Concrete

swimminghersheyUrban and Civil

Nov 25, 2013 (3 years and 6 months ago)

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Concrete

Unit 24

Carpentry and Building Construction

Concrete Ingredients


Cement


Measured by the sack = 94 lbs. = 1 cu. Ft.


Water


Fine Aggregate


Sand or other suitable material up to ¼” Dia.


Coarse Aggregate


Gravel


Crushed Stone


Material larger than ¼” Dia.

Admixtures


Change the characteristics or workability of
concrete


Air
-
entraining admixtures


Retarding admixtures


Accelerating admixtures


Water
-
reducing admixtures


Superplasticizing admixtures

Testing the Mix


Slump Test


Concrete is placed in a conical shape and
measured to see how much it loses its shape

Placing the Concrete


Should be poured continuously when
possible


Keep level


Vibrate or spade the concrete to remove air
bubbles


Protect the concrete from rapid drying


Keep concrete above freezing temperatures
to cure

Reinforcing


Welded
-
wire fabric


Steel bars


Reinforced Concrete has excellent
compression strength

Estimating Concrete


Sold by the cubic yard ( 3’ x 3’ x 3’ )


To calculate, figure the volume needed.


T x W x L


If volume calculated = cubic feet, divide by
27


I.e. 4” x 20’ x 40’ = 267 cubic feet


267/27 = 10 cubic yards