Mechanical stress that wears away the primary and all subsequent layers, until they are completely removed from the substrate.
A chemical that has a pH of less than 7
They are somehow aggressive products showing an acid behaviour generally used to remove lime scale or cement, and to dissolve salt crystallization. Therefore, they can only be used on surfaces that are resistant to this attack, or where such aggression does not lead to damage of the surface. They should not be used on polished marble, limestone absorbent surfaces, on non -acid resistant porcelain enamels. Given the wide substrates variety and the often present uncertainty as to their nature, it is always good to make a preliminary test.
A natural or artificial something (such as a chemical) that is added in pre-set precise amounts to a substance to confer special features (e.g.: appearance, durability, performance, durability, hardness, elasticity, malleability, volume, or to eliminate) or reduce some of its defects, before, during and after ‘application.
A thing that causes something to happen
It is obtained by heating compact limestone, that becomes Calcium Carbonate which breaks down to form Calcium Oxide and Carbon Dioxide. Calcium Oxide is slaked either with an excess of water, then “slaked lime” is produced, or with the strictly necessary water amount to hydrate it, in which case “ hydrated lime” is produced.
Aluminous cement also known as ‘high-alumina cement’ or HAC or “ciment fondu” is made by heating limestone and bauxite: it is a cement that reaches very high mechanical strength within a very short time. It is well-adapted for use in refractory material for high-chemical resistant artifacts, for low temperature environments, etc.. One of the problem with this cement is that it undergoes a crystalline re-arrangement known as conversion which leads to a loss in mechanical strength. The higher the water/cement ratio, the greater the loss.
Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substitute such as an organic group. According to the number of hydrogen substituted, the amines are classified as primary (NH2R), secondary (NHR2) or tertiary (NR3).
Anhydrous Calcium sulfate (CaSO4)
Additive that prevents the formation of foam and consequently also any possible density change.
Antifreezes are chemical compounds added to reduce the freezing point of a cementitious mixture at temperatures below 0 ° C by acting on both cement setting speed and heat of hydration development during the casting phase. It is very effective when added to thick casting, but almost ineffective if added to a plaster or a thin casting, in which cases the surface area exposed to low temperatures would be very large.
A substance to be added during the production of paints, plastics and adhesives to reduce and / or delay the normal oxidation process and thus maintaining the physicochemical characteristics of the product.
Treatment or coating that can be applied to any walkable surface to prevent slipping.
Material not capable of retaining an electrostatic charge when it is placed in contact with the earth.
A general technical term indicating / that stands for a resistant structure positioned side by side to an artefact or incorporated into it, to constitute an element resistant against weight and / or external forces.
Fibrous and flexible aggregate composed of silicates that is highly resistant to fire, heat and chemical attacks (particularly acids attack). It is easily workable and very strong. In the past it was especially used as an acoustic insulator, thermal insulator and reinforcement for cement (asbestos cement), as well as in paints, varnishes, flooring materials and textiles. When asbestos was at its peak, some medical studies showed that a long exposure to high concentrations of asbestos fibers is more likely to cause health problems. Since the ’80s, the World Health Organization recommends not to use it as it is considered a potential health hazard. In Italy the law has banned all use of asbestos and extraction, manufacture and processing of asbestos products. The remediation of several tons of Asbestos (asbestos cement and different types of insulation materials) remains so far an unsolved problem.
Particular type of fiber cement consisting of a mixture of cement and asbestos with very high tensile, flexural and compressive strength, but low impact strength. In the past it was widely used to make either corrugated sheets or roofing for both covering and coating of commercial or industrial buildings or for the construction of tanks, pipes and ducts.
It was banned from use since it has been proven that it poses a potential risk to human health.
Are base or alkaline behaviour products, usually used for removing oil, grease, smog or air pollution deposits. Are used to clean facades suspended from floor slabs made of marble, limestone, sandstone. They must not be used on polished marble and metals like aluminum or galvanized surfaces. Given the wide variety of and the often present uncertainty as to their nature, it is always good to make a preliminary test.
solutions with a pH greater than 7 are basic.
It is an essentially impure clay characterized by great plasticity, ion exchange capacity, detergent and stabilizing effect, but overall by the ability to absorb a significant amount of water re-inflating several times its volume giving rise to the so-called thixotropic gels.
The word “binder” stands for “binding layer”, namely a cohesion layer applied to ensure the proper anchorage of the material to be installed with the substrate. The choice of the right binder depends on the type of substrate, the type of the material to be bonded, the thickness to be achieved and both the facility’s characteristics and its intended use.
A substance composed mainly of a mixture of natural hydrocarbons derived from distillation of petroleum, characterized by remarkable binding properties. The are two types of bitumen: petroleum based bitumen and natural bitumen.
A phenomenon occurring during the drying phase that causes the migration of one or more components of the product toward the surface. The dishomogeneous surfacing of pigments leads to changes in colour and this (depending on the case) can be considered as either a defect or an essential characteristic of paint products. Any surfacing may occur in paint or varnish cans, if not irreversible, does not create problems on the finish, as it is sufficient to evenly mix the product to give it the desired appearance and characteristics.
Phenomenon caused by the concrete natural aging because the Calcium Hydroxide Ca (OH) 2 is attacked by Carbon Dioxide of the air and converted to Calcium Carbonate CaCO3. Therefore, the lowering of the pH value from 12 ÷13 to approx. 9 results in a power loss of the protective reinforcement.
A substance that speeds (positive catalysis) or slows (negative catalysis) the rate of a chemical reaction without affecting in any way the final reaction outcome.
Capable of corroding a material or a substance and causing burns ulcers or simple irritation to people skin, eyes, throat etc..
It is produced by the addition of cement paste mixed with foam liquids that in turn are diluted in water in percentages varying from 2 to 3% . Then while the cement sets and over the time, the water slowly evaporates leaving all the micro cavities formed by the foam empty, consequently tiny air bubble are created inside the micro cavities this conferring insulating properties to concrete.
Very liquid cementitious mortar, obtained by mixing equal parts of sand, cement and water used for laying either masonry/stone flooring (tiles, porphyry, bricks) or brick walls.
Sedimentary rock, with low cohesion values and an earthy appearance. Depending on impurities contents clay varies in colour from blue to red; however, also black and green clays may be found. Among its most important characteristics there are both plasticity and hygroscopic capacity.
This term which, according to use, has two distinct meanings: 1) material that is obtained by mixing and then pulverizing some substances made from limestone and clay. It is the main component of Portland cement. 2) Klinker tiles are an extruded tile which is very dense and fired at very high temperatures mainly used as a cladding material for walls and floors.
Set of raw materials that under certain conditions of temperature are used to produce a compound with special properties useful for the construction of prefabricated waterproofing membranes. This word stands for “Bitumen Compound”.
Is a composite construction material, obtained by mixing water with cementitious materials (especially lime or cement resulting from processes that do not use foreign substances or industrial waste) and clean not radioactive aggregate (sand, gravel, brick dust) which are widely used in construction. The main concrete features are its ability to resist the attacks of weathering action and its mechanical strength. To achieve a clean release after removal of the formwork, the shutter faces should be treated with natural oils prior to casting concrete.
Motor-machine, usually electric, with either a tilting drum or a drum that is used for mixing concrete and mortar preparation.
Polymer formed from two or more different monomers.
They are cracks wider than 1 mm, with either a linear pattern in presence of static movements of the substrate or cross-shaped if applied to too high material thicknesses in just one coat and when the product is too much fluid.
It is the ability of an artifact to keep intact the structural and architectural features for which it was designed, built and used.
When a sufficient load is applied to a metal or other structural material, it will cause the material to change shape. This change in shape is called deformation. A temporary shape change that is self-reversing after the force is removed, so that the object returns to its original shape, is called elastic deformation. In other words, elastic deformation is a change in shape of a material at low stress that is recoverable after the stress is removed. This type of deformation involves stretching of the bonds, but the atoms do not slip past each other. Strain is directly proportional to stress (Hooke’s law). To describe the elastic properties of a body, a convenient parameter is the ratio of the stress applied to a body to the strain that results in the body in response to it. This parameter is called the “Young’s modulus” or “Modulus of Elasticity” of the material and the greater the tenacity of the material, the greater is the modulus of elasticity.
Natural or synthetic polymer with elastic properties similar to rubber. At room temperature can be repeatedly deformed and return approximately to its initial size once the stress come to an end.
Substance capable of promoting the mixing of immiscible compounds with each other (e.g. Detergents to mix water and fat).
Heterogeneous system consisting of liquid particles (dispersed phase) evenly dispersed in a liquid immiscible with them (dispersing phase).
This feature, shown as a percentage, has in the restoration plasters, particularly high values. This property, in fact, is one of the required conditions to obtain the right water vapour permeability as required by this type of plasters.
See “epoxy resins”.
EXPANSION JOINT (FRACTIONING JOINTS)
Interruption between sections of the screed to allow the two facing structural parts respective movements caused by temperature changes or other causes.
It is a special type of concrete reinforced with steel fibres, alkali resistant glass fibres or other synthetic fibres widespread in no more than 2% of the concrete total volume to improve its resistance to bending and torsion.
Formation of a resin film achieved via the coalescence of the dispersion resin.
Anchoring elements to walls. Good thixotropy, easy mixing, high strength and rapid setting time requirements must be met.
It is a roof with a maximum gradient of 5%
The gloss is measured on a scale ranging from 0 to 100.
Some common names for levels of gloss include: normally opaque/matte if it has a gloss percentage ranging from 1 to 10, opaque/matte with gloss from 11 to 30, medium- opaque with gloss from 31 to 40, semi-opaque with gloss ranging from 41 to 50, semi-gloss with gloss from 51 to 80; brilliant with gloss greater than 80.
An instrument that measures the brightness of the surface of a product, according to the assessment of the reflection of such surface under certain angles of incidence.
Indicates the size of the grains that constitute a material. It is usually detected by sieving.
HEAT OF HYDRATION
The term ‘heat of hydration’ is applied to the heat generated by the chemical reactions, which occur in setting concrete between the water and cement.
HEAT OF REACTION
Amount of heat transferred or absorbed by a chemical reaction. The reactions that give off heat are called exothermic, endothermic those that absorb it.
It is obtained either by thermal decomposition of compact limestone that contains varying amounts of clay (natural hydraulic lime) or by mixtures of hydrated lime with pozzolana, clay or blast furnace slag (artificial hydraulic lime).
Thermal, acoustic or electrical separation of two bodies or environments by material or insulating bodies.
Is obtained by adding aggregate to the normal concrete mixture.
Also called “quicklime” or Calcium Oxide it refers to an earthy-looking, whitish and solid substance made by heating limestone. By treating it with water, lime swells, develops heat and becomes Calcium Hydroxide, namely “slaked lime”. By adding a quantity of water equal to two and a half times its weight to quicklime, the so called “slaked lime putty” is formed, that is the binder normally used to prepare the mortar. By mixing slaked lime together with excess water, a white liquid called “Milk of Lime ” is obtained, that is a slurry commonly used as a basis for dry paints. Lime is classified into fat (fat lime) and lean (lean lime), the first resulting from the heating of nearly pure limestone, while the second comes from magnesium limestone or clay (less pure).
Cracks are less than 1 mm wide, radiated from the center in the style of a spider’s web, usually on the surface and caused by hydraulic shrinkage.
MICROCRACKS (HYDRAULIC) CEMENT
Hydraulic binder that, once mixed with water, can can harden even underwater or when exposed to open air. Cements are classified into fast-setting cements (Roman cement) and slow-setting cements (Portland cement). Cement is nowdays widely used to make bastard mortar’ plaster, while in the past it was also used to build precast or cast in situ decorative elements, as an alternative to putty.
This term refers to the ability of materials used for thermal insulation to oppose a very high resistance to heat transfer. This type of materials are consequently called “building insulation materials”.
Oxidised bitumen is obtained by blowing oxygen at 250 ° C to distilled liquid bitumen.
Oxygen “hook up” with each other bitumen molecules and creates a kind of three-dimensional network in its mass.
Grout based on corrosion inhibitors.
It ‘a sloped roof with a maximum gradient of > 5%.
PLASTIC OR PERMANENT DEFORMATION
Plastic deformation is the permanent and consequently not elastic deformation that a body undergoes under the action of a given applied load and thus is related to its value. It consists of an instantaneous deformation and a slow deformation which grows slowly with time until the load is maintained.
The Portland cement is one of the most important hydraulic binders and it is obtained by mixing clinker and dihydrate gypsum
RECLAMATION OF ASBESTOS CEMENT (Ministerial Decree of 20 August 1999)
Treatment of surfaces containing asbestos cement with penetrating and / or coating products. When the treatment is applied it penetrates the asbestos fibres, binding them to the substrate and creating on the surface an impermeable and tough film The products used must comply with the performance characteristics specified in the Italian Ministerial Decree of 20 August 1999, Appendix 1, for encapsulating coating type A. In particular, the average thickness of the dry encapsulating coating shall not be less than 300μm and at no point be less than 250μm.
The application of a barrier seal that separates the asbestos from the occupied areas. Therefore, before applying new covering elements (insulation layers, new sheets) the asbestos-cement sheets should be treated with products that inhibit any detachment of amino fibres during operations on work site and contribute to the treatment of the confinement to inhibit the detachment of the same fibres. The products used must comply with the performance characteristics specified in the Italian Ministerial Decree DM of 20 August 1999, Appendix 1, for types C encapsulating coatings. In particular, the dry encapsulating coating thickness shall not be less than 200µm and no measurement shall be less than this value.
Among the precautions to be used while carrying out such intervention, there is the surfaces treatment with impregnating products that inhibit the separation of asbestos fibres during the work-site operations. The products used must comply with the performance characteristics specified in the DM 20/08/99, Appendix 1, for encapsulating coatings of type D. In particular, the encapsulating coating must be of a colour contrasting the substrate colour. The supplier shall indicate the dry film thickness, the amount to be applied per square meter and the drying time.
Reinforced concrete is concrete in which an appropriate steel reinforcement has been incorporated, while casting it, to increase the strength in tension and torsion. The reinforcement shall be realized taking into consideration all possible electromagnetic interferences may be induced by the reinforcement itself removing all closed metal meshes and earthing so that all individual parts are equipotential. A proper reinforced concrete manufacturing will prevent carbonation and any possible oxidation of the metal parts.
Rising Damp occurs as a result of capillary suction of moisture from the ground into porous masonry building materials such as stone, brick, earth and mortar.
Formation of a salt deposit on a wall surface. Generally found on walls subject to rising damp, but also in cases of acid rain infiltration and broken pipes.
Finishing operation performed by a metal toothed scraper to crumble the surface of the material when it is in the process of hardening.
The ability of a material to evenly spread on its own over a laying surface, producing a perfectly flat surface, free of irregularities.
A peculiar characteristic of cement adhesives that allows the imprint of the notched trowel to be completely levelled under the weight of the tile by lightly pressing . Moreover, it allows to obtain a full contact surface between the substrate, the adhesive and the tile with minimum effort.
Treatment for façade materials that underwent degradation due to their high porosity and low or no water-repellency and that consecutively became flaky. Essentially, it is about hydrophobic materials capable of slightly binding disaggregated superficial layers with layers that are in good condition, so as to prevent their loss due to the persistence of atmospheric actions.
Finishing performed with a sponge float (satin finish) or plastic spatula (ribbed finish) on stricken off and smoothed products.
It is a waterproofing product primarily derived from coal distillation for the production of town gas.
It is the ability of a homogeneous and isotropic medium to transmit heat when heat exchange occurs exclusively by conduction.
Three-dimensional Increase in the volume of a material, as a result of temperature changes. This particular attitude of each body is indicated by the coefficient of expansion: the coefficient indicates the change in millimeters of a body for every meter of its length and for each degree of temperature change. The coefficient of expansion of the concrete for instance, is variable depending on the nature of the aggregates and the quality and quantity of cement, the average one does not differ very much from that of steel, which is either 1.2 x10-5 m / ° C or 0.012 mm / ° C, and this makes the steel-cement coupling possible in concrete.
TO BUSH HAMMER / BUSH HAMMER
To work marble using a bush hammer, namely a masonry tool used to texturize stone and concrete. Bush hammers exist in many forms and sizes, but the basic functional property of the tool is always the same – a grid of conical or pyramidal points at the end of a large metal slug. The repeated impact of these points into stone or concrete creates a rough, pockmarked texture that resembles naturally weathered rock.
System consisting of a usually waterproof continuous film with water vapour impermeability properties. It is used to prevent the passage of water vapour from the interior side of exterior roofs and walls to the outside. It must therefore be a material resistant to water vapour diffusion, in order to be able to monitor any possible phenomena of condensing steam and prevent this from occurring in the insulating layer.