Building Materials: Properties and Classification

Posted on Dec 13, 2024 in Geology

Item 34: Introduction to Building Materials

1. Introduction

Building materials, understood as such since primitive architectural constructions appeared, are still true architectures with which humans tried to solve a fundamental building problem: to cover and close a space protected from nature. The Industrial Revolution entailed, among other things, the provision of large quantities of building materials, and even new building materials at low prices, with more uniform quality and even higher than those offered to the ancient crafts, using architects and engineers. This meant some major changes within the building and construction industries.

2. Constitution of Matter

Matter is the name known to all that occupies space and has mass. The material consists of molecules, which in turn are made of atoms. The molecule is the smallest part of matter that can be obtained without the disappearance of the characteristic properties of such matter. The atom is the smallest fraction of a molecule.

2.1. States of Matter

Material contains a certain amount of energy associated with atoms or molecules that comprise it. Most of this energy consists of two summands:

  • Kinetic energy: Due to the motion of particles and depends mainly on temperature.
  • Potential energy: Due to the attractive forces between atoms or molecules and that depends critically on the distance between atoms or molecules.

The differences between the three states of matter (gas, liquid, and solid) are due to differences between the amounts of kinetic energy and potential of atoms and/or molecules. The vast majority of construction materials are solids. The solid state is characterized by the ions, atoms, or molecules not being able to move. Kinetic energy is gone; their only movement is the vibration around a fixed position. Instead, the forces between different particles have become very large, and this is what prevents any movement. Solids are submitted in two fundamentally different states:

  • Crystalline state: Ions, atoms, or molecules are grouped neatly in the space, forming a three-dimensional network.
  • Amorphous state: The atoms or molecules are grouped at random without the position of some of them having any relation to the positions of others (bituminous materials, some plastics, glass, etc.).

2.2. Changes in State

State changes occur when you vary the amounts of energy, i.e., when you heat or cool a body.

3. Classification of Construction Materials

3.1. Natural

3.1.1. Stone Materials

Being a natural material, stone does not need to use more than the extraction and processing elements so adequate. Stone materials can be classified according to their origin, which may be:

  • Igneous rocks: Igneous rocks derived from molten masses at high temperatures inside the earth and have gone abroad, but quickly dropped like stones from volcanoes, or slowly moving earth.
  • Plutonic or intrusive rocks: Formed within the earth’s crust, they have a granular structure without a specific direction. The most important are:
    • Granite: A mixture of quartz, feldspar, and mica. It is a building material able to withstand heavy loads, but not great styling. A drawback is cracking with fire; it is damaged by increasing its volume with water or absorbed by the decomposition of feldspar.
    • Syenite: Composed of feldspar and mica. Softer than granite, by contrast, it is more tenacious and uniform.
  • Effusive volcanic rocks: Flowed to the surface during the upheavals of the crust or after them, scattering in the form of lava.
    • A) Porphyry: It’s a very hard rock, consisting of phenocrysts.
    • B) Basalt: It is a very hard rock but fragile and very little fire-resistant and weatherproof.
    • C) Trachyte: Presents the composition of the syenite. It adheres well to the mortars, but they are very resilient.
  • Sedimentary rocks: They are rocks that come from the destruction of the eruption by the action of the rains, frost, winds, etc. Dispersed, they were deposited in their own bed or further afield, leading to other kinds of rocks, of a different nature.
    • A) Coarse aggregate or gravel: Rock fragments with a diameter less than 15 cm.
    • B) Fine aggregate or sand: Grains smaller than 5 mm.
    • C) Clays: Finest particles, less than 0.06 mm in diameter. It is characterized by its plasticity in contact with water and being refractory, i.e., it resists high temperatures.
    • Limestones.
    • Dolomite: Very resistant to fire.
  • Metamorphic rocks: This kind of rock is formed by the transformation of igneous and sedimentary rocks. This transformation occurs as a result of high temperatures and high pressures that occur within the soil.
    • A) Gneiss: Fissile structure.
    • B) Slate: Low hardness and can be easily separated into layers.
    • C) Marble.

DRESSING STONES: Once we have extracted the stone blocks, we proceed to give them the way they have to be placed in the work. This work is called till.

3.1.2. Wood

Wood is the solid part of the trunks of trees that lies beneath the crust. If we make a cross-section to the trunk of a tree, we find the following parts:

  • The marrow, located in the center of the trunk, with a roughly cylindrical shape, is usually softer than the rest of the wood surrounding it.
  • The heartwood, composed mainly of woody tissue, which is itself part of the tree as wood used in construction.
  • The sapwood, a light-colored layer, which is the living part of the tree where the sap flows gross. Over time it becomes heartwood.
  • The bark is the outer layer responsible for protecting the tissues of the tree from atmospheric agents.

The moisture content of wood is one of the main factors taken into account when using it. The fundamental characteristic of wood is its hardness. Hardness is understood by the resistance of being scratched or penetrated. The hardness of the wood depends, among other things, on its density, age, structure, and meaning of the court. Usually, when a wood is older, the greater its hardness; the wood from a slow-growing tree is harder than the fast-growing trees, and hardness also lessens the unranked moisture.

We can classify timber according to its origin:

  • Softwood or softwood: Pine, fir, cypress, cedar, etc.
  • Timber hardwoods: Oak, oak, beech, chestnut, poplar, eucalyptus, etc.
  • African-tropical timbers: Mahogany, Walnut, Okoume, limbo, ukola, etc.
  • Exotic woods: Ebony (black), palo santo (green), sandalwood (red), and so on.
  • Other materials-wood:
  • Woods improved: Wood that has been subjected to special treatment can make them tougher, more resistant to chemicals, etc. (Plywood, laminated wood, compressed wood, fiber boards, particle boards, laminated plastic coating boards)
3.1.3. Cork

Cork is the bark of the cork. This material is rot-proof and elastic, with slow combustion. It is a very good insulator.

3.1.4. Bitumen

Bitumen is a natural substance obtained by the application of heat in limestone or sandstone, which are impregnated with that substance. It is used in paving and techniques to prevent the entry of water and other liquids. We find:

  • Bitumen: It gets oil in commercial quantities.
  • Asphalt.
  • Tar.
  • Creosote.
  • Products made with bitumen: (Bituminous emulsion, coatings waterproofing, Mastic asphalt to fill joints and surface preparation, paints)

3.2. Artificial

3.2.1. Ceramics

The ceramic materials used in construction are more bricks, tiles, flooring blocks, and tiles.

  • Fired clay bricks: It defines the whole piece obtained by molding, drying, and baking at a high temperature, a clay paste for the construction of walls or paramentos. Three known types of brick in construction are solid, perforated, and hollow.
  • Tiles: It is a material force of fired clay, which is obtained by molding, drying, and firing of a clay paste. Its purpose is to cover the building. Depending on the geometry that occurs, they may be curved, flat, or mixed.
  • Cove: It is a clay material obtained by molding, drying, and firing of a clay paste, used for one-way slab construction. According to their function, they are distinguished as lightening cove, durable, and resistant to compression layer incorporated.
  • Tiles: They are thin plates made of clay, silica, fluxes, colorants, and other materials commonly used as floor coverings, walls, and facades.
3.2.2. Binders

Binders are defined as those materials capable of joining others and giving cohesion to the whole, through chemical processes that occur in their body mass and giving rise to a new set. They are classified into two groups:

  • Air binders: They are the ones after mixing with water only setting and hardening in the air, and are not water-resistant. Gypsum and lime.
  • Hydraulic binders: They are those who, after being kneaded with water, set and harden both in contact with air and submerged in water. Cement.

If we analyze these materials:

  • Gypsum: It is obtained from gypsum, plaster, or natural stone, consisting of dehydrated calcium sulfate. It resists the evil action of atmospheric agents, as is typically used in interior construction. It adheres to the stones and some wood, oxidized iron, but is a good acoustic and thermal protector.
  • Plaster: This is the best quality gypsum. It is used in interior decoration and finish, very fine plaster and stucco, and other special purposes.
  • Lime: By calcination or decomposition of the limestone, heating them to temperatures above 900ºC, we obtain quicklime (calcium oxide). If we add water, we will have calcium hydroxide, which is lime ready for use on site, slaked lime.
  • Cement: Often used mixed with water and forming a paste. Its most common use is in combination with other materials in the formation of clusters (mortars and concretes). It is a material that comes from Clinker (resulting from the calcination of a mixture of limestone and clay) combined with a bit of gypsum. It is commonly known as Portland cement.
  • Mortars: It is a combination of one or more clusters and aggregates, kneaded with water, resulting in a smooth plastic paste which sets and hardens after a result of the chemical processes that occur therein. They are used to join elements of the works concerning coating. Mortars are named for the binder used. Those that involve more of a mortar binder are called bastards.
3.2.3. Aggregates

Concrete is a material that comes from mixing cement, water, sand, and gravel to settle, and when hardened, it acquires a consistency similar to the best natural stone; the binder can be considered as natural stone which is to add gravel to a mortar. According to its composition and its applications, concrete receives different headings: mass concrete, cyclopean, armed, light, pre-stressed, tamping, vibrating, spinning, etc.

3.2.4. Metals

Iron is needed to transform it into products suitable for direct use, such as armor for steel. The armor for steel and concrete shall comprise deformed bars, welded mesh, and welded armor boom.

3.2.5. Paints

These are products for coating surfaces to protect them from external agents and simultaneously give a specific color for aesthetic or purely decorative purposes. The paintings include lime paints, tempera, oil, enamel, plastic, and special.

3.2.6. Glass

It is a hard substance, whether regular, brittle, and constructed by fusing a mixture of one or more oxides of silicon, boron, or phosphorus with other basic oxides undergoing fusion. The most common glass used in construction are common glass, paper, concrete, molding, and special.

3.2.7. Prefabricated
  • Terrazzo tile: Precast concrete, properly compacted, of uniform shape and thickness. The tile can be monolayer (consisting only of a layer of trace) or bilayer (composed of a layer of track and a base layer or support). The materials used for the manufacture of tiles are cement, aggregates, water, and additives.
  • Concrete blocks: The first blocks were solid, but as they were too heavy and expensive, they were lightened, making holes in the sense of its height. They are compressed using hydraulic presses and unmold immediately, leaving twenty-four hours on the plate that forms the bottom of the mold, placing them in a moist chamber, watered twice daily during the first week; they could be used in work a month.
  • Artificial stone cement: It is made with mortar light gray or white Portland, sand, crushed limestone, and marble; it can, before you have completed the tightening plowing, chopping, grinding, etc. Steps, sinks, ornaments, etc.
  • Cement pipes: For both drinking water and waste.
  • Slate: It is a material composed of cement mortar which is arid asbestos or other mineral or vegetable fibers. Corrugated sheets, tiles, gutters, skylights, chimneys, etc.

4. Properties

We can define the material properties and the characteristics of the material response to external actions which seek to modify its equilibrium. All materials possess all the properties; however, we say that a material has a certain property when the quality of this is in it than an arbitrary limit and variable, depending on the operation you want to do on that property.

4.1. Physical Properties

4.1.1. Cohesion

It is the force that holds together the different particles of a material, and by reason of which is resistant to breakage. In general, we can say that cohesion is high in solids, liquids, and small zero in gases.

4.1.2. Density

Density is called the mass per unit volume that a body has. This is related to the distance between atoms in the body.

  • Density: Is the mass of the sample divided by the actual volume of material, excluding this all holes.
  • Density or real: Is the relationship between the mass of a sample and the net volume of the same.
  • Bulk density or elemental: Is the relationship between the mass of a sample and the total volume of the sample.
4.1.3. Porosity

The materials may contain holes in it, in greater or lesser amounts. The importance of this property is on the influence of this in the amount of water that can absorb and retain the material.

4.1.4. Compactness

It is the ownership of the bodies of some porous texture and tight.

4.1.5. Absorption

It is the amount of water absorbed with respect to the mass of dry material, expressed in percent.

4.1.6. Permeability

It is the easiness of a material to let through by a fluid when there is a pressure difference between the two sides of that material.

4.1.7. Capillarity

It is the property under which a liquid enters and ascends through the pores of a material due to the action of the surface tension of the liquid.

4.1.8. Helicity

It is said that a material is broken down by frost action.

4.1.9. Solubility

The solubility of a substance into another is defined as the maximum amount of solute that can dissolve in a solvent at a given temperature.

4.1.10. Fineness

It is determined as the surface area per unit mass.

4.1.11. Thermal Properties

Thermal conductivity: The amount of heat that would pass through a wall section and unit thickness in unit time between their faces when there is a temperature difference of 1 degree Celsius is what is known as the coefficient of thermal conductivity. Q = (T1-T2) x (Surface / Thickness) x T. Depending on its thermal conductivity, materials can be classified as good conductors (metals), drivers media (glass, bricks, concrete), and insulation (cork, fiberglass, in general, all porous materials).

Dilation: It is known as dilation to the increased dimensions of a body resulting from the change in their temperature. Within temperature limits at which the expansion coefficient remains constant: Lf = Li (1 + alpha x Increase t).

4.1.12. Electrical

Electrical conductivity is defined as the easiness of a material to electric current passing through it. It is used more often the term electrical resistance, defined by the expression: R = Ro (l / s).

4.1.13. Acoustic Properties

The acoustic properties of a material are defined from the ability of it to prevent the passage of sound. The effectiveness of acoustic insulation is defined by the transmission losses that occur and that express, in decibels, the difference between existing noise levels on both sides of that insulation.

4.2. Mechanical Properties

The mechanical properties of the materials show the same behavior to external mechanical factors acting on them. In the materials used in construction, they are generally more properties that characterize the quality of the material.

4.2.1. Resistance to Two Forces Traction

If two equal but opposite direction forces act on a material, if the forces F increase so as to become superior to the cohesive forces that bind molecules, the piece is broken into two pieces. Metals, in general, are characterized by excellent tensile strength, much larger than stone materials.

4.2.2. Shear

The maximum shear stress a material can withstand without breaking defines its resistance to shear or shear of the material.

4.2.3. Compression Resistance

The compressive strength of a material is defined as the maximum compressive stress may be subjected to this, without causing breakage.

4.2.4. Bending Resistance

A constructive element is subjected to bending when a force or supports a system of transverse forces on its longitudinal axis.

4.2.5. Hardness

Hardness is the property that expresses the ability of a material to resist being deformed at its surface by the physical action of another. It differs from scratch hardness, penetration, elastic, and shear.

4.2.6. Abrasion Resistance

It is the resistance of a material to be worn by friction with another material or by being subjected to repeated impacts from another material.

4.3. Deformability and Related Properties

A material, when subjected to external efforts, is deformed. The deformability is the defining property of a material’s ability to reach deformation without rupture.

4.3.1. Elasticity

Elastic bodies are called who, after performing a system of charges and when they are terminated, they regain their original state, erasing the distortions that have been previously.

4.3.2. Viscosity

If a fluid is subjected to the action of a force, a deformation of the fluid is caused, but this deformation is caused only by a part of the energy that we applied to the fluid; the other portion is used as heat energy, due to internal friction that occurs in the fluid. Viscosity is a property that decreases with increasing temperature since the attraction decreases body molecules.

4.3.3. Plasticity

When we apply stress to a body, two things will happen: the body returns to normal, without a trace of strain to which we have submitted, in which case we say that the body has behaved elastically, or the body maintains a residual deformation, proportional to the effort put in which case we say that the body has behaved plastic. Inside the plastic state may include three properties that are intimately related:

  • Ductility: It is the ability of a material to undergo plastic deformation under high tension.
  • Malleability: It indicates the ability of a material to undergo plastic deformation under high compressive stress.
  • Fragility: Opposite is a property of plasticity. A material is brittle when very little plastic deformation before failure.
4.3.4. Resilience

Tenacity and toughness represent the ability of a material to absorb labor in the form of mechanical energy of deformation, which is communicated to either slowly or abruptly as shock. The rate shock resistance of a material is called resilience; its value indicates the potential energy stored for a ruptured section bar unit.

4.3.5. Fatigue

When a material is subjected to variable and repeated efforts many times, it may burst.

4.4. Chemical Properties

Corrosion means the destruction of a solid material due to a chemical or electrochemical cause, which begins on the surface.