Concrete Materials and Techniques

Concrete

• A construction material made from Portland cement, aggregate, and water
• Normal-weight concrete typically weighs 140-160 lb/cu ft
• Lightweight insulating concrete weighs 15-90 lb/cu ft and has a 28-day compressive strength of 100-1000 psi
• Mass concrete used in structures like dams, where the weight provides strength
• Heavyweight concrete use heavy aggregates (barite, magnetite, steel) for radiation shielding
• Refractory concrete is cast into the desired shape before placement.
• Leveling refers to achieving the correct grade with mortar
• Edging rounds off slab edges to prevent chipping
• Screeding moves a straight edge across freshly placed concrete
• Jointing uses preformed inserts to control cracking due to shrinkage
• Bleeding is the settling of dry materials to the bottom of concrete, displacing water
• Troweling is the process of smoothing surfaces with a tool
• Scaling is the breaking away of hardened concrete surface (1/6-3/16 inch depth) usually in early age of the slab

Harbor Terms

• A protected water area for ships (loading, unloading, repairs, etc.)
• Natural harbors are protected by natural land formations
• Artificial harbors are protected by breakwaters or dredging
• Port is a sheltered place for cargo loading/unloading
• Fairway is a navigable channel for ships
• Wharf is a structure parallel to water for cargo handling
• Pier is a landing stage, jetty, floating barge, or pontoon
• Jetty is a structure extending into the sea
• Dolphin is a berth structure for mooring ships
• Significant wave is the hypothetical wave with the average height/period of a group
• Highest wave is the tallest wave in a wave group
• Mean wave is the wave with average height/period of a wave group

Water Terms

• Deepwater waves are where the water depth is at least half the wavelength
• Mean Sea Level is the average of sea water level for a period of 19 years
• Mean Low Water is the height of low water over a 19-year period
• Mean Lower Low Water is the average height of lower low waters over 19 years
• Storm Surge is a temporary rise in sea level due to pressure reduction caused by storms and wind
• Tsunamis are waves with long periods, often caused by significant sea floor movements
• Seiche is a phenomenon of water oscillation with periods of a few minutes to tens of minutes
• Seal coat is a thin bituminous surface treatment
• Tack coat is an initial bituminous application
• Prime coat is a bituminous application on a prepared surface
• Perception time is the time for a driver to realize the need for braking
• Intellection time is the time to understand a situation and consider options
• Emotion time is the time for emotional response to a situation
• Volition time is the time taken for the final action

Traffic Terms

• Traffic sign is a device conveying information for regulating, warning, or guiding traffic
• Regulatory signs inform drivers of traffic laws
• Warning signs alert drivers of road conditions
• Guide signs show directions, distances, and routes
• Roadwork signs provide information about roadwork
• Overhead signs display traffic information on wide roads
• Plate line capacity is the volume of a bucket when the load is struck off
• Struck capacity is the bucket volume when the load is struck
• Water line capacity is a level of material within the bucket
• Heaped volume is maximum placement in a bucket without spillage
• Grade resistance is the vehicle weight component parallel to the inclined surface
• Rolling resistance is due to tire flexing/penetration of the travel surface
• Total resistance is the combination of grade & rolling resistance
• Aggregate is concrete material to reduce cost and shrinkage
• Water is required in concrete for hydration of cement
• Hydration is the chemical reaction between cement and water to produce hardened cement
• Water-reducing agent increases workability and consistency in concrete without altering amount of water

Other Construction Terms

• Retarder slows concrete hardening
• Accelerator decreases setting time, increases early strength
• Pozzolan reduces heat of hydration, increases workability, and reduces segregation
• Plasticizers increase concrete workability
• Batching is the process of proportioning concrete ingredients.
• Admixture is any material added to concrete besides cement, aggregates, and water, altering its properties in various ways