Unit_6.en

UNIT 6 MODERN MATERIAL MATERIALS S AND DECORATIVE DECORATIVE TREATMENTS TREATMENTS

Modern Materials and Decorative Treatments

Structure 6.1

Introduction Objectives

6.2

Polymers

6.3

Polymer Concrete Composites 6.3.1

Polymer Impregnated Concrete (PIC)

6.3.2

Polymer Concrete (PC)

6.3.3

Polymer Cement Concrete (PCC)

6.3.4

Sandwich Material

6.4

Glass

6.5

Decorative Plastering

6.6

Exterior Finishing Materials

6.7

6.6.1

Stone Facing

6.6.2

Granite

6.6.3

Limestone

6.6.4

Marble

6.6.5

Brick Veneer

6.6.6

Terracotta Facing (Ceramic Veneer)

6.6.7

Texture Finishes

Interior Finishing Materials 6.7.1

Wood Finishes

6.7.2

Gypsum Finishes

6.7.3

Clay Finishes

6.7.4

Stone Finishes

6.7.5

Concrete Finishes

6.7.6

Hardboard Finishing Panels

6.7.7

Fibre Board Panels

6.7.8

Wall Paper

6.7.9

Steel, Non-ferrous Metal and Plastics

6.7.10

Cork Tiles

6.8

Miscellaneous Decorative Finishes

6.9

Summary

6.10 Answers to SAQs

6.1 INTRODUCTION The construction industry is ever increasing in its technological advancement. Hence, it is necessary to get acquainted with the modern construction materials and prevailing trends in decorative treatments. The main consideration for this development is the change in the outlook of the designer as well as of the user. Nowadays, building has become more aesthetically pleasing and structurally sound. 119

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In this unit, our particular emphasis will be on modern construction materials and decorative treatment & finishes on different surfaces in a building.

Objectives This unit will help you to develop clear understanding of the modern construction materials such as polymer products, polymer composite concrete, glass and various finishes. After studying this unit, you should be able to • •

describe different uses of polymer in construction, describe various types of polymer composite concrete and its  properties,

•

identify different varieties of glass, and

•

describe decorative finishes for different surfaces in a building.

6.2 POLYMERS The polymers find a lot of usage in construction and building industry. Some of these will be discussed in this section.

6.2.1 Sealants Sealants are elastomeric materials used for the sealing of joints against wind and water in the construction industry. The largest variety of sealants fall into the classification of solvent release and are composed of three component  parts; these are : The Basic Non-volatile vehicle

It is the main compound, adhesive in nature, which seals the gap. The Pigment Component

It introduces colour to the material and also assist rheology and flow control. A Solvent or Thinner

It is used to reduce the viscosity, so that the sealant can be applied easily. After application, solvents evaporate leaving the sealant in place. The butyl rubber solution and the acrylic copolymer fall into this category. Another category of sealant is those which are chemically cured. Examples of such sealants are polysulphide and silicon base compound. The desired properties of sealants are : (i)

Good adhesion with the joint,

(ii)

Permanent elasticity,

(iii) Low rate of hardening, and (iv)

Low rate of shrinkage etc.

6.2.2 Adhesives Adhesives are used extensively for bonding building materials. Some of the resilient adhesives are of the following types : (i) 120

Rubber based mastic with water vehicle.

(ii)

Rubber based mastic with alcohol solvent.

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(iii) Linoleum paste. (iv) Epoxy resin mastic. (v)

Polymer adhesives, particularly resin bonded system are used extensively in the manufacture of plywood and particle boards.

6.2.3 Moisture Barriers Plastic films serve as permanent moisture barriers, preventing the deleterious ingress of water through various building and construction elements.

6.3 POLYMER CONCRETE COMPOSITES It is well known that ordinary concrete is a composite material consisting of relatively inert (naturally cured) aggregate, bounded with hydrated cement. The strength is imparted by the bond between aggregate and the cement paste. The nature of hydration and grading requirement of aggregate etc. limits the strength of ordinary concrete. Therefore, one way to enhance the binder’s (cement paste) capacity so as to obtain concrete of higher strength is to supplement or replace the cement binder with a more efficient binder like polymers. These composite using  polymers as a sole binder material or as a supplement to cement are known as  polymer concrete composites. There are three types of concrete composites which utilize polymer for their  production. (i)

Polymer Impregnated Concrete

(ii)

Polymer Concrete

(iii) Polymer Cement Concrete

6.3.1 Polymer Impregnated Concrete (PIC) Polymer Impregnated concrete is the hydrated Portland cement concrete, which has been impregnated with a monomer to fill up the voids present, totally or  partially, and subsequently polymerized there itself. The hardened concrete after curing contains considerable amount of free water in the voids ranging from 5% in dense concrete to 15% in gap graded concretes. This water has to be removed before filling up the pores with monomer. This is achieved by heating the concrete so as to drive the water out by evaporation. About 6 to 8 hours of heating is sufficient to remove the larger part of free water. The concrete is then cooled to avoid the risk of flammability. The evacuated concrete is then soaked at atmospheric pressure to attain partial saturation. Improvement in saturation may be obtained by application of pressure. The  polymerization is then done either by chemical, radiation or catalytic action. Properties of Polymer Impregnated Concrete (PIC)

(i)

The modulus of elasticity increases by 1.5 to 2 times than that of actual concrete.

(ii)

The creep of the PIC is 25% lower at the same stress.

(iii) Durability of the PIC is superior than ordinary concrete because of low porosity. (iv)

It is more resistant to sulphate attack. 121

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6.3.2 Polymer Concrete (PC) Polymer concrete is a composite material, where cement is completely replaced  by polymer and is formed by polymerizing polymerizing the monomer and aggregate mixture. The polymerized monomer acts as a sole binder for the aggregate system. Properties of Polymer Concrete

(i)

Compressive and tensile strength of polymer concrete is higher than those of ordinary concrete.

(ii)

The creep is comparable with ordinary concrete at lower temperature  but is much higher at higher temperature and humidity.

(iii) The strength decreases by 30-40% at higher temperature (about 88°C). (iv)

Chemical resistance of polymer concrete is far superior than ordinary concrete.

6.3.3 Polymer Cement Concrete (PCC) It is a composite made by adding a polymer or a monomer to a fresh concrete during the mixing stage itself and subsequently allowed to cure or polymerize if required. The binder of the PCC should not interface with the hydration process and must be able to form an emulsion or dispersion or a solution in water. Properties of Polymer Cement Concrete

(i)

The strength is 50 to 100% more than that of ordinary concrete.

(ii)

The tensile strength is twice that of ordinary concrete.

(iii) Durability is better. (iv)

The creep is lower than ordinary concrete.

(v)

Dry shrinkage is of same order of plain concrete.

6.3.4 Sandwich Material Sandwich material consisting of polymer composite skins with a low density core are widely used for light weight panels, where main loads are usually flexural. Typical examples of such material used in construction industry are Glass Fibre Reinforced Plastic (GRP). Use of sandwich materials in box beam or in hollow column is possible but their common use in construction industry is in the form of panels. Structural units used in building may be divided in two categories. Primary units, which are load bearing and failure of such units, may cause damage to building. Secondary units, which when fail, will cause only local damage. Wall panels are basically secondary units. The sandwich construction incorporating fibre reinforced polymer skins and synthetic foam can be used in such wall panels. Structurally such panels shall be able to withstand the wind  pressure, self weight and handling loads. Aesthetically, these need to be pleasant with low maintenance cost. They must exhibit good environmental behaviour and to have low thermal conductivity, and also must be the fire resistant.

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SAQ 1 (a)

Enumerate in short various types of polymer product used in construction.

(b)

Differentiate between Ordinary Cement Concrete and Polymer Cement Concrete.

(c)

Distinguish between PIC and PC.

(d)

Explain Sandwich construction.

6.4 GLASS Glass is produced from three major ingredients – sand (silica), soda (sodium oxide), and lime (calcium oxide). About 50 other compounds are also used in varying proportion to affect colour, viscosity or durability or to impart some desired physical property. An average batch contains about 70% silica, 13% lime and 12% soda and small amounts of other material.

6.4.1 Float Glass It is manufactured by pouring the molten glass over the liquid (molten) tin. It is allowed to spread to form a wide, flat ribbon of glass that remains untouched until it hardens. The speed with which it flows over the molten tin determines the thickness. Generally, slower the speed, thicker the resultant glass product. Float glass manufacturing accounts for over 90% of the flat glass produced today. The product are clear glass, heat absorbing glass, and tinted glass. Clear Glass

Clear glass is colourless. It is available in the thicknesses from construction  purposes ranging from 3/32 inch to 1¼ inch and from 48 × 84 inches to 120 × 204 inches in size. Heat-absorbing Glass

Heat-absorbing glass is intended for glazing where reduction of solar radiation is required and is available in bronze, grey and blue-green colour. Heat absorbing glass is produced by adding selected metallic oxides in small amounts to the basic glass mixture. Those oxides reduce light transmission, control solar transmission and glare, and absorb solar heat.

6.4.2 Rolled Glass Rolled glasses are made by pouring molten glass from a furnace and then passing it between the rollers to obtain the required thickness. It is then annealed in a layer and cut to required sizes. The types of glass produced under this category of rolled glass are: figured or patterned glass; wire glass; and stained glass. Figured or Patterned Glass

Figured or patterned glass is produced by the use of rollers that have a  pattern etched on either one or both sides which imparts the pattern to one 123

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or both surfaces of the glass as it passes through the rollers. A variety of  patterns is available with differing degree of obscuration. Figured glass can  be coloured, but only a limited number of colours is available. Thicknesses are usually of the order of 1/8 to 7/32 inch. Wire Glass

Wire glass is produced in a manner similar to that used for figured glass, with the addition of welded wire nettings or parallel wires placed in the molten glass prior to rolling. Wire glass can be obtained with a pattern or with polished faces (polished wire glass). Wire glass, usually 6 mm thick, is used in doors and windows where security is also the concern.

6.4.3 Heat Treated Glass It is made by reheating and rapid air cooling of the annealed glass. As a result of heat treating, the outer surface of the glass is put in compression and the central  portion or core is in the compensating tension. Heat treatment of glass results in increased tensile or bending strength which enables to withstand greater uniform loading pressures, and solar-induced thermal stresses. As a result, for high-rise structures with varying wind-induced pressure zones, the use of the same thickness heat treated glass in vision areas allows uniformity of light transmission, colour density, and glazing detail.

6.4.4 Insulating Glass Insulating glass units are factory fabric modules consisting of two panes of glass separated by a metal spacer around the perimeter, with an entrapped, sealed and desiccated air space in between. It is used where the inside is to be protected from harsh outside climatic conditions. Sometimes, triple glazed unit utilizing a third  pane and second metal spacer is used in extreme conditions like northern climates where winter temperature is unusually very low.

6.4.5 Laminated Glass Laminated glass consists of a combination of two or more panes of glass with a layer of transparent plastic sandwiched between the panes under heat and  pressure to form a single laminated unit. The introduction of plastic interlayer  produces a unit that will prevent sharp fragments from shattering when it is subjected to sharp impact and breaks since the glass adheres to the vinyl interlayer. It is used as safety glass as it minimizes the risks of injury from breakage or accidental impacts. It is useful for entrance doors, sliding doors, shower enclosures, sky lights and sloped glazing. The laminated glass unit utilizing the pigmented interlayer of polyvinyl butyral can reduce solar energy transmission, control glare and brightness and provides aesthetical qualities too. The use of plastic in laminated glass unit provides a damping characteristic which enhances the acoustic performance as compared to insulating glass.

6.4.6 Reflective Glass Reflective glasses have a transparent, thin metal or metal oxide coating deposited on one surface. These glasses are very popular due to its aesthetical appeal and solar control capabilities resulting in energy saving and occupants’ comfort. 124

The metallic film provided acts as a one way mirror, a person to exterior of the  building has difficulty in looking in during the day. However, However, at night with interior lights on, an occupant cannot see out but anyone on the exterior may see in. The metallic film reflects sunlight and reduces heat gain remarkably.

Modern Materials and Decorative Treatments

SAQ 2 (a)

Describe the manufacturing of rolled glass and its uses.

(b)

Distinguish between heat treated glass and insulated glass

6.5 DECORATIVE PLASTERING Plastering is the process of covering uneven surfaces in structures with a plastic material known as plaster. It is also referred to as “rendering” when describing the plastering applied to the external surfaces of walls to improve their appearance and to protect them from environmental agencies like sun and rain. It also provides the satisfactory base for decorating the surface by applying colour wash, distemper or paint on it. While there are several types of plasters, the most common are cement mortar, lime mortar and cement lime mortar plaster. However, in this unit, we shall study the special material used in decorative finishes in plaster.

6.5.1 Special Materials Used in Plastering Decorative appearance or finish is obtained in plastering by use of special materials in the finishing coat. Let us study some of these now. Plaster of Paris

When finely ground gypsum rock is heated to a temperature between 100 o and 140 C, three-fourths of the combined water passes off as steam. The residue is known as Plaster of Paris which hardens in 3 to 4 minutes on addition of water and hence retarders like glue, sodium citrate etc. are added in small amounts. Plaster of Paris is used for cast ornamental plaster work in interiors. Keene’s Cement

This is obtained by calcining Plaster of Paris with alum. It is the hardest form of gypsum plaster and sets within a few days. It is white in colour and can take high glass like polish. It is used for internal plastering and in situations like skirtings. It is also used for ornamental work and highly decorative plaster finishes because of its good polishing characteristics. Parian Cement

This is obtained by calcining Plaster of Paris with borax. It is cheaper than Keene’s cement and is suitable for large areas which are intended to be  painted at the earliest. Martin’s Cement

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In this case, Plaster of Paris is calcined with pearl ash. It is quick setting, and gives white hard surface on drying. It is considered suitable for internal work. Sira Pite

This material is produced by slaking Plaster of Paris in petroleum. This is also quick setting and gives white hard surface. It has high fire resistance qualities and is, therefore, used in internal fire-resistance plastering work. Scagliola

This material is obtained by dissolving Keene’s cement and suitable colouring pigments in glue. It has the appearance of imitation marble, and is used for columns, panels, etc. Marezzo

This is also an imitation marble, which is set upon a smooth surface, and is formed by mixing Keene’s cement and colours. Barium Plaster

This plaster material is made from barium sulphate and is used in the final coat of plaster to the walls of X-ray rooms in hospitals. It acts as a  protection to the personnel and technicians working in these rooms, as it absorbs X-rays. Acoustic Plaster

This is a proprietary material which consists of gypsum mixtures combined with water and used as final coat in plastering. This plaster undergoes a chemical reaction releasing gas bubbles and hence forming tiny openings in  plaster coat. Thus, a honey-combed surface is obtained which absorbs the sound. This acoustic plaster is applied in two coats of 6 mm thickness each and finished with a wooden float. Asbestos Marble Plaster

This consists of a mixture of finely crushed marble, asbestos and cement. It is quite expensive and is used in decorative finishes. It imparts a pleasing marble like finish. Granite Silicon Plaster

This type of plaster is quick setting and elastic and therefore does not crack. It is used for finishing coat in the superior type of constructions. Marble Finish Plaster

It is decorative, smooth and even surface finished and is applied to interior and external dado work to obtain a marble like appearance. The base surface is kept rough. It is thoroughly cleaned with water and a thin coat of white cement slurry is applied. Now the marble finish plaster is applied. The mix for this plaster is one part white cement and two parts coarse calcite powder. Calcite powder imparts brightness to the plaster. This mortar/plaster is applied with a steel float on the rough surface on which white cement slurry has been applied. Now a coat of white cement and lime is given to get a smooth finish.

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To obtain black streaks, white cement is mixed with black oxide colour and is applied randomly on the surface to get the desired design and levelled

smoothly by a steel float. The final surface is cured for two days. This  plaster surface is easily ea sily washable, requires no painting, is weather resistant and requires little maintenance.

Modern Materials and Decorative Treatments

Stonecrete Plaster

This is a plain white cement plaster having Ashlar stone finish. It is used for external surfaces. This plaster is carried out over a base coat of grey cement  plaster. A dry mix is prepared with one part white cement and one part coarse dolomite powder. Different shades are obtained by adding suitable  pigments while dry mixing. The mortar is prepared and applied on the walls with a steel float. The surface is levelled with gentle pressure. It is then cured with water for 48 hours. Finally, chiselling is done to obtain Ashlar stone finish. Grit Wash

This is permanent decorative finish used on external walls. Here also, the  base surface should be rough and even. Firstly, panels are prepared of the desired design on the surface with batten strips. Now mortar consisting of white cement, dolomite powder and aggregate chips or grit in the ratio of 1:1:2.5 is applied. The surface is levelled with a float applying gentle  pressure. After initial setting, say after about 1 to 2 hours, the surface is scrubbed gently with a nylon brush and water. Now the cement on the surface of chips is washed away thus exposing the aggregates. It is also called exposed aggregate plaster. Tyrolean Plaster

This finish is used in interiors and exteriors to obtain a long lasting and maintenance-free plaster. It is a sand face spray plaster coating, which is easy to apply. The mix consists of 3 parts white cement, 1 part marble  powder and 1 part coarse white sand or fine grains of marble chips by volume. Colour pigments are added to achieve desired shades. This  plastering is applied in two to three coats. After proper curing, the finished surface is left to dry. In order to avoid accumulation of dust, a coat of silicon should be applied on perfectly dry surface.

SAQ 3 Collect the cost of the special materials used in decorative plastering and  perform ‘Rate Analysis’ for the plastering as an item.

6.6 EXTERIOR FINISHING MATERIALS Exterior finishing materials are used in exterior walls of the buildings. Commonly used exterior wall facings and materials are discussed in the following sub-sections.

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6.6.1 Stone Facing The term ‘stone’ usually designates blocks or pieces of the basic rock material. It is one of the oldest building materials known to mankind. Because of its unique characteristics, stone has been regarded as the preferred material in the construction of permanent buildings. Stone used for building purposes can be classified according to the form in which it is available commercially, such as : (i)

Rubble (field stone),

(ii)

Cut stone,

(iii) Flag stone (flat slabs), (iv)

Crushed rock.

Stones which are commonly used in buildings include granite, limestone, travertine, marble, serpentine, sandstone and slate. Stone work may be divided into three general categories e.g., rubble work, ashlar, and trim. Rubble work involves using stones which have not been cut but which may have had one face – the face that is to be exposed – split or chipped. Two types of rubble work used are random and coursed. In random rubble work, no attempt is made to produce either horizontal or vertical course lines. In coursed nibble work, horizontal course lines are maintained with no vertical course lines incorporated (Figure 6.1).

Figure 6.1 : Random and Coursed Rubble

The term ashlar means only that the stone face showing on the finished surface has its beds and joints sawed or dressed. Ashlar stone work can have a rough, smooth or polished finish, depending on the treatment of the face. Coursed ashlar has continuous vertical and horizontal joints and random ashlar has neither continuous horizontal nor continuous vertical joints as shown in Figure 6.2.

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Figure 6.2 : Different Types of Ashlar

Modern Materials and Decorative Treatments

Ashlar work requires the use of cut stone and includes broken ashlar, irregular coursed ashlar and regular coursed ashlar (Figure 6.2). Field stone always has a rough, irregular appearance as the natural surface or broken surface of the stone is exposed. Stone trimming involves the use of stones cut for a specific purpose and includes quoins, jambs, sills, belts, copings, cornices, lintels, steps and arch stones. Quoins are stones laid at the intersection of two walls. They can be emphasised by letting them project beyond the vertical plane of the wall or by using a contrasting colour or type. Usually, they are laid so that they appear alternately as long and short stones on each side of the corner as shown in Figure 6.3.

Figure 6.3: Stone Quoins

6.6.2 Granite Granite comes in combinations of coloured crystals which give an overall appearance of a white, grey, pink, red, brown, green, blue or black stone. Granite  building stones are divided into two general types which are cut stone and ashlar type stone. Cut stone, which consists of large thin slabs of sawed or polished granite 7/8′′ thick at the minimum and going upto 2 1/2 ′′ (63 mm) at the most, is applied to exterior surfaces of buildings. Molded sills, copings, lintels, window and door trims, columns and stair treads are built with cut stone, or ashlar type stone work shown in Figure 6.4.

Figure 6.4 : Cut and Ashlar Type Granite Stone

6.6.3 Limestone Limestone is sedimentary rock made up chiefly of calcareous shells of organisms that live in oceans and lakes. 129

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Building limestone is available in grey and buff colours and in combinations of these two colours. Building limestone is described under two general categories such as cut stone and ashlar. (a)

Cut stone includes veneer and stock shapes such as molded sills, copings, lintels, window and door trims and columns which are used with cut stone veneer or ashlar type stone work. Veneer consists of large, thin slabs of limestone applied as exterior or interior surface finish to a building. Veneer slabs are also formed into panels for curtain-wall construction.

(b)

Ashlar stone consists of smaller, thicker pieces of limestone which are laid in various ashlar patterns and used as veneer on the exterior or interior of buildings.

Figure 6.5 : Toilet Room Partition Joints

6.6.4 Marble The word marble is derived from the Latin root marker, meaning a shining stone. Marble varies in its colour from white to black and is found in innumerable variations of veining and colour combinations. Marble for use in the exterior and interior of buildings comes in various sizes and thicknesses, and requires various kinds of setting beds and types of joints. Marble finds great use as a material for all types of sculpture and monuments. Cut stone usually consists of large, thick slab of stone with its face smooth, textured, slightly textured or polished.

6.6.5 Brick Veneer Brick is one of the oldest building materials known to mankind and the manufacture of this clay product still follows the same basic procedures developed in the past. Common bricks are normally made with smooth surfaces, but bricks to be used for facing are very often given some type of surface treatment – a texture applied at the columns of clay leave the die in the stiff-mud process, a glaze or a colour variation produced by flashing. Bricks are used in the building walls in the following ways : (i)

To form a solid brick wall,

(ii)

To build a cavity wall,

(iii) To build a partition wall, and 130

(iv)

To face walls built of some other material with a veneer of brick, usually 4" thick (Figures 6.6 and 6.7).

Modern Materials and Decorative Treatments

Brick veneering over a light wood frame is done in two ways. One is to use regular brick, laid up to produce a 4" thickness of veneer. The other method is to use thin slabs of brick manufactured for the purpose. There are two methods of these constructions: one is to lay up the brick over the sheathing, using metal ties railed to the sheathing to hold the brick in place; and the other is to cover the studs with paper backed wire mesh, apply a 1" thick layer of mortar and set the  bricks with their backs in the mortar. Any type of face brick can be used. When the veneer slabs are used, they are set in a mortar base which is applied over a stucco wire backing.

Figure 6.6: Exposed Steel Frame

Figure 6.7: Brick Keyed to Spandrel Beam

Brick curtain walls may be formed in several different ways in conjunction with steel or reinforced concrete frame buildings. The wall can be covered with face  brick (over a back up wall of common brick), clay tile or concrete block.

6.6.6 Terracotta Facing (Ceramic Veneer) In Italian language, ‘Terracotta’ literally means cooked or baked earth. It was first used extensively as a construction material by Egyptians, Greeks and Etruscans. The Romans also used terracotta as a substitute for stone in construction work, and developed its ornamental use in buildings. Today, terracotta is known as a ceramic veneer. The colour range of this natural, unglazed ceramic veneer is usually dull ochre to red. It can vary according to the composition of the clay and the temperature of firing. Finishes

The surface features of ceramic-veneer finishes vary over a large range which includes the following types : (a)

Smooth finish

(b)

Scored finish 131

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(c)

Combed finish

(d)

Roughened finish

(e)

Ceramic glaze

(f)

 Non-lustrous glaze

(g)

Ceramic colour glaze

(h)

Polychrome finish

Texture refers to surface qualities other than colour and includes the surface finishes just listed and any elaboration thereof. Extruded ceramic veneer is available in smooth, bevelled, fluted and scored surface texture. In handmade types, varieties of textures are possible. Extruded Ceramic Veneer

This includes : (i)

Adhesion type of ceramic veneer (not more than 1" thick), and

(ii)

Anchor type (not less than 1" thick).

Handmade Ceramic Veneer

This may be of three types : (i)

Closed back

(ii)

Open back

(iii) Solid slab (anchor type) The shells and webs of handmade ceramic veneer must be properly  proportioned and able to resist expansion and contraction stresses when they are burned. Prefabricated Ceramic Veneer Panel

A prefabricated ceramic veneer panel consisting of a ceramic veneer facing with a light weight concrete backing and reinforcing is available for curtain wall construction (Figure 6.8). Ornamental Uses

Sculptural reproduction can be obtained in ceramic veneer, either plain or in  polychrome colours. Decorative, perforated ceramic veneer units are now available for use as screens, grills and facades for architectural work.

Figure 6.8 : Brick Veneer Set in Mortar Backing

6.6.7 Texture Finishes Stucco

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Stucco is a type of plaster made with Portland cement which is applied to exterior surfaces as a finish coating. It can be applied directly to masonry walls, but over the wood sheathing some type of wire must be used to tie the sheathing and stucco together. Either a woven wire mesh or expanded metal lath can be used. In either case, the openings should be large enough to permit the first coat to be forced through the openings to embed the wire completely. Wire should not be less than 1/4" away from the sheathing and should be railed every 8" to 9" (Figure 6.9).

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Figure 6.9 : Expanded Metal Lath

Stucco is applied in three coats, a base or scratch coat, a second or brown coat and a final finish coat. All three coats are composed of 1 volume of Portland cement to 3-5 volumes of clean sharp sand. The scratch and brown coats should be applied about 3/8" thick with sufficient time between applications to allow for proper curing. Each coat should be kept moist for at least 48 hours. The final coat should not be less than 1/8" thick and should be applied not sooner than seven days after application of the brown coat. Mineral colour may be added to the finish coat, or already prepared and coloured dry stucco is available for finish coats. A variety of treatments can be given to the finish coat to produce certain textures. Among the treatments, commonly used, are French trowel, spatter dash, Italian finish and travertine coarse; and coloured pebbles may  be sprayed against the newly applied finish coat to produce a pebble dash finish. Granule-Texture Finishes

These finishes are made up of granules of various materials like mosaic, glass, sand, plastic, other synthetic materials etc. These are mixed with colouring pigments to get the required shades and appropriate resin is used as binding material to help fixing on the wall. Flaked-Textures

These are same as above except for the fact that granules will be replaced  by flake of the same basic material.

SAQ 4 (a)

Explain the various ways in which stone is used as a facing material.

(b)

What is meant by brick veneering?

6.7 INTERIOR FINISHING MATERIALS The materials which are used to finish the interior walls and ceilings of buildings include wood, gypsum, clay products, stone, concrete, fibre boards, paper, glass,

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steel, nonferrous metals, plastics and paints. A variety of products have been developed from each basic material so that a wide choice of finishes is available in respect of any material.

6.7.1 Wood Finishes Interior finishing materials of wood can be divided into two basic groups : (i)

those used to cover walls and ceilings, and

(ii)

those used as trim materials around door and window openings, as  base board and as various decorative mouldings.

Wall and ceiling coverings can also be divided into two groups : (i)

those made of solid wood, and

(ii)

those made of ply wood.

6.7.2 Gypsum Finishes One of the best known types of interior finishes is produced by the plastering material in which gypsum is one of the basic ingredients. Plaster surfaces can be troweled smooth, stippled or sand finished. Gypsum Board is also used as an interior finishing material.

6.7.3 Clay Finishes Clay products of all kinds can be used for interior finishing. They include common brick, face brick, glazed brick, structural tile, glazed tile, ceramic veneer, ceramic wall tile and ceramic mosaic.

6.7.4 Stone Finishes Stone interior finishes can be produced by using solid stone on exposed interior as well as exterior surface of a wall. Any type of building stone may be used for this purpose. The other method is to cover the interior surface with thin stone slabs, from 1" - 2" thick. The stone is applied over a back up wall of concrete, concrete block, brick or tile and is held in place with some type of stone anchor. A number of imitation stone products made from terracotta are also used for this  purpose.

6.7.5 Concrete Finishes Concrete is used in various ways for interior work. Plain concrete walls are often given special treatment to make them as smooth as possible. Textured and  patterned surfaces are produced by special treatment of the form face. Pre-cast concrete panels often have one face finished for interior exposure. The face may be textured, patterned or coloured, or it may consist of exposed aggregate. Concrete blocks with a glazed face are also produced for interior use.

6.7.6 Hardboard Finishing Panels Tempered hardboard is treated in many ways to produce interior facing panels.

6.7.7 Fibre Board Panels These panels may be used as interior finish material on ceilings or on walls,  particularly above dado level. 134

For ceilings, the board may be in the form of tiles, strips and panels. Panels may  be plain faced or marked off by V grooves in file pattern.

Modern Materials and Decorative Treatments

6.7.8 Wall Paper Paper has been used as an interior decorative material for a long time and still finds wide acceptance in many situations. In addition to the conventional designs, wall paper is produced in a wide range of wood grain, fabric, stone, brick and mural patterns. Wall papers are produced in single and double rolls 20- 36" wide containing 36 sq ft per single roll.

6.7.9 Steel, Non-ferrous Metal, Plastics All of these materials are used to produce a number of products adopted to interior finishing.

6.7.10 Cork Tiles Cork, an excellent acoustic material, is available in the form of tiles. It can be used for almost any interior application in floors, walls, panels, partitions and ceilings. They are resistant to fire, chemicals and are quite durable.

SAQ 5 (a)

Enumerate some interior finishing materials.

(b)

What are the different materials materials used to clad the internal walls of of any  building?

6.8 MISCELLANEOUS DECORATIVE FINISHES 6.8.1 Decorative Ceiling Tiles There are several types of decorative ceiling tiles available. One type is made from special quality three layered particle board. It is flat pressed and boarded with BWP-grade Phenol Formaldehyde Synthetic Resin. This material is ideal for making rigid and strong decorative ceiling tiles. They are available in embossed designs also. These tiles are available both half and full perforated in size of 60 × 60 cm and 12 mm thick. They are fire resistant, termite, weather and fungus proof, dimensionally stable and warp free, and provide excellent insulation against heat and sound. Topline Ceiling Tiles is one such type. Another type is Anchor Ceiling Tile. Similarly, there are other brands, which come in different architectural patterns, and are considered ideal for homes, offices, showroom, restaurants, auditoriums, airports and factories. They come in designs like diamond, chequered, Paragon, Serrated and Gothic. They combine beauty and safety.

6.8.2 Decorative Ceilings False ceilings are used in buildings for architectural applications. These ceilings come in different materials, and they offer solutions for commercial design  problems. Recently, colour coated steel sets of false ce iling panel have entered the market. They come in different colours, finishes and patterns.

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Engineering Materials

Some such ceilings are called “Trac” and “Supersil”. Another decorative ceiling consists of aluminium sheets slates/louvers. This ceiling system is suitable mainly for centrally air-conditioned building.

6.8.3 Decorative Films for Glass Surfaces Another decorative finish which is becoming popular is the decorative adhesive coated film on glass in windows, doors and on mirrors, shower partitions, acrylic ceiling, panels and showcases. It renders glass shatter-resistant and diffuses sunlight so as to lend soft glow and prevent discolouration of interiors. It is ultra violet rays resistant. It reduces heavy air-conditioning bills and lends sophistication and style to the interiors. These films come in range of finishes and  patterns, stained glass or embossed. One such material is known as “Glass Décor”.

6.8.4 Decorative Damp Proofer  Now damp proofers are available which protect as well as decorate. They protect surfaces from dampness, leakage, seepage, fungus growth, sunlight, week acids, etc. and also decorate like a paint. They are inherently coloured in as many as 30 shades or more and can be applied directly over the plaster providing a smooth satin finish. One such damp proofer is known as “Chemistik Pro Décor”.

6.8.5 Decorative Laminates Another material which is becoming very popular in imparting decorative finish in interiors is decorative laminate. These laminates are available in several types of finishes like plain shade, geometrical, textile marble and granite, metallic etc. They generally come in sizes of 8′ × 4′ with general size thickness of 1.0 and 1.55 mm.

6.9 SUMMARY In this unit, you have seen how the polymers enhance the quality of normal concrete. This new type of the material is used increasingly nowadays. The use of glass too has become an important aspect in the construction industry. Various finishing materials play an important role in the decoration and aesthetics of  buildings. The decorative finishes encompass all surfaces in a building like wall, floor and ceiling etc. The decorative finish not only adds to aesthetic appearance, but also  provides protective coating to the surface. The decorative finishes in plast er are diverse in nature with rough finishes like pebble dash and rough cast, at one end, and textured or ornamental finish, at the other end. Thus, overall, it is observed that there is an explosion of information about new decorative finishes, and almost in every quarter, a new decorative finish is entering in the building industry.

6.10 ANSWERS TO SAQs Refer the relevant preceding text in the unit or other useful books on the topic listed in Section “Further Reading” to get the answers of the SAQs.

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FURTHER READINGS

Modern Materials and Decorative Treatments

Materia ls, Standard Publishers Distributors. Gurcharan Singh, Building Materials

 Naville, A. M., Properties of Concrete, The English Language Book Society and Pitman Publishing, London. Shetty, M. S., Concrete Technology, S. Chand and Company Ltd., New Delhi. IS : 456-1978. Mater ials, Konark Publishers Pvt. Ltd. Surendra Singh,  Engineering Materials

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