Concrete 6831 18 Concrete Cement Sand Gravel Water

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Concrete 6831. 18

Concrete 6831. 18

Concrete • Cement • Sand • Gravel • Water

Concrete • Cement • Sand • Gravel • Water

Portland Cement • A dry powder made from limestone and is usually packaged in

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

Portland Cement • When mixed with water, it forms the “glue” to hold the

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

Fine Aggregate • Sand • It should be clean of clay, silt, and organic

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

Course Aggregate • Gravel and rocks over ¼” in diameter

Course Aggregate • Gravel and rocks over ¼” in diameter

Water • Should be clean

Water • Should be clean

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

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

Mortar • Does not contain coarse aggregates and is used to join bricks or

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

Cement • Although many people call concrete “cement”, cement is the powdered material and

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

Weight • 150 -160 lbs. per cubic foot

Weight • 150 -160 lbs. per cubic foot

Slump • Stronger concrete requires less slump • The consistency or wetness of the

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

Slump • If concrete has too much slump (is too wet), adding aggregate such

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

Uniformity • Is thoroughly mixing all ingredients so that the “glue” which is wet

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

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

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

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

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

Ratio • The first number is parts of cement • Second number is parts

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

Ratio • The third number is parts of large aggregate (gravel) • Parts may

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

Ratio • Less sand, gravel, and water are used for the same amount of

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

Fuller’s Rule • The mixing of a total of 42 volumes of cement, sand,

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

+ 1 cement 2 1/4 sand + 3 = gravel 42 = volumes 27

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

Hand Mixing • May be done in a wheelbarrow or mixing box (mortar box)

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

Hand Mixing • Add sand then cement and mix thoroughly • Then add and

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

Hand Mixing • Last thing to add is water and mix well

Hand Mixing • Last thing to add is water and mix well

Machine Mixing Uses a concrete or mortar mixer

Machine Mixing Uses a concrete or mortar mixer

Machine Mixing First, add about 10% of water needed so that ingredients will not

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

Concrete 6831. 18

Concrete 6831. 18