1. Concrete By John Templeton

2. What is concrete used for? SidewalksDrivewaysFoundations

3. Advantages of Using Concrete: Fire Proof Low Maintenance Durable Termite and Rodent PermanentWatertightSanitaryEconomical Storm Resistant

4. Agricultural Uses of Concrete: DrivewaysPorches Walls and Foundations Steps Small Bridges Setting Posts Walks Water Troughs

5. Quality Concrete Hardened Concrete should have the following qualities: –Durability: refers to resistance to chemical actions, freezing, and thawing. –Strength: measured as compressive and tensile. –Water tightness: the ability to prevent water passage through the mass. –Wear resistance: the ability of hardened concrete to resist abrasive action of vehicles, feet, and flowing water.

6. Quality Concrete Fresh concrete should have the following qualities: –Consistency: refers to the “wetness” and “dryness” of the mix. –Uniformity: refers to the thorough mixing of all ingredients –Workability: refers to the ease with which concrete can be placed and shaped.

7. Concrete Ingredients PORTLAND CEMENT –Most cement used today is portland cement. –This is a carefully proportioned and specially –This is a carefully proportioned and specially processed combination of lime, silica, iron oxide, and alumina. –It is usually manufactured from limestone mixed with shale, clay, or marl.

8. Concrete Ingredients PORTLAND CEMENT –Properly proportioned raw materials are pulverized and fed into kilns where they are heated to a temperature of 2,700°F and main tained at that temperature for a specific time. –There are five types of Portland cement covered under “Standard Specifications for Portland –There are five types of Portland cement covered under “Standard Specifications for Portland Cement.”

9. Concrete Ingredients AGGREGATES –The material combined wi th cement and water to make concrete is called aggregate. Aggregate makes up 60 to 80 percent of concrete volume. –It increases the strength of concrete –It increases the strength of concrete reduces the shrinking tendencies of the cement and is used as an economical filler.

10. Concrete Ingredients AGGREGATES –Aggregates are divid ed into fine (usually consisting of sand) and coarse categories. –For most building concrete, the coarse aggregate –For most building concrete, the coarse aggregate consists of gravel consists of gravel or crushed stone up or crushed stone up to 1 1/2 inches in to 1 1/2 inches in size.

11. Concrete Ingredients AGGREGATES (SAND) –Finer aggregates such as sand fill-in between the larger partials (gravel). –They give strength between the larger partials.

12. Mixing Ratio 1 part Cement 2 parts Fine Aggregate 3 Parts Coarse Aggregate

13. Pouring Mixture

14. Preparation Concrete may be mixed –In a wheelbarrow using a shovel or –Shoveled into a small electric or gasoline powered mixer Most people purchase ready-mixed concrete from a local supplier.

15. Digging In many cases the area where concrete is to be poured or placed must be dug out. –Example: Driveways and sidewalks are generally one inch above the ground level when finished. Small areas: A shovel may be used

16. Forms Concrete form: Frame or mold that holds new concrete in shape until it has set or hardened. The forms must be strong and rigid to prevent sagging, bulging, and spreading

17. Reinforcing Bars and Wire If heavy equipment will drive over concrete or freezing and thawing will be a problem, concrete should be reinforced Reinforcing bars: Steel bars with ridges that bond with the concrete –Commonly seen in the construction of highways and bridge decks

18. Moving and Spreading Concrete Common tools used to move and spread material: –Shovels, –Spades, –Rakes, and –Concrete drags

19. Floating Pushing the rocks down and bringing sand- cement paste to the surface and beginning the smoothing process Magnesium or wooden hand float: Used to smooth the area near the edge of the work area ( Picture Courtesy, Interstate Publishers, Inc.)

20. Floating Darby: Two handed float usually 18” long that is also used near the edge Bull float: 36 or 42 inch float with long round handle used to reach areas away from the edge

21. Calculating Material Needed Example: –You are going to pour a concrete slab for a small pump house the slab will need to be: 8’X6’X4” –8 feet wide –6 feet long –4 inches thick How much concrete will be needed?

22. Calculations