- Facing brick:
- generally, a rectangle, obtained through moulding, drying and firing a clay paste at a high temperature. Its largest dimension is no greater than 29 cm, with the distinctive feature that some of its surfaces will not be covered.
- the stable organisation of bricks, manufactured through a generally manual construction process by applying a binding technique using mortar.
- exterior wall covering of a building, which is generally the main covering.
- a moulding of the clay paste which gives a definite shape to the piece, by forcing the paste to escape through a nozzle.
- the bonding rule which governs the way bricks should be laid on a brickwork structure to guarantee constructive unity.
- dimensions that correspond to the larger or long arris.
- the dimensions that correspond to the intermediate or wide arris.
- the dimensions that correspond to the smaller or height arris.
- largest surface of the brick (stretcher x thickness)
- medium surface of the brick (stretcher x thickness)
- Header face:
- smallest surface of the brick (header x thickness)
- Bed joint:
- continuous joint made with mortar which is applied between two courses or ring courses, which are generally horizontal.
- Heading joint:
- joint formed by the mortar found between two successive pieces of the same course or ring course. Generally discontinuous from one vertical course to another.
- the space between two continuous elements of the construction or parts of the construction.
- exterior face of a wall.
- interior face of a wall, or surface below a lintel or arch.
- Element or group of construction elements which define the upper closing space of a gap with a straight intrados.
- Lintel superior:
- structural or resistant part of a lintel.
- each one of the vertical elements which laterally limit a gap and serve as a lintel support.
- face of the jamb, which is at a right angle to the wall covering.
- Guarding wall or parapet:
- lower closing gap of a window space, which constitutes a protective parapet.
- Window sill:
- lower plane of the window gap that defines the corona of the parapet.
- small wall which is built above the cornice and which hides or limits the roof.
- ridge or small roof place on the top of a wall to prevent water penetration into the wall.
- a mixture of one or more inorganic conglomerates (cement and/or lime), sand, water and sometimes additives. Used in bricklaying to secure the bricks in place.
- elements used to tie or link two brickwork surfaces or walls together. Their use provides greater wall stability.
- Compression resistance:
- Ethe breaking stress of a compression force at the perpendicular axis of a supporting face or surface of the brick.
- Water absorption:
- the percentage of water taken on by the corresponding sample, referred to as the weight of the fired dry brick.
- the initial speed with which the brick takes on water through capillary action, measured in grams of water absorbed per cm2 of surface in contact with water during one minute.
- stains, generally of a whitish colour, appearing on the visible surface of the brick. These are formed by different types of salts, mainly sulphates, but can also be carbonates and chlorides.
- Expansion due to damp:
- an increase in the dimensions of many materials, produced by the effect of damp.
- Frost resistance:
- the behaviour of bricks when exposed to frost action, indicative of their durability.
- a chemical product which gives ceramic materials water-repellent properties, and reduces the rate of water entry into their capillary system.
- receptionWhen the bricks arrive at the work site, they should comply with the conditions specified within current regulations. Below is a series of recommendations relating to the reception of bricks onto the work site, some of which are included in the document cited.
- - Reception of materials should be carried out by the site managers or by a delegated and duly authorised person.
- - The dispatch note and the packaging should contain the name of the manufacturer and their commercial logo, the technical properties of the bricks and the AENOR trademark.
- - If required, before the start of the supply process, the supplier will provide the site management with two factory samples taken at random. One of these should be sent to the laboratory to verify that it complies with the specifications provided, while the other sample should remain on site to be used as a reference when receiving different consignments.
- - When the materials arrive on site, the management should check that: the bricks have arrived in good condition, the material is identifiable according to the specifications in the delivery note and on the packaging, and that the products correspond to the accepted comparison sample.
- - When the tiles supplied are covered by the AENOR trademark, the site management will be able to simplify reception of the consignment by doing away with the control trials.
- - Any anomaly detected in the tiles supplied should always be communicated to the manufacturer before they are used in the building work.
storageStorage of the bricks on site is an important phase to keep in mind so as to avoid the development of subsequent problems. Follow the recommendations below:
- - Unloading should take place directly by the floor levels of the building, and the pallets should be situated close to the pillars of the structure.
- - The bricks should not be in contact with the ground as they may absorb damp, soluble salts, etc. which may cause the appearance of marks and efflorescences after they have been laid.
- - The bricks should be stacked on clean, flat, horizontal surfaces where there is no likelihood of accumulating water.
- - Water-resitant bricks should be stacked completely dry. The pallet’s plastic protection should be removed at least two days before they are used on the building works.
Laying the bricks on siteWhen laying the bricks, pieces should be selected randomly, working with the maximum accuracy and care.
- - Begin by tracing the base of the wall to be constructed, preparing the first and second course without mortar.
- - Firstly, lay the corners, paying special attention to the gaps, and lay these for the first course.
- - The joints should have a regular distribution and be of equal thickness.
atmospheric conditionsIt is convenient to be aware of the local atmospheric conditions where the work is taking place. These will influence both the brickwork design and the choice of building materials, while keeping in mind the influence of the weather during the build. Do not lay brickwork during heavy rain, winds that may endanger the stability of the recently erected brickwork, or when temperatures are below 4°C protection of completed brickwork In adverse weather conditions, the following precautions should be taken against:
RainRecently-constructed brickwork needs to be protected from the rain with plastic sheeting, particularly on the upper parts. This will avoid:
- - The fine particles in the mortar being washed away by the rainwater thereby considerably reducing its physical properties.
- - The salts and other substances being dissolved, causing the appearance of efflorescences and stains.
- - The water eroding the mortar joints and deteriorating the functional and aesthetic appearance of the enclosure. When it rains, also take any necessary steps to avoid rainwater accumulating on the slabs, terraces and roof spilling onto the brickwork, by directing it to a convenient place away from the brickwork.
FrostWhen it is cold, precautions should be taken to ensure that the mortar is not affected by frost during its preparation and during construction of the brickwork as, due to its high water content and the reduced joint thickness, it is very sensitive to frost.
- - SIf the mortar freezes before it has hardened, its adherence, resistance and durability will be reduced.
- - If it freezes at the beginning or during the working day, work should be postponed, and the recently constructed brickwork should be protected with insulating blankets and plastic sheeting. If it is frosty before the work day begins, a detailed inspection of any walls constructed during the previous day should be carried out. If any parts of these have been affected by frost, they should be demolished and re-built when the weather conditions allow.
- - When anti-freeze additives are used in the mortar, the manufacturer’s instructions on amounts to use, conditions for use, etc. should be followed carefully, ensuring that they do not have any adverse effects on the brickwork.
HeatIn extremely dry and hot weather the brickwork should be kept damp to avoid the rapid evaporation of water in the mortar. Any such evaporation would alter the normal setting process and the hardening of the mortar, causing cracks due to shrinkage. Be careful not to wet the brickwork excessively, and do not use running water or pressure, as this could remove the mortar and thereby weaken the joint.
- Below are the steps to follow for the erection of facing brickwork.
- placing the levelling poles and counterweightsPlace the counterweighted levelling poles firmly with all their surfaces at right angles, at distances of no more than 4 metres apart and at each corner or pilaster Mark the vertical spacings, placing a tensioned line between them and resting this on the marks to use as reference points for laying the horizontal courses correctly. The levelling poles should also be marked with the levels of the railings and lintel gaps.
- laying the bricksBefore moving on to laying the bricks, check that the supporting surface is perfectly clean and level so that it provides the correct starting point for the brickwork. Place the levelling pole line so that it coincides with the upper angle of the course to be laid, using it as a reference to ensure the horizontal alignment of the course. To achieve the maximum homogeneity in size and colour, use bricks in staggered batches from 2 to 3 packets at a time. Always place the bricks by rubbing them into the line. Do this by spreading a sufficient quantity of mortar on the base of the course to be laid, or the last course, so that that bed joint and the head joint are of the specified dimensions and level these off with the trowel. Place the brick on the mortar at a horizontal distance to the next laid brick of approximately five centimetres. Press vertically on the brick and rub it towards the laid brick until the mortar spills out of the bed and head joints, and remove any surplus mortar with the trowel. Do not move any of the bricks after completing this process. If it is necessary to adjust the position of any brick, remove it, and also remove the mortar around it. Once the first course has been completed, place the line in the next mark and proceed with the next course, and all other courses in the same way. Whenever possible, the brickwork should be raised by horizontal courses throughout the whole construction.
- creating the joints
- mortar jointsAt the layout stage, determine the thickness of the mortar joint, which should be constant throughout the entire brickwork. Using prepared mortars is recommended to guarantee that the properties of the mortar available will be consistent during the development of the whole build. The joints require a controlled and correct amount of mortar filling. A deficient use of mortar will, in times of rain, allow the water to penetrate towards the intrados of the wall when it finds any vulnerable point, which generally seems to be a badly worked mortar joint, or a badly finished joint. For this reason, it is very important to create the vertical joint with the correct thickness throughout the brickwork, as the common practice of only blocking the joint on the outside will not assure the waterproofing of the wall covering. In brickwork erected without mortar, maintain a minimum separation of 2 mm between header faces of two contiguous pieces. From a technical point of view, contact between bricks is not advisable, as any movement of the façade may cause the concentration of stress at those points, which will damage the pieces. The joint should be made with the maximum precision and according to the project specifications relating to thickness, form, texture, colour, etc. As joints make up 20% of the visible wall surface, they will influence the final appearance of the façade. The shape and definitive appearance of the joint is obtained through its jointing. This process is carried out when the brickwork is being laid and before the mortar has set, finishing the joints with a jointing knife or trowel. In this way the behaviour of the mortar and the aesthetic appearance of the façade is improved. When finishing the joint, be careful not to drag the mortar. In order to achieve the maximum uniformity in the colour of the joints, it is useful to always carry out the jointing immediately after carrying out the work, first making the vertical joints, which will give a cleaner finish to the horizontal joints. .
- cutting bricksIf no special pieces are available when constructing facing brick walls, it is normal practice to cut any required pieces whether to adapt the layout or to resolve particular points. Keep in mind that you should never use less than 1/2 a brick. Below is some advice to follow when you need to cut bricks.
- - Do not cut the bricks with a trowel, as the cut will be imperfect and it will require the breaking of various pieces to get an acceptable cut.
- - Bricks should be cut on a cutting table, which should always be clean, and provide a stream of water over the cutting disk
- - When water-resistant tiles are cut, these should be completely dry, leaving them for 48 hours after cutting before laying them so that any dampness caused by cutting is completely dry.
- - Once the piece has been cut correctly the visible surface needs to be cleaned and then the brick should be left to dry before being used in the brickwork.
- - Clean the cutting machine to prevent the bricks from getting dirty, particularly each time a new colour brick is cut.
- - Choose bricks to cut from each consignment being laid. In this way, any changes in colour between cut bricks and whole bricks will be avoided.
- cleaning the completed brickworkBoth the bricklayers and other labourers working on the construction should take care not to stain the brickwork. The task of cleaning the brickwork should be carried out when the construction is completed. Below is a list of recommendations to follow in order to achieve a thorough and easy clean of the brickwork:
- - Try to avoid staining the brickwork during the building phase and it will be easier to clean at the end.
- - Do not use scrubbing pads or wet sponges to remove the mortar chippings while erecting the brickwork.
- - Protect the brickwork with plastic sheeting or other elements when other work is taking place nearby that may cause it to get dirty, for example, the application of spray mortar, paints, polishing of terrazzo flooring, tipping of debris, etc.
- - Before cleaning, the brickwork should be completely dry.
- When necessary, the cleaning procedure should be as follows:
- - Dampen the area to be cleaned with water.
- - Apply a cleaning product which is specific for cleaning bricks, or mix one part of commercial hydrochloric acid with ten parts of water, and apply to the visible surface of the brick.
- - Brush briskly in the direction of the bed joints.
- - Rinse off with as much water as is necessary and with sufficient water to rinse away the dissolved salts.
- - To avoid any remaining acid continuing to react with the brickwork, the cleaning and rinsing process needs to be carried out simultaneously and without delay between the two stages.
- - When using nitric acid for cleaning, keep in mind that it may oxidise some types of bricks and change their colour.
- - Prior tests on the bricks should be carried out to establish the effectiveness and reaction of the acid or cleaning product on the brick.
- - To clean efflorescences, try to remove them beforehand by dry brushing, as this may be enough to eliminate them.
- - When using a jet of pressurised water, carry out a test to check that the mortar joint will not be damaged.
- - Before starting the cleaning task, protect all the elements of the façade which may be damaged in any way.
- - Start cleaning at the top of the façade to avoid dirtying areas that have already been cleaned.
- - For all the reasons given previously, entrusting the cleaning task to specialists is recommended.
- a) regulations
- All our bricks are subject to UNE regulations, which require obligatory compliance and are included in the brick regulation 771-1. Therefore the UNE regulation is of an obligatory nature and specifies the values that need to be complied with for each one of its characteristics in order to assure the quality of the product and of the construction in which they are used. Due to the obligatory compliance, all our bricks carry the EC standard for ceramic products. The EC standard indicates product compliance with the essential regulations from the Construction Products Directive (89/106/CEE) relating to it, and with the specifications of the harmonised standards that apply to it. The EC standard is an essential requirement for products to be marketed within any State of the European Union. The responsibility for a product being in possession of the EC standard falls to the product manufacturer. To obtain the EC standard, the following tasks need to be completed:
- - Carry out the initial type trials
- - Definition, development and implementation of the Manufacturing Process Control (MPC)
- - Trials for the samples taken from the factory in accordance with the trial plans established in the MCP
- - MCP Certification and monitoring of this
- - EC declaration of conformity
- - EC product standard The trials should be carried out by a Member State Trials Laboratory registered to carry out this work. The EC standard should appear on the packaging and on a sheet which should include additional information referring to the product characteristics. There are product standards, also of a voluntary nature, that guarantee the quality of the product holding this distinction. The most important product standard is the N Standard from AENOR. The requirements for the N Standard are the points indicated in Annex V of the Standards Regulations RP 34.00, which entail a series of controls both in the production and in the manufactured piece. The control of the final products is subject to internal control by the manufacturer and external control which needs to be carried out by accredited laboratories. To obtain the N standard, an external audit of the quality system carried out by an accredited body must be successfully passed, as well as a further production inspection every six months. In order to obtain the AENOR N standard, all our tiles have undergone a control process and have been manufactured according to a quality system which is periodically audited. All manufactured products and the quality control system for the manufacture of roofs with clay tiles comply with all Spanish regulations, and due to this, we possess the N standard. All manufactured products comply with the legal requirements of the European Directives 89/106/EEC (and the later modifications in Directive 93/68/EEC) for “Construction Products" and, due to this, we possess the EC standard. We have a firmly-established quality control system which involves employees and managers om all levels on a daily basis, with the objective of improving the product, production safety, and the maximum care for the environment. Our technical development department and our own laboratories work daily on projects whose aim is to offer innovative products and improve the characteristics (colour, finish, resistance, ease of attachment, etc.) of existing tiles. We collaborate with the best architects on innovative projects, such as the re-creation of the Fisac brick, or the creation of exclusive pieces for a ventilated façade, such as the one installed at the Toledo Archive. Both companies have the Integrated Environmental Authorisation, which certifies that they comply with all the environmental requirements stipulated by current legislation and the Environmental commitment of the company. Prevention and Environmental standards ISO 9001, OSHAS 18001 and ISO 14001. As our products are certified by both the EC and the N standards, there are certain pathologies which may arise due to poor worksite practices.
- b) the most important controls
- MEASUREMENT OF DIMENSIONS AND DISTORTIONS
- How should each dimension be measured?
By using a gauge, ruler or metric tape measure with sections no smaller than 1 mm. Proceed as indicated in the following figures:
- Which standards indicate how to measure dimensions and distortions?
The UNE 772-16 standards for dimensions and UNE 772-20 for distortions - Which standard indicates acceptable values?
The UNE 67019 standard. The values guaranteed by the manufacturer are those stated in the EC standard and the AENOR technical file, which should be the same.
- What are the dimensional tolerances?
• On the nominal value
STRETCHER 240 + (≥) 4 mm 236 a 244 mm HEADER 114 + 3mm 111 a 117 mm THICKNESSES 48 + 2mm 46 a 50mm 38+2mm 36 a 40mm 37 +2mm 35 a 39 mm 68+2mm 66 a 70mm
• • On the dispersion (average difference and the most distant value) STRETCHER AND HEADER 5mm THICKNESS 3mm
- - What are the tolerances within the distortions?
Face: 3mm Edge: 2mm Header face; 2mm
- - What is "caliche"?
This is a calcium oxide grain produced during firing which increases in volume and causes spalling when exposed to a damp environment.
- - Where does calcium oxide come from?
It is formed by firing calcium carbonate grains in limestone and marine fossils.
- - Which standards are used to determine the calcium carbonate contents?
The standard UNE 67039 EX.
- - How is this standard applied?
Cut the edge facing on 6 pieces (with a surface greater than 100 cm2) and place them on a container under steam for 3 hours. The distance between the edge facings and the water should be between 5 and 10 cm.
- - What is spalling?
It is the cracking produced by a caliche of medium dimensions, that is, over 7 mm.
- - What is a spalled piece?
It is a piece with more than one spalled area (a crack with dimensions over 7 mm) on its facing edges..
- - What standards indicate the specifications for a facing brick with calcareous content?
The standard UNE 67039, which states the following:
• Of every 6 pieces, the number of spalled pieces should be no more than one..
• No spalling should have an average dimension greater than 15 mm.
- - What is the pressure resistance of a brick?
It is the breaking pressure created by compressive stress on the perpendicular axis of the face or supporting edge of a brick.
- - Which standard describes the compressive resistance trials for clay bricks?
The standard UNE EN 772-1.
- - What properties should the machine used comply with?
It should be a press which contains a ball and socket joint, and steel plates which guarantee a uniform distribution of load.
- - How is the standard applied?
Firstly, the six bricks need to be re-faced by testing them with a layer of mortar with a quantity of cement and sand of 1:1. This is done to achieve a flatness of the faces where the mortar load will be applied (to avoid any irregularities in the bricks). After 24 hours, if re-facing with sulphur, or when the mortar setting time is reached, the mortar is applied in the centre of the test brick face at a speed of less than 20 MPa/min. The value obtained is multiplied by a number called the shape factor (the “Lambda symbol”) and this gives the normalised compressive resistance. This factor is extracted from a table included in the Standard and is based on the header and thickness.
- - What is the equivalence between the different units used for compressive resistance?
Three units are used:
• Megapascal, MPa.
• Decanewton per centimetre squared, daN / cm2.
• Kilogram force per centimetre squared, kgf / cm2. 1 MPa = 10 daN / crn2 = 9.8 kgf / cm2 Example: A brick with a compression resistance of 23.5 MPa, has 235 daN /cm2 y 230.3 kgf / cm2.
- - Which standard indicates the minimum value for compression resistance for a perforated facing brick, and what is the minimum value?
The standard UNE 67019 states that the compression resistance will have a characteristic value greater than 100 daN / cm2 (or 10 MPa).
- - What is absorption in a brick?
It is the percentage of water taken on by the corresponding sample, referred to as the weight of a fired, dry brick.
- - Which standard defines the absorption trial?
Standard UNE EN 772-21.
- - What is the process to follow?
The sample size is 6 bricks, which should be dry, for which they should be kept in a stove at 110 ºC; then cool them in the air. Place them in a deep tank and allow the bricks to immerse gradually (over a time span of 3 hours at least). When the weight does not vary more than 0.1% after two consecutive weighings, the absorption can then be calculated.
- - How is this calculation made?
The weight of the soaked brick is deducted from the weight of the dry brick, and then divided by the dry weight and multiplied by 100.
- - Which standard gives the acceptable absorption value?
Standard UNE 67019 only states that the manufacturer should provide the average absorption value if this is requested.
- - Is there any value we should adhere to?
Yes, the one provided in the technical files, in the column of “Values guaranteed by manufacturers”: After water-resistance, all our bricks have an absorption value of <6 % except for the Dune and Vison models.
- - What is suction?
It is the initial speed at which the brick takes on water by capillary action, measured in grams of water absorbed by each cm2 of surface that is in contact with the water over the space of one minute.
- - Which standard indicates how the suction trial is conducted?
Standard UNE-EN 772-11.
- - - What is the process for this?
Three bricks are dried to a constant weight in a stove at 110 ºC. Then, the face area is calculated, discounting any perforations. Add water to a tray until it covers some supports for the bricks, around 3 mm. Place each piece on its face onto the supports and leave them there for one minute. After this, dry the piece superficially and weigh it.
- - How is suction calculated?
After the trial, the weight of the brick is deducted from the weight of the dry brick and this is divided by the face area.
- - How does suction affect water-repellent bricks?
It is the only physical characteristic which is modified by the water-resistant treatment, which reduces by 80-90%. The water penetrates the brick much more slowly although, over a long enough period of time, it could become saturated.
- - What are efflorescences?
These are stains, generally whitish in colour, which appear on the brick face. They are formed by different types of salts, mainly sulphates, but also carbonates and chlorides.
- - How can you avoid the soluble salt content in the raw materials of bricks?
By adding a chemical product called barium carbonate. This reacts with the salts and makes them insoluble, so the water cannot carry them to the face of the brick.
- - How do the efflorescences appear during the brick laying process?
The water in the mortar dissolves the various constituents (cement, sand, etc.), it enters the brick through capillary action and then evaporates through the brick face, depositing the salts it has transported.
- - How can you guard against salts from external sources?
We have developed a water-resistant treatment (which will be discussed in BOOKLET No 9) to protect against salts from external sources (cement, sand, topsoil, etc.).
- - Which standard indicates the brick rating in reference to efflorescences, and what should the rating be?
Standard UNE-EN 67029 EX states that it should be a maximum of NO EFFLORESCENCE.
- - Which standard defines the trial method for determining the behaviour of faced bricks when dealing with efflorescences?
Standard UNE 67029 EX.
- - What is the trial process?
Six bricks are taken, one is kept as the control and the trial is carried out on the other five. The bricks should not have any external adhesion. The trials are carried out in a room with a relative humidity of between 60 and 80%, a temperature between 15 and 25 ºC and without any air currents or drafts. The 5 bricks are placed in a container with a closing system which only leaves the brick edge showing; bricks should be separated by at least 5 cm (see figure). Add distilled water until 2.5 cm of the lower part of the bricks are under the water. After seven days. Lift out the bricks from the tray and leave them 24 hours in the environment described previously. After this, place them for another 24 hours in a stove at 110 ºC + (approximately) 5 ºC.
- - How can bricks be defined?
Brick with no efflorescence (BNE) Brick with light efflorescence (BLE) Brick with efflorescence (BF) Brick with heavy efflorescence (Heavy BE)
- - What factors should be considered to assign those definitions?
The intensity of efflorescence and the surface affected.
EXPANSION DUE TO HUMIDITY
- - What is expansion due to humidity?
It is an increase in the dimensions of a multitude of materials caused by the effect of humidity.
- - Is there any value in the regulations that we should observe?
There is no reference to a maximum value for humidity expansion that the face of a brick should comply with. Observe the value in the technical file.
- - How long does expansion due to humidity take to occur?
It is a slow process which naturally takes place over various years. Nonetheless, it is known that during the first 2-3 weeks after being fired, 25% of the total expansion will take place: a brick with a total expansion of 0.6 mm/m will have expanded 0.15 mm/m in some 15 to 21 days.
- - - Is there any advantage to giving the bricks a water-resistant treatment to prevent their expansion due to humidity?
Yes, when placed in contact with water (they become water-repellent by being immersed) you will observe that even in the first week, their expansion accelerates between 15 and 25%: this way, less expansion will take place at the building site.
- - What method can be used to find out about expansion without having to wait so long?
The one described in standard UNE 67036.
- - What is this method?
Cut six sample pieces of 200-250 mm in length, 30-60 mm in width and no larger than 30 mm. Then, perforate the ends of two semi-circular cavities which will allow the adequate placing of the following measurement apparatus: Firstly, insert the samples into a stove for 24 hours at 110 ºC. Then re-fire them for 6 hours at 600ºC, with a minimum time of 2 hours to reach that temperature. Cool them in a dessicator and measure them (L1). After this, place them in a bath of boiling water for 24 hours. Let them cool to ambient temperature and measure them again (L2).
- - Are all cases of fissures and cracks which appear in brickwork due to humidity expansion?
Recently, the allegation that humidity expansion is the cause of all brick problems has become a simplistic claim. However, you need to keep many other factors in mind:
• Thermal expansion
• Settlement of the building
• Cementing defects
• Structural movement
• Slab deformities
• Lack of use of expansion joints or placing at distances greater than those recommended (15 metres)
• Incorrectly made expansion joints
- - What is being determined by the frost trials?
The behaviour of the bricks affected by frost action, which indicates their durability.
- - Why is frost action destructive?
The water penetrates the capillarity of the brick with ease; any drop in temperature below 0 ºC will cause it to change into ice, which occupies a greater volume and, therefore, it creates interstitial pressure.
- - - Which standard describes the trials method for frost?
Standard UNE 67028 EX.
- - What is the method used?
Six sample pieces are placed in a tank of water at a temperature of 15 ºC + 5 ºC for 48 hours, so that they are completely immersed in the water for a period of 3 hours. After this, they are removed and left to drain for 1 minute and then placed in a freezer at -15 ºC + 5 ºC for 18 hours. The sample pieces should remain at least 11 hours at -15 ºC + 5 ºC. After this, return them to the thawing tank for another 6 hours. This freeze-thaw cycle should be repeated 25 times. During any period in which the trials are interrupted, the sample pieces should be kept in a refrigerated chamber. Cycles of 5 hours of freezing and 1 hour of thaw can be used, as long as the chamber is capable of reaching -8 ºC APPROXIMATELY ºC in a maximum of 2 hours after the bricks have been placed in it. The speed of the decline in temperature, in both cases, should not be more than 20 ºC / hr.
- - How should the bricks behave during the frost trials?
After the 25 cycles, breaks, exfoliation, spalling of an average size of 15 mm, or the appearance of more than 1 fissure are not acceptable. If any of these defects can be seen, the brick is defined as frost damaged (then the laboratory report should be accompanied by photographs showing the defects observed). If no damage is observed, the brick is defined as NOT FROST DAMAGED. .
- - Which standard states the definition that a facing brick should have
Standard UNE 67019 states that it should possess the definition NOT FROST DAMAGED.
- - What is a water-repellent?
It is a chemical product that gives ceramic materials the ability to repel water and reduce the rate of water entry into their capillary system. The water-repellent molecules have two extremes: One fixes to the material and the other, which stays on the outside surface, repels water in the same way as oil (SEE FIGURE).
- - Are all water-repellent treatments the same?
No. Firstly, different chemical products can be used (silicates, silane siloxane, etc.); it can also be done by immersion or pulverisation on the visible face; lastly, the immersion time and the concentration of the product used can vary, etc.
- - Why was the faced water-repellent brick developed by the Diaz Redondo Group?
To deal with the different efflorescences due to salts caused by external sources, the work site, and those which originate from the basic mortars.
- - Will the water-repellent brick never have efflorescences?
The water-repellent brick reduces the entry rate of water into the brick (suction) by more than 80%; this is sufficient to force the drying of water from the mortar through the heading joint and it is here that the salts are deposited. Therefore, in normal work and project conditions, no efflorescences will develop. The water-repellent brick should not be considered as a magic solution for any construction idea: the intrados overhang on a terrace and window boxes need to be waterproofed, use coping with guttering on the tops of walls, systems which carry the water from the roofs away from the facades, etc.
- - - What other physical characteristics, apart from suction, are changed by the ICD water-repellent treatment?
Suction will be reduced, the brick is always defined in trials as without efflorescences. All other properties do not undergo any variation. In particular, the frost trials carried out in our laboratories have gone beyond eighty freeze-thaw cycles without observing any damage in the pieces. The absorption also does not change: with a sufficient immersion time, the brick will take on the same quantity of water (see diagram).
- - What other advantages does the water-resistant brick possess?
Its behaviour is improved when faced with problems caused by the entry of water into the brick interior: Resistance to freeze-thaw cycles, Thermal insulation of walls (by avoiding cooling produced by the slow evaporation of rainwater) Hinders dust incrustation. Impedes the development of mosses and lichens
- - Is it true that the adherence of mortar to the water-resistant brick is less than to a normal brick?
Yes, but in the same way that it is reduced in any low-suction brick, such as stoneware bricks: they are fired at higher temperatures, we use a water-repellent.
- - How long does the water-repellent treatment with the chemical products used in our bricks last for?
Studies carried out by the French CTTB (Centre Tecnique de Tuiles et Briques, Technical Centre for Tiles and Bricks) have demonstrated a permanent water-repellent effect on exposed materials during a period of eleven years. Weathering tests carried out in a Xenon chamber by the Toledo Centre for Fired Clay (Centro Tecnológico de la Arcilla Cocida de Toledo) (at the request of HISPALYT, the association of manufacturers), have shown that after ten years, between 80 and 90 % effectivity of the treatment remains. With reference to temperature resistance, when water-repellent bricks are placed at 200 ºC for 48 hours they do not suffer any deterioration in behaviour.
Our products are certified with both the EC and N standards, nonetheless, there are pathologies that may arise from incorrect brickwork.
Building pathology is the area of construction that studies the defects and problems that appear within the building during or after the build; their causes, evolution and symptoms. The most common pathologies are damp, frost, efflorescences and expansion caused by damp.
Damp is one of the most common pathologies that appear due to the incorrect erection of the façade. There are different types, such as damp caused by incorrect building techniques, façade damp, damp caused by capillary action and accidental damp.
Damp caused by building technique, also known as construction or worksite damp, appears during the building process of the unit, and manifests on the surface of the pieces in the form of stains or efflorescences from the mortars, from water used during construction or used previously for dampening ceramic materials, from the curing of mortars and cements or from rain falling on the building.
This type of damp has its origin in the water used during the construction process, which may originate from water used for mixing the mortar, water used in the prior dampening of ceramic materials, in the curing of mortars and cement, or from the rainwater taken in by the building during its construction. This water tends to disappear during the natural drying out process, and for this reason, this type of damp should not cause any problems.
The problems arise if, before the drying out process is complete, the evaporation of water to the exterior of the building is restricted.
To avoid the appearance of this type of damp, allow the natural drying out of all worksite units, particularly before applying any layers of wall coverings or paint which may hinder this process.
Damp in facades appears due to filtration or penetration of water with the subsequent appearance of damp stains
The causes of water entry into a building through the facade vary according to the area where this takes place. Critical areas where water entry may occur are: the base of enclosures, where the entry of water can be produced due to the existence of cavities or any type of crack in the brickwork; on areas of plaster without openings (such as windows), water entry may be caused by the existence of cracks, fissures or cavities in the joints, or due to the excessive permeability of the mortar; water accumulates in the joints between slabs and this facilitates its filtration towards the interior; in gaps within the façade water entry is facilitated by the superior lintel of a gap without guttering, by a lack of sealant in the joinery work where it meets the enclosure, in the guttering without an exterior gradient. Additionally, water penetrates into the tops of walls due to the existence of very common errors, one of which is the use of porous copings and gutters with little overlap over the brickwork, through joints that are too open and have no gradient or guttering. Another entry point is the lack of, or the position of existing eaves without guttering for collecting rainwater from the roof.
To avoid the filtration or penetration of water through the façade, it is essential to protect the brickwork with water-resistant wall covering materials in areas where there is a potential for splashing water during the building of base boards. Dampen ceramic pieces before placing them to avoid excessive suction of water from the mortar mix. Use the appropriate mix and plasticity of mortar when laying the brickwork. Design and lay the finishing pieces for brickwork, such as copings, guttering, etc.
Damp caused by capillary action is produced by water rising through the capillary structure of the materials. This is due to the phenomenon of existing superficial tension between the liquid and the walls of the structure containing it. The existence of damp due to capillary action can be seen in the surfaces of the walls in the form of stains and, occasionally, in the presence of salts which have been carried up by the water as it rises, forming efflorescences or crypto efflorescences.
The most common errors in laying brickwork in which damp patches later appear are: the impact of brick walls directly supported by foundations or those in contact with the ground, the omission or inadequate use of waterproofing elements within the plans, the laying of continuous wall coverings without observing the discontinuity of the waterproof barrier, and the inadequate making of water channels which cause damp on the foundations or brickwork. These are the main causes for the appearance of damp
To avoid the problems of capillary action, the following measures need to be carried out: Place a horizontal waterproof barrier throughout the whole thickness of the brickwork. Create adequate drainage in the foundations of walls that are in contact with the ground. Ventilate brickwork in spaces within cellars and under floors. Avoid the design of elements in walls that may accumulate water.
Frost is another common pathology. One of the most interesting properties of fired ceramic bricks is their durability, maintaining their aesthetic and functional characteristics over long periods of time without any maintenance requirements.
Their durability is based on their good resistance to atmospheric agents, particularly their resistance to frost damage.
Frost damage is defined as a low resistance to the frost cycles, and this can be seen in some ceramic pieces. It causes brick deterioration by creating internal pressure due to the water increasing in size as it freezes in the brick pores during times of frost.
The behaviour of bricks against frost cycles depends on three factors: the nature of the ceramic material, the design of the building and climatic variables.
To avoid the effects of frost it is important to follow the recommendations below, which will prevent frost damage:
- - - Always use pieces that comply with that specified in the current regulations relating to frost damage.
- - - When designing buildings in areas of potentially hazardous climates affecting the durability of ceramic pieces, it is convenient to boost the evaporation of water absorbed by the pieces. Expansion caused by damp is another pathology that may appear due to a poor build of the brickwork. Bricks have the ability to increase their dimensions as they capture environmental humidity. The consequences of this will have an impact on the brick. The expansion of bricks caused by damp and the impact of this on the building will depend on the following factors:
- - The type of clay used as a raw material
- - The temperature and firing cycle for the pieces
- - The time elapsed from firing the piece to its use on the construction
- - The level of damp
- - Its use on site
- - The distance between joints in the brickwork The expansion value, its impact on the building works and the scale of the phenomenon will depend on the combination of these factors. To avoid expansion caused by damp in plans and building works it is important to consider the following recommendations:
- - Do not lay bricks with high humidity expansion values before their potential expansion has been reduced to the appropriate values, and never use if less than two weeks have passed since their manufacture.
- - Always place joints between elements which restrict the movement of the brickwork.
- - Check the distances between joints.
- - Make adequate calculations for joints.
- - Correctly calculated and correctly made movement joints will absorb any potential expansion.
- - Use mixed cement and lime mortars on the bricks.
- relating to on site installation
- Avoid any direct contact between the brick and the ground surface in storage areas in order to prevent contamination with soluble salts. To obtain maximum uniformity in wall colour, bricks should be used from various packets simultaneously, destacking each packet in a staggered manner to achieve a mixture of the different layers. This recommendation is particularly important in the layout as, this way, the true measurements of the bricks will be obtained.
- Given that the greatest part of an efflorescence is produced by the interaction of the mortar with the brick, before starting the work, building a test wall is recommended to check how they behave together.
- Given that water is the vehicle for transporting the soluble salts which cause efflorescences, try not to wet the brick wall after it has been built, as this, along with the previous wetting of the brick, will allow the setting process will develop normally. Only in hot weather should the required humidity be provided in order to avoid dehydration of the mortar.
- Avoid the brickwork getting wet on the inside, both during the construction phase and when it is completed, as the dampness will promote efflorescences and stains on the brick.
- During the building work, cover the upper part of the walls to protect them from rainwater.
- In the same way, protect the facing bricks in the gaps of the façade and tops of the walls until the gutter and copings have been installed.
- The removal of efflorescences (not to be confused with mortar stains) should be made by dry brushing or by washing with pressurised water without damaging the head joints.
- The application of commercial hydrochloric acid diluted in water to 10%, is only necessary to clean stains and mortar particles which have arisen due to lack of care when building the brick wall.
- To achieve the maximum uniformity in joint shade, it is best to create the head joint at the same time as the building the brick wall. Joint the verticals first and thereby obtain a cleaner horizontal joint.
- relating to the project
- To avoid the rise of damp by capillary action through walls in contact with the foundations, place a layer of damp-proofing the full width of the wall between two layers of fresh mortar.
- The backs of containing walls, planters, and other brickwork elements in contact with the ground, should be made appropriately water-resistant. If this is not done, the constant taking on of soluble salts will produce efflorescences which may affect the durability of the brick. The use of cement and lime mortars is recommended, as they reduce the risk of cracks, the appearance of efflorescences and improve the workability of the mortar.
- The joints of the sills with the jambs and the joinery around their whole perimeter should be carefully sealed.
- Water from the roofs should never run down the surface of the walls, the use of guttering and eaves is required. Rainwater spouts on planters, terraces, etc. should be long and angled enough to avoid the return of water which then runs down the wall.
Coping, eaves, lintels, balconies, etc., that is, any changes in level in a vertical section of wall, should be supplied with a drip channel.
To avoid the production of cracks on walls on long lengths due to hygrothermal variations, expansion joints should be created:
- - At distances no greater than 15 m in continental climates and 25 m in maritime climates, paying particular attention to curved walls.
- - Where the most rigid parts of the building with pavilions are found, including wings and other elements with a linear layout which should generally correspond to structural joints.
- - In walls with a length greater than 6 m, where changes of wall levels of less than 70 cm may increase wall movement, the concentration of stresses may produce fissures.
- - Along the length of lines that change thickness and in load-bearing walls on each side of large openings.
- The thermal insulation layer should always be separate from the external layer by means of an air ventilation chamber. Supplementing the edge of the floor slab with a steel angle will increase the security and stability of the wall surface supported by the floor slab.