Plastics and Rubbers in Building

7/29/2019 Plastics and Rubbers in Building

1/37

Plastics and Rubbers in Building


2/37

Background

The use of rubber and plastics materials in buildings,both for construction and decoration, continues toincrease, particularly as architects, designers andbuilders appreciate their advantages in construction

terms and in the provision of so called maintenancefree structures. Today, plastics materials are so widelyused in the building industry that it would be difficultto envisage the construction of any building without

them. Many products are available which meet thevarious building and fire regulations. Some of the areasin which these materials are used are listed in table 1.


3/37

Adhesives

Sealants

Roofing materials

Waterproof membranes

Floor coverings

Sound insulation

Thermal insulation

Anti-vibration mountings

Window frames

Glazing

Pipes and gutters

Drainage systems

Fascia boards

Cladding panels

Decorative laminates

Geotextiles for earthworks

Laminates for formwork

Laminates for decoration

Flexible foams for upholstery

Fibres for carpets and fabrics

Paints and varnishes

Table 1.Application of plastics and rubbers in building


4/37

Pipes and Gutters

For many years we have seen thegradual replacement oftraditional materials such as lead,copper, steel, cast iron andceramic waste systems withplastic pipes and fittings. Some of

the advantages gained are areduction in weight, ease offabrication and installation, easeof repair and in many cases areduction in cost. Because plasticpipes have a smoother bore thantheir metal counterparts, flowrates can be increased and scaleformation is reduced. Plasticpipes also offer advantages incorrosion resistance.


5/37

Push-Fit Plastic Piping

Within buildings the push-fitwaste systems have madeplumbing much quicker, andalso safer from fire hazards,since blow lamps are no longer

necessary to wipe lead joints.Externally, a wide range of soilpipes and fittings are availableto carry waste to the mainsewers. Here the advantagesof lighter weight, longer pipe

lengths without joints andease of fabrication have madethese an absolute boon to theindustry.


6/37

Push-Fit Plastic Fittings

Whilst the bulk of thematerials used arethermoplastics, such asPVC (polyvinyl chloride),

ABS (acrylonitrilebutadiene styreneterpolymer) andpolypropylene, without

the use of rubber O-ringsand compression gasketspush-fit systems would beimpractical.


7/37

Polyethylene pipes

With potable water distribution,polyethylene pipes are now widelyused. Pipes are available in diametersfrom a nominal 8 mm bore up to1000 mm and above, made fromspecially developed grades of MDPE(medium density polyethylene) whichmeet a range of water industryspecifications .

One advantage of plastic pipes overmore traditional materials is that inthe smaller diameter sizes they areavailable in continuous lengths of upto 100m or even 250m in some cases.

This reduces the number of jointsneeded and hence the number ofpotential leaks.


8/37

For underground potable

water distribution pipes are

coloured blue. This enables

the contents of a buried

pipe to be immediatelyidentified on a construction

site. Above ground black

coloured polyethylene is

used to ensure adequateUV stability.


9/37

Disadvantages of Plastic Piping

One disadvantage of plastics materials is their

tendency to soften at elevated temperatures.

This has restricted their use in hot water

systems. However, two materials have found

application in underfloor heating systems and

to a limited extent for hot water distribution.

These are polybutylene (PB) and crosslinkedpolyethylene (PEX).


10/37

Polybutylene

Polybutylene can be used insystems with a continuousoperating temperature of 82Cand will survive short peaktemperatures of up to about110C but does require

continuous support at thesehigher temperatures.

With underfloor heating systemscontinuous support presents noparticular problem. Althoughfailures have occurred in the USA

where high levels of chlorine arepresent in the water supply,similar problems have not arisenin the UK and Europe where thechlorine content is lower.


11/37

Crosslinked Polyethylene

Crosslinked polyethylene (PEX) ismade from normal polyethylene by,for example, crosslinking it using aperoxide catalyst.

The cross-linking raises the thermalstability of the material under load.Thus, the resistance to environmentalstress cracking, creep, and slow crackgrowth are greatly improved overpolyethylene.

PEX pipe is approved for potable hot-and cold-water plumbing systemsand hot-water (hydronic) heatingsystems in all model plumbing andmechanical codes across the U.S. andCanada.

PEX piping systems are durable,provide security for safe drinkingwater, and use reliable connectionsand fittings. There are currentlyabout ten domestic producers ofquality PEX piping.


12/37

Gas distribution

Yellow coloured polyethylene

pipes are now used for gas

distribution, particularly where

existing domestic supply pipes

have corroded. In this case the

replacement plastic pipe isthreaded through the existing

pipe.

This overcomes the need for a

trench to be excavated andconsiderably reduces the cost

of replacement. Because the

pipe bore is smoother the gas

flow is hardly reduced.


13/37

Electrofusion

One recent innovation in jointing pipes hasbeen the introduction of the electrofusiontechnique. Here special couplers areavailable which incorporate a heating coil.

The coupler is clamped in . position over thetwo pipe sections to be joined and power issupplied to the heating coil by means of anelectronic control unit. The pipe and coupler

melt at the interface between the twomaterials and a permanent fusion bond isformed. This enables consistent joints to bemade using relatively unskilled operatives.

Using these couplers, permanent repairs canbe made to buried pipes with minimalexcavation, since only the damaged part ofthe pipe needs to be replaced rather than acomplete section.

Plastic guttering and drainage pipes can befound on most buildings today, and usage issuch that these products are taken forgranted in the same way as bricks, concreteand timber are in building construction.

coupler


14/37

Roofing Systems

Corrugated plastic sheetinghas been used for roofing inconservatories andbuildings where transparentpanels have been required.

However, in more recenttimes double and triplewalled polycarbonatesheeting has becomeincreasingly used, since this

provides not only diffusedaylight for illumination butalso heat insulation andhence reduced heatingcosts.


15/37

Twin or triple walled polycarbonate

Provides a number ofadvantages during installationsince it can be cut withconventional tools, is rigid tohandle, does not require

closely spaced supports, islight in weight and can beeasily fitted. In addition, it canbe cold formed orthermoformed into a varietyof shapes to provide attractive

and functional curvedsurfaces. Edges and joints canbe sealed to prevent draughts.Another major advantage is itsresistance to breakage.


16/37

Roofing Systems continued

Polycarbonate sheeting is availablewhich meets BCA for surface spreadof flame. This has enabled thematerial to be used in public areas ofbuildings where strict fire regulationsapply. Specially UV stabilised gradesof polycarbonate are used, often with

an additional UV barrier filmincorporated under the outer skins.

Fixing is usually by means ofaluminium or UPVC (unplasticatedPVC) glazing bars. However, unlikeglass, holes can be drilled throughthe material for screw fixings. More

recently, similar twin walled sheetingmade from clear UV stabilised PVChas become available. Both materials,polycarbonate and PVC, are availablein clear and bronze colours.


17/37

Cladding Panels

UPVC products are now frequently used inplace of the more traditional timber productsfor external cladding panels, fascia and softboards, particularly on new buildings. Someof the advantages offered by UPVC arelighter weight, resistance to rot, lack of warpand lack' of need for regular maintenancepainting. In addition, UPVC meets BS 476:

Part 7: Class 1' for surface spread of flame. Products are available in a variety of colours,

including wood grain finishes. These may beof solid UPVC, double skin or foam filleddouble skin construction.

When fixing UPVC products, unlike theirtimber counterparts, due allowance must be

made for expansion and contraction toprevent buckling of the sheets due to theheating effect of sunlight. Normally anallowance of 2 mm per metre length must beprovided between sections. To allow for thisspecial UPVC jointing and corner sections areavailable.


18/37

Unitex cladding fixtures The Unitex range of lightweight cladding

solutions has been tailored to suit the

needs of specifiers, designers,developers, builders and most

importantly the home owner.

The Uni-EIFS (External Insulation

Finishing System) range is designed so

that the insulation is placed on the

exterior of the building, equalising the

effects of outside temperatures and

reducing thermal stresses and strains in

the structure.

Cold spots and drafts are eliminated

because the entire surface is insulated. With Uni-EIFS your house is insulated in

summer against heat from the outside,

insulated in winter against cold from the

outside which means true living comfort

all year round.


19/37

Plastic Fascia


20/37

Rubber Anti-Vibration Mounts

In many buildings there is a need to prevent external vibrationsfrom affecting sensitive equipment within the building. Thisnecessitates the incorporation of anti-vibration mounts during theconstruction of the building. In the UK, laminated elastomericbearings are usually chosen but in France and Germany, steel coilsprings are more often used. Although rubber vibration isolatingsystems have been known for many years, it is only in the last 10years or so that methods have become available for designing andanalysing high efficiency compound systems.

Rubber springs tend to be less massive than the equivalent steelsprings for any particular application. In addition, the dynamic

properties of rubber can result in such mounts providing protectionover a wider range of frequencies, particularly at high frequencies.

Rubber mounts are also used to isolate individual items ofequipment, such as air conditioning and refrigeration equipment,from the main structure of the building.


21/37

Plastic anti-vibration mounts


22/37

Sound Insulation

Sound within buildings may be general

noise transmitted through walls and floors

or a specific noise from vibrating machinery.

The latter can be dealt with by using

vibration mounts as mentioned above. Air-

borne noise can also present problems andmust be taken into account when designing

sound insulation systems.

With general noise, the traditional method

was to build very thick and heavy walls and

floors. However, as buildings have become

lighter, other methods of sound reductionhave become necessary. As a general

principle, sound insulation can be provided

by either a simple and heavy or a light and

complex construction. It is in this latter area

that rubber and plastics materials have

come to the fore.


23/37

The performance of party walls and

floor is controlled by the BCA which give

typical constructions that meet the

performance requirements. To meet the

regulations with light weightconstructions some form of dry lining,

floating floor or suspended ceiling is

needed. However, in all these cases the

method of fixing can reduce the

efficiency of the system.

With floating floor construction, an air

gap, created by placing a resilient

material such as rubber or foamed

plastic between the timber raft and the

concrete floor, can achieve the desired

result. Since the demand for light

weight constructions is increasing, this

will provide a steadily increasing outlet

for rubber and foamed plastics.

Rubber placed under the timber floor


24/37

With walls in housing,

dry lining is often used

but in offices and

factories, compositewall panels

incorporating foamed

plastics are available

that are easily installedand that provide

adequate sound

insulation.


25/37


26/37

Thermal Insulation

As well as sound insulation, buildings need thermal insulation. This can bemet by using light weight aerated concrete building blocks during theconstruction of the building or by incorporating foamed plastic sheetingwithin the structure. Typical foamed plastics include rigid polyurethanefoam and expanded polystyrene, although various other foamed plasticsmay also be used.

Plasterboard can be readily obtained with a 25 mm foamed polystyrenebacking. Other composite sheet building products can be obtained withpolyurethane foam cores. One particularly important use of polyurethanefoams is in the construction of cold rooms for food storage. Here a 100mm thick sheet of polyurethane foam is sandwiched between two layersof glass fibre reinforced polyester (GRP) or two layers of sheet steel. Thesurface of the GRP can be flat or lightly embossed to give a semi-decorative appearance. Such surfaces are ideal for use in food storageareas since they can be kept clean with very little effort.

For all these applications, whether for sound or thermal insulation, fireretardant foams are available which meet the appropriate building andfire regulations.


27/37

Polyester Thermal Insulation


28/37

Window Frames

UPVC has been in use for many years for the manufacture

of window frames and in particular, frames used for doubleglazed windows. These comply with BS 5720. One of themajor advantages is the reduced thermal conductivity overequivalent metal frames. This in turn reduces condensationon the frame. UPVC frames can be easily assembled and donot require regular maintenance. Neither do they need awooden surround or sub-frame, which can rot. Framescome complete with window as well as other parts of theframe and surround, all manufactured from the same gradeof white UPVC. With larger frames, steel reinforcement isoften added for extra strength and security.

A water tight seal to concrete and brickwork is achieved bybedding the frame in silicone rubber and by injecting asilicone rubber bead along all joints.


29/37

Plastic Window Frames


30/37

Plastic Decorative Laminate The normal structure of a plastic

decorative laminate includes a sheet

of decorative paper impregnated(saturated) with one or severalaminic resins, covering the surface of a supporting

structure formed by a particleboard(for low pressure laminates) or by

kraft paper sheets impregnated withPhenolic resin (high pressurelaminates).

Plastic decorative laminates have awide range of uses, they can be usedin the furniture industry for kitchen

cabinet counters, bookshelves anddoor linings, among many otherthings. In the building industry theycan be used for partitions screens inorder to divide space in offices,houses, etc


31/37

Plastic Decorative Laminates


32/37

Construction adhesives

There are also water-based versionsthat can provide better heatresistance, and for superior heatand water resistance, specialpurpose products such as SelleysLiquid Nails Landscape or LiquidNails Mirror, Metal and Glass areavailable.

Construction adhesives lose solventor water to gain strength they willbe slow to cure between non-

porous materials such as metals,plastics, dense timbers and paintedsurfaces.

When bonding big broad sheets toflat surfaces, apply beads in onedirection only, leaving channels for

evaporation.

Water based adhesive


33/37

Construction Adhesive

Generally solvent-based, these cost

effective, gap-filling adhesives are

suitable for bonding sheet flooring,

adhering skirtings and architraves,

signs and wall panels.

They have good adhesion to most

substrates (especially porous

materials such as wood, concrete,

brick, fibre cement and plasterboard).


34/37

Stud adhesives

A stud adhesive is a thick,ready-to-use, water-based, gap-fillingadhesive which drieshard. Apart from bondingplasterboard to timberand metal frames, studadhesives are quite goodgeneral purposeadhesives for porous

materials in internal (notwater-exposed)applications.


35/37

Adhesive-sealants

Sealants muststick/adhere in order toperform the sealingfunction and tough

polyurethane sealants,such as SelleysProseries Adhesive +Sealant, create a

flexible, durable bondwhich is vibration- andshock-resistant.


36/37

Two-part epoxy glues

These two-part systems mustbe measured and thoroughlymixed before use. The mixingprocess starts a chemicalreaction which causes theadhesive to gain strengthquickly, so jobs can becompleted faster. Epoxy gluesproduce rigid, high-strengthbonds and work well

on porous surfaces. Non-

porous surfaces such as metalsshould be roughed for betterresults. Not all have high heatresistance and can be undoneby high temperatures.


37/37

Two-part tile adhesives

These adhesives workwhen a powder(cement) and a liquid(polymer emulsion) are

mixed together. Mixingin the liquid can makethe cement componentstronger, better

bonding, more flexible,or more chemical-resistant.

Documents

Plastics and Rubbers in Building