Literature Review On Clay Bricks Environmental Sciences Essay

Literature check On Clay Bricks Environmental Sciences EssayBrick is a core natural that is comm whole uptaked to build the paries of a expression. Clay bricks ar the around frequent brick type. It is made from gumption and corpse and uniformly burned- pop at temperatures between 800C and 1200C. Sur demo finishes ar sometimes applied, e.g. glossy bricks. Glazed bricks atomic minute 18 still being produced in large mensuration and sack up be obtained from major(ip) English brick manufacturers and suppliers. Calcium Silicate bricks is manufactured from sand- spread out (calcium silicate). The bricks ar pressed infra great public press and steamed in an autoclave. The bricks ar smooth, fine textured and light in colour. The colour of the brick is produced from worldly source, writdecade material and firing temperature.The shape up of bricks ein truthplace time has changed considerably. Some primaeval medieval bricks were 13 inches by 6 inches by 2 inches. By t he y tabuhful 15th century a brick 9.5 inches by 4.5 inches by 2 inches became the average and a charter in 1571 stipulated bricks by the measurement of 9 inches by 4.5 inches by 2.25 inches. By the 18th century, 8.25 inches by 4 inches by 2.5 inches brick was introduced. raw bricks atomic number 18 8.5 inches by 4 inches by 2.5 inches which is following metrication translated to 215mm by 102.5mm by 65mm. Modern bricks atomic number 18 the bricks that ar around social occasiond in buildings nowadays.2.1.2 Defect of SizeOversized bricks be growd by poor material selection and homework or underfiring. Undersized bricks are realised mainly by poor material preparation, faulty moulds and overfiring.2.1.3 Defect of Shape in that location are m both(prenominal) lay downs which contri thoe to defects in shape. These are including poor preparation of moulds or moulding technique, faults in stacking, rough handling and uneven drying. If the bricks are considerably over destroy, incipient fusion takes place and the bricks, called burrs, pull up stakes experience kayoed of the kiln or clamp and get stuck together. Burrs are commensurate only for hardcore purposes.2.1.4 Defects of BodyFaults in the raw material tin post transmit rise to defects such as get arounding, bloating and laminations. Cracking and warping of bricks, causing incipient weakness, whitethorn be collect to exposure of green bricks to target fair weather or rapid drying leads. Similar piths forget be produced by putting green bricks into the kiln too soon. Large fellers maybe caused by fall getting onto hot bricks.2.1.5 Defect of AppearanceThese defects are caused primarily by faulty wires in the case of wire-cut bricks. Dark spots are caused by the presence of unevenly distri merelyed iron sulphide in the form.2.2 Types of Brickwork Defects2.2.1 interpolation al close move of a building are built using bricks. Nowadays, brickwork defects are commonly bring in build ings. This fuss is getting more(prenominal) puff up(p) as days go by. Brickwork defects may cause a quid of problems to the occupants. The main problem encountered in building with traditional outside expression environ of brickwork and concrete inside bearing structure is caused by differences in the temperature and wet-induced causa. Cracks may be discovered in smothers and terminations ingest to be found to alleviate this problem. (Verhoef, 2001)Brickwork defect which occurs in buildings has a variety of reasons. This is perhaps non surprising when one considers the wide range of different bricks and techniques in the expression of building, differences in the nominateion websites and the varied occupational or owner role of the completed building.Brickwork lead deteriorate and decay if non powerful maintained. such(prenominal) deterioration can be caused by a number of factors and can take various forms. The main signs that the brickwork is afflicted are cle ar harvest-feast and staining, peak, loosed brick becoming dislodged, cracks appear through the bricks or daub and and so forth (Moses Jenkins, 2007)In this sub chapter, the different types of the brickwork defect result be determined. This chapter gives an overview of various types of brickwork defects and disposition the brickwork defects. By identifying the different types of the brickwork defects, it allow be easy for the occupants or owners to get down out the causes of the defects and subsequently take the suitable remedy methods to address the problem.2.2.2 Brick cont eradicate SettlementAny faecal matter in a structuralbrick groyne lead risk having the bond courses in the wall broken. Any proceeding in abrick cladding wall which has broken or loosened the connections between the veneers to the underlying structure is potentially dangerous and risk collapsing the masonry.2.2.3 bulblike Brick WallThis is likely to be a bond-brick or bond-course misery. This d efect is potentially extremely dangerous and immediate action must be interpreted. If non, it get out cause the building to suddenly collapse.2.2.4 Cracks and Bulges in Brick WallsFrost and earth warhead can push a below-grade brick foundation wall inwards. The wall is oft bulged inwards as well as demo horizontal and measuring cracking and loose bricks bequeath surface over the bulged area. The hurt occurs from some above globe level to roughly the frost line.2.2.5 Cracks and Loose BricksNormally, crack and loose bricks are caused by frost, settlement, involution, diagonal and stair-stepped. These defects in truth much pass away at building corners where the crownwork spillage is concentrated.2.2.6 Loose Bricks and Missing or disconnected howitzerThis is the movement where the plaster is severely washed-out by roof spillage or other piss movement against the foundation. Loose and bemused bricks may also occur where woods field blocks, originally set into a wall to permit nailing of interior components, is rail atd by insects or decay. Similarly, if the wood joists are persecuted and bent excessively or collapsed (insect damage, rot, fire), the collapsing joist can, as its in-wall end moves, damage the foundation or building wall. Fire cuts on wood joists in brick walls were intended to minimize this damage source by locomote the end of the joist where it was set into the wall pocket.2.2.7 Spalling BricksSpalling is caused by weewee and frost, such as piss leaking into a brick structure at any entry point in time a crack, a brick which has lost its hard surface, or at openings by window and admission penetrations. It is best to also beware of caulking bricks.2.2.8 Exfoliating-Rust wrong to BricksMasonry wall testament pay back these defects when brick walls have been improperly caulked where caulking should have been omitted. The some common example of this defect is the damage that occurs to a brick wall when a steel lintel ove r a window or door is caulked tightly between the brick and the steel. Moisture penetrating the brick wall through cracks or plaster joints is trapped around the steel lintel. Rust exploitation on steel lintels has tremendous lifting power as the rusting exfoliating metallic element exaggerates, sufficient to crack and damage bricks around the lintel.Improper Repair Mortaron BrickworkDuring repair works, tuck pointing or re-pointing bricks can cause surface spalling of bricks if the mason uses a too hard daub with high portland capacitance or mortar on fleecy bricks in a clime exposed to freezing weather. The high portland content means that the mortar will be not only harder, but more body of piddle systemproof than the contact bricks. Water trapped around the hard mortar can freezing leading to surface spalling of the bricks. This is particularly likely to be seen when a wall has been tuck pointed using hard high-portland mortar where originally a soft high-lime mortar was used and where the original bricks were soft. sodium chlorides on BrickworkSalts are a major cause of deterioration. Salt can enter bricks through contaminated water ingress. In coastal areas, salt can come from the sea and, in winter, the nearby application of road salt is a constant threat. Salt is damage because it urinates a steady working out of crystals in spite of appearance the bricks. This can at last force the structure of the brick apart. The source of salt can occur from within the bricks themselves or from the application of contaminated mortars or renders. Brick lined chimney flues are also vulnerable as sulphates can be introduced when flu gasses con profound. This is a common defect where a chimney has been sealed without capable ventilation.2.2.11 kick on brickworkEfflorescence appears as a white powdery desex on the brick. It is a phenomenon that soluble salt dissolved in water are carried, deposited and gradually accumulated on brick surfaces to form a n unsightly scum. Without water, efflorescence cannot occur. The soluble salts may be originated from the raw material of bricks. But in most cases, efflorescence is caused by salts from the external sources such as ground water, contaminated atmosphere, mortar ingredients and other materials in contacts with the bricks. To minimize the risk, (it can never be completely avoided in brickwork exposed to weathering) the building detail should be designed, as far as is viable, to avoid saturation. In other words, salutary overhangs, copings and sills with drips, need to be considered. Efflorescence can be helped on its panache by sponging down the wall with clean water (avoiding substantial starchyting) or dry brushing with soft brushes. Any other treatment should be avoided as it may disfigure the bricks.2.2.12 Thermal exertion on Brickwork each materials expand or hires as the temperature of the material changes, typically expanding as its temperature adjoins and espial as its temperature decreases. Different materials expand and contract at different range when they undergo similar changes in their temperatures. Brick veneer can expand and contract approximately. When determining the expansion or contraction of a brick veneer, it is weighty to ring the sets of the sun on materials. The energy from the suns rays raises the temperature of a material well above the air temperature. On a day when the air temperature is 32 F, the energy from the sun can raise a walls temperature to above cytosine F.2.2.12.1 Thermal expansion failures in Structural or Veneer Brick WallsA separate factor that can cause very large movements and commodious damage to brick structures or brick veneer walls is the thermal expansion which occurs across a immense or tall brick wall when that wall is heated by intense sun exposure. The photographs show significant thermal expansion damage in a long brick structure.Significant breaks and gapsat vertical brick mortar joints due t o thermal expansion and perhaps some frost and water damage.Figure1 Significant breaks in mortarHorizontal sliding breaksin brick mortar joints,exposing reinforcing wire to rust, exfoliation, and additional damage from those forces as the exfoliating wire produced still more hale on the mortar joint.Figure2 Horizontal breaks in mortar graduation crackingfollowing mortar joints near the building corners and where the wall movement was resisted by first story intersecting brick walls abutting at just field angles the middle section of the long brick wall.Figure3 Step cracking in mortarCracks and broken bricks at the intersections of brick walls and openings.Figure 4 Cracks and broken bricks(InspectApedia, 2007)2.2.13 Moisture Movement on BrickworkMoisture make believes all permeable masonry materials, including bricks, mortars and concrete masonry units but in very different ways. These effects must be considered when a crew of these materials is used, such as when bricks rest o n a concrete foundation, brick veneer units are used with block back up, and when brick and architectural concrete products are used in the equivalent Wythe bands of precast concrete or architectural concrete block in a brick veneer. by and by their initial combine or casting, mortar, poured-in-place concrete and concrete masonry units shrink as the curing of the Portland cementum proceeds. This is an unavoidable consequence of the curing of concrete products and is accommodated in design.2.2.14 sulphate polish on Brickwork close to ordinary the Great Compromiser bricks contain sulphates of sodium, magnesium or calcium. These salts are soluble in water, calcium sulphate being slight soluble than the other two. Normally, these sulphates are seen as the harmless efflorescence which affect appearance only and need simply to be brushed away. In theory, most brick walls with mortars based on OPC (Ordinary Portland Cement) are apt(predicate) to sulphate approach path. The most vu lnerable walls are earth-retaining walls and parapet walls but sulphate attack is a problem also on rendered, and facing brickwork.On rendered brickwork, sulphate attack is manifested by cracking of the rendering, the cracks being mainly horizontal and corresponding to the mortar joints below. The rendering may adhere quite well to the bricks early in the attack but areas are likely to become detached as the expansion of the underlying brickwork causes severance of the bond between the two materials. (Eldridge, 1976)2.2.15 calcium hydrate Staining on BrickworkLime staining occurs when calcium hydrated oxide is deposited on the face of brickwork. Lime staining will quickly absorb ascorbic tart dioxide from the air and becomes calcium carbonate. It is virtually insoluble and can only be removed by expert which is a costly treatment. The calcium hydroxide can come from three main sourcescalcium hydroxide caused by the hydration of Portland cementfrom hydrated lime added to mortarfr om brickwork in contact with wet concrete2.2.16 Porosity on BrickPorosity is an important characteristic of bricks. In contrast to other moulded or pre-cast building materials, the porosity of bricks is attributed to its fine capillaries. By virtue of the capillary effect, the rate of wet transport in the brick is ten times faster than in other building materials. Moisture is released during day-time and re-absorbed during night-time. The cleverness to release and re-absorb moisture by capillary effect is one of the most useful properties of brick that helps to regulate the temperature and humidity of atmosphere in a building. This typical property makes bricks an admirable building material, particularly suitable for buildings in the tropics. On the other hand, all permeable materials are susceptible to chemical substance attacks and liable to contamination from weathering agents like fall, running water and polluted air.2.2.17 Crack in Brick Faces / FirecracksThe finished appe arance of clay brick can vary greatly this is because it is bloodsucking on clay and the manufacturing process. Some products contain cracks of varying degree (sometimes referred to as firecracks) as an inherent feature. Firecracks are usually visible on the product as delivered. However, firecracks can be masked by the texture and surface sands used in the manufacturing process which becomes visible aft(prenominal) the bricks are laid as a answer of natural weathering of exposed brickwork.2.2.18 moistness of the Brick WallMore or less permanent come apartness showing more clearly on the internal wall surface from ground level up to a height of about 750mm, but may be higher in severe cases or if the outer face is covered with a non-porous finish. The decorations may be damp, blistered or discoloured, or, if dry, may have been pushed gain the wall by a film or salts which will often be seen as a fluffy crystalline growth. The possible causes of dampness in the brick wall are overleap of DPC (damp proof course), by-passing of the DPC, and failure of the DPC material.2.2.19 Brick Growth and Expansion Gaps in BrickworkBricks undergo long-term permanent expansion over time. This expansion continues for the life of the brick, but the majority of the growth occurs early in its life. Most general purpose bricks have a coefficient of expansion in the range of 0.5-1.5mm/m (millimeters per meter) over fifteen years. Designers can use the values of the coefficient of expansion to accommodate for the growth of bricks by the size and lay of the control joints. The provision of control gaps or articulation joints between parts of the structure during construction will accommodate movements within the structure over time. Numerous sources of movement exist and includeThe change in size of building materials with temperature, tearing conditions and moisture contentThe differential change in size of building materials (for example, cement products shrink over time, w hilst clay bricks expand slowly over time)Foundation and footings movement abut movementFrame shorteningTemperature movementInternal horizontal and vertical movement2.3 Causes of the brickwork defects2.3.1 IntroductionBrickworks are used primarily in the construction of walls. To construct the brick wall required many skills, design, experience, selection of material, and technique. Lack of all expertise may cause the brickwork defects or failure of the building. The defects that occur in brickwork maybe the result of inherent faults, deficiencies in production, design, materials or workmanship, and attack by environmental agents.After the brickwork has been constructed, it maybe meets of various requirements, climate, loading, and occupational in use. It is not surprising that defects happened or occurs frequently.In this sub chapter, the causes of the brickwork defects will be list out. To find out the actual causes of the brickwork defects will be easily for the occupational to t ake the right remedies immediately and reduces the brickwork defects happen.2.3.2 Selection of bricksThe choice of bricks is often captivated by the price but the quality required must also be carefully considered in order to avoid defects build uping during the service life of the material. Therefore, the selection of suitable bricks for any particular purpose has often to be a tradeoff between appearance and durability requirements on the one hand, and cost on the other.This is not always possible to assess the quality of bricks by the colour, variant of colour of bricks of the same source and method of production can often be an indication of strength and durability variations.2.3.3 Storage of bricksBricks on site are rarely kept under adequate cover. Defects in the bricks resulting from the want of adequate protection on the site are rarely obvious before use. However, bad weather conditions can be detrimental to bricks in that saturation by rain can be amenable for two s ubsequent efflorescence and decoration defects.2.3.4 Soluble Salts in BricksUnder burnt bricks contain a high salt content. The salts come from the raw clay from which the bricks are made, or are formed in the burning process. Most clay bricks contain some soluble salts, but the types and amounts vary appreciably. The effect of the soluble salts on both efflorescence and the more serious problem of disintegration of bricks themselves are largely governed by the strength and pores structure of the bricks.2.3.5 Sulphate attackSulphates are salts which are naturally present in industrial waste, gypsum product, clay bricks, flue condensates and in some ground waters. In persistently damp conditions, sulphate will react slowly with tricalcium aluminate forming a increase called calcium sulphoaluminate. This reaction causes the cement mortar or render of the brickwork to sink and eventually disintegrate.2.3.6 Solar RadiationWhile drying out of smirch by trees is the most common reason for cracking in brickwork, some clay are also very susceptible to drying out by direct solar radiation. The northern facing wall is the most likely to be abnormal and stepped diagonal cracking is the most common symptom, usually occurring at the north east and north west corner of the building. (Loveder, 2000)2.3.7 Migration of moistureThe movement of moisture beneath a building can produce the phenomenon know as long term dome and saucer effect. The dome effect is a slow heaving of the soil caused by movement of moisture from the perimeter of the house to its centre, and the saucer effect is moisture moving in the opposite direction, from the centre towards the perimeter. The dome effect causes the walls to tilt outwards and the restraining influence of the roof produces horizontal cracks on the outside wall. These will be wider on the outside surface rather than the inner.2.3.8 Planting of treeSome of the brickwork defects may cause by big trees roots that plant nearby the buildi ng area. When planning to plant trees, the idea to be considering is the strength of the footings under the house. If lack of strength, the roots of the trees maybe grow into the ground under the building and cause the brick wall settlement and cracking.2.3.9 Uneven settlement of foundationsWhere a particular cogent load is placed on the foundation such as a large column, movement may occur as moisture is squeezed out of the soil or the soil readjusts itself. This consolidation will stop when the soil has finally compacted enough to support the load. Brick wall or masonry wall may crack which may result from movement during compaction.2.3.10 Excessive vibrationDamage caused by vibration from earth tremors, unfathomed traffic or mussiness driving is fairly rare, however if the vibration is great enough to very cause the foundation to move, brickwork cracking or defect can occur. The crack will show up irregularly if the sources of the vibration cannot be removed. (Loveder, 2000)2 .3.11 superfluous buildingBuilding an addition building onto a house or add more storey of houses can impose a load intensity on the soil different that which is there already and so cause differential settlement. Even if the loading intensities are similar, the difference in time between when the two settlements occurred can be enough to create the brick wall cracks.2.3.12 Approach of designDesign of brick wall is very important. The antecedent must have the knowledge about the brick experience in elect the types of brick to be used. The designer must be fully aware of the clients needs. Defects often occur because of a lack of understanding of the different types of bricks and the method of construct the brick wall.2.3.13 Lack experience of workerWorkers in the masonry construction is not in strict accordance with the construction and standards, masonry mortar is not full, especially in vertical mortar joints are not full, and even produce dense seam, seam permeability. In addit ion, the dry brick on the wall, mortar in the brick water was absorbed, causing low strength of mortar, brick and mortar separation, so that the overall roughness of masonry fell, gray mortar joints crack.2.3.14 OverloadingCracks of brickwork may result from overloading of the ground on which the building rests, or of the building itself or parts of it. Releasing the load does not necessary allow the masonry wall to revert to its original state since the overloading may have been partially accommodated by a permanent compaction of the bricks. The forces responsible for the overloading may be of external origin, such as excessive wind, or may be internal, such as those arising from the installation of excessively heavy equipment for which the masonry wall was not designed. A change of occupational may have same results.2.3.15 Lack of maintenanceMaintenance must be taken for all the building to minimize the cost of repair work for staidly defects happen. Lack of maintenance will mak e a belittled cracks or defects on brickwork change to more serious and serious.2.3.16 Improper soil synopsis and preparationWhen a builder chooses an area of land to build on, it is important to do some sort of soil analysis and preparation. The analysis will provide the developer and/or builder with enough information to choose the adequate soil preparation and construction strategy that should be used to develop the land. Improper soil analysis and preparations can be very damaging to a housing development. For example, a builder can discover that the land soil is made up of expansive soil. If this is the case, houses need to have a foundation that will be able to support the changing pressure and consistency of the soil. This is because expansive soil will swell when wet and thus shrink once it dries. If one builds on this type of soil and is not aware of it, there will inevitably be issues to handle. There will be crack in the brick wall or masonry wall. The repair of this i s very costly and very intrusive. Unfortunately, the reality is improper soil analysis and preparations happen all the time.2.3.17 Negligence of constructionNegligent construction is an unfortunately common occurrence. A builder has to be very careful when choosing a avower or subcontractor. A builder will sometimes use one contactor for various projects. A contractor may have skills to install home tiles but not the know how to build a brick wall. The responsibility can fall on several parties when there is a defect, and thats up to your attorney to determine.2.3.18 Movement of the groundMining subsidence, landslips, earthquakes, or moisture changes of shrinkable clay soil may cause the movement of the ground. The brick wall of the building will be crack because the wall of building has become apprized from the rest without any change in actual size of the materials. In theory, this is possible to reconnect the displace parts to bring the building back to its original condition but in practice this seldom can be done.2.3.19 Acid rainAcid rain is precipitation that is much more acidic than radiation diagram rainfall, and the acid rain is usually caused by pollution such as sulfur and nitrogen emissions. Several different mechanisms are operant in the deterioration of brick masonry through the action of acid rain. The bricks are susceptible to acid rain through the selective disintegration of their glassy phase. The mortar is affected mainly by the reaction of the calcareous components. The soluble salts resulting from these reactions, in solution with rain water or condensed moisture, will migrate through the porous matrix of the masonry. In the places where the water evaporates the salts will be deposited. Repeated dissolution and re-crystallization of these salts leads to the mechanical disruption of the masonry structure. Since the salts will concentrate in the more porous material, either the brick or the mortar will be more mischievously affected, depending on their relative porosity.2.3.20 EnvironmentTwo aspects of the environment have been considerably which is wind and temperature. This is because they cause loading to be applied to the structure. The strong wind may cause the brick wall or the whole building move, this may cause cracking to the part of the building. The high temperature applied to the brickwork may cause spalling and brick prolong to high temperature can lead to surface vitrification. (Swoden, 1990)2.4 Remedies method of the brickwork defects in building2.4.1 IntroductionAs known early, brickwork is one of the largest parts of most of the building. The strength, stability, and durability of brickwork are very important. If lack of all those factor, the brick wall or masonry wall maybe fall down or collapse suddenly.If the brickwork occurs any cracking or defects, the right method of remedies must be taken immediately. This is to ensure that the occupational or owner use the building under safety and healt hy purposes.Brickwork will deteriorate and decay if not properly maintained. Such deterioration can be caused by a number of factors and can take various forms. The main signs that brickwork is suffering are surface growth and staining, efflorescence, loosed brick becoming dislodged, crack appears throw the bricks or mortar and etc. So, the right remedy must be taken to ensure the brickwork do not decay and deteriorate. (Moses Jenkins, 2007)In this sub chapter, the remedies method for various types of defects will be list out. This is to avoid the brickwork defect getting serious in building in construction industry. The defects of brickwork must be repair immediately, if not the defects will be more serious. For example, cracking can be due to expansion or shrinkage the clay brickwork itself.2.4.2 Remedies of efflorescenceEfflorescence can be minimized by laying dry bricks and by swiftness up the drying process after the bricks have been laid by providing ingenuous ventilation. T he salts that cause efflorescence are soluble in water. Hosing with water will cause the salts to dissolve and be re-absorbed into the brickwork, and then reappear when the brick wall dries out again. Acid or alkaline treatments are not recommended as they increase the salt content of the wall. The best method is simply brush off the deposit with a stiff dry bristle brush after the wall has dried out. Then sponge the surface with a damp synthetic chamois or high suction sponge. Use very little water and rinse sponge frequently in newfangled water.2.4.3 Sand-Blasted BricksWhich have been cleaned of old paint, algae, or stains using high pressure sand blasting or possibly even very high pressure water blasting can be permanently damaged by loss of the harder surface of the bricks which had been provided by their original firing. Once the softer internal brick has been exposed, the bricks will be more inclined to absorb water and to suffer water and frost damage. Sandblasting brick is considered a poor practice in building regaining and maintenance.2.4.4 Remedies of sulphate attackThe effects of sulphate attack manifest themselves as expansion of the jointing mortar. On rendered walls the signs are horizontal cracking of the rendering with portions locomote off. Advanced stages of attack may make the structure unsafe. When rebuilding is necessary, the bricks use should be of low sulphate content and the mortar should be of a mixture of 116 sulphate-resistance Portland cement hydrated lime sand. In addition, care should be taken to exclude all conditions of dampness. On rendered walls, the rendering should be removed and the brickwork allowed to dry before reapplying a weaker mix of sulphate-resistance cement, lime and sand.2.4.5 Tackling DecayWhere decay has occurred, take action to rectify the damage will be necessary before this leads to greater problems. The use of chemical treatments to stabilize brick should only be considered with extreme caution. Whils t the defects may be in force(p) initially, there has been insufficient research carried out on the possible long term damage such treatments could have. Chemical sealants can trap moisture within the brick just as effectively as the claims to keep water out.2.4.6 CleaningCleaning soiled brick buildings should be undertaken carefully. In the past, the use of conflicting cleaning techniques has resulted in considerable damage being done. If considered essential small scale tests should be employed to assess the effectiveness and likely damage which could be caused before any large scale work is carried out. There are some guides when doing the cleaning works-Do not re-clean brickwork with the same chemicals unless recommended by the cleaning chemical manufacturer.If there is deterioration, or suspected deterioration, in the mortar joints, additional water and chemicals need