2. Concrete 6831.18

3. Concrete Cement Sand Gravel Water

4. Portland Cement A dry powder made from limestone and is usually packaged in bags containing 1 cubic foot and weighs 94 pounds

8. Portland Cement When mixed with water, it forms the “glue” to hold the aggregate together

10. Fine Aggregate Sand It should be clean of clay, silt, and organic matter

11. Course Aggregate Gravel and rocks over ¼” in diameter

13. Water Should be clean

14. Concrete Trucks Most concrete is delivered by trucks to the construction site as ready-mixed concrete

16. Mortar Does not contain coarse aggregates and is used to join bricks or blocks

17. Cement Although many people call concrete “cement”, cement is the powdered material and concrete is the mixture of ingredients

18. Weight 150 -160 lbs. per cubic foot

19. Slump Stronger concrete requires less slump The consistency or wetness of the mixture

20. Slump If concrete has too much slump (is too wet), adding aggregate such as sand and gravel will correct the problem

21. Uniformity Is thoroughly mixing all ingredients so that the “glue” which is wet cement will be around all sand and gravel particles (aggregates)

22. Workability Refers to the ease with which concrete can be placed and shaped

23. Ratio Expressed as a three digit number Example: 1,2,3

24. Ratio The first number is parts of cement Second number is parts of fine aggregate (sand)

25. Ratio The third number is parts of large aggregate (gravel) Parts may be shovels full, pounds, cubic feet, etc.

26. Ratio Less sand, gravel, and water are used for the same amount of water to make concrete stronger

27. Fuller’s Rule The mixing of a total of 42 volumes of cement, sand, and gravel will produce 27 volumes of concrete

28. 1 2 1/4 3 27 Volumes Concrete =+ + cement sand gravel = 42 volumes

29. Hand Mixing May be done in a wheelbarrow or mixing box (mortar box) by using a shovel or hoe

31. Hand Mixing Add sand and then cement and mix thoroughly Then add and mix gravel

32. Hand Mixing Last thing to add is water and mix well

33. Machine Mixing Uses a concrete or mortar mixer

35. Machine Mixing First, add about 10% of water needed so that ingredients will not stick to mixer

36. Concrete 6831.18