in the following order; Cement first, then Sand, then Gravel (or Stone). Example: A "standard 1-2-3" mix consists of One part Cement + Two parts Sand + Three parts Gravel (or Stone).
Concrete, Refractory: Any concrete formulated specifically to achieve thermally resistant or insulating properties and suitable for use at high temperatures. Calcium-Aluminate cement and refractory aggregates are normally used for the manufacture of this product.
Concrete Sealers: A group of liquid compounds specifically designed for the purpose of protecting cured concrete or any cement-based medium from surface wear or the intrusion of damaging environmental contaminants. They are also commonly used to create a specific surface treatment and enhance the coloration of the substrate to which it is applied. They are commonly available in two basic formulations:
1. Water-Based Film Forming Sealants
2. Solvent-Based Penetrating Sealants
The proper formulation choice depends on a range of appearance & performance factors that must be determined by the applicator. (For a more thorough treatise on these materials see the following information in the Concrete Sealer 101 for Artists & Crafters page.
Consistency: The degree of plasticity demonstrated by fresh concrete or mortar. The standard measures of consistency are "slump" for concrete, and "flow" for mortar. (Also see "Slump")
Cure: The method by which sufficient internal humidity and proper temperature are maintained to insure that the hydration process of the cement within the freshly placed concrete or mortar is uninterrupted allowing full and proper hardening to take place.
Cure, 28 Day or 28 Day Strength: The arbitrary period chosen as the standardized engineering reference point at which hydration is considered adequate for a given concrete mix to have achieved 100% of its design strength. Concrete gains strength very rapidly at first, then the process slows proportionally over time. Typical strength gain is about 45% in 3 days, 75% in 7 days and 100% of design strength in 28 days. Note that this standard refers only to "design" strength. Concrete will actually continue to gain strength and further harden for an indeterminate period spanning decades or possibly even centuries making the measurement of its ultimate strength impractical. This standard point of reference measures what is believed to be approximately 90% of concretes final, ultimate strength.
Curing: The processes involved in or the period of time during which hydration is taking place.
Drying Shrinkage: The decrease in volume that occurs while concrete is drying.
Durability: The general measure of a particular concrete formulations ability to resist weathering , chemicals and abrasion.
Ferrocement: Any cement-based material (generally referring to concrete) that is internally reinforced with some form of ferrous metal (iron, steel). Such internal structure may or may not be load bearing, but the metal employed must exhibit expansive & contractive properties consistent with the concrete surrounding it. Patented in 1868 by French gardener Joseph Monier.
Fibers: The general term used to describe a family of additives designed to mechanically strengthen cementitious materials during their early set stages and help prevent early onset cracking. Widely used in casting & shotcrete where high water/cement ratios can lead to this type of problem. Available in a range of cut lengths and a variety of materials including different polymers, glasses & metals. NOTE: Any fibers used in a cementitious mixture must be alkali resistant or they will degrade rapidly.
Fly Ash: The finely divided residue that results from the combustion of ground or powdered coal which is used as a micro-aggregate and additive in concrete. When combined with cement, it becomes a reactive pozzalan that is used to strengthen and densify concrete. Some modern formulations now replace as much as 60% of the Portland in the mix with fly ash.
Freeze/Thaw Resistance: The ability of a specific cementitious formulation to withstand the effects of repeated freezing & thawing which can destroy most "basic concrete" due to the expansion and contraction forces of moisture within the cured mass. Air entrainment and/or densification are typically employed to counter these effects and provide their benefit throughout the cured structure. Sealers can also be beneficial, but are limited to simply reducing the migration of any additional moisture into the mass from its outer surfaces.
Grout: A mixture of cement, sand, and water or (2) cement and water: the hardened equivalent of such mixtures.
Hickey or Rebar Hickey: A sturdy steel hand tool for bending rebar. It consists of a handle 30 to 36 inches in length welded to a triangular head bearing three stout posts for leveraging the rebar into various shapes. The single post on the reverse of the head can be fitted into a hole in a worktop allowing it to rotate around that point for additional leverage & control.
Hydration: Formation of a compound by the union of water with some other substance. In concrete it is the chemical reaction that occurs when the water and the cement are combined which causes the resulting paste to harden.
Hypertufa: A cement-based formulation designed to reproduce the porous look of the naturally occurring lightweight rock known as Tufa and the resulting products manufactured from this formulation. Mix ratios vary wildly, but the most common "basic recipe" consists of 1 part Portland cement + 1.5 parts Peat + 1.5 parts Perlite. The term literally translates as "Fast" or "Beyond" (hyper)...and... "Tufa" (the name for an unusual porous geological formation).
Integral Color: Any such color medium introduced into a cementitious formulation during the mixing stage which permeates the entire mix throughout. Available in both dry powder and liquid forms, these colorants can also be either natural or synthetic. Most are based on naturally occurring mineral oxides and are utterly permanent and will not fade or diminish due to environmental exposure.
Mixer: A piece of equipment used to mix or blend materials used in the production of concrete, grout or mortar.
Mortar: A mixture of cement, sand and water typically used in masonry construction. The mixture may contain masonry cement, or standard Portland cement with lime or other ad-mixtures added to produce greater degrees of plasticity and/or durability.
Peat: A soft brown mass consisting of compressed, partially decomposed mossy vegetation that forms in a water-saturated environment such as bogs & turfs and which has a carbon content of 50%. Dried peat can be burned as fuel and is commonly used as a soil amendment & mulch.
Peat Moss: Any of various pale or ashy mosses of the genus Sphagnum which often grows abundantly in damp boggy or peaty places whose decomposed remains form peat. One of the principal ingredients in a cementitious product known as Hypertufa which is meant to replicate a porous natural rock type called Tufa.
Perlite: A fine white aggregate formed by heating and expanding siliceous volcanic glass. Commonly used as a soil amendment and to produce lightweight insulating concrete.
Plastic: The condition of freshly mixed concrete, mortar or cement-paste that indicates it is workable, readily re-moldable, cohesive and has an ample content of fines & cement but is not over wet.
Plasticity: Property of freshly mixed concrete, cement paste or mortar which determines its ease of molding or resistance to deformation.
Plasticizer: An admixture formulated to increase the fluidity or flow rate of a concrete mixture, mortar or cement paste without additional water.
Porosity: The ratio of the volume of voids in the material to the total volume of the material, including the voids, usually expressed as a percentage.
Portland Cement: The man-made hydraulic cementitious product patented in 1824 by English stonemason Josepf Aspdin. So named for it's resemblance to the gray natural stone quarried near the city of the same name. It is the result of specific manufacturing processes that involve heating a limestone and clay mixture in a kiln and pulverizing and processing the resulting material.
Portland Cement, White: White Portland cement is made from raw materials containing little or no iron or manganese, the substances that give conventional cement its gray color.
Rebar: The common name for the mild steel reinforcing bar specifically designed for use in concrete. Its metallurgy is engineered to match the thermal expansion & contraction rates of concrete and intended to help overcome concretes inability to carry tensile loading. It is manufactured in a wide range of diameters and is usually formed with ridges or "cleats" along its surface to aid in adhesion with the cementitious material. Sizing of rebar is commonly called out based on the number of eighths of an inch that make up the diameter. Examples: #3 = 3 eighths(3/8"), #4 = 4 eighths(1/2"), #5 = 5 eighths(5/8"), etc., etc.
Sand: Any fine, granular inorganic material that results from natural or manufacturing processes that reduce rock or stone into fine particles.
Sand, Mason's: Classified as a fine aggregate meeting ASTM C 144 for masonry mortar. It is washed and double screened to be a finer sand and is generally lighter in color than torpedo sand.
Sand, Torpedo: Classified as a fine aggregate with the largest particle size less then 3/8". Yellowish, beige in color, it is washed and screened. Meets ASTM C 33 sand for use in concrete.
Set: The term used to describe the natural, progressive and observable stiffening of cement paste that results from the process of hydration and which takes place in definable stages.
Initial Set refers to the first phase of stiffening and loss of plasticity.
Final Set is used to describe the attainment of a significant degree of rigidity.
Stucco: A durable mixture of cement, sand, lime and water applied over metal lath or chicken wire or wooden lath used to form the finish covering of walls and ceilings.
Stucco Lath, Metal: A galvanized expanded metal mesh product with diamond-shaped openings designed specifically for the purpose of adhering cementitious & plaster-based materials to various surfaces. It can be readily nailed or stapled onto wooden surfaces such as walls & ceilings or wired in place on metal frameworks or armatures.
Tufa: The name for an unusual and naturally occurring geological formation that is the basis for the production of a man-made cementitious mixture known as "Hypertufa" meant to mimic it's lightweight and porous properties. NOTE: The rock type "tufa" is commonly confused in name by laypersons with the rock type "tuff", which is a rock formed from welded volcanic ash. These rocks are nothing like each other. Tufa is a rough, thick, rock-like calcium carbonate deposit that forms by precipitation from bodies of water with a high dissolved calcium content.
Vermiculite: An altered mica that expands greatly at high temperature forming a water-absorbent substance. Commonly used as a base for growing seed plants, an insulating material & as a lightweight aggregate in cementitous mixtures.
Waterproof: Any surface or material that is unaffected by and impervious to penetration by water in its liquid state.
Weathering: Changes in texture, color, chemical composition, strength or other properties due to effects of the environment or weather. Independent of any changes due to direct mechanical wear.
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