1. Concrete Lesson 1: Components of Concrete
Ag Structures
Mr. Dieckhoff

2. What is this…..

3. What Is This…..

4. What is this….

5. What is This…..

6. Did you Get the Right Answers:
Concrete Truck
Concrete Sidewalk
Bag of Cement
Concrete Block
So……what is the difference of cement and concrete?

7. Concrete Components
Portland Cement
Aggregate
Water

8. Component 1: Cement Acts as a bonding agent in concrete
Makes up 7%-14% of concrete
Types:
I – common applications
II – where heat buildup is a concern
III – early strength, when needs strength within 2-3 days
IV – low heat, confined indoor spaces
V – used on alkaline soils

9. Component 2: Aggregate Sand, Crushed Stone, Gravel 60%-70% of concrete
Categories:
Fine: <1/4” – sand
Course: >1/4” – gravel
The larger the aggregate size – the stronger the concrete

10. Component 3: Water pH of 6-8 works best
Increase of water, decreases the cement bonding

11. Water-Cement Rati0 1 gallon of water = 8.33 lbs
1 bag of cement = 94 lbs
PSI = Pounds per square inch
4.5 gal mixture x 8.33 lbs = lbs water / 94 lbs cement = .398 (5700 psi)
5.5 gal mixture x 8.33 lbs = lbs water / 94 lbs cement = .487 (4500 psi)
Too much water = aggregate segregation

12. Mixing Concrete Hydration – chemical reaction between cement and water
Ways:
# bags of cement in cubic yard of concrete
Foundation walls – 5 bags of cement/yard
Floors, Driveways, Sidewalks – 6 bags of cement/yard
Severe Conditions – 7 bags of cement/yard
Show relative amount of each component
1:2:3-6 ratio means – 1 part cement, 2 parts sand, 3 parts gravel, 6 parts water
Gallons of water mixed with each sack
5.0 means 5 gallons of water with each sack

13. Admixtures – substances added to concrete to modify it’s properties

14. Mixing Concrete Lab
In groups of 3, research how much of the following ingredients you want to mix to have the strongest concrete.
Create a form using 2x4 and a sheet of plywood for the bottom. 2 – 2x4 cut 4” long and 2 – 22” long.
Wearing gloves, mix up your concrete mixture in the pan provided.
Place mixture in the form for at least 3 days.
Test your concrete beam using the diagram:
Write up a Lab Report:
What was your mixture (measurements & percentages)
How much weight did your mixture support?
What would you do different if you did this over?
Other than the mixture, what other factors affected the
strength of your concrete.

15. Slump test Determines if the concrete is of the proper consistency
Indicates if more or less water is needed

17. Review Components of Concrete Types of Cement Categories of Aggregate
Water-Cement Ratio
Hydration
Mixing Concrete
Slump Test

18. True / False Quiz (14 Points)
Concrete is comprised of only two primary components, (cement and water), in varying proportions.
The percentages of cement, aggregate, and water used in any concrete mix vary according to the characteristics required for a particular application and concrete material conditions.
Water makes up the largest volume (60% to 75%) of material used in concrete.
The amount of aggregate in the concrete mixture is the primary factor in determining concrete quality and strength.
In order for hydration to occur, the water used for concrete must have a pH of 6 to 8.
During hydration, the water in the concrete mixture evaporates.
Bleedwater is excess water that collects on the surface of concrete as aggregate material sinks in the concrete mixture.