Concrete

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Presentation Transcript

FRESH CONCRETE: 

FRESH CONCRETE To the designer, fresh concrete is of little importance. To the constructor, fresh concrete is all-important, because it must be mixed, transported, placed, supported, consolidated, finished, and cured.

FRESH CONCRETE: 

FRESH CONCRETE

CEMENT TRUCK: 

CEMENT TRUCK

CONCRETE PLANT STANDARDS: 

CONCRETE PLANT STANDARDS Cement of cementitious materials shall be batched by weight. Aggregates shall be batched by weight. Water shall be batched by weight or volume.

BATCH PLANT: 

BATCH PLANT Accurately proportions aggregate and cement. Water is measured in the mixer truck.

MIXER TRUCK: 

MIXER TRUCK

MIXER TRUCK: 

MIXER TRUCK

MIXER TRUCK: 

MIXER TRUCK

HAULING CONCRETE: 

HAULING CONCRETE Transit mixer truck Maximum duration 1 ½ hr or 300 drum revolutions from introduction of water until placement.

MIXER DRUM: 

MIXER DRUM

MIXER DRUM: 

MIXER DRUM

CENTRAL MIX PLANT: 

CENTRAL MIX PLANT

CENTRAL MIX PLANT: 

CENTRAL MIX PLANT Accurately proportions aggregate, cement and water, and mixes these materials automatically.

CENTRAL MIX PLANT: 

CENTRAL MIX PLANT

CENTRAL MIX PLANT: 

CENTRAL MIX PLANT

CENTRAL MIX PLANT: 

CENTRAL MIX PLANT

CENTRAL MIX PLANT: 

CENTRAL MIX PLANT

Quantities of Cement, Aggregate and Water : 

Quantities of Cement, Aggregate and Water Specifications may simply define strength: 28 day strength (i.e. 2,500, 3,000 or 6,000 psi)

Quantities of Cement, Aggregate and Water : 

Quantities of Cement, Aggregate and Water Specs may define other requirements: Maximum size aggregate (i. e. 1½ in.) Minimum cement content (sacks per cy or lb/cy) Maximum water cement ratio by weight or in gallons per sack of cement)

Quantities of Cement, Aggregate and Water : 

Quantities of Cement, Aggregate and Water One sack of cement weights 94 lbs. One barrel of cement contains four sacks Specific gravity of cement, 3.15

Quantities of Cement, Aggregate and Water : 

Quantities of Cement, Aggregate and Water Specific gravity (average) of course or fine aggregate, 2.65 Water weights 62.4 lb/cf One cf of water = 7.48 U.S. gal. One gallon of water weights 8.33 lb.

Quantities of Cement, Aggregate and Water : 

Quantities of Cement, Aggregate and Water Usually the proportion of fine aggregate varies between 25 and 45% of total aggregate volume. Absolute volume of any ingredient in cubic feet equals:

Quantity Example: 

Quantity Example Max. size aggregate 1½ in. Min. cement content 6.0 sacks/cy Max. water/cement ratio 0.65

Quantity Example: 

Quantity Example Cement/cubic yard 6.0 sacks 6 sacks  94 lb/sack = 564 lb Absolute volume of cement

Quantity Example: 

Quantity Example Water/cubic yard 564 lb  0.65 = 366.6 lb Absolute volume of water

Quantity Example: 

Quantity Example Absolute volume of 1 cy of concrete = 27.0 cf Assume 6% air voids

Quantity Example: 

Quantity Example Absolute volume of aggregate =16.63 cf

Quantity Example: 

Quantity Example Absolute volume of sand Assume fine aggregate 35% Weight fine aggregate = 962.4 lb/cy

Quantity Example: 

Quantity Example Absolute volume of coarse aggregate Weight course aggregate = 1,787.5 lb/cy

Quantity Example: 

Quantity Example Assume a 700 cy placement. Cement required 197.4 tn

Quantity Example: 

Quantity Example Assume a 700 cy placement. Water required 30,807 gallons

Quantity Example: 

Quantity Example Assume a 6 hours for the placement. Or 86 gallons/minute

Quantity Example: 

Quantity Example Assume a 700 cy placement. Sand required 337 tn

Quantity Example: 

Quantity Example Assume a 700 cy placement. Course aggregate required 626 tn

Quantity Example: 

Quantity Example Assume a 700 cy placement. How much for waste??

HAULING CONCRETE: 

HAULING CONCRETE Wet Central Mix Concrete Using dump or agitor trucks, 30 minute maximum haul at 70 to 90 degrees.

CABLE & BUCKET SYSTEM: 

CABLE & BUCKET SYSTEM

CABLE & BUCKET SYSTEM: 

CABLE & BUCKET SYSTEM

CONVEYOR SYSTEM: 

CONVEYOR SYSTEM

CONVEYOR SYSTEM: 

CONVEYOR SYSTEM

PUMPING: 

PUMPING

SLIPFORM PAVER: 

SLIPFORM PAVER

SLIPFORM PAVER: 

SLIPFORM PAVER

PAVING OVER DOWELS: 

PAVING OVER DOWELS

PAVING OVER REBAR: 

PAVING OVER REBAR

SIDE FEEDER: 

SIDE FEEDER Side feeder when paving over dowels or rebar.

PAVING the MIDDLE LANE: 

PAVING the MIDDLE LANE

CONCRETE: 

CONCRETE

SMOOTHNESS: 

SMOOTHNESS Specifications require smoothness. A “Profileometer.” is used to measure smoothness.

SMOOTHNESS: 

SMOOTHNESS Monitor supply of concrete. Mix design is but a prerequisite. Many of the problems occurring in pavements concern what is done with the mix.

SMOOTHNESS: 

Control density. Vibration is a vital part of the paving process. SMOOTHNESS Paver Vibrators

SMOOTHNESS: 

SMOOTHNESS Weight & Traction The principle which makes a slipform paver work is the consolidation of the concrete in a confined space.

SMOOTHNESS: 

SMOOTHNESS Paver attitude. The paver attitude is the attack angle in relation to the concrete.

SAWING JOINTS: 

SAWING JOINTS

SAWING JOINTS: 

SAWING JOINTS Saw depth Resulting crack

SLIPFORM PAVER: 

SLIPFORM PAVER

CONCRETE PLACEMENT: 

CONCRETE PLACEMENT Very important to prevent segregation of the coarse aggregate during placement.

CONSOLIDATION: 

CONSOLIDATION Consolidation is normally achieved through the use of mechanical vibrators.

SCREED: 

SCREED

BRIDGE DECK: 

BRIDGE DECK

FORM SYSTEMS: 

FORM SYSTEMS

TEMPERATURE: 

TEMPERATURE When the temperature of fresh concrete exceeds 85 or 90°F, the resulting strength and durability of the concrete can be reduced.

TEMPERATURE: 

TEMPERATURE Most specifications require that concrete be placed at a temperature of less than 90°F. In hot weather it may be necessary to cool the ingredients before mixing

CURING: 

CURING Do not forget about the curing requirements.

LABOR: 

LABOR Carpenters Labors Cement masons Ironworkers Teamsters Operating engineers