Clay Products Brick
Lastingness of structural clay merchandises
Materials and procedures
Brick clay and fireclay are the stuffs used to do bricks such as facing and technology bricks. Both of these stuffs are basically sedimentary mudstones. The fireclay is given its name due to its ability to defy heat and hence doing it ideal for confronting bricks because of this it has high lastingness under emphasis from fire and is hence a great stuff used to line furnaces.
Structural clay merchandises are fired in kilns and during the firing procedure vitrification occurs, which makes the clay in to a difficult, solid and a non-absorbent mass which is lasting by cut downing H2O soaking up ( porousness ) and in bend increasing the ability to defy hoar. Through this procedure the clay merchandises lastingness is extremely increased.
Structural merchandises can besides be glazed and there are two types of glazing. Single and dual discharged glazing this is where the clay merchandises are sprayed with ceramic glaze before or after drying and so kiln fired, this procedure makes the clay merchandises imperviable to H2O and H2O vapor. This therefore increases the lastingness of the clay merchandise in footings of being able to defy H2O from infiltrating which is the cardinal ingredient that causes the clay merchandise to interrupt down and diminish the lastingness to a really low degree.
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( 11/11/07, hypertext transfer protocol: //brickinfo.org/BIA/technotes/t9.pdf )
Types of harm
Chemical harm to structural clay merchandises is largely due to the leeching of chemicals from the land into the brick.
“Efflorescence is the sedimentation of soluble salts left on bricks when the H2O in which they were dissolved evaporates”
( 11/11/07, hypertext transfer protocol: //www.student.cardonald.ac.uk )
Flower does non usually do structural harm and will lessen and vanish with clip and weathering. The soluble salts that cause flower come from of course happening salts in clay, the sand and cement used in howitzer or from stuffs touching the bricks i.e. rain, land H2O etc. Calcium hydrated oxide is bought to the surface by the wet as it is soluble at low temperatures and on the surface it reacts with C dioxide which leaves a milky sedimentation that becomes flower.
Due to the types of stuffs used to do clay merchandises it is virtually impossible to extinguish all the soluble salts that cause the flower. Its non convenient to take all the salts from the clay merchandises or to forestall them from going saturated. Certain stairss can be taken to seek to understate the visual aspect of flower, these stairss are restricting H2O entry, doing certain that there is equal drainage and guarantee that the clay merchandise has gone through a proper hardening procedure. Flower can be removed manually but this may do a unsatisfactory visual aspect.
Sulphate onslaughts on clay merchandises affect the howitzer and the existent brick work. The sulfate onslaughts occur when the sulfate solution, from the of course happening soluble salts within the clay merchandise reacts with an ingredient of the Portland cement.
“Sulphate onslaught to brick and hardened howitzer articulations occurs when sulfates in solution reacts with the tricalcium aluminate component, C3A, in Portland cement to organize a compound called ettringite or tricalcium sulfoaluminate hydrate, 3CaO·Al2Oxygen3·3CaSO4·32H2O. The reaction is accompanied by enlargement and when it occurs in brickwork howitzers, the consequence is an overall enlargement of the brickwork”
( 12/11/07, hypertext transfer protocol: //www.sciencedirect.com/science? )
The brickwork expands doing clefts to propagate and this weakens the brick and the howitzer articulations doing the lastingness of the stuff to be affected.
These sulphate onslaughts can be avoided under certain conditions. If the brick work is protected from impregnation, so the sulfates can non respond with the tricalcium aluminate which hence stops the enlargement of the howitzer and brickwork this so reduces the opportunity of clefts propagating through sulfate based onslaughts.
Sulphate onslaughts can be prevented by utilizing clays with low degrees of soluble salts. The howitzer used should besides incorporate a high content of cement which will defy the H2O incursion as H2O is the cardinal ingredient of sulfate onslaughts. The cement used should besides be sulphate immune cement.
Frost onslaught occurs when the clay merchandises become concentrated with and the temperature drops below stop deading. This type of onslaught is normally occurs in the winter. In this procedure the H2O enters the pore in the clay merchandise and becomes saturated and when the temperature drops below stop deading it causes the H2O to stop dead and turns into ice. This H2O so expands doing the pores in the brick to acquire bigger and so the procedure repeats itself until the brick crumbles. Note that stop deading temperatures entirely do non impact the clay merchandises it is merely when they become concentrated.
Frost onslaughts can be prevented by planing the structural clay merchandises to avoid being saturated, and in the topographic points where the freezing melt procedure is likely to happen hoar immune clay merchandises should be used. Masonry pigments can be used to forestall the clay merchandise from going saturated. Acid rain is produced by the chemicals from our autos, mills and the fuels that are burned mundane. The gasses from these pollutants react with the bantam droplets of H2O in the clouds to organize azotic and sulfuric acids and these come down with the rain as weak acids.
The acid rain leaves sedimentations of acerb atoms on the surface of the clay merchandises which cause a reaction with the minerals within the clay merchandises ; this so corrodes the clay merchandises doing them to crumple and breakdown hence weakening the construction in footings of lastingness.
All the above types of amendss that are caused to structural clay merchandises can non be to the full avoided but efforts can me do to protect them from the environmental factors. The clay merchandises can be treated to go H2O immune but if a batch of harm has occurred so there is small opportunity of mending the damaged members, the best that could be done is to replace the structural member be it a brick, tile or pipe. They can merely be cut out or removed and so replaced with new members to let the construction to retain its lastingness by taking the affected members.
( 13/11/07, hypertext transfer protocol: //www.geocities.com/capecanaveral/Hall/9111/DOCS.HTML )
Rising moistness in edifices can be defined as the perpendicular flow of H2O up through a permeable wall construction, the H2O being derived from land H2O. The H2O rises through the pores ( capillaries ) in the masonry by a procedure slackly termed capillary action. This is the self-generated motion of liquids up or down the capillaries.
Rising moistness may non be a job in most of the edifices as there possibly other beginning of wet as was found by the BRE digest.
“The BRE have advised that lifting moistness was present in merely 10 % of the edifices they examined where moistness was assumed to hold been a problem”
( 13/11/07, hypertext transfer protocol: //www.propertylore.co.uk/factbook/building-defects/rising-damp )
Before any appraisals are carried out external, internal and secondary scrutinies should be completed to do certain than the proper beginning of the wet is identified. Therefore the most economic method of work outing the job can be used.
But in general the appraisal of lifting moistness looks for the undermentioned to make up one’s mind if the job is lifting moistnesss or something else i.e. surface condensation or rain incursion.
First the electrical wet metre should demo that there is a crisp alteration in wet at the top of the moistness, this point is normally identified by a general salt set at the maximal tallness of rise. Next there should be small or no mark of mould growing, and there should be no free fluxing H2O on the surface. Because land H2O contains little sums of soluble salts such as chlorides, nitrates and sulphates these should besides be present in the wall or the portion of the construction where the moistness is being identified. Any lumber that is in direct contact with the wall should besides bespeak high wet content. The most conclusive grounds of lifting moistness will be to take samples of howitzer from a certain deepness of the wall and trial this for wet and salt content.
The redresss for lifting moistness are moist cogent evidence classs ; these are normally some type of injections of a chemical solution into the walls which create wet barriers that stop the wet lifting any farther up the wall. The walls have 10mm holes drilled into them, these holes must be 150mm above the land and 170mm apart, so the solution is injected into these holes
After the solution has been injected into the walls the wet from the solution evaporates go forthing behind a gel which crystallises to organize a wet barrier, in bend halting the moistness from lifting.
( 13/11/07, hypertext transfer protocol: //www.thedampexperts.com/pages/dampproofing.htm )
These cause wetting of the surface of the masonry and hence when the masonry pigments are spread they adhere as a thin uninterrupted bed on the surface, this in bend reduces porousness and increases the lastingness as it allows small or no H2O to perforate into the clay merchandise. The pigment besides stops the wall from take a breathing ; this traps the wet that is already in the wall. So when the winter comes the wet in the wall freezes and expands by 10 % and this in bend is doing the freezing melt affect finally doing the masonry to cleft and dislocation. Different types of masonry pigment can be used which allow the wall to breath and halt the freezing melt affect from happening as sharply.
hypertext transfer protocol: //www.buildingconservation.com/articles/risingdamp/risingdamp.htm
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hypertext transfer protocol: //www.ecoconstruction.org/env_impact_bottom.html
hypertext transfer protocol: //www.ibstock.com/pdfs/technical-support/TIS16Howbricksaremade.pdf
hypertext transfer protocol: //www.ihbc.org.uk/context_archive/72/clay/tiles.html
hypertext transfer protocol: //www.mineralsuk.com/britmin/mpfbrickclay.pdf
hypertext transfer protocol: //www.newbuilder.co.uk/archive/sustainable_roofing.asp
hypertext transfer protocol: //www.scotland.gov.uk/Publications/2007/06/04121200/1
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