MT_old

Question 1

Soundness def

Which if the three are sound hence frost resistant

Basalt
Sandstone
Limestone

Answer 1

Basalt: sound
High strength
Low porosity

Sandstone: medium sound
Medium pore and
less strength than basalt

Limestone: not sound
A lot of pores
Not relatively high strength
We can crush it if we want to use it in cold

Question 2

Produces less CH from clinker

Answer 2

C3A and C2S

Question 3

What leads to higher heat evolution

Answer 3

C3A

Question 4

What concrete type for low temp?

Answer 4

Type 2 which has less C3S

As concrete cools down, thermal shrinkage air entrainment will reduce pressure

Question 5

What raw materials are used to make Portland cement

Answer 5

FeO3
Al2O3
SiO2
CaCO3

Question 6

E modulus from graph

Answer 6

Do .4 times f’c
Go to value on y axis

E = delta stress /delta strain
Chord method : 50x10^-6 for strain 2 and 0 for stress 2

Your E can be found here.

Question 7

3 precautions to sulfate attack

Answer 7

Type 5 cement should be used
W/c >.45
Fly ash

Question 8

How can you know if the concrete was attacked by sulfate

Answer 8

Concrete will be flaking off

If sulfate attack, we can check porosity, aggregate check etringite formulation

Question 9

Why is there no frost damage with .3 water cement ratio

Answer 9

This is because there is 0 porosity. No free water in the concrete to expand and cause damage

Question 10

Permeability in .4 and .5 water cement ratio? Same? Lower? Higher?

Answer 10

Similar permeability

30% porosity is when permeability changes

Question 11

,5 w/ c or .4 w/c for fire resistance

Answer 11

.5 is better because we have more water in the concrete

Question 12

.5 w/c or .4 w/c more resistance to frost.

Answer 12

.4 will be more resistance to frost because less overall porosity. There will be less capillary pores