concrete

Question 1

who was the first to create concrete

Answer 1

romans

Question 2

who rediscovered the cement we know today and when and where?

Answer 2

Joseph Aspidin, 1824

-Isle of Portland, England –> “Portland Cement”

Question 3

what are 3 main ingredients to concrete and % used

Answer 3

1. water 15-20%
2. aggregates 60-75%
3. cement 10-15%
4. entrained air 5-8%

Question 4

what does water have to be in order to be used to make concrete?

Answer 4

potable

Question 5

what does aggregates have to be in order to be used to make concrete?

Answer 5

1. clean

2. inert

Question 6

3 ingredients in cement

Answer 6

1. lime
2. silica
3. alumina

Question 7

what are minor components added to cement

Answer 7

1. flyash

2. blast furnace slag

Question 8

what is fly ash a biproduct of and what are its benefits

Answer 8

• residue from coal burning plants

- makes stronger, more durable, easier to work with

Question 9

where does blast furnace slag come from and what are its benefits

Answer 9

• iron ore

- lowers heat of hydration, increase workability

Question 10

how is cement bound together?

Answer 10

ingredients mixed, ground and super heated to point where bound together –> Clinker
-pulverized to create cement powder

Question 11

what is heat of hydration

Answer 11

resulting heat generated by chemical reaction between cement and water

Question 12

what are 2 factors most likely to cause excessive ‘Heat of Hydration’

Answer 12

1. large pours of concrete

2. concrete with high cement content

Question 13

what is the most common type of cement

Answer 13

Portland

Question 14

what is another type of white cement

Answer 14

Medusa

Question 15

why add entrained air to concrete?

Answer 15

1. increased durability

2. increased workability

Question 16

what is the slump test

Answer 16

• create a frame and pour concrete in
• remove frame, measure how far concrete drops
• high slump= wet concrete
• low slump= dry concrete

Question 17

what are the 4 steps to lay concrete

Answer 17

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
4. curing

Question 18

name 5 types of ways to finish concrete

Answer 18

1. bull floating
2. broom
3. rake
4. darby
5. spin float

Question 19

name 4 ways to aid in curing concrete

Answer 19

1. wet burlap
2. liquid membrane
3. polyethelyne sheets
4. straw/ hay (in xtreme cold)

Question 20

name 2 ways to reinforce concrete

Answer 20

1. rebar

2. steeplates

Question 21

name 3 joints in concrete

Answer 21

1. control joints
2. isolation/ expansion joints
3. construction joints

Question 22

name 2 ex of isolation joints

Answer 22

bitumous fibre

‘Flexcell Foam