Civil Engineering Dictionary Terms : S

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Sr.TermDefinition
1Sagging MomentA bending moment which causes a beam to sink in the middle. Usually described as a positive moment.
2SandGrandular material passing through a #4 sieve (4.76 mm), but predominantly retained above the No. #200 sieve (74 micron).
3Sand EquivalentA measure of the amount of clay contamination in fine aggregate.
4Saturated Surfae Ddry (Ssd)A condition of an aggregate which holds as much water as it can without having any free surface water between the aggregate particles.
5ScalingA delamination of a thin portion of the top of portland. cement concrete.
6Scarifier, Riper Or RooterAn implement which may be self-propelled or towed behind a tractor, with downward projecting tines for breaking a road surface for approximately two feet deep or less.
7Scour Or ErosionRemoval of the sea bed or of a river bed or banks by erosive action of waves or flowing water.
8Screed, Screed Board, Screed Rail Or Tamper(1) A wood or metal templet with which a concrete surface is finished. Screeds are set to the correct level for the slab surface. The screed rail may be cambered but is usually straight. (2) A layer of mortar 2 to 7 cm thick, laid to finish a floor surface or as a bed for floor tiles.
9Sealand Orsealing Compound(1) A fluid of plastic consistency laid over a joint surface or the outside of a joint filler to exclude water. Hot bitumen, rubber strip, plastic strip, hessian caulking, synthetic resins and building mastics are used as sealant. (2) A durable coating of plastics such as epoxy resin or polyurethane, painted on the face of form lining or timber formwork to enable it to be reused many times. (3) Liquid-membrane curing compound. A coating for roads (e.g., bituminous emulsion) over a damp, recently cast concrete surface, which prevents loss of water, and thus ensures proper curing of the concrete. (4) A treatmemt for a set concrete floor which strengthens the concrete surface or binds the aggregate, ensuring that it does not dust. Sodium silicate solution has been successfully used for many years.
10SedimentAny material, mineral or organic matter deposited by water, air, etc., often called silt.
11Septic-TnakUnderground sewage collecting tank.
12Settlement Or SibsidenceDownward movement of a structure such as a railway bridge, dam, or building, due to compression or downward movement of soil below it. It need not be harmful unless different parts settle by different amounts.
13Shear(1) The strain upon, or the failure of a structural member at a point where the lines of force and resistance are perpendicular to the member. (2) The load acting across a beam near its support. For a uniformly distributed load or for any other symmetrical load, the maximum shear is equal to half the total load on a simply supported beam, or to the total load on a cantilever beam. Maximum shear occurs at both ends of a simply supported beam (the acting moment equal to zero near the support's ends).
14SheathingA sheet metal covering over underwater timber to protect it against marine borers; sheeting.
15Sheet PilesClosely set piles of timber, reinforced or prestressed concrete, or steel driven vertically into the ground to keep earth or water out of an excavation.
16Short ColumnA column which is so short that if overloaded it will fail not by crippling but by crushing.
17ShouldersThe portion of the roadway continguous with the traveled way for accommodation of stopped vehicles, for emergency use and for lateral support of base and surface courses.
18ShovingDisplacement of flexible pavement caused by high shear stresses or because of deficient pavement material.
19ShrinkageThe shrinkage of concrete during hardening can amount to 0.0004 of its length at one year or half this value at two months. Cement mortar shrinks by a similar amount.
20ShutteringThat part of formwork which either is in contact with the concrete or has the form lining attached to it.
21SidewalkThat portion of the roadway primarily constructed for the use of pedestrians.
22SiltGrandular material passing the No. 200 sieve (74 micron), finer than sand but coarser than clay, such particles in the range from 2 to 50 micron. It feels gritty between the fingers but the grains are difficult to see. It can be distinguished from clay by the shaking test or by rolling it into a thread. A thread of silt crumbles on drying, a clay thread does not. Rock flour and loess are materials of silt size.
23SlabA flat, usually horizontal cast concrete member of uniform thickness which extends over three or more supports in a given direction.
24SlagThe waste glass-like product from a metallurgical furnace, which flows off above the metal.
25Slag CementsCements made by grinding blast-furnace slag and mixing it with lime or portland cement or dehydrated gypsum. Slag is also used in making expanding cement and supersulphated cement.
26Slip-FormA narrow section of formwork in slab or wall shuttering that can easily be pulled or raised as concrete in place, and is designed to be removed first, thus making it easy to remove the remaining larger panels. It may also be called a wrecking piece or wrecking strip.
27SlumpThe decrease in height of wet concrete when a supporting mold is removed. It is a measure of consistency of freshly mixed concrete.
28SlurryA thin, watery mixture of neat cement or cement and sand.
29SoilSoil is gravels, sands, silts, clays, peats and all other loose materials including topsoil, down to bedrock.
30Soldier PileAn upright pile used to hold lagging.
31SoundnessResistance to both physical and chemical deterioration.
32SpallingPeeling away of a surface, particularly of portland cement concrete.
33SpanThe distance between the supports of a bridge, truss, arch, girder, floor, beam, etc.
34Spillway Or WastewayAn overflow channel.
35Spread FootingA footing used to support a single column. This is also known as an individual column footing and isolated footing.
36SpecificationsWritten or printed description of construction work to be done forming part of the contract, describing qualities of material and mode of construction, and giving dimensions and other information not shown in drawings. It includes bidding procedures, legal requirements, insurance requirements, material and workmanship requirements, inspection and testing procedures, and procedures for measurement and payment of the work, also the specifications establish obligations of the contracting parties with respect to the State (Client) and his Engineer, it is the obligation to clearly define what is required; to establish a plan for its enforcement to the extent required during the period of execution; and to indicate how the work will be measured and paid for. With respect to the Contractor, it is the obligation of complying with the Contract requirements during the construction period. The Specifications includes Standard Specifications and Special Provisions.
37Special ProvisionsApproved supplementary provisions, additions, revisions or deletions to the standard specifications which may cover conditions peculiar to an individual project.
38Soil StabilizationModification of soils or aggregates by incorporating materials that will increase load bearing capacity, firmness and resistance to weathering or displacement. Common methods are mixing the soil with cement or waste oil or imported soil, also compaction or merely covering with a primer.
39Standard SpecificationsThe current edition of the State's Standard Specifications for State Road and Bridge Construction.
40Standard DeviationsA measure of variability that can be calculated form the differences between individual measurements in a group and their average.
41Steady FlowFlow which does not vary with time.
42StrandA number of steel wires grouped together by twisting.
43StreetA general term denoting a public way for purposes of vehicular travel, including the entire area within the right-of-way.
44Stress-Absorbing Membrane Interlayer (Sami)A low-stiffness mixture of asphalt cement, rubber and mineral aggregate placed between layers of pavement to retard the transfer of stresses between the layers.
45StructuresBridges, culverts, catch basins, drop inlets, retaining walls, cribbing, manholes, headwalls, buildings, sewers, service pipes, underdrains, foundation drains and other structural features.
46Stripping(1) Loss of binder (Bituminous film) from aggregate particles or from a road surface, due to presence of water. (2) Removing formwork. (3) Clearing a site of turf, brush-wood, topsoil, or the first layer of soil.
47Subbase CourseOne or more layers of specified or selected materials, of designed thickness, placed on the subgrade to support a base course.
48SubcontractorAn individual, partnership, firm, corporation or any acceptable combination thereof, or joint venture, to which the contractor sublets a part of the contract.
49SubgradeThe roadbed materials beneath the pavement structure. The top prepared surface of the subgrade is called finished subgrade elevation.
50SubstructureAll that part of the bridge below the bridge seats, tops of piers, haunches of rigid frames or below the spring lines of arches. Backwalls and parapets of abutments and wing walls of bridges shall be considered as parts of the substructure.
51Subsoil (1) The weather soil directly below the topsoil. (2) The ground below formation level also called the subgrade or foundations.
52Sulphate-Bearing SoilsIf ground water contains more than 0.1% of SO3 or if a clay contains more than 0.5% of SO3, high-alumina cement should be used for all concrete in the ground. Portland pozzolana cement may sometimes give enough protection at lower cost. No precautions needed with foundation concrete in water containing less than 0.02% of SO3 or clay which contains less than 0.1% of SO3.
53SumpA pit in which water or sewage collects before being baled or pumped out.
54SuperelevationExaggerated tilt of roadway on a curve to counteract centrifugal force on vehicles.
55SuperstructureAll that part of a structure above and including the bearing of simple and continuous spans, skewbacks of arches and top of footings of rigid frames, excluding backwalls, wingwalls, and wing protection rails.
56SuretyThe corporate body bound with the contractor for the full and complete performance of the contract and for payment of all debts pertaining to the work.
57SurchargeA surface loading in addition to the soil load behind a retaining wall.
58Surface RecyclingRecycling an existing pavement surface by heating, scarifying (Milling), remixing, rejuvenating with an emulsified recycling agent, placing and compacting.
59Surface WaterWater carried by an aggregate in addition to that held by absorption within the aggregate particles themselves. It is water in addition to saturated surface density water.
60SurfacingThe uppermost layer of material placed on the traveled way, or shoulders. This term is used interchangeably with pavement.
61Surface CourseOne or more layers of specified materials designed to accommodate the traffic load; the top layer of which resists skidding, traffic abrasion and the disintegrating effect of climate. The top layer is sometime called a "wearing course".
62Swelling PressureThe pressure exerted by a contained clay when it absorbs water. It can amount to considerably more than the pressure of the overlying soil.

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