Construction

circle diagram or circle notation

A simple form of the activity on-node diagram. in which each activity is represented by a circle containing the activity description, an identifying number, and the activity duration.

0.40 to 0.70

Water/cement ratios normally used range from about by weight.

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.

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.

Composite piles

are piles made up of two or more different materials.

Cranes

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

Waterstops

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

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.

Pozzolans

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

Steel-troweled concrete surfaces

are very smooth and become slippery when wet. They can be slightly roughened to produce a nonslip surface by brushing or brooming them.

Vacuum wells

are wellpoints that are sealed at the surface by placing a ring of bentonite or clay around the well casing.

bar graph or bar chart schedule

is a graphical schedule relating progress of items of work to a time schedule

fog seal

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

Caissons

is a structure used to provide all-around lateral support to an excavation.

Precast concrete

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

Leveling

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

Hydration

is 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.

qualification of a contractor

is the determination that the contractor possesses both the technical and financial ability to perform the work required by the contract.

Dewatering

is the process of removing water from an excavation.

Aggregate

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

Edging

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

Flat Slabs

Slabs may be supported directly by columns without the use of beams or joists.

change order

The usual construction contract contains a clause authorizing the owner or owner's representative to order changes to the project within the general scope of the contract. The document directing such a change is referred to as a

Bulb piles

They are a special form of cast-in-place concrete pile in which an enlarged base (or bulb) is formed during driving.

Dummy Activity

They do not represent any work and, hence, always have a duration of zero.

Prequalification

Under this procedure only those contractors determined to be capable of performing are invited to submit bids for the project.

Mat or raft foundations

consist of a heavily reinforced concrete slab extending under the entire structure, in order to spread the structure's load over a large area.

Coarse aggregate

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

Flashing

consists of layers of impervious material used to seal out moisture or to direct any moisture that does penetrate back to the outside.

Recycling

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

Specifications

constitute that portion of the written requirements for a building construction project that are contained in the divisions of a project manual.

Fixed price with escalation contracts

contain a provision whereby the contract value is adjusted according to a specified price index.

Special Conditions

contain any additional contract provisions applicable to the specific project.

Asphalt emulsions

contain particles of asphalt dispersed in water by means of emulsifying agents.

General Conditions

contain those contract provisions applicable to most construction contracts written by the owner.

agreement

describes the work to be performed, the required completion time, contract sum, provisions for progress payments and final payment, and lists the other documents making up the complete contract.

activity-on-arrow

each activity is represented by an arrow that has an associated description and expected duration.

Financial planning

for a construction project includes cost estimating prior to bidding or negotiating a contract, forecasting project income and expenditure (or cash flow), and determining the amount of work that a construction firm can safely undertake at one time

performance bond

guarantees completion of the project as described in the contract documents.

bid bond

guarantees that a contractor will provide the required performance and payment bonds if awarded the contract.

payment bond

guarantees the payment of subcontractors, laborers, and suppliers by the contractor.

Air-entrained concrete

has significantly increased resistance to freezing and thawing as well as to scaling caused by the use of deicing chemicals.

Claim

is a request by the contractor for a time extension or for additional payment based on the occurrence of an event beyond the contractor's control that has not been covered by a change order.

project manual

is a single volume that contains all written requirements for a building construction project.

dust palliative

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

tack coat

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

floating foundation

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

dragline

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

precedence diagram is

is an extension of the activity-on node format that provides for incorporation of lag-time factors as well as permitting additional precedence relationships.

slipform paver

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

sand seal

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

emulsion slurry seal

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

No-slump concrete

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

Refractory concrete

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

Architectural concrete

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

Prestressed concrete

is concrete to which an initial compression load has been applied.

Mass concrete

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

single-pass surface treatment

is constructed by spraying on a layer of asphalt and covering it with a layer of aggregate approximately one stone in depth.

Troweling

is done on slabs that are to be left exposed or to receive thin finishes, such as resilient flooring, carpet, tile, or paint.

Total equipment owning cost

is found as the sum of depreciation, investment, insurance, tax, and storage.

English bond

is made up of alternate courses of headers and stretchers, with headers centered on stretchers.

Heavyweight concrete

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

Lagging

is nothing more than sheeting placed horizontally.

negotiated contract

is one negotiated between an owner and a construction firm.

A plastic concrete

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

Quality control (QC)

is primarily concerned with the process control function.

Rolling resistance

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

Concrete

is produced by mixing portland cement, aggregate, and water.

Water

is 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.

Sheet piling

is sheeting of concrete, steel, or timber that is designed to be driven by a pile driver

Pier

is simply a column, usually of reinforced concrete, constructed below the ground surface.

Trafficability

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

Float (slack in PERT terminology)

is the amount of scheduling leeway available to an activity.

Value engineering

is the analysis of a design with the objective of accomplishing the required function at a lower cost.

Dusting

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

Scaling

is 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). It usually occurs at an early age of the slab.

Struck capacity

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

Plate line capacity

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

Heaped volume

is 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.

Crazing

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

wellpoint

is the perforated assembly placed on the bottom of the inlet pipe for a well.

Electroosmosis

is the process of accelerating the flow of water through a soil by the application of a direct current.

Trimming

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

Grading

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

Finishing

is the process of bringing the surface of concrete to its final position and imparting the desired surface texture.

Compaction

is 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.

Grouting or pressure grouting

is the process of injecting a grouting agent into soil or rock to increase its strength or stability, protect foundations, or reduce groundwater flow.

Earthmoving

is 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.

Batching

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

Consolidation

is the process of removing air voids in concrete as it is placed.

spread footing

is the simplest and probably the most common type of building foundation. They include individual footings, combined footings, and mat foundations.

flash point

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

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.

Lump-sum contract

provides a specified payment for completion of the work described in the contract documents.

Type II (modified/moderate) portland cement

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

Type V (sulfate-resistant) cement

provides maximum resistance to alkali attack.

Stack bond

provides no interlocking between adjacent masonry units and is used for its architectural effect.

Soil Stabilization

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

Grade resistance

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

Investment cost

represents the annual cost (converted to an hourly cost) of the capital invested in a machine.

Repair cost

represents the cost of all equipment repair and maintenance.

Insurance cost

represents the cost of fire, theft, accident, and liability insurance for the equipment.

Service cost

represents the cost of oil, hydraulic fluids, grease, and filters as well as the labor required to perform routine maintenance service.

Tax cost

represents the cost of property tax and licenses for the equipment.

Storage cost

represents the cost of rent and maintenance for equipment storage yards and facilities, the wages of guards and employees involved in handling equipment in and out of storage, and associated direct overhead.

Depreciation

represents the decline in market value of an item of equipment due to age, wear, deterioration, and obsolescence.

Variable time

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

Fixed time

represents those components of cycle time other than travel time.

Asphalt cutback

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

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

Drawings

Construction documents that "show in graphic and quantitative form the extent, design location, relationships, and dimensions of the work to be done.

Jointing

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

consequential costs

Frequently, it will be found that changes or delay in one activity will necessitate changes in resource allocation or progress on other activities that result in additional project cost. These costs are sometimes referred to as

bleeding

Generally, the dry materials used in making quality concrete are heavier than water. Thus, shortly after placement, they have a tendency to settle to the bottom and displace the mixing water to the surface, which is called

liquefaction

If the water pressure exactly equals soil weight, the soil will behave like a liquid and we have a condition called

boiling or piping

If the water pressure is strong enough to move subsurface soil up through the bottom of the cut, this condition is called

balancing

In highway construction, the process of cutting down high spots and filling in low spots of each roadway layer is called

retainage or retention

It is customary to withhold a percentage of the value of work completed as a guarantee against defective work and to ensure that the remaining work can be completed within the unpaid amount of the contract. The amount withheld is referred to as

spading or puddling.

Medium- to high-slump concrete should be compacted and worked into place by

loosening, loading, hauling, and compacting.

The process of rock moving may be considered in four phases:

batching, mixing, transporting, placing, consolidating, finishing, and curing.

The construction operations involved in the production of concrete include

punch list of record

The list of deficiencies to be corrected which is prepared at the final inspection is sometimes referred to as the

ground modification or soil stabilization.

The process of giving natural soils enough abrasive resistance and shear strength to accommodate traffic or design loads is called

critical path.

That path through the network which establishes the minimum project duration is referred to as the

Early event time

The earliest time at which each event may occur based on an arbitrary starting time of zero

placing.

The movement of plastic concrete into its final position (usually within forms) is called

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

Contract Time

The time allowed (expressed as either days allowed or as a required completion date) for completion of a construction project is normally specified in the contract along with the phrase "time is of the essence."

early start schedule

When all activities are scheduled to start at the earliest allowable time, such a schedule is referred to as an

late start schedule

When all activities are started at their latest allowable starting time

Type I (normal) portland cement

a general-purpose cement suitable for all normal applications.

Accelerators

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

Vibratory compaction

also called vibroflotation and vibrocompaction, is the process of densifying cohesionless soils by inserting a vibratory probe into the soil.

Flemish bond

alternates stretchers and headers in each course with headers centered over stretchers in the course below.

Steel piles

are capable of supporting heavy loads, can be driven to great depth without damage, and are easily cut and spliced.

Cast-in-place concrete piles

are constructed by driving a steel shell into the ground and then filling it with concrete.

Subcontracts

are contracts between a prime contractor and secondary contractors or suppliers

Disputes

are disagreements between the contractor and owner over some aspect of contract performance.

Construction plans

are drawings that show the location, dimensions, and details of the work to be performed.

Shop drawings

are drawings, charts, and other data prepared by a contractor or supplier which describe the detailed characteristics of equipment or show how specific structural elements or items of equipment are to be fabricated and installed.

Owning costs

are fixed costs that are incurred each year whether the equipment is operated or not.

Operating costs

are incurred only when the equipment is used.

Progress payments

are made at the interval specified in the contract, usually monthly or upon completion of certain milestones.

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.

aggregate surface treatments

are made up of alternate applications of asphalt and aggregate.

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:

Water line capacity

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

Expansion or control joints

in masonry walls are used to permit differential movement of wall sections caused by shrinkage of concrete foundations and floor slabs, temperature and moisture changes, and foundation settlement.

liquidated damages clause

in the contract may be used to simplify the process of establishing the amount of damages resulting from late completion.

Quality management

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

Accelerators

increase the rate of early strength development in concrete.

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.

Workability agents or plasticizers

increase the workability of a mix.

Dynamic compaction, or deep compaction

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

Cost estimating

involves estimating the total cost to carry out a construction project in accordance with the plans and specifications.

Finish grading

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

Project cost control

involves the measurement and recording of project costs and progress and a comparison between actual and planned performance.

bond beam

is a continuously reinforced horizontal beam of concrete or masonry designed to provide additional strength and to prevent cracking in a masonry wall.

Slump

is 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.

Loadability

is a measure of the difficulty in excavating and loading a soil.

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.

Bidding

is a process whereby a prime design professional engaged by an owner, and the design professional's consultants, prepare bidding documents and issue them to a group of constructors.

Negotiation

is a process whereby an architect engaged by an owner, and the architect's consultants, prepare negotiation documents.

Construction Management

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

floating

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

Vacuum dewatering

may be employed to reduce the amount of free water present in plastic concrete after the concrete has been placed and screeded.

Lightweight insulating concrete

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).

Construction technical specifications

provide the detailed requirements for the materials, equipment, and workmanship to be incorporated into the project.

cost plus percentage

of cost contract pays the contractor a fee that is a percentage of the project's actual cost.

Fuel-resistant asphalt

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

Surcharging

or placing additional weight on the soil surface, has long been used to densify cohesive soils.

Soil permeability,

or the ease with which water flows through the soil, is primarily a function of a soil's grain size distribution.

Trench shields

or trench boxes are used in place of shoring to protect workers during trenching operations.

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.

Pretensioning

places the prestressing material (reinforcing steel or prestressing cables) under tension in the concrete form before the member is poured.

Posttensioning

places the prestressing steel (usually placed inside a metal or plastic tube cast into the member) under tension after the concrete member has been erected.

Building Information Modeling (BIM)

presents a database that includes design data, drawings, specifications, materials and systems parameters, and life cycle data, for all the various disciplines involved in a project and relates those data to each other and to the project as a whole to present an overall view of the project.

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.

Retarders

slow the rate of hardening of concrete.

Unit-price contracts

specify the amount to be paid for each unit of work but not the total contract amount.

Common bond

uses a header course repeated at regular intervals; usually every fifth, sixth, or seventh course.

Running bond

uses only stretcher courses with head joints centered over stretchers in the course below.

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.