1. Concrete Unit 24 Carpentry and Building Construction

2. 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.

3. Admixtures Change the characteristics or workability of concrete Air-entraining admixtures Retarding admixtures Accelerating admixtures Water-reducing admixtures Superplasticizing admixtures

4. Testing the Mix Slump Test –Concrete is placed in a conical shape and measured to see how much it loses its shape

5. 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

6. Reinforcing Welded-wire fabric Steel bars Reinforced Concrete has excellent compression strength

7. 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