Homework 4
Due: April 12th, 2022 by 11:59:59 PM on Canvas
Please refer to the syllabus for information on formatting your homework
(Reminder, formatting is worth 25% of your homework grade)
Question 1.
Discuss the primary goal in steel production. Describe metallic bonds, why they result in
wellordered crystals, why metallic bonds can be conductive, and three different types of
defects that can occur in crystal structures.
The basic purpose of steel manufacturing is to manufacture it with high resistance and strength under a
variety of situations. Steel is one of the most adaptable materials, capable of being welded and molded
in a variety of inventive ways.Metallic bonds are the forces that keep and stick the atoms bonded
together in any metallic material, and these substances are made up of packed atoms in shells, with
valence electrons that constantly move to overlap with neighboring atoms. They do produce a
wellordered crystal because they always contain valence electrons that are shared with neighboring
atoms, resulting in a large net of atoms that leads to a well-ordered crystal.In terms of conductivity,
atoms with metallic bonds have conductivity because the energy is always delivered via the flow of
electrons around the metal.There are three types of flaws that can occur: point surrenders, line
imperfections, and surface deformities.
CE 360: Sustainable Civil Engineering Materials
Spring 2022 – Prof. Korayem
Student Name:Marco Habib
Question 2.
Using the following phase diagram to answer this question:
a. At what temperature will 30% (by weight) combination of aluminum and lithium be in
a fully liquid phase?
About 660 degrees Celsius
b. What range of lithium weight percent will result in the Al 2Li3 phase at 200 C
b) 21% to 29%
Question 3.
Describe the pros and cons of using epoxy coated rebar.
The term "epoxy coat" refers to a coating that is applied to a surface in order to protect it against
oxidation, also known as "oxygen and chlorides." It essentially aids in the prevention of rusting. Pros: It
prevents corrosion and extends the life of substances, resulting in efficiency and cost savings. Cons: It
has a weak adhesion to concrete and must be handled and coated with caution. Furthermore, any flaw
in the coating will result in corrosion.
CE 360: Sustainable Civil Engineering Materials
Spring 2022 – Prof. Korayem
Student Name:Marco Habib
Question 4.
Discuss corrosion in concrete including its causes and different ways to delay it.
Corrosion in concrete is defined as any rust that happens in its steel rebars and may be characterized as
any deterioration in steel rebars caused by electrochemical processes.Corrosion in concrete can occur
for a variety of causes. It occurs inside the concrete environment over time, and the water absorbed by
the concrete breaks through the passive layer, causing corrosion of the steel rebars. Another reason for
corrosion is the neutralization of concrete PH by air carbonation, which also destroys the passive
layer.However, concrete is being considered as a protection for steel rebars as well, since it prefers to
form a passive layer on top of the steel due to its high alkalinity, although with time and environmental
circumstances, it occasionally fails.Companies should use suitable coatings such as epoxy to produce a
protective layer to postpone corrosion. Another option is to limit the amount of moisture in the
surrounding environment or to create a more porous concrete to prevent moisture content.
Question 5.
Explain what makes steel a good candidate for use in concrete reinforcement.
Concrete and steel have a very strong relationship. Furthermore, they expand at the same pace,
resulting in a perfect fit in terms of tension and compression, as well as their ability to carry the imposed
weights.Steel is very simple to form. As a result, it may be formed to strengthen the needed concrete
portion. It is also reasonably priced and widely accessible. Because concrete has a high alkalinity level, it
forms a passive coating around the steel rebars to protect them from the atmospheric and moisture
conditions.
Question 6
Explain why concrete cracks when steel reinforcement corrodes. Why does carbonation of the
concrete cause steel reinforcement to corrode?
The most widely recognized reason for substantial corruption is consumption of building up steel and
other installed metals. Whenever steel consumes, the resultant rust occupies more room than the
prepare itself. Pliable burdens are made in the substantial because of this extension, which can
ultimately prompt breaking, delamination, and spalling.
Carbonation brings down the pH of the substantial, bringing about the deficiency of the defensive layer
on the steel. At the point when the steel is depassivated and the substantial has a low pH level,
consumption starts when dampness enters the substantial.