Civil Engineering

Construction Management

the contractual arrangement under which a firm supplies construction management services to an owner.

Quality management

includes such activities as specification development, process control, product acceptance, laboratory and technician certification, training, and communication.

Quality control (QC)

primarily concerned with the process control function.

Earthmoving

the process of moving soil or rock from one location to another and processing it so that it meets construction requirements of location, elevation, density, moisture content, and so on.

Trafficability

the ability of a soil to support the weight of vehicles under repeated traffic.

Loadability

a measure of the difficulty in excavating and loading soil.

Plate line capacity

the bucket volume contained within the bucket when following the outline of the bucket sides.

Struck capacity

the bucket capacity when the load is struck off flush with the bucket sides.

Water line capacity

assumes a level of material flush with the lowest edge of the bucket.

Heaped volume

the maximum volume that can be placed in the bucket without spillage based on a specified angle of repose for the material in the bucket.

Dragline

a very versatile machine that has the longest reach for digging and dumping of any member of the crane shovel family.

Cranes

primarily used for lifting, lowering, and transporting loads. They move loads horizontally by swinging or traveling.

Grade resistance

represents that component of vehicle weight which acts parallel to an inclined surface.

Rolling resistance

primarily due to tire flexing and penetration of the travel surface.

Fixed time

represents those components of cycle time other than travel time.

Variable time

represents the travel time required for a unit to haul material to the unloading site and return.

Ground modification or soil stabilization

the process of giving natural soils enough abrasive resistance and shear strength to accommodate traffic or design loads.

Compaction

the process of increasing the density of a soil by mechanically forcing the soil particles closer together, thereby expelling air from the void spaces in the soil.

Dynamic compaction

involves dropping a heavy weight from a crane onto the ground surface to achieve soil densification.

Vibratory compaction

the process of densifying cohesionless soils by inserting a vibratory probe into the soil.

Surcharging

placing additional weight on the soil surface to densify cohesive soils.

Soil Stabilization

the improvement of the engineering properties of a soil by use of physical or chemical admixtures.

Grading

the process of bringing earthwork to the desired shape and elevation (or grade).

Finish grading or finishing

involves smoothing slopes, shaping ditches, and bringing the earthwork to the elevation required by the plans and specification.

Balancing

the process of cutting down high spots and filling in low spots of each roadway layer.

Trimming

the process of bringing each roadway layer to its final grade.

Rock moving

may be considered in four phases

Concrete

produced by mixing portland cement, aggregate, and water. The construction operations involved in the production of concrete include batching, mixing, transporting, placing, consolidating, finishing, and curing.

Normal-weight concrete

usually weighs from 140 to 160 lb/cu ft (2243–2563 kg/m3), depending on the mix design and type of aggregate used.

Lightweight insulating concrete

concrete that may weigh from 15 to 90 lb/cu ft (240–1442 kg/m3) and have a 28-day compressive strength from about 100 to 1000 lb/sq in. (690–6895 kPa).

Mass concrete

concrete used in a structure such as a dam in which the weight of the concrete provides most of the strength of the structure.

Heavyweight concrete

concrete made with heavy aggregates such as barite, magnetite, and steel punching; it is used primarily for nuclear radiation shielding.

No-slump concrete

concrete having a slump of 1 in. (2.5 cm) or less.

Slump

a measure of concrete consistency obtained by placing concrete into a test cone following a standard test procedure (ASTM C143) and measuring the decrease in height (slump) of the sample when the cone is removed.

Refractory concrete

concrete that is suitable for high temperature applications such as boilers and furnaces.

Precast concrete

concrete that has been cast into the desired shape prior to placement in a structure.

Architectural concrete

concrete that will be exposed to view and therefore utilizes special shapes, designs, or surface finishes to achieve the desired architectural effect.

Type I (normal) portland cement

a general-purpose cement, suitable for all normal applications.

Type II (modified/moderate) portland cement

provides better resistance to alkali attack and produces less heat of hydration than does Type I cement.

Type III (high early strength) cement

provides 190% of Type I strength after 1 day of curing. It also produces about 150% of the heat of hydration of normal cement during the first 7 days.

Type IV (low heat) cement

produces only 40–60% of the heat produced by Type I cement during the first 7 days. However, its strength is only 55% of that of normal cement after 7 days.

Type V (sulfate-resistant) cement

provides maximum resistance to alkali attack.

Aggregate

used in concrete to reduce the cost of the mix and to reduce shrinkage.

Water

required in the concrete mix for several purposes. Principal among these is to provide the moisture required for hydration of the cement to take place.

Hydration

the chemical reaction between cement and water which produces hardened cement. The heat that is produced by this reaction is referred to as heat of hydration.

Water/cement ratios

normally used range from about 0.40 to 0.70 by weight.

Air-entrained concrete

has significantly increased resistance to freezing and thawing as well as to scaling caused using deicing chemicals.

Water-reducing agents

increase the slump or workability of a concrete mix. Thus, with a water-reducing agent the amount of water in the mix may be reduced without changing the concrete’s consistency.

Retarders

slow the rate of hardening of concrete.

Accelerators

act in the opposite manner to retarders. That is, they decrease setting time and increase the early strength of concrete.

Pozzolans

used to reduce the heat of hydration, increase the workability, and reduce the segregation of a mix.

Workability agents or plasticizers

increase the workability of a mix.

Batching

the process of proportioning cement, water, aggregates, and additives prior to mixing concrete.

Truck mixers or transit mix trucks

are truck-mounted concrete mixers capable of mixing and transporting concrete. The product they deliver is referred to as ready-mixed concrete.

Coarse aggregate

consists of gravel, crushed stone, or another suitable material larger than ¼ in. (6.4 mm) in diameter.

Admixtures

are materials other than portland cement, aggregates, and water that are added to concrete either immediately before or during its mixing to alter the properties of the concrete in a variety of ways.

For example, they can be used to:

Improve workability

Reduce separation of coarse and fine aggregates due to settling out of the heavier coarse aggregate

Entrain air

Accelerate or retard setting and hardening

Water-reducing admixtures

permit a lower water content, improve workability, and increase the efficiency of the portland cement in a mix, which lowers a concrete's cost relative to its performance.

High-range water-reducing admixtures (super plasticizers)

are mostly used in concrete that is to be pumped. They produce a mix that flows easily, with no increase in its water content.

Retarders

admixtures that have a retarding effect on the set of portland cement overcome the accelerating effect that temperature has on setting during hot weather and in large masses of concrete, and delay the early stiffening of concrete placed under difficult conditions.

Accelerators

increase the rate of early strength development in concrete.

Formwork

Because concrete is unable to maintain a particular shape before it sets, it must be placed in a form or mold. In building construction, this form or mold is called formwork.

Flying forms

are made by building a large section of form, as described earlier for centering, and supporting the entire section on deep steel trusses.

Slip forming

is a method of continuously moving a form for vertical structures, such as elevator or stair shafts, upward on jacks as new concrete is placed on top of the old.

Waterstops

are rubber or vinyl inserts designed to be placed in concrete joints to prevent water from penetrating the joint.

Isolation and separation joints

are often necessary to separate concrete sections and prevent the bonding of one concrete section with another, or to separate a concrete section from another material or structural part so that one can move independently of the other.

plastic concrete

is one that is readily molded and yet will change its form only slowly if the mold is removed.

Concrete is handled and transported by:

•        • Chutes

•        • Push buggies

•        • Buckets handled by cranes

•        • Pumping through a pipeline

•        • Pneumatically forcing through a hose (shotcrete)

Concrete

is either delivered to the site by truck or, in small projects, mixed at the site and moved to its placement location by:

•        • Dumping directly from a truck's chute.

•        • Buggy.

•        • Dumping from a truck's chute into a large bucket, which is then lifted by crane and deposited in its proper location.

•        • Dumping from a truck into a concrete pump which delivers the mix to its final location through a hose. Pumps are capable of delivering concrete over long distances and up many floors.

Shotcrete

is pneumatically placed concrete, used primarily for swimming pools and other in-ground and aboveground free-form structures and for repairing damaged concrete.

Concrete should be compacted by a method appropriate to the material and its location to:

•        • Eliminate stone pockets and large air bubbles

•        • Consolidate each layer with that previously placed

•        • Completely embed reinforcing and fixtures

•        • Bring just enough fine material to the faces and top surfaces to produce the desired finish

Medium- to high-slump concrete compaction

it should be compacted and worked into place by spading or puddling.

Finishing of standard-weight concrete slabs

it proceeds through several steps in a defined order. These steps are screeding, leveling, edging, jointing, floating, troweling, and broom finishing or other surface texturing.

Bleeding

shortly after placement, the dry materials used in making quality concrete tend to settle to the bottom and displace the mixing water to the surface, which is called bleeding.

Screeding

the surface of newly placed concrete is struck off (screeded) by moving a straightedge back and forth with a sawlike motion across the top of the forms and screeds.

Leveling

it is the bringing of a concrete surface to true grade with enough mortar to produce the desired finish.

Edging

it rounds off the formed edge of a slab to prevent chipping or damage.

Jointing

immediately following or during edging, premolded inserts are placed in concrete slabs to control cracking in the concrete as a result of shrinkage, except when joints will be later sawed.

floating

It may be done when the water sheen has disappeared and the concrete will support the weight of the finisher.

The purpose of floating is to:

•        • Embed large aggregate just beneath the surface

•        • Remove slight imperfections, humps, and voids to produce a level or plane surface

•        • Consolidate mortar at the surface in preparation for other finishing operations

•        • Open the surface to permit excess moisture to escape

 

Troweling

the process of finishing concrete slabs that are to be left exposed or to receive thin finishes, such as resilient flooring, carpet, tile, or paint.

Broom Finishing

a method of roughening a smooth, steel-troweled concrete surface to produce a nonslip surface by brushing or brooming it.

Scaling

the breaking away of the hardened concrete surface of a slab to a depth of about 1/6 to 3/16 in. (1.6 to 4.8 mm), usually occurring at an early age of the slab.

Crazing

the occurrence of numerous fine hair cracks in the surface of a newly hardened slab due to surface shrinkage.

Dusting

the appearance of a powdery material on the surface of a newly hardened concrete slab.

Fuel-resistant asphalt

asphalt often based on a polymer-modified asphalt (PMA), available and demonstrating high resistance to rutting and cracking as well as to petroleum fuels.

Asphalt cutback

a liquid mixture created when petroleum distillates are mixed with asphalt cement, which is liquid at room temperature.

Asphalt emulsions

a mixture of asphalt dispersed in water by means of emulsifying agents.

Flash point

the temperature at which a liquid produces sufficient vapor to ignite in the presence of air and an open flame.

Slipform paver

a machine capable of spreading, consolidating, and finishing a concrete slab without the use of conventional forms.

Tack coat

a thin coating of light bituminous material applied to a previously paved surface to act as a bonding agent.

Dust palliative

a substance applied to an unpaved surface to reduce the amount of dust produced by vehicular traffic and wind.

Fog seal

a light application of a slow-setting asphalt emulsion diluted by one to three parts of water.

Emulsion slurry seal

a mixture of slow-setting asphalt emulsion, fine aggregate, mineral filler, and water.

Sand seal

a light application of a medium-viscosity liquid asphalt covered with fine aggregates.

Single-pass and multiple-pass surface treatments

alternate applications of asphalt and aggregate used for aggregate surface treatments.

Single-pass surface treatment

a construction method that involves spraying on a layer of asphalt and covering it with a layer of aggregate approximately one stone in depth.

Recycling

the process of demolishing old pavement, recrushing the pavement material, and reusing it in new asphalt or concrete mixes.

Foundation

the part of a structure that supports the weight of the structure and its applied loads.

Spread footing

the simplest and most common type of building foundation, including individual footings, combined footings, and mat foundations.

Mat or raft foundation

a heavily reinforced concrete slab extending under the entire structure, used to spread the structure’s load over a large area.

Floating foundation

a type of mat foundation in which the weight of the soil excavated approximately equals the weight of the structure being erected.

Ground modification or soil stabilization

the process of improving soils in place.

Pile

a column driven into the soil to support a structure by transferring building loads to a deeper and stronger layer of soil or rock.