1. More about concrete Ag III and IV

2. Today’s objectives Define properties of hardened concrete Discuss selection of materials for quality concrete

3. So, about those cards from yesterday… Grab a notes sheet that is coming around. One at a time, share your definition.

4. More than you wanted to know about Portland cement It’s the active ingredient in concrete. Created by an English mason who named it because of the resemblance to stone found in quarries in Portland, England. First produced in U.S. in 1872 in Pennsylvania

5. What exactly is it? Raw materials making up Portland cement include: Limestone Oyster shells Clay Shale Gypsum And many more!

6. It’s a powder… Regardless of composition, the size of particles is very important. Affects how it reacts with water If the powder absorbs water, quality goes to the crapper. Must be kept dry Closed storage best, up off of the ground

7. High Quality H20 http://www.metacafe.com/watch/yt- Um0tEvQ5gVM/the_greatest_moment_of _waterboy/ http://www.metacafe.com/watch/yt- Um0tEvQ5gVM/the_greatest_moment_of _waterboy/

8. If you wouldn’t drink, don’t use it. Only about half of mixing water hydrates cement; other half increases durability. Too much of a good thing can be a bad thing. Questionable water quality can affect quality of concrete Can also affect setting time and strength

9. Don’t get aggravated about the aggregates. Aggregates are 60-80% of total volume 3 main functions in concrete: Cheap filler Resists action of applied loads, abrasion, percolation of moisture, and action of weather Reduces volume changes from hardening process

10. What type of aggregate should you pick? Hard Sound Durable Clean Free from silt and organic matter

11. Fine and coarse Fine- smaller than 1/4 in in size (sand) Coarse- greater than 1/4 in size Gravel, crushed rock, other similar material Large aggregates are stronger and cheaper

12. Let’s think about it. On half of a sheet of paper (1 per 2 people), compare the benefits of using a fine aggregate or a coarse aggregate.

13. Today’s objectives Define properties of hardened concrete Discuss selection of materials for quality concrete