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.