Construction materials. For centuries and centuries man has used materials to build. He learned to work and manage natural stone as a weapon, as a tool and as a raw material for the construction of his first shelters and monuments.
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- 1 Background
- 2 The rocks
- 1 Main uses of stones in construction
- 2 Stonework
- 3 Binders
- 1 Classification
- 2 Plaster
- 3 Cal
- 4 Sand or fine aggregate
- 5 gravels
- 6 Additives
- 7 Steel
- 8 bricks
- 9 Cement
- 1 Types of artificial cements
- 10 Clay
- 11 Basalt
- 12 Adobe
- 13 Tepetate
- 14 Texas
- 1 Flamenco tile
- 2 Flat roof tile
- 3 Arabic tile
- 15 Tiles
- 16 Functions of building materials
- 1 Physical function
- 2 Constructive function
- 3 Economic function
- 4 Plastic function
- 5 Mechanical function
- 17 Source
- 18 Bibliography
Many of these objects and primitive constructions have reached us, thanks to the exceptional conditions of the material with which they were made.
The rocks are found in nature in large formations, shapeless determined and constituting the main component of the solid part of the Earth ‘s crust. Because it constitutes a natural material, the stone does not need to be used more than the extraction and transformation into elements in an appropriate way. However, it is necessary that you meet a series of qualities that guarantee your aptitude for the job to which it is intended. These qualities depend on its structure, density , compactness , porosity , hardness , composition , durability , strength. to the efforts to which it will be subjected, etc.
Main uses of stones in construction
- As a resistant element.
- As a decorative element.
- As raw material for the manufacture of other materials.
Once the stone blocks are extracted from the quarries or rock formations in operation, we proceed to give them the way they are to be placed in the work. This work is given the name of labra. The stone work includes two primary works: roughing and the work itself. The roughing consists in preparing the block in an approximate way in excess of what it will definitely receive.
It is usually done in the quarry itself, leaving all its dimensions a few centimeters larger than those of the element that must be obtained from it. These excesses called quarry growths , are intended to prevent possible damage that may occur in transport and handling and ensure the work of the farm against a possible lack of material. These operations were being done manually using special tools. At present, a variety of machines are used from farms of some importance.
It is possible to define the Conglomerates as the materials capable of adhering to others and giving cohesion to the whole, due to the effects of chemical transformations that occur in their mass and that originate a new set. Among the best known are plaster and lime .
- Aerial binders: are those that mixed with water, not only forge and harden in the air, not being resistant to water .
- Hydraulic binders: these, after being kneaded with water, set and harden both in the air and submerged in water, the resulting products being stable in both media. Setting means the initial work and consistency of a binder; Once set, the material can continue to harden.
This binder is obtained from the natural stone plaster or stone, consisting of dehydrated calcium sulfate. Starting up the quarry of the quarries, it is crushed and subjected to cooking to extract, totally or partially, the water of crystallization that contains a natural state, converting it into calcium sulfate hemihydrate. Finally, the resulting product is ground. It is usually a white, compact, tough and so soft material that is scratched with the nail. Plaster is a material that badly resists the action of atmospheric agents, so it is preferably used in interior works. It adheres little to stones and wood, and oxidizes iron. It is a good sound insulator and protects wood and iron against fire .
Its applications are multiple: In masonry : preparation of simple or composite mortars, construction of walls, partitions and pillars, pavements, arches and vaults, ceilings, etc. In the manufacture of artificial stones and prefabricated: bricks and blocks, tiles, panels for false ceilings dovetailed walls closely panels nest bee , etc. In decoration: coffered ceilings, friezes, soffits, florones, motifs of ornament, etc. Plasters are classified as semi-hydrated and anhydrous, the former being the most used in construction; Black and white plasters belong to this group. While anhydrous belong hydraulic and lighting plasters.
By means of the calcination or decomposition of the limestone rocks by heating them at temperatures above 900 ° C, the so-called quicklime is obtained, mainly composed of calcium oxide . From the point of employment in construction, limes are classified as: Dolomitic or gray lime, grease lime and hydraulic lime.
The sand or fine aggregate
It is the material that results from the natural disintegration of the rocks or is obtained from the crushing of the rocks, and whose size is less than 5mm. For its use the sands are classified by their size. To this end they are passed through sieves that retain the thickest grains and let the finest pass through.
- Fine sand: is that its grains pass through a sieve of meshes of 1mm in diameter and are retained by another 0.25mm.
- Medium sand: it is one whose grains pass through a sieve 2.5mm in diameter and are retained by another 1mm.
- Coarse sand: is that its grains pass through a sieve of 5mm in diameter and are retained by another 2.5mm.
The Arenas coarse grains give generally more resistant mortars thin, while having the drawback of requiring much paste binder to fill their holes and be adherent. On the other hand, the mortar is plastic, which is very porous and not very sticky. Kneading the mortars is done by stirring and stirring the mixture components as many times as necessary to achieve their uniformity.
This operation is called whipping the mixture. Preferably, kneading is done in kneaders or concrete mixers, beating the mixture with a minimum of one minute. Kneading by hand should be done on a waterproof and clean platform, with at least three shakes.
Rock fragments with a diameter of less than 15 cm are considered as gravels. Thick aggregate resulting from natural decay and abrasion of rocks or transformation of a weakly cemented conglomerate. They have application in masonry, construction of reinforced concrete and for paving of railway lines and roads. In addition to the rocks that are already cut in nature, gravels can be obtained from crushed rocks in the quarries.
Like fine sands or aggregates, gravels are small fragments of rocks, but larger. In general, aggregates that are retained in a 5mm diameter mesh screen are considered gravel. They can be the product of the natural disintegration of the rocks or the crushing or crushing of the rocks.
All the conditions we indicated that the sands had to meet for mortars, are applicable to gravels. As for the shape, rolled aggregates are preferred, that is, those from rivers and beaches . Natural aggregates, more or less rounded, give more docile concrete and easier placement than those obtained with crushed stone.
Additives are called a series of products that are added to concrete in order to improve some of its characteristics; Normally some additives are added to the kneading water, but it is very important to control the necessary dosage since otherwise it distorts the desired result; In general, only the use of those additives guaranteed by companies of recognized solvency is recommended; according to current regulations, the use of additives is authorized provided that it is justified, through tests that the substance added in the proportions provided and dissolved in the water produces the desired effect.
Carbon construction steels
In recent years, and with the development of the electro-vacuum technique, semiconductor electronics, atomic energy production and the extensive use of the technique, it has allowed the creation of new types of chemical-thermal treatment of steel based on the alloys thereof and high corrosion resistance, refractory alloys as well as alloys based on aluminum, titanium and other metals have been introduced. In addition, that rare metals and new alloys have been obtained.
Construction steels are those that are used to manufacture machine elements, structures and constructions. The carbon content in these steels commonly does not exceed 0.5-0.6%. They can be carbon and alloy steels.
Construction steel must possess high strength, plasticity and viscosity in combination with excellent engineering properties.
This steel must be made easily by pressure (rolling, forging, stamping, etc.) and by cutting, have good weldability and calcination capacity and low tendency to deformation and crack formation during tempering.
The different types of steel are grouped into:
- Carbon steels: more than 90% of all steels are carbon steels. These steels contain various amounts of carbon and less than 1.65% manganese, 0.60% silicon and 0.60% copper. Products made of carbon steels include machines, car bodies, most of the steel construction structures , ship hulls, bed bases and hairpins or hair pins. Carbon construction steels are melted by Martin-Siemens, Bessemer and conversion methods (with oxygen insufflation from above)
- Ultra resistant low alloy steels. This family is the most recent of the five great kinds of steel. Low alloy steels are cheaper than conventional alloy steels as they contain smaller amounts of expensive alloy elements. However, they receive a special treatment that gives them much greater resistance than carbon steel. For example, freight wagons made of low alloy steels can carry larger loads because their walls are thinner than would be necessary if carbon steel is used. In addition, as low-alloy steel cars weigh less, the loads can be heavier. At present, many buildings with low alloy steel structures are built. The beams can be thinner without decreasing their resistance,
- Stainless steels. Stainless steels contain chromium, nickel and other alloy elements, which keep them shiny and resistant to rust and oxidation despite the action of moisture or corrosive acids and gases. Some stainless steels are very hard; others are very resistant and maintain that resistance for long periods at extreme temperatures. Due to their bright surfaces, in architecture they are often used for decorative purposes. Stainless steel is used for pipes and tanks of oil refineries or chemical plants, for aircraft fuselages or for space capsules. It is also used to make surgical instruments and equipment, or to fix or replace broken bones, as it resists the action of body fluids.
The properties of steel depend largely on the chemical composition of the metal and the technology of the steelmaking processes, which influence the crystalline structure of the alloys. In addition to the fact that in the case of construction, the structural shape of the element, the shape, magnitude, speed and direction in which the force works (traction, compression, torsion, flexion) influences; temperature.
The bricks are classified among the materials that are obtained by placing previously molded natural clays, or ceramic materials.
The operations that comprise brick making can be summarized as follows:
- Extraction and crushing of clay.
- Preparation and kneading of the pasta.
The molding is done with machines called cookies or with presses. Cooking takes place in fixed or intermittent, continuous, etc. ovens.
Unlike plaster and lime, cement is rarely used alone, kneaded with water and forming a pure paste. Its most proper use is, in combination with other materials, in the manufacture of conglomerates, especially mortars and reinforced concrete. Kneading with water, the cement sets, and hardens both in the air and submerged in water. It is, therefore, a quintessential hydraulic binder.
A first division of the different varieties of cement is established between natural and artificial cements.
Types of artificial cements
Portland Cement: It is dark gray, is the most economical and the most widely used. They are hydraulic cements composed mainly of hydraulic calcium silicate, that is, they set and harden when chemically reacting with water. In the course of this reaction, called hydration, cement combines with water to form a paste and when sand and gravel are added, what is known as “concrete” is formed. It is commonly packaged in bags of 50 kg. Each bag is labeled “CP” followed by 2 numbers (example: 250/315) that indicate the class characterizing its resistance of 7 days and 18 days of setting. It is the most frequently used hydraulic cement, whose composition includes approximately 95% clinker and 5% plaster (or some other component).
- Steel Cements
- Pozzolanic Cements
- Addition cements
- Aluminous Cements
They are very fine particles smaller than 0.06 mm in diameter, coming from the decomposition of feldspathic rocks. Pure clay is called kaolin. One of the main properties of clay is its plasticity, in addition to being refractory. It plays a great role in construction because it is a raw material in the manufacture of cements and ceramics.
They are very compact rocks composed of feldspar , augite , olivine and iron ores, their color is blackish gray that sometimes acquires a metallic luster. They are very hard stones that prevent their use in carved works and resist very little fire.
The adobe is an uncooked mud partition, the earth with which it is made must be clean without stone and with the least amount of sand possible. In a dig more previously made on the ground, let it soak the earth from one day to another to rot kneaded sufficiently adding water to form a well mixed mud and solid, will stir some of the following materials: straw, take off, manure, pine leaves , mane and beast hair in the ratio 1: 5 to serve as a mooring material.
The tepetate is a clay found in solid thick mantles. It is a grainy, thick, light material, yellowish color and medium consistency. Resists 3Kg / cm2, obtaining ashlars for walls (40 x 60). It is porous and water absorbent material. It is a good insulator of cold and heat so it should be used in extreme climates, a mixture for the manufacture of bricks.
It is a tile with characteristics similar to Arabic but, in this case, it has a protrusion on the back to facilitate the engagement with the following.
Flat roof tile
The flat tile without lace can be molded in a row or biscuit press. The dough used is the lace and this must be molded in metal mold presses; their drying is done by placing them on shelves intended for that purpose, so that air circulates on both sides; its cooking is equal to that of the bricks.
It has conical channel shapes and its most common dimensions are 45cm long by 12 and 16 wide, 8cm high and 12mm thick. It is usually molded by hand by a trapezoidal metal rack, and when the molding paste acquires consistency it is curved. Drying is done in the same way as in bricks.
It is a piece of ceramic paste of little thickness, covered by a layer of enamel that can be smooth or with drawings in different colors. shapes and sizes: the preferred shapes are square and rectangular, their dimensions range from 10×10, 15×15, 20×20 and 20×30 cm. Currently they are also manufactured with other non-rectangular shapes.
Functions of building materials
The reasons that lead to the correct use of building materials come from the function or work that these materials must perform. These functions can be grouped as follows: physical function, constructive function, economic function and mechanical function . In turn, each function is modified by a series of factors
The factors that modify physical function are:
- The thermal factor: forces the use of materials capable of withstanding, as appropriate, high temperatures (in ovens), low temperatures (as in refrigerators) and temperature changes. This thermal factor also forces us to worry about the expansion or contraction that materials suffer as a result of heat and cold.
- The water factor: it is present in the materials subjected to the action of the waters and the rains, so that an adequate use of those will consist in the use of waterproof materials.
- The acoustic factor: indicates the use of materials capable of absorbing, reflecting or completely isolating the sound or noise, depending on the
case to which we refer.
- The optical factor: leads to the selection of materials that in a given program should be transparent, translucent or completely opaque.
The factors that modify the constructive function are:
- The workability factor: the use appropriate to its workability, is a factor that allows us to see in a material, if it is easy or not to be able to use it, since there are materials that although they have a magnificent quality, are difficult to work on the works.
It refers to the ease of working with a material in an effective, simple and economical way.
- The appropriate techniques, equipment and tools: these are essential elements to be able to use the required materials correctly. Without this factor it would be practically impossible to do any work, with efficiency, safety, and speed.
- The conjugation of the material with the architectural form: it forces us to think that there are very direct relationships between the material to be used and the form that material will take. The dimensions, shapes and treatments in the architectural complex are related to the strength, properties and aesthetic effects of the material. The domes of the ManaguaCathedral is an element where the material plays with the shape, because the properties of the concrete , its plasticity and possibilities are known.
- The investigations, tests and tests of the materials: they constitute the ideal vehicle to know the properties of the materials and their behavior, as well as the construction techniques to be used, as the case may be.
The factors that modify the economic function are:
- Ease of obtaining: it is a determining factor for the selection of materials. A hard-to-obtain material is more expensive, is obtained in certain places and is generally scarcer.
- Ease of transport: it is another factor that makes materials more expensive or cheaper, so it is more rational, provided that the use of local materials can proceed.
- Cost according to its use: determines that sometimes it is impractical for example, to use expensive materials in provisional works.
- Maintenance cost: it is a consequence of the selection of the material according to its use, since it depends on the permanent or provisional nature of the work.
The factors that modify the plastic function are:
- Shape and dimension: it is closely related to the constructive function, resistance and aesthetics.
- Texture: indicates that a material can have a smooth, rough, or rough appearance etc.
It is the function performed by the materials that subjected to the action of external forces and the effects of their own weight, must have the necessary resistance factors to absorb the different efforts to which they will be subjected.