1. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Unit 40 Concrete and Masonry

2. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Introduction Most buildings have concrete and masonry components in their construction Masonry: anything constructed of brick, stone, tile, or concrete units set or held in place with portland cement Concrete: mixture of stone aggregates, sand, portland cement, and water

3. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Masonry Has been used for thousands of years Basic materials used come from the earth Similar to the advantages of concrete Durability, moisture-resistance, and hardness of the masonry units determine the characteristics of the structure

4. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Concrete Characteristics –fireproof –insect and rodent proof –decay resistant –highly storm resistant –wear resistant –waterproof –strong –attractive –easy to make on the job –locally available –low in costs –sanitary –easily broken up when needed

5. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Concrete (continued) Strength and durability depend on –strength of stone particles –proportion of stone particles by size –type of portland cement –type(s) of aggregates added –purity of water –uniformity of the mixture –procedures used in finishing, placing, and curing

6. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Mixing Concrete Cement paste: made by mixing portland cement and clean water in precise proportions All sand has water attached to its particles, so an allowance must be made when making the mixture A more durable concrete contains less water

7. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Mixing Concrete (continued) Rule of thumb: Concrete will be about two thirds the combined volume of the cement and aggregate used in the mix The correct mixture –Assures that each particle of sand and gravel is covered with cement paste –Each particle is bound to others when the cement paste dries and hardens

8. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Workable Mix The consistency of the wet concrete after the various ingredients have been mixed together Characteristics –aggregates are clean –portland cement and water are mixed into a paste –no dry powder evident –every particle is covered with cement paste –aggregates distributed evenly throughout mix –not too much water –no lumps –uniform color and consistency –can be mixed, moved, and placed with a shovel or spade

9. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Forms Form: a metal or wooden structure that confines the concrete to the desired shape until it hardens When constructing forms –Use soft, clean, straight lumber –Sharpen stakes evenly –Place stakes 30 inches apart for 4-inch-thick concrete –Use a transit or level to adjust the height of the forms –Drive nails into stakes, but not through –Stakes should not stick up above top of forms –Construct inside surfaces of forms to the desired shape of the finished concrete –Brush used motor oil on wood surfaces that will be touched by concrete

10. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Joints Needed when slabs of concrete are poured larger than 10' by 10' Construction joint: place where one pouring of concrete stops and another starts Control joint: a planned break that permits concrete to expand and contract without cracking

11. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Reinforcing Concrete Reinforced concrete: concrete strengthened by steel reinforcing rods or wire mesh Any slab that will carry vehicles must be reinforced Reinforcing rods are made of steel with a rough surface and are classified according to diameter Can be wired together to make longer units Be sure reinforcing bars are free of oil, dirt, rust, etc.

12. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Pouring Best to move concrete downhill with a chute Best to move concrete across level surfaces with a wheelbarrow Before pouring, wet stone base with water to prevent loss of water from mixture Be sure all materials are on hand before mixing Hardens about 15 minutes after mixing

13. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Finishing After spreading, must screed, float, and finish Be sure to perform all procedures before the concrete begins to set After setting starts - Create a broom finish to improve traction - Wash away paste for a rough finish - Trowel to create a smooth finish

14. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Curing Curing: the proper drying of concrete Protect from air, heat, and freezing temperatures for several days Cover with plastic or canvas to prevent evaporation Keep forms up for up to a week until curing is complete

15. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Masonry Masonry units: blocks made from concrete, cinders, or other aggregates Held together with mortar Laying block: process of mixing mortar, applying it to block, and placing the block to create walls

16. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Types of Blocks Standard blocks are 15⅝'' long and 7⅝'' high Available in 4-, 6-, 8-,10-, and 12-inch widths Wider at top than bottom Hollow core block: block with two or three separate cores Stretcher block: block with ears used in straight wall sections Sash block: grooves to receive windows Jamb block: grooves to receive doors

17. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Estimating Block When estimating the number of blocks needed, multiply the length of the wall in feet by 3/4 to get the course Multiply height of wall by 3/2 to get number of courses needed Then multiply number of blocks per course by the number of courses needed to get the total number of blocks needed for the wall Be sure that the dimensions utilize full- or half- length blocks

18. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Footers Continuous slabs of concrete that provide a solid, level foundation for block and brick walls Should be at least as deep as the wall is wide Always placed below the frost line

19. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Mixing Mortar Combination of portland cement, finishing lime, sand, and water Different combinations produce different characteristics Small batches can be mixed in a pan or wheelbarrow with a hoe Large batches should be mixed with a motor-driven mixer

20. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Laying Block When laying block, be sure that blocks are straight and plumb with a corner pole or a level Corner pole: a straight piece of wood or metal held plumb by diagonal supports Brace walls higher than 8 feet on both sides at 8- to 10-foot intervals Protect from freezing until cured

21. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Important Terms Portland cement: dry powder made by burning limestone and clay Sand: small particles of stone Finishing lime: powder made by grinding and treating limestone Fine aggregate: small particles Coarse aggregate: large particles (gravel) Silt: intermediate-sized soil particles Clay: smallest group of soil particles Washed sand: sand flushed with water to remove clay or silt

22. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Important Terms (continued) Ratio: proportion of cement to aggregate Mix: ratio as represented by a three-digit number Footer: concrete base that provides a solid, level foundation for brick, stone, or block walls Moisture/vapor barrier: prevents moisture from passing through Insulation: retards heat movement Air-entrained concrete: ready-mixed concrete with tiny air bubbles trapped throughout mixture

23. Copyright © 2010 Delmar, Cengage Learning. ALL RIGHTS RESERVED. Important Terms (continued) Screeding: striking off excess concrete to create a smooth, level surface Bull float: tool used to smooth concrete Broom finish: rough surface created by pulling a broom across concrete Mortar bed: layer of mortar Cores: hollow spaces in blocks Ears: slight extensions on ends of block Course: row of masonry units Frost line: maximum depth that the soil freezes