asignatura joining and fastening elements - la · pdf filejoining and fastening elements...

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JOINING AND FASTENING ELEMENTSMATERIALS AND SYSTEMSConstruction I. Materials and techniques. 1st year

Àrea de Construcció2016-2017

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Index (It also serves as a classification scheme for all type of joints)

1. Introduction 1.0. Definitions1.1. History1.2. Requests1.3. Classification system

2. Joints and fastening elements according to their geometry2.1. Joints According to gravity (R) Superposition

HangingAccording to its geometry (SR) Folding

BraidedSewing and linking

According to its mechanical fit in (R) According to its anchoring system (SR)

2.2. Fixations Nail driving (SR)Pins and cotter pins (R) also: driftbolts, driftpins?Clipping (R)Screwing (R) Screws and dowelsRiveting: Hot temperature (SR)Riveting: Room temperature (SR)

3. Fastening and joints elements according to the process of welding (I)3.1. Using heat Homogeneous (strong)

Heterogeneous (weak) 3.2. Chemical welding

4. Fastening elements according to their adherence (I)4.1. Micro-mechanical (geometric) adherence 4.2. Chemical adherence

5. Information sources

(R) = Reversible joints

(SR) = Semi-Reversible joints

(I) = Irreversible joints

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DefinitionsConstruction is the reasonable and efficient addition of materials in order to achieve the demanded requirements by a building or by an architectonical element. Therefore, these materials not only have to be sustainable among them, but must be able to maintain stable the projected addition in order to guarantee its own function and durability.

From here the importance of the resources we use to guarantee this stability.

To join: “to form a whole with two or more elements / fasten (something) with joints”

Generally, in construction, joints are planned with the materials which are going to join.

To fix: “is to hammer, drive, attach, etc… something in a way so it wont move nor fall down”

Generally, in construction, the fixing elements between two materials is achieved by using a third specific fixing element, that as can be deduced from the Dictionary’s definition, this will be a chemical or mechanical type of fixing elements.

From now on, in construction, when we still do not have a definitive way to join two elements, the only correct acceptation to define it will be: fixing if it has an specific element that will intervene or joint when it does not have one.

Present ? (Presentar): In construction, to provisionally place an element in its definitive place without fixing it or using provisional fixing elements in order to check that it adjusts to its place, before definitively placing it.

Introduction l Geometry l Welding l Adherence l Information sources

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HistoryThe technique of fastening and joining is present in nature and used by many species of animals (linking and self-producing adhesive animals): such as spider webs, worm’s chrysalis, egg bag from fishes and amphibians, bird’s nest, etc…

Prehistory:

•Adhesive elements: animal blood, vegetal resin

•Mechanical elements: tied with rope, upturn with vegetal fibers

Ancient civilizations (Egypt, Mesopotamia):

•Adhesive elements: Bitumen, natural adhesives (egg’s shell)

•Mechanical elements: nail, pins (cotter pins)

Roman Empire:

•Adhesive elements: tars, beeswax

•Mechanical elements: rivets placed in warm.

1800s:

•Adhesive elements: casein glue, cork, latex.

XIX century:

•Adhesive elements: Formaldehyde phenol (laminated). The beginning of synthetic elements.

•Mechanical elements: Rolled pin (1850), screw

XX century:

•Adhesive elements: Cyanoacrylates, anaerobic, copolymers, acrylics, silans. Epoxy resin (1950)

•Mechanical elements: Specialized screws, dowels, mechanical+adhesive solutions

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RequirementsStructural behavior: tensile, compression, shear and bending forces.

Nails Screws Adhesive elementsLinked and upturned

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Type of classification. Sustainability degrees

There are many types of classifications, although during this class we will show the ones which interest us the most; as we describe the types of fastening elements.

Reversibility

As a general aspect, we can use the classification from the index and combine it with the joint’s reversibility one; which is important especially for deconstruction or the use of the materials, and that affects its degree of sustainability, although it is not the only factor for measuring it.

PHYSICAL SYSTEMSReversible: these elements can be undone; recuperating the pieces that are joined and the joining elements also. Semi-reversible: these elements can be undone; recuperating the pieces that are joined but not the joining elements.Irreversible: these elements can be undone but it is mostly impossible to recuperate without any damage the joined pieces nor the joining elements. (Welding)

CHEMICAL SYSTEMSIrreversible: this pieces can not be undone, because it involves using chemical reactions, except for some weak adhesives which allow the separation and reuse, and some others that have a solvent material that dissolve them.

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•02JOINTS AND FASTENING ELEMENTS

ACCORDING TO THEIR GEOMETRY

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SuperpositionDefinition: Joining method consisting on putting elements one over the other. The elements stay still thanks to friction forces, geometry, adhesion or combinations of the previous.Related properties: Materials must be resistant to compressive stress.

Types: Dry systems (trunks, stones, etc.), or wet systems. Wet systems can contain water in the main material (rammed earth, concrete) or in the joining material (mortars) of the solid pieces.

Giza pyramids. Egypt Swiss Pavilion. Hanover, Germany. 2000. Peter Zumthor

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Roughness and bond

Roughness: The point is to have the contact surface of the elements (blocks, bricks, etc) irregular enough to let the mortar introduce into the element holes when laying them on the wall with some pressure. Once hardened, it has a bond geometry that doesn't permit the elements to slip.

Bond: It is the interlocked way of layering the bricks or blocks in correlative courses, avoiding continuous vertical joints, but labyrinth shaped. Otherwise the "wall" would be a juxtaposition of separated columns, likely to move differently from one each other, not working as a whole and breaking the unity

Dry stone wall Wall without linking joint in Machu Pichu. Peru 15th centurySource: La Feixa pedra seca

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Hanging

Definition: Mechanical and dry joining method that consists on suspending elements from others. Geometry is crucial to ensure the stability of the elements.Related properties: Hanged elements must resist tensile stress, at least to be able to support their own weight.Types: It is a dry joining method, but in some cases the stillness of the elements can be granted with an adhesive (silicone, etc)

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Folding

Definition: Mechanical and dry joining method, that takes advantage of the folding shaping process (Vidshaping processes) of two elements, folded together in a way that they can not disjoint.Related properties: Often applied with metal sheets.Types: It is common to find folded joints in metal sheets in roofing and facade systems, where waterproof performance is essential.

Aluminum

Zinc

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BraidedDefinition: Mechanical and dry joining method based on flexibility of lineal elements to make them work together by friction.Related properties: Material must resist tensile stresses.Types: It is often applied in textiles, nets, cables, ropes, shading elements, etc

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SewingDefinition: Mechanical and dry joining method, that uses the tenacity of lineal elements in order to join one piece to another piece, or some pieces between them through the means of upturning. Related pieces: The material has to be able to support tearing efforts. Types: It is usually applied on fabrics

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LinkingDefinition: Mechanical and dry joining method, that uses the tenacity of lineal elements in order to join pieces among them through the means of wrapping up the pieces. The pieces usually help themselves using knot techniques. Related properties: The linking material has to be able to support a tensile effort.Types: These joints are usually seen in simple vegetal constructions.

Villa Mairea. Pori. Finland. 1937-39. Alvar and Aino Aalto

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Mechanical fit inDefinition: Joining method of elements based on their geometry. Many joining systems could be included in this category, for example screwed. There are specific classifications for many materials, specially for wood. Related properties: Joining elements can not be very deformable. They must be rigid enough to keep their geometry.

Jointing method named dovetail (CAT:cua d’oreneta, ESP:cola de milano)

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AnchorageTypes: mechanical anchoring elements used in concrete Definition: Mechanical joining method, that uses the geometry of lineal elements in order to join pieces between them using a mechanical fit it or friction. The pieces are usually previously fasted on to the element which they are going to be fasted further on. Related properties: The linking material must resist tensile forces.

Detail of a steel anchoring plate from a calculation program of the engineering CYPE Source: CYPE engineers

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AnchorageTypes: bracket, jamb anchor.Definition: Mechanical joining method, that uses the geometry of lineal elements in order to join pieces between them using a mechanical fit it or friction. The pieces are usually previously fasted on to the element which they are going to be fasted further on. Related properties: The linking material must resist tensile forces.

Welded bracket Angular piece welded on to the base

Movable bracket Welded bar for concrete

Welded omega profile used for dry or metallic walls

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AnchorageTypes: staples, strapping bands (fleixos), TiesDefinition: Mechanical joining method, that uses the geometry of lineal elements in order to join pieces between them using a mechanical fit it or friction. The pieces are usually previously fasted on to the element which they are going to be fasted further on. Related properties: The linking material must resist tensile forces.

Font imatges: Constructalia

Strapping bands

Staples (or ties)

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AnchoragesTypes: ties, adjustable ties.Definition: Mechanical joining method, that uses the geometry of lineal elements in order to join pieces between them using a mechanical fit it or friction. The pieces are usually previously fasted on to the element which they are going to be fasted further on. Related properties: The linking material must resist tensile forces.

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AnchorageTypes: chemical anchors with resins, grouts o mortars.Definition: Chemical joining method, due to adherence. First we make the hole, afterwards we put resin or mortar inside, and finally we introduce the anchoring element. The adhesive resins are often polystyrene, vinyl or epoxy resins. It is very important that during the curing process, the anchoring element does not move at all.Related properties: The supporting material must be able of being perforated and to withstand forces without being disintegrated; due to the fact that resins have more resistance than most of the materials.

Gamma of different types of chemical anchoragesImage source: IBMH Corp. Constructalia and Vikipedia

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Fastening elements, classification

Nails

Pins

Screw

Screw with nut

Screw for wood or chipboard screws

Screws for metallic sheet

Mechanical dowels

Dowels for laminated plasterboards

Wall

Concrete

Chemical dowels

Rivets

Rivets

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Nail drivingDefinition: Mechanical joining method, dry, that consists on introducing a nail, usually metallic, into the mass of a material, generally with no previous drilling. The nail itself makes its space into the piece, putting apart the material. This material tries to recover the original position, pressing on the nail. It is necessary to avoid the nail to be expulsed by the material. There are special nails with not-cylindrical shapes to grant that. We can join elements by crossing them with the same nail.Related properties: Normally the nail material is harder than the elements materials. The material of the elements to join must be elastic enough to let the nail deform them. It can't be brittle. If so, previous drilling is needed. Nail must resist tensile, shearing and compressive stresses.Types: The most common nailing join uses steel nails on wooden elements. Many other nails are available (stainless steel, zinc, copper, brass, etc) and we can drive them on wood and timber, but also on ceramics, concrete, steel, etc. We can nail a nail manually, using a hammer, but there are also many mechanical drivers (electrical, compressed air) and even powder-powered ones (pistols).

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Nail drivingTypes: Type of nail with or without head, and self-tapping, which are a type of mixed nails that are perforated first and after the hole has been done, are driven into the material being fastened.

Self-tapping screw

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Cotter pins and pinsTypes: Lineal element that is introduced into a perforated hole which has been done with the same diameter than the pins; therefore, through the means of friction, the cotter pin is fastened in its designed place. These elements usually work under shearing stress.

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ClippingDefinition: Mechanical joining method that takes advantage of the elasticity of the clips. Those, when deformed, tend to return to their original shape, pressing on other objects, fastening their position.Related properties: Clip materials must be elastic. Usually they are some metallic or plastic elements. Types: Very commonly used in metal sheets finishing, in aluminum doors and windows, in dry paving systems, facilities, electrical devices, etc.

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Screwing using nuts

•Normal screwing•Screw works under shearing stress, guiding the forces through it. It works as a through bolt. The pressure that it does to the elements helps, but is not the basic way of transferring forces.

Definition: Mechanical joining method, using screws. There is always a screw and a nut. Washers are used to distribute the stresses to the elements. Normally is necessary a previous hole or drill, that can be screwed or not.Related properties: Material must resist tensile and shearing, compressive and tensile stresses. They are almost always metallic pieces.Types: Normal and high resistance

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Screwing using nuts

•High resistance screwing•Nuts only compress the elements to join one to each other. Screw only pulls from the two extreme nuts, so it only has tensile stress. Forces are transferred from one element to the other by friction on their surfaces, and not trough the screw.

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Screwed. Put into works

Preparation of the piecesWhen we pose a structure bolted, it is necessary to consider previous work, which involves the preparation of the parts to be assembled in order to have a correct fit between them.


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Screws for woodDefinition: Mechanical and dry joining method, using cone point screws (wood or chipboard screws if they are very long) which by spinning are introduced into the fastening element. It is not always necessary, but sometimes, a previous perforation must be done in order to join the pieces. Related properties: The screw’s material must resist tensile and shear stress; this is why most screws are metallic.Types: For the type of head: if they have or not a smooth part used to fasten the top piece, and for the type of wood (or wood-based products): with wings and separated between soft and hard wood.

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Screws for metallic sheetsDefinition: Mechanical and dry joining method, using cone point screw which by spinning are introduced into the fastening element. It is not always necessary, but sometimes, a previous perforation must be done in order to join the pieces.When the perforation isn’t done, self-tapping screws are used that first drill the sheet and then do the twist in it. The application is with a special gun for self-tapping screws. Related properties: The screw’s material must resist tensile and shear stress; this is why most screws are metallic.Types: For the type of head, metal and screw’s protection, and for the type and thickness of the metallic sheet that is going to be fastened.

Self-tapping screwScrews for metallic sheets

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Mechanical dowelsDefinition: Mechanical and dry joining method, using screws which are introduced by spinning into the

fastening element and using dowels which are the ones in charge of making the transmission between the mineral element and the screw. It is necessary a previous perforation of the mineral piece in order to introduce the dowel (except for laminated plasterboards). Once we introduce the screw, this causes the dowel to expand and to strongly press the walls of the hole, therefore, though the means of rubbing/friction (fregament), the pieces stay anchored and are not able to move.

Related properties: The screw’s material must resist tensile and shear stress; this is why most screws are metallic.

Image source: Hilti

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Mechanical dowelsTypes: For laminated plasterboardsDefinition: Mechanical and dry joining method, using screws which are introduced by spinning into the fastening element and using dowels which are the ones in charge of making the transmission between the mineral element and the screw. Not always it is necessary a previous perforation of the mineral piece in order to introduce the dowel.Related properties: The screw’s material must resist tensile and shear stress, but no more than their own plasterboard, so they are almost always made of plastic

Source: Pladur cataloguedifferent types of dowels for plasterboard

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Mechanical dowelsDefinition: Mechanical and dry joining method, using screws which are introduced by spinning into the fastening element and using dowels which are the ones in charge of making the transmission between the mineral element and the screw. It is necessary a previous perforation of the mineral piece in order to introduce the dowel (except for laminated plasterboards). Related properties: The screw’s material must resist tensile and shear stress; this is why most screws are metallic.Types: Used for brickwork walls. Used for small loads from plastic dowels, or bigger loads from metallic ones.

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Mechanical dowels (expansion bolts?)Definition: Mechanical and dry joining method, using screws which by spinning are introduced into the fastening element and using dowels which are the ones in charge of making the transmission between the mineral element and the screw. It is necessary a previous perforation of the mineral piece in order to introduce the dowel (except for laminated plasterboards). Related properties: The screw’s material must resist tensile and shear stress; this is why most screws are metallic.Types: Used for concrete and other very hard materials

Source: Hilti

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Chemical dowelsDefinition: Mechanical and chemical joining method, this method combines screws, which are introduced on the fastening element, which break a glass bottle when are turned, and the adhesive, which hardens when gets in contact with air and creates a transmission and adherence between the mineral element and the screw. It is necessary a previous perforation of the mineral piece in order to introduce the dowel. Related properties: The screw’s material must resist tensile and shear stress; this is why most screws are metallic.Types: Uses for heterogeneous and separated supports.

Source: Brikomark

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Riveting: HotTypes: To joint metallic sheetsDefinition: Historical and mechanical joining method, applying heat and using rivets. First, a perforation must be done. The rivet, with a head already formed, is placed in the hole using pressure, and introducing the hot bolt until it touches the element. Then, we hit the bolt that it is sticking out on the other side until we deform it in order to create another head. While the rivet’s head is cooling down, the rivet is also shrinking, helping both heads and applying a certain pressure against the pieces which are being fasten. Rivet works under shearing stress, transferring the forces through it. The pressure applied on to the pieces help, but it is not a basic mechanism of transferring stress. Conceptually, works as a cotter pin, but with the security given by the heads, where these avoid any movement made by the bolt.

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Riveting: HotRelated properties: Materials must resist high temperatures without burning, and must have a high linear expanding coefficient, and a high resistance to tensile, compressive and shearing stresses. Normally made out of cast iron.

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Riveting: room temperatureTypes: To joint metallic sheetsDefinition: Mechanic joining method using small rivets. This rivets are small tubular elements made of a plastic and easily deformable material (normally soft alloys) to make it possible to work it at room temperature. It works as a rivet, but for less demanding joints, not structural.Related properties: The material must be plastic, and able to resist compressive and shearing stresses.

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•03FASTENING AND JOINTS ELEMENTS

ACCORDING TO THE PROCESS OF WELDING

Introducció l Per geometria l Per soldadura l Per adherència l Fonts d'informació

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Welding using heatDefinition: Not-reversible physical joining method, based on applying heat to a material until melting it. When it solidifies it joins the different elements. Normally applied with metals, but also with plastics and oil based products, as asphalts.Related properties: The materials used must be able to melt and solidify again without burning. In the case of metals, rising their temperature cause a risky situation, because oxidation processes are accelerated. Preservative atmospheres can be used during the process.

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Welding using heat. TypesHomogeneous welding, when the material of the elements to be joint and the jointing material is the same, for example carbon steel or asphaltic sheet. With this process part of the elements are melted, and when solidifying a single object is created, without discontinuities. Heterogeneous welding, when the material of the elements to be joint is different from the jointing material, for example welding of copper wires or pipes with tin

Homogeneous welding

.

Heterogeneous welding

.

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Welding heat. Type of heat contributionHot airBlowtorches, melting the metal of the two piecesElectric welding, adding other metals to the weldLaser weldingFriction welding (by rubbing at high speed and pressure the two pieces)Ultrasonic welding, by "bonding" the crystals of the different elements. It doesn’t joins exactly by warmth

.


Blowtorch welding Electric welding Laser welding

Hot air Welding

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Chemical weldingDefinition: Not-reversible physical joining method, based on creating a chemical reaction to the point of linking molecularly the different joining elements. It is very used on synthetic materials such as EPDM and PVC. Related properties: The materials used must be able to melt and solidify again without losing its characteristics. Types: welding made by the vulcanization of EPDM

welding of PVC pipes, with a plastic melt adhesive

EPDM welding with bands EPDM welding with adhesive

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•04FASTENING ELEMENTS ACCORDING TO THEIR

ADHERENCE

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Definition of adhesive System of forces

- Adhesion (substrate - adhesive)

adherence according to its geometry: Mechanical or physical part similar to the mechanical fit in but at a microscopic level. It depends on roughness, surface finishing and porosity of the substrate.

adherence according to affinity: Proper adherence (chemical) caused by thermodynamic forces and secondary links between the adhesive’s molecules and the substrate.

Most adhesives work by using both phenomenon

- Cohesion (between the adhesive’s molecules)

Ability of holding together the adhesive’s molecules when it is submitted under any type of forces.

Functioning of the adhesive

Contact: Wetting of the substrate. The more surface contact, the more effective is the adhesion.

Hardening or curing process: The step between the fluid adhesive (usually liquid) to a solid with elastic degrees, in function of its requirements. It can last from seconds to weeks, according to its type of adhesive.

This process is due to a solvent which evaporates or due to a chemical reaction between two components.

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Classification of the adhesivesThere are many classifications according to the parameters that are taken into account:

Curing phase: Reactive: when the curing is made after the application (epoxy, cyanoacrylate, polyurethane)

Non reactive: when the pre-curing has been already made before the application (white and contact glues, sticky tapes, PVC)

Material: Thermoplastics (PVC)

Vulcanized elastomers or elastomers with cross links (silicones)

Termoestable (epoxy)

Origin: Naturals, animal o vegetal origin (casein, collagens and starch, Arabic glue).

Synthetics: phenolic resin, epoxy, polyurethanes, thermoplastics and elastomers

Types of adhesion: Micro-mechanical (mortars, pastes, white glue)

Chemical (adhesives, glues and resins)

In the Area of Construction, this last classification is the one that interests us the most; since its effectiveness will depend on the material’s characteristics of flatness and porosity when they have to be joined (this is usually a known data)

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Micro-mechanical adhesionDefinition: adhesive penetrates the roughness – at a microscopic level- of the materials which are going to be joined and once curing takes place, it creates geometric forms which prevent separation. It depends on roughness, surface finishing and porosity of the two substrate that are going to be joined. The more surface contact, the more effective is the adhesion.

These are adhesives that mostly work according to their geometry:

- all mineral binders, such as cement, lime, gypsum and plaster.

- white and yellow glue

Related properties: At a microscopic level, the Portland cement has a greater power of adhesion and cohesion that most of the other binders-adhesives, because during its curing process, the cement molecules crystallize into thin needles that penetrate very deep into the substrate’s pores, and strongly link together in such a way that they also have a lot of cohesion.

Diagram of how these adhesives work Portland cement crystals under a microscope

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Micro-mechanical adhesion by settingDefinition: Adhesive joining method of hydraulic binders when they react with water. The initial hardening of many mixes used in construction by drying and recrystallization. This reaction occurs in cement (so in concrete and cement mortar), in lime and in plaster. From the starting moment when crystallization delicate processes occur, too fast drying, freezing or movements can drastically reduce the final resistance of the material.Related properties: Joining materials must react with water..

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Micro-mechanical adhesion by settingAdhesion can also collaborate to the same effect, at a macroscopic level, if a geometry is given to the substrate, such as tiles or bricks which create water channels, holes or grooves for this same reason.

Grooved shapes are created on the exterior finishing of many ceramic pieces in order to increase the contacting surface among these, and the fastening mortars or coats of plaster, in order to improve the adherence between ones and others.

In perforated bricks (“gero”) the geometry of the horizontal face of the pieces is irregular because when the binding mortar is placed with a certain pressure, it penetrates inside the holes, therefore, once is it pressed, it fixes a form that prevents the sliding of a row in respect to the next row of mortar.

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Chemical adhesionDefinition: Chemical joining method, so not reversible, based on the application of a fluid material to the surfaces of the elements to be joined. A chemical reaction occurs in the adhesive, so it becomes solid. Normally it has to be in contact with the air to start the chemical reaction.Related properties: Adhesives must to be compatible with the materials of the elements to be joint, and if possible it has to penetrate through their porous structure.

Microscopic structure of an adhesive

Source: Article’s scheme : “adhesivos, el reto de unir todo con todo”

Substrate 1

Substrate 2

Adhesive molecules

AdhesiveCohesion

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Chemical adhesion using pressureDefinition: Chemical joining method, so not reversible, based on the application of a fluid material to the surfaces of the elements to be joined. A chemical reaction occurs in the adhesive, so it becomes solid. In order to improve the wetting process and adherence, we apply strong pressures between the substrates that are going to be fastened. Phenol and urea resins and binding glues are materials from this family, among others.

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Chemical adhesion of mortars and pastes Definition: Chemical joining method, so not reversible, based on the application of a fluid material to the surfaces of the elements to be joined. A chemical reaction occurs in the adhesive, so it becomes solid. These elements are usually helped by pressure. They are ideal to join elements with non-regular faces that need a mass with a body which absorbs these irregularities in order to be adhered. Adhesive mortars and silicon adhesives are examples of the most common ones in construction. There are also other materials which are starting to be intensively used that are know are polyurethane mono-component Sika-flex type.

Application of an adhesive mortar Sikaflex adhesive cartridge

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Chemical adhesion of mortars and pastes For the placement of tiles, adhesive mortars or adhesives are used on those coating and pavement materials with little porosity (stoneware, porcelain stoneware) on which mortars do not make an effect. There is an extensive range of mortars in function of the requirements that have to be complied.

Source: ANFAPA

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Prescription of adhesivesAs a summary, increasingly, each type of adhesive is specialized for its pair of material or substrate that it has to join, so you should always consult the manufactures for the type of adhesive which is mostly appropriate to each situation or requirement.

Example: Table of compatibilities of some adhesives and their

respective substrate

Source: table of the article : “el ABC de los pegamentos”

WOOD PAPER METAL

PLASTICS WITH STYRENE

VINYL PLASTICS *Cola blanca – white glue

*Cola amarilla – yellow glue*Epóxidos – epoxides*Gomas – gums*Cianocrilatos – cianocrilate*Pto. de contacto –contact glue*Pegamento de contacto –contact adhesive/glue*Pto. para plásticos –plastics glue

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Propietats dels materials i elements de construcció (Ramon Sastre, Edicions UPC)

Diccionari manual de la construcció (ITEC)

Diccionari visual de la construcció (ITEC) (Baixable en format PDF)http://www10.gencat.net/ptop/AppJava/cat/documentacio/llengua/terminologia/diccvisual.jsp

Diccionario Visual de Arquitectura. (Francis D.K. Ching). GG. See “UNIÓN”

Article : “adhesivos, el reto de unir todo con todo”. (Javier Oñoro) UPM

Article: “el ABC de los pegamentos”. (V. Alberto Herrera Carrera)

Fulletó ANFAPA. Asociación Nacional de fabricantes de morteros industriales

Information sources


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