Concrete and Cement Contractors Industry Terminology

ACI (American Concrete Institute)

The leading technical society that publishes widely used concrete codes, guides, and certification programs (e.g., ACI 318 for structural concrete).

Detail the slab per ACI 302 and ACI 360 jointing recommendations.|Our technicians are ACI Field Testing Grade I certified.|The mix must comply with ACI 301 specifications.

Admixture

A material other than water, aggregates, or cement added to concrete to modify properties (workability, set time, strength, durability).

Use a mid-range water reducer to improve workability.|Dose the accelerator for cold weather per the supplier’s chart.|We’ll add a retarder to extend set in hot weather.

Aggregate

The granular materials (fine: sand; coarse: gravel or crushed stone) that make up most of concrete’s volume and influence strength, workability, and durability.

Specify 3/4-inch coarse aggregate, well graded.|High fines content is increasing water demand.|Angular aggregate improves interlock in pavements.

Air Entrainment

Intentional incorporation of microscopic air bubbles in concrete (typically 4–7%) to improve freeze–thaw durability and scaling resistance.

Exterior slabs need air-entrained concrete.|Don’t hard trowel air-entrained mixes; risk of delamination.|Verify air content per ASTM C231.

ASTM (American Society for Testing and Materials)

Standards organization that publishes concrete/material test methods and specifications used in procurement, QC, and design.

Cement shall conform to ASTM C150 Type I/II.|Test cylinders per ASTM C39 and slump per ASTM C143.|Aggregate quality per ASTM C33.

Batching

Measuring and combining concrete ingredients by mass or volume at the plant or on site to produce a consistent mix.

Use automatic weigh batching for cement and aggregate.|Adjust water at the plant; minimize on-site additions.|Check yield to confirm batching accuracy.

Bid Bond

A surety guaranteeing the contractor will honor its bid and provide required performance/payment bonds if awarded the contract.

The RFP requires a 5% bid bond.|Our surety has preapproved the bid amount.|Without a bid bond, your offer is nonresponsive.

Bleed Water

Water that rises to the concrete surface after placement due to settlement of solids; excessive bleeding weakens the surface.

Don’t start finishing until bleed water dissipates.|High slump increased bleeding and crusting.|Cover with curing blankets to reduce bleed and evaporation.

Bull Float

A long-handled float used immediately after screeding to embed aggregate, level ridges, and bring paste to the surface.

Bull float the slab perpendicular to the screed pass.|Use a magnesium bull float to avoid sealing the surface.|Excess bull floating can cause paste-rich surfaces.

Cement

The hydraulic binder (commonly Portland cement) that reacts with water to form the glue (C-S-H) in concrete; not the same as concrete.

We’re using Type IL (limestone) cement per ASTM C595.|Cement content is 560 lb/yd³ in this mix.|Don’t call concrete “cement” in specs—be precise.

Change Order

A formal modification to the contract scope, price, or schedule initiated by the owner, contractor, or designer.

Submit a change order for the added thickened edge.|This RFI response results in a no-cost change order.|The CO extends substantial completion by 7 days.

Compressive Strength

The capacity of concrete to withstand axial loads, typically measured at 7 and 28 days (e.g., f’c = 4,000 psi).

Break the cylinders at 28 days to confirm f’c.|Early strength gain is critical for formwork stripping.|Specified strength is 5,000 psi with performance criteria.

Control Joint

A planned, weakened plane (saw cut, tooled, or formed) that induces cracking at predetermined locations as concrete shrinks.

Saw cut joints at 12-foot spacing within 6–12 hours.|Depth should be at least 1/4 of slab thickness.|Lay out the jointing plan to maintain square panels.

CPM (Critical Path Method)

A scheduling technique that identifies the sequence of critical activities determining the overall project duration.

The critical path runs through forming, placement, and curing.|Added curing time introduced negative float.|Update the CPM to reflect the revised pour sequence.

Curing

Actions to maintain adequate moisture and temperature in concrete to allow proper hydration and strength/durability development.

Wet cure for 7 days per ACI 308.|Use curing compound where wet cure is impractical.|Cold weather curing blankets prevented thermal shock.

Dowel

Smooth steel bars across joints that transfer load between slabs while allowing horizontal movement.

Install 1-inch dowels at 12-inch spacing with sleeves.|Use dowel baskets to maintain alignment.|Epoxy-coat dowels in pavements to reduce corrosion.

Drying Shrinkage

Volume reduction as concrete loses moisture over time, leading to cracking, curling, and joint opening if not controlled.

Reduce drying shrinkage with lower w/c and SCMs.|Provide tighter joint spacing to accommodate shrinkage.|Curing and humidity control limit shrinkage cracking.

Efflorescence

A white crystalline deposit of salts on concrete or masonry surfaces, often due to moisture migration and evaporation.

Efflorescence appeared on the north facade after rain.|Improve drainage and sealing to reduce recurrence.|Clean deposits with a mild acid wash per manufacturer.

Expansion Joint

A full-depth, full-width separation (often with filler) allowing slabs or structures to move independently from thermal/moisture changes.

Provide isolation/expansion joints at columns.|Seal joints to keep out incompressibles.|Place preformed filler per detail at 20-foot intervals.

F-Numbers (FF/FL)

Numerical indices that quantify as-constructed floor flatness (FF) and levelness (FL) for slabs-on-ground and elevated slabs.

Warehouse aisles require FF 50/FL 35.|Laser screed helped us meet the F-number spec.|Perform ASTM E1155 testing the morning after placement.

Fiber-Reinforced Concrete (FRC)

Concrete containing steel, synthetic, glass, or natural fibers to control plastic shrinkage cracking and improve toughness/impact resistance.

Specify 0.5% macro-synthetic fiber by volume.|FRC reduced joint spacing in the slab-on-ground.|Use fibers in lieu of light WWF for temperature/shrinkage.

Formwork

Temporary or permanent molds into which concrete is placed; includes forms, bracing, ties, and form-release systems.

Formwork must resist hydrostatic pressure at high slumps.|Use release agent compatible with planned coatings.|Strip forms when concrete reaches required strength.

Grout

A flowable cementitious or polymer material used to fill voids, set baseplates, anchor bolts, and in masonry cells (often specified as non-shrink).

Place non-shrink grout under column baseplates.|Pump grout into congested block cells.|Follow manufacturer’s grout fluidity and strength data.

Hydration

The chemical reaction between cement and water that forms C-S-H and other products, generating heat and developing strength over time.

Cold weather slows hydration; use accelerators or heat.|Monitor heat of hydration in mass concrete.|Adequate curing ensures complete hydration.

Mix Design

The proportioning of cementitious materials, water, aggregates, and admixtures to meet specified performance (strength, durability, workability).

Target a 0.42 w/c with 20% slag.|Submittal includes proposed mix designs and test history.|Switch to a performance-based mix per ACI/ASTM.

OSHA (Occupational Safety and Health Administration)

U.S. agency that sets and enforces workplace safety standards relevant to concrete work (silica, fall protection, PPE, trenching).

Implement an OSHA-compliant silica exposure control plan.|Guard rebar caps to meet OSHA impalement protection.|Train finishers on OSHA slip/trip hazards.

Performance Bond

A surety instrument guaranteeing the contractor will complete the project in accordance with the contract; protects the owner.

Provide a 100% performance bond and 100% payment bond.|The surety was notified of the default under the performance bond.|Bond premiums are included in general conditions.

Placement

The act of depositing and spreading concrete into its final position, coordinated with consolidation and finishing to avoid defects.

Coordinate chute access for continuous placement.|Limit free fall to prevent segregation.|Stagger placements to avoid cold joints.

Post-Tensioning

A prestressing method where tendons are tensioned after concrete hardens to reduce cracking and increase span capacity.

Stress tendons to 33 kips after 3,000 psi is reached.|Coordinate tendon layout with slab openings.|Patch and grout PT anchor pockets after stressing.

Pozzolan

A siliceous/aluminous material that reacts with calcium hydroxide in the presence of moisture to form cementitious compounds (e.g., fly ash, natural pozzolans, silica fume).

Use Class F fly ash as a pozzolan to reduce heat of hydration.|Pozzolans improve sulfate resistance and durability.|Adjust set time when adding silica fume.

QA/QC (Quality Assurance/Quality Control)

Management systems and procedures to ensure concrete meets specified requirements via planning (QA) and testing/inspection (QC).

Submit a QC plan with testing frequencies.|QA audits submittals and field reports.|QC techs cast cylinders and check air/slump each load.

Quantity Takeoff

The measurement and calculation of materials and labor quantities from plans/specs used for estimating and procurement.

Perform a concrete takeoff by pour break.|Include rebar laps and waste in takeoff quantities.|Use on-screen takeoff to count control joints.

Ready-Mix Concrete

Concrete produced in a batching plant and delivered to the jobsite in a truck mixer; can be central-mixed or transit-mixed.

Schedule five ready-mix trucks per hour.|Verify ticket times to meet 90-minute limits.|Specify plant certification and mix ID on tickets.

Rebar

Steel reinforcing bars used to resist tension, control cracks, and provide ductility; identified by size and grade.

Place #5 Grade 60 rebar at 12 inches on center.|Tie rebar to chairs to maintain cover.|Lap splices per ACI 318.

Retainage

A portion of the contract payment withheld by the owner to ensure completion and correction of defects, released at milestones.

The contract holds 10% retainage until substantial completion.|Request partial release of retainage on finished areas.|Retainage affects cash flow; plan billing accordingly.

RFI (Request for Information)

A formal question from contractor to designer/owner seeking clarification of drawings, specs, or site conditions.

Submit an RFI on conflicting slab thickness notes.|The RFI response changes the joint layout.|Track RFIs in the project log with due dates.

SCC (Self-Consolidating Concrete)

Highly flowable concrete that fills formwork and encapsulates reinforcement without vibration; characterized by slump flow and passing ability.

Specify slump flow 22–26 inches for SCC walls.|SCC improved finish quality around congested rebar.|Perform J-ring and L-box tests for SCC.

Screed

The tool or process used to strike off and level freshly placed concrete to the correct elevation and slope.

Use a straightedge to hand-screed edges.|Laser screed the warehouse slab to meet FF/FL.|Check screed rails for deflection.

Slump

A measure of concrete consistency/workability determined by the vertical subsidence of a cone-shaped sample (ASTM C143).

Target a 4-inch slump for slabs-on-ground.|Recheck slump after water or admixture additions.|High slump caused edge sloughing at forms.

Spalling

The breaking, flaking, or scaling of concrete surface, often due to freeze–thaw cycles, corrosion of reinforcement, or impact.

Spot spalling near joints from de-icer exposure.|Repair spalls with polymer-modified patching mortar.|Seal to reduce moisture ingress and future spalling.

Subgrade

The prepared native soil or improved base beneath a slab or pavement; its stiffness and uniformity affect performance.

Proof-roll the subgrade and recompact soft spots.|Place a 6-inch granular base over the subgrade.|Subgrade pumping led to slab faulting.

Supplementary Cementitious Materials (SCMs)

Materials such as fly ash, slag cement, and silica fume used with cement to improve durability, reduce heat, and lower cement content.

Specify 30% slag for sulfate resistance.|SCMs help reduce embodied carbon of mixes.|Adjust set time when using high SCM dosages.

Superplasticizer

A high-range water-reducing admixture that greatly increases flow without increasing water content, improving placement at low w/c.

Dose HRWR to achieve a 7-inch slump at same w/c.|Add superplasticizer at the site for pumpability.|Watch for slump loss with certain HRWR chemistries.

Trowel

Hand or power tool used during finishing to produce a smooth, dense surface; technique affects flatness and durability.

Power-trowel in multiple passes after bull floating.|Avoid hard troweling air-entrained exterior slabs.|Burnish the final pass in interior floors per spec.

Vapor Retarder/Barrier

A membrane placed below slabs-on-ground to limit moisture migration from the subgrade; thickness and placement affect curling and flooring.

Use a 15-mil vapor barrier directly under the slab for resilient flooring.|Seal all laps and penetrations.|Balance curling risk with moisture control needs.

Vibrator

A device (internal or external) that consolidates concrete by removing entrapped air and ensuring paste-to-aggregate contact.

Use a 1.5-inch head with 8,000–12,000 vpm.|Delay withdrawal to avoid voids; don’t over-vibrate SCC.|Vibrate in a grid pattern to consolidate the lift.

Water-Cement Ratio (w/c)

The mass ratio of water to cementitious materials in a concrete mix; the key factor controlling strength, permeability, and durability.

Limit w/c to 0.45 for exterior exposure.|Lower w/c improves durability but may reduce workability.|Track w/c by monitoring total water additions.

Welded Wire Reinforcement (WWR)

Prefabricated welded wire mats or rolls used to control temperature/shrinkage cracking and distribute loads in slabs and pavements.

Specify WWR 6x6 W2.9/W2.9 placed at mid-depth.|Chairs are needed to keep WWR in the correct position.|Laps must meet sheet designations per ASTM A1064.

Workability

The ease with which concrete can be placed, consolidated, and finished without segregation or excessive effort.

Improve workability with a water reducer and better gradation.|High workability is needed for congested reinforcement.|Workability isn’t the same as slump alone.

Yield

The actual volume of concrete produced per batch relative to theoretical volume; used to verify batching accuracy and billing.

Field yield checks show a short load—notify the plant.|Adjust batch weights to correct low yield.|Use yield to reconcile tickets and installed volume.