Flashcards in concrete Deck (22):
who was the first to create concrete
who rediscovered the cement we know today and when and where?
Joseph Aspidin, 1824
-Isle of Portland, England --> "Portland Cement"
what are 3 main ingredients to concrete and % used
1. water 15-20%
2. aggregates 60-75%
3. cement 10-15%
4. entrained air 5-8%
what does water have to be in order to be used to make concrete?
what does aggregates have to be in order to be used to make concrete?
3 ingredients in cement
what are minor components added to cement
2. blast furnace slag
what is fly ash a biproduct of and what are its benefits
- residue from coal burning plants
-makes stronger, more durable, easier to work with
where does blast furnace slag come from and what are its benefits
- iron ore
-lowers heat of hydration, increase workability
how is cement bound together?
ingredients mixed, ground and super heated to point where bound together --> Clinker
-pulverized to create cement powder
what is heat of hydration
resulting heat generated by chemical reaction between cement and water
what are 2 factors most likely to cause excessive 'Heat of Hydration'
1. large pours of concrete
2. concrete with high cement content
what is the most common type of cement
what is another type of white cement
why add entrained air to concrete?
1. increased durability
2. increased workability
what is the slump test
-create a frame and pour concrete in
-remove frame, measure how far concrete drops
-high slump= wet concrete
-low slump= dry concrete
what are the 4 steps to lay concrete
1. placing--> do so close to where will be finished
2. Consolidation--> removes pockets of air
3. finishing/ strike off --> removes excess concrete (screed) , levels to top of forms
name 5 types of ways to finish concrete
1. bull floating
5. spin float
name 4 ways to aid in curing concrete
1. wet burlap
2. liquid membrane
3. polyethelyne sheets
4. straw/ hay (in xtreme cold)
name 2 ways to reinforce concrete
name 3 joints in concrete
1. control joints
2. isolation/ expansion joints
3. construction joints