Trowel finish is the most common and popular finish of concrete used for major types of applications. After placing the concrete in the formwork and leveling it, the trowel is used to smooth and finely level the concrete surface. Bag see bag (cement) (preferred term). Sack scrub a finish for formed concrete surfaces, designed to produce a uniform texture and fill the pits and ventilation holes; after moistening the surface, the mortar is rubbed onto the surface, then, before the surface dries, a mixture of dry cement and sand is rubbed onto it with a plug of burlap or a sponge rubber float to remove excess mortar and fill in voids.
See also air gaps in the surface and finish, rubbed. Sand, natural sand resulting from natural disintegration and abrasion of rock. See also sand and aggregates, fines. See also aggregates, fines and sand.
See also abrasive blasting. Sand-lime brick see brick, calcium silicate (preferred term). Local descaling or peeling of the near-surface portion of the hardened concrete or mortar; also of a layer of metal. See also flaking and flaking.
Scarf gasket see scarf connection (preferred term). Larger vesicular volcanic dross ejections, generally of basic composition and characterized by a dark color; material is relatively heavy and partially vitreous, partially crystalline; vesicles generally do not interconnect. See also added, lightweight. See also Rod.
See also coating and compounding, curing. See also bleeding and separation. Self-stressing concrete (mortar or grout) see Concrete (mortar or grout), self-stressing. A sensor of a device designed to respond to a physical stimulus (such as temperature, lighting, and movement) and transmit a resulting signal for interpretation, measurement, or operation of a control.
Separation the tendency, as concrete is caused to pass through the unconfined ends of gutters or conveyor belts or similar arrangements, for coarse-grained aggregate to separate from the concrete and accumulate on one side; the tendency, as processed aggregate exits the ends of conveyor belts, gutters or similar devices with confining sides, so that the larger aggregate separates from the mass and accumulates on one side; or the tendency of solids to separate from water by gravitational settling. See also bleeding and segregation. Separation joint see gasket, insulation (preferred term). Set (n).
See also set, permanent. See also set, flash. See also set, false. Set, hesitation see set, false (preferred term).
Game, rubber see set, false (preferred term). Assembly, warehouse (the partial hydration of cement stored for a time and exposed to atmospheric moisture; and (the mechanical compaction that occurs during storage). See also cement, sticky. Final Set Time: The time required for a freshly mixed cement, mortar, or concrete paste to reach final set.
See also time, initial setting. See also time, final setting. Collapse of solid particles in fresh grout, mortar or concrete, after laying and before initial setting. Shale, expanded light vesicular aggregate (clay or shale) obtained by firing suitable raw materials in a furnace or on a sintering grid under controlled conditions.
Coating cover around the prestressed steel to prevent temporary or permanent bonding between the steel and the surrounding concrete. See also conduit. Shelly structure see pearlitic structure (preferred term). See also shooting.
See also L-head and T-head. See also raker. See also shrinkage, elongation and contraction. See also pneumatic feed; positive displacement; shotcrete, dry mix; and shotcrete, wet mix.
See also shrinkage and volume change. Shrinkage, settling, reduction of the volume of concrete before final setting of cementitious mixtures, caused by sedimentation of solids. See also shrinkage, plastic and volume change, autogenous. See also expansive cement.
Silica powder see silica flour (preferred term). Silicon carbide, an artificial product (SiC), whose granules can be embedded in concrete surfaces to increase wear resistance or as a means to reduce skidding or sliding on steps or pavements of stairs; it is also used as an abrasive in saws and drills for cutting concrete and masonry, and as a grain abrasive in particle size range. Size, nominal, see maximum nominal size (of assembly). A rearwardly sloping surface on which the end of an arch rests, such as a concrete thrust block that supports the thrust of an arch bridge.
See also strapping, chamfer. See also slab, plan and plate, plan. See also flat plate. The process of lifting concrete slabs or filling voids under them, or both, by pressure injecting a material (cementitious, non-cementitious, or asphalt) under the slabs.
Slab above grade slab, continuously supported by the ground, whose total load, when evenly distributed, imparts a pressure to the slope or ground that is less than 50% of the permissible load capacity thereof; the slab can be of uniform or variable thickness, and can include reinforcement elements such as ribs or beams; the slab can be smooth, reinforced or prestressed concrete; reinforcing or prestressed steel can be provided to accommodate the effects of shrinkage and temperature or structural load. Also known as slab above ground; slab above grade is the preferred term. Slip resistance: the frictional force that opposes the movement of an object across its surface. See also coefficient of friction.
See also chain drag or, more generally, acoustic impact. See also spreader. See also ferrule, slab. See also coat, dashbond and parge.
Specification (in ASTM) an explicit set of requirements that a material, product, system, or service must meet. Spectrophotometer instrument for measuring the intensity of radiant energy of the desired frequencies absorbed by atoms or molecules; substances are analyzed by converting the absorbed energy into electrical signals proportional to the intensity of the radiation. See also spectroscopy, infrared and photometer, flame. Spinning is the essential factor in the production process of spun concrete.
See also concrete, spinning. See also splice, turn. Spreader (a piece of wood, usually about 1 by 2 in. Spun concrete see Spin Cast Concrete (preferred term).
Stalactite: a downward-pointing deposit formed as an accumulation of mineral matter caused by the evaporation of water dripping from the surface of rock or concrete, commonly shaped like an icicle. See also stalagmite. See also stalactite. See also central coincidence.
See also steam curing room. Stearic acid, a white crystalline fatty acid, obtained by saponification of tallow or other stearin-containing hard fats. See also butyl stearate. See also steel, prestressed.
See also prestressed; prestressed concrete; prestressed and post-tensioned. Steel reinforcement, galvanized steel that has been passed through a molten bath of zinc at a temperature of about 860°F (460°C); generally used for applications requiring steel strength and corrosion resistance. Hardening, see Premature, False and Set Assembly, Flash (preferred term). Stitching: A method of repairing cracks that involves drilling holes on both sides of the crack and grouting seam dogs (U-shaped metal units with short legs) that span the crack; can be used when tensile strength must be restored in major cracks.
Stone, crushed the product resulting from the artificial crushing of rocks, boulders or large pavers, whose faces substantially have well-defined edges as a result of the crushing operation. See also aggregates, coarses. Strength, nominal design resistance of a member multiplied by a drag reduction factor (Φ). See also force, nominal and factor, phi.
Strength, bending the property of a solid indicating its ability to resist failure in bending; in concrete bending members, the stress at which a section reaches its maximum usable bending capacity; for weakly reinforced concrete bending members, the stress at which deformation is applied by compression in concrete reaches 0.003; for bending members of overreinforced concrete, the stress at which the compressive stress reaches 85% of the strength of the concrete cylinder; for non-reinforced concrete members, the stress at which the tensile strength of concrete reaches the modulus of rupture. Force, nominal bending the bending strength of a member or cross section calculated in accordance with the provisions and assumptions of the strength design method prior to the application of any strength reduction factor (Φ). Force, nominal shear the shear strength of a member or cross section calculated in accordance with the provisions and assumptions of the strength design method prior to the application of any strength reduction factor (Φ). Resistance Design Method A design method that requires that the service loads increase according to the specified load factors and that the calculated rated resistances be reduced according to the specified phi (φ) factors.
Reinforce the process of restoring the capacity of weakened components or elements to their original design capacity or increasing the strength of components or elements of a concrete structure. See also external strengthening. Reinforcement, primary type of system required when design service loads (without load factors) exceed the rated strength of an unreinforced element; includes section extension, span shortening, and supplemental supports. Reinforcement, type of add-on system suitable for situations where design service loads (without load factors) are less than the existing capacity of the non-reinforced element.
Effort intensity of the internal force (i.e., e. Tension, average of the maximum and minimum stress in a fluctuating load cycle (such as in a fatigue test); tensile stress is considered positive and compressive stress is negative. Force, normal the component of stress that is perpendicular to the plane in which the force is applied; it is designated traction if the force is directed away from the plane and compressive if the force is directed toward the plane. See also stress.
See also flow, plastic and creep. Stretcher: a masonry unit positioned with its horizontal length and parallel to the face of a wall or other masonry member. See also heading. See also do.
See also demoulding and peeling. Strip, in the center of the flat slab structure, the part of slab that occupies the middle half of the span between pillars. See also column strip. Unformwork removal of formwork or molds.
See also demoulding. Surface, brushed a sandy texture obtained by brushing the freshly laid or slightly hardened concrete surface with a stiff brush to achieve an architectural effect or, in pavements, to increase slip resistance. See also finish, broom. See also scrub sacks.
Surface repair, repair of a concrete surface, for example. See also repair, partial depth. Protective surface treatments 10 mils (0.25 mm) or less thick, typically applied with a brush, roller, squeegee, or spray. Surface water see moisture, surface (preferred term).
Roll tie rod: A diagonal brace used to resist wind or other lateral forces. See also bracing; cross bracing; and Xbrace. See also contraction; expansion; volume change; and volume change, autogenous. Grout is a thin layer of particles weakly adhered to the surface of fresh concrete caused by an upward movement of water.
Grout must be removed before applying a decorative coating. Smooth trowelling concrete is created when the cement mason uses a manual trowel or steel machine to close the exposed surface of the concrete project. The most basic type of concrete finish is a smooth surface created through the use of screeds and trowels. Immediately after placing the concrete in the forms, the concrete finishers use a rule to level the concrete surface.
Screeds often consist of long pieces of metal or wood that are pulled and pushed across the concrete surface to remove excess concrete and fill voids in the concrete surface. A concrete slab is a common structural element of modern buildings, consisting of a flat, horizontal surface made of cast concrete. Strength, bond strength to the separation of mortar and concrete from reinforcement and other materials with which it is in contact; a collective expression of forces such as adhesion, friction due to shrinkage and longitudinal cutting in concrete engaged by bar deformations that resist separation. Concrete has low thermal diffusivity, high heat capacity and its thermal mass is negatively affected by insulation (e.
Screeds are usually made of long pieces of metal or wood that are pulled and pushed across the surface of the concrete to remove excess concrete and fill in gaps. Space, capillary void space in concrete that resembles microscopic channels small enough to draw liquid water through them by the molecular attraction of water adsorbed on their inner surfaces. It gives the concrete surface an aesthetically pleasing appearance that is preferred for outdoor applications because it not only adds beauty to the surface, but also makes it safer to walk and stand than smooth surface concrete finishes, especially during the wet season. The key with any of these additives is to avoid iron-containing materials, which can stain concrete.
Exposed aggregate concrete is the first finished concrete product on the list that uses a different aggregate than the smooth trowel or broom finish. Concrete finishing is the process of leveling, smoothing, compacting, or treating the surface of freshly poured concrete. Insufficient or no curing of the concrete surface often results in a soft concrete surface, which easily dusts under traffic. In addition to filling the downhill side, this area of the slab can be supported by concrete pillars that extend into the ground.
Designs may consist of bricks, stones, or other decorative patterns to provide the desired look, sometimes imitating other common building materials, but retaining the strength and durability of concrete. Strength, rupture, tensile strength, tensile strength of concrete determined by a diametral compression test. Steel reinforcement, high-strength steel prestressing, most commonly strands, wires, or bars that are used to impart permanent prestressing forces to concrete. Energy efficiency has become a primary concern for the construction of new buildings, and the prevalence of concrete slabs requires careful consideration of their thermal properties to minimize energy waste.