Building Materials Chapter 1

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Questions and Answers

What are the two main factors that determine the properties of materials?

Chemical composition and mineral composition

What happens to the strength, hardness, and toughness of carbon steel as the carbon content increases?

They change

Why is stainless steel resistant to rust?

Because of the addition of chromium, nickel, and other chemical components

What are minerals in the context of materials composition?

Monomers and compounds with a certain chemical composition and structure Signup and view all the answers

Why do different clinkers in cement result in different characteristics?

Because of their different mineral compositions Signup and view all the answers

What is the macro-structure of materials?

The thick structure above millimeter that can be identified with magnifying glass or naked eyes Signup and view all the answers

What are the three levels of material structure?

Macro-structure, meso-structure, and micro-structure Signup and view all the answers

What determines the properties of natural stone and inorganic gel?

Their mineral compositions Signup and view all the answers

What is the significance of material structure in determining properties?

It is a key factor Signup and view all the answers

What is the relationship between the composition and structure of materials?

They are key factors for the properties of materials Signup and view all the answers

What are the building blocks of elements?

Atoms Signup and view all the answers

What is the net charge of the nucleus?

Positive Signup and view all the answers

What is the type of bond that involves the transfer of an electron?

Ionic bond Signup and view all the answers

What is the most common bond in organic molecules?

Covalent bond Signup and view all the answers

What is the bonding force of a covalent bond?

Strong Signup and view all the answers

What is the simplest model of metallic bonding?

The 'sea of electrons' model Signup and view all the answers

What is a characteristic of metal materials?

Good thermal and electrical conductivity Signup and view all the answers

What is the tendency of atoms in bonding?

To complete or fill their outermost electron orbits Signup and view all the answers

What is a limitation of the ionic bond?

It can only occur between atoms of different elements Signup and view all the answers

What is the result of electrostatic attraction between the nucleus and electrons?

Electrons are held in position Signup and view all the answers

What is considered at the engineering level of material structure?

Total material, considered continuous and homogeneous, with average properties throughout the whole volume Signup and view all the answers

What is the minimum volume of the material that represents the entire material system?

Representative cell Signup and view all the answers

What is the shape of the representative cell if the material is isotropic?

Cube Signup and view all the answers

What is the level of structure that can be observed by an optical microscope?

Meso-structure or sub-microstructure Signup and view all the answers

What is mainly studied in the meso-structure of a material?

Size, shape and interface of grains and particles, and size, shape and distribution of pores and micro-cracks Signup and view all the answers

What is the size range of particles in a material at the meso-structure level?

From 5 × 10-6 m to 0.225 m Signup and view all the answers

What is the level of structure that can be studied by electron microscopy, X-ray diffractometer, and other means?

Microstructure Signup and view all the answers

What is anisotropic material?

Material with properties that can only be described with reference to orientation Signup and view all the answers

What is the shape of the representative cell if the material is anisotropic?

Parallelepiped Signup and view all the answers

What is the main difference between the meso-structure and microstructure levels of a material?

Size, with meso-structure being a step up in size from the molecular level Signup and view all the answers

Study Notes

Materials Composition and Structure

Materials composition includes chemical composition and mineral composition, which are key factors for the properties of materials.
Chemical composition refers to the chemical constituents, and varying chemical compositions result in different properties.
For example, increasing carbon content in carbon steel changes its strength, hardness, and toughness, making it prone to rust, which can be addressed by adding chromium, nickel, and other chemical components to create stainless steel.

Mineral Composition

Many inorganic materials consist of various mineral compositions, which are key factors for the properties of some building materials (e.g., natural stone, inorganic gel, and other materials).
Cement exhibits different characteristics due to different clinkers.

Structure of Materials

The structures of materials can be divided into macro-structure, meso-structure, and micro-structure, which are key factors related to the properties of materials.

Macro-structure

Macro-structure refers to the thick structure above millimeter that can be identified with a magnifying glass or naked eyes.
At the engineering level, the total material is considered, and it is normally taken as continuous and homogeneous, with average properties assumed throughout the whole volume of the material body.
The minimum scale that must be considered is governed by the size of the representative cell, which varies from 10^(-3) m for metals to 0.1 m for concrete and 1 m for masonry.

Meso-structure

Meso-structure refers to the micro-level structure that can be observed by optical microscope.
It includes the size, shape, and interface of grains and particles, and the size, shape, and distribution of pores and micro-cracks.
The material is considered as a composite of different phases, which interact to realize the behavior of the total material.

Microstructure

Microstructure refers to the atomic and molecular structures of materials that can be studied by electron microscopy, X-ray diffractometer, and other means.
Atoms consist of a nucleus surrounded by a cloud of orbiting electrons, and the nucleus consists of positively charged protons and neutral neutrons.

Bonding of Atoms

Atoms tend to arrange themselves in the most stable patterns possible, which means they have a tendency to complete or fill their outermost electron orbits.
Ionic bonding involves a transfer of an electron, resulting in high strength, hardness, and melting point, but also volatility and medium density.
Covalent bonding involves the sharing of electrons between two atoms, resulting in strong bonding force, high strength, hardness, melting point, and density.
Metallic bonding involves sharing electrons, resulting in volatile strength and hardness, high density, and good thermal and electrical conductivity.

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Description

This quiz covers the first chapter of building materials course, Civil Engineering Department, University of Halabja.