Construction Materials and Engineering - Module II - Lecture Notes

Construction Materials and Engineering
Diploma (Polytechnics)

1. Construction Materials and Engineering Module - II

2. Paints Applied on surfaces of timber, metals & plastered surfaces On drying paint forms a thin film on the painted surface A liquid Surface coating material

3. Functions of paints For pleasing appearance Check/stop penetration of water Check the formation of bacteria and fungus Check corrosion of structures Act as a protective coating against climatic changes Provides smooth surface for easy cleaning.

4. Properties of an Ideal Paint It should be possible to apply easily and freely. It should form hard and durable surface. It should not be harmful to the health of workers It should not be easily affected by atmosphere. It should possess attractive and pleasing appearance. It should dry in reasonable time. It should not crack and should be cheap It should possess good spreading power. Ordinary paint hardens by oxidation

5. Ingredients in paints Base Vehicle (Carrier) Drier Pigment Solvent

6. Base 1 Solid fine substance which forms bulk of paint Eg : White lead Determines character and durability of paint Red Lead Zinc White (Oxide of Zinc) Oxide of Iron Titanium white Principal constituent forming the body of paint Lithophone

7. Vehicle (Carrier/binder) 2 Liquid substances holding ingredients of paint Eg : Linseed oil Defines the spreading power of paint Tung oil Poppy oil Nut oil

8. Drier 3 To accelerate process of drying and hardening Eg : Litharge While hardening driers absorb oxygen from atmosphere and transfers it to linseed oil. Red lead

9. Pigments 4 Ingredient which provide colours to paint Eg : Black  Add Graphite Pigments available in form of fine powders. Green  Copper Sulphate Red  Red lead Available in different colours and qualities.

10. Solvent (Thinner ) 5 Makes the paint thin and helps for easy application Eg : Turpentine Not used in finishing coats (damage to firmness) Naphtha Have high penetration power Benzene

11. Types of Paints Aluminium Paint Anti-corrosive Paint Asbestos paint Bituminous paint Cellulose paint Cement paint Colloidal paint Emulsion paint Enamel paint Graphite paint Inodorous paint Luminous paint Oil paint Plastic paint Silicate paint Synthetic rubber paint

12. Aluminium paint 1 Contain finely ground aluminium in spirit/ oil varnish It is visible in darkness High corrosion resistance – commonly used for metals Oil/spirit evaporates and thin film layer forms on surface High spreading power – 200 m 2 / Litre Uses: for painting gas tanks, radiators, oil storage tanks

13. Anti-corrosive paint 2 Consist of oil and strong drier It is Cheap and black in colour Durable – last for a long duration Resist corrosion well

14. Asbestos paint 3 Applied to surfaces exposed to acidic gases and steams Bituminous paint 4 Manufactured by dissolving asphalt or vegetable bitumen in oil or petroleum It is black in colour Used for painting under water iron works.

15. Cellulose paint 5 Prepared from nitro cotton, celluloid sheets and photographic films Hardens by evaporation (not by oxidation) of thinner Hardens quickly Can withstand extreme cold and hot Can be washed & cleaned easily Widely used to aint motor vehicles

16. Cement paint 6 White cement + pigment + accelerator + additives Available in dry powder form Mixed with water immediately before its application Water proof and durable Applied in two coats Requires less skill

17. Colloidal paint 7 Requires more time to settle High penetration power No inert materials is mixed in this paint Used for interior and exterior walls

18. Emulsion paint 8 It contains binding materials such as polyvinyl acetate, synthetic resins , etc Easy to apply Dries quickly (1.5 – 2 hours) High alkali resistance

19. Enamel paint 9 White lead + Oil + Petroleum spirit + resins Available in different colours Dries slowly and form hard and durable surface Not affected by acids, alkalies , gases, hot and cold water, steam, etc For good appearance, titanium white is also added

20. Graphite paint 10 Black colour Applied on iron surfaces Used in mines and underground railways Inodorous paint 11 No turpentine is used in this paint White lead (or Zinc white) + Spirit Not durable, but dries quickly.

21. Luminous paint 12 Contains calcium sulphide and varnish Shines after the light is off Oil paint 13 Ordinary paint Applied in 3 coats Cheap and easy to apply Primer undercoat finishing coat

22. Plastic paint 14 Contains necessary variety of plastics Good appearance- showrooms, auditoriums, etc Silicate paint 15 Silica + resinous materials High temperature resistance Not affected by alkalies

23. Synthetic rubber paint 16 Prepared from resins Good resistance to water Easy to apply on surfaces Good chemical resistance

24. Preparation of paint Paste 1 = Base + Vehicle = Muller Muller is prepared by grinding base and vehicle to the consistency of a paste in a stone pestle 1 Paste 2 = Pigments + Linseed oil Mix the pigments and linseed oil separately using wooden puddle to form second paste 2 Paste 3 = Drier + Linseed oil Mix drier and linseed oil separately to form third paste 3

25. Preparation of paint Mix three pastes The mixture is stirred continuously till a consistency cream is obtained 4 Sieve the mixture This cream is passed through fine sieves and paint is now ready to use 5 Control workability To increase workability/consistency, oil or thinners are added 6

26. Stage - 1 Stage - 2 Stage - 3 Consistency cream Paint Base + Vehicle = Muller Linseed oil, pigments Mixing & Grinding Driers, chemicals, linseed oil Dilution Sieve Stir continuously

27. Application of paint - factors Make the surface ready for application of paint Surface to be painted should not be oily Cracks should be filled with putty & then with sand paper Apply one coat of primer Painting work should be carried out in dry weather The under coats and first coats must be allowed to dry before final coat is applied

28. Plastics Plastic is an organic substance It consist of natural or synthetic binders/resins Capable to flow when heated (Plasticity) Can be moulded into required size and shape

29. Classification of Plastics Behaviour w.r.t heating Thermo-plastics Thermo-setting plastics Structure Homogeneous Hetrogeneous Phy & mech properties Rigid plastics Semi-rigid plastics Soft plastics Elastomers

30. Behaviour w.r.t heating Softens on heating Hardens on cooling Reversible - reusable Formed by Addition polymerization Have long chain molecular structure Eg :- Nylon 6 Thermoplastics Thermo-setting plastics Cannot be reused Chemical reaction in this process cannot be reversed Formed by condensation polymerization Eg :- Electrical equipments , switches (Bakelite)

31. Characteristics and properties 1 Good appearance Available as transparent, opaque, attractive, stable and translucent colours 2 Good chemical resistance Offers great resistance to moisture, chemicals and solvents. 3 Sufficient dimensional stability 4 Sufficient ductility Members may fail without warning

32. Good durability and weathering resisitance Good electrical insulation Low weight and good finishing Good fire resistance Can be easily fixed in position Easy maintenance, cheap and can be recycled Characteristics and properties

33. Uses of plastics PVC Pipes - fixtures Utensils, bottles, etc Bath and sink units Corrugated and plain sheets Floor and wall tiles Overhead water tanks Safety glass Electrical conduits Wire insulations Pen coverings Lighting fixtures Concrete curing sheets

34. Advantages of plastics Offers great resistance to moisture, chemicals and solvents. Good durability Plastic possess good insulating properties Can be easily fixed in position Weight of material is low compared to others and cheap Have high tensile strength Require no maintenance. Occasional cleaning only required Can be mould into any shape without cracks over other building materials

35. Limitations of using plastics on environment Harmful to the nature - pollution Causes environmental degradation Burning of plastics causes health hazards – toxic fumes Have low melting point  Fire hazard Plastics usually have short useful life compared to metals Non renewable - Cost of recycling is high. Threat to animal life  suffocation

36. PVC – Polyvinyl Chloride Synthetic plastic polymer Formed by polymerization of vinyl chloride monomer Applications Pipes and ropes Electric cables Construction works Flat sheets Clothing Flooring

37. Characteristics and properties Rust proof, thermal proof and water proof Provide alternative to wood in many cases Resist dust penetration Unaffected by coastal saline air and dry heat Available in different colour and shade They don't fade, corrode, flake or warp Require no maintenance. Occasional cleaning only required Better thermal insulator

38. Rubber Polymers capable of undergoing large deformations under load and returning to their original shape Uses Conveyor belts Linings of tanks Automobile tyres Gasket of doors and windows Ropes and wires Cycle tyres and tubes Footwears, etc

39. Types of rubber Natural rubber Synthetic rubber Obtained from latex Also called as artificial rubber Poly Butadiene Rubber (PBR) Poly Isoprene Rubber (PIR) Synthetic Butadiene Rubber (SBR)

40. Characteristics and properties It can adsorb shocks due to impact It can contain liquids and gases It extends in length as result of applied force It is bad conductor of heat Good flexibility Resists abrasion Great resistance to acid and petroleum products Can undergo great deformation without structural damage

41. Good conductor of heat and electricity Highly resistant to corrosion Have good scrap value Light weight and takes more load Specific gravity = 2.7 Possess great toughness and tensile strength Ore: Bauxite (Al 2 O 3 .2H 2 O) Aluminium It readily dissolves in Hydrochloric acid

42. Hand rails and balusters Paneling and false ceiling works Building facades Furnitures Aluminium fabrication works Doors and windows – airtight/ AC buildings Aluminium used for building construction Facades Body parts of equipments

43. Glass Super cooled solution of various metallic silicates having infinite viscosity. Melting point = 800 – 950 o C

44. Available in beautiful colours Hard and extremely Brittle Properties of glass Amorphous – no definite crystalline structure Transparent or translucent Can absorb, refract, reflect and transmit light Has no sharp melting point - range

45. It is an excellent electrical insulator Not easily attacked by chemicals Properties of glass Possible to weld glass pieces by fusion It is affected by alkalies Not usually affected by water or air

46. Vehicle glasses and goggles Medicine bottles Furnitures, lampshades, bathroom fittings Photographic developments Prisms, lenses, mobile screens Laboratory equipments Furnitures, lampshades, bathroom fittings Uses of glass

47. Types of glass Soda Lime glass 1 Potash Lime glass 2 Potash Lead glass 3 Common glass 4

48. Sodium silicate + Calcium silicate Uses: Manufacture of glass tubes Window glass Plate glass Laboratory equipments Also known as soda glass 1. Soda Lime glass Fuses easily

49. Potassium silicate + Calcium silicate Uses: Combustion tubes Also known as Bohemian or hard glass 2. Potash Lime glass Difficult to fuse – high temperature needed Glassware for heating operations - bulbs

50. Potassium silicate + Lead silicate Uses: Manufacture of artificial gems Electric bulbs Lenses, prisms Also known as Flint glass 3. Potash Lead glass Fuses easily, lustre , and great refractive power

51. Sodium silicate + Calcium silicate + iron silicate Uses: Medicine bottles Also known as Bottle glass 4. Common glass Fuses with difficulty

52. Types of glass used for glazing Floating glass 1 Laminated glass 2 UV resistant glass 3 Reinforced glass 4 Reflective glass 5

53. Monolithic and highly transparent Most widely used type of glass 1. Floating glass Produced by flowing molten glass over a bath of molten tin and slowly cooling Uses: Windows, doors, etc

54. Made by sandwiching two glass plates with a high resistance plastic skin in between. 2. Laminated glass Uses: Facades, balconies, guard rails, partitions, showcases, floorings

55. Resist UV rays entering rooms 3. UV Resistant glass Uses: Laboratory and research spaces Reinforced with steel mesh to make it stronger 4. Reinforced glass Uses: Partition walls, external walls, ocean walls

56. Ordinary float glass with a metallic coating 5. Reflective glass Uses: Façade glazings Reflects and creates a mirror effect For providing aesthetic appearance

57. Special varieties of glass Bullet proof glass 1 Fiber glass 2 Float glass 3 Foam glass 4 Glass blocks 5 Heat excluding glass 6 Obscured glass 7 Perforated glass 8 Safety glass 9 Shielding glass Soluble glass Structural glass UV ray glass Wired glass 10 11 12 13 14 (Glass used for Structural applications)

58. Miscellaneous materials Abrasives 1 Adhesives Asbestos Asphalt Bitumen Cork Plaster of Paris 2 3 4 5 6 7 Acoustic materials 8 Fiber glass Thermocole 9 10

59. Hard materials used to cut/shape/polish other materials 1. Abrasives Natural abrasives and synthetic abrasives Diamond Garnet Emery Sandstone corundum Carbide of Aluminium boric acid silicon Forms – Sand paper, stones, grinding paste with oil

60. To join or create bond b/w two or more materials so as to form a single unit. 2. Adhesives (Glues) Examples of adhesives Albumin glue Animal protein glues Glues from natural resins Glues from synthetic resins Starch glues Vegetable glues

61. Naturally occurring fibrous mineral substance 3. Asbestos Excellent insulator of heat and electricity Composed of hydrous silicates of calcium and magnesium with small amount of iron oxide and alumina . Can be cut into pieces, holes can drilled Good adsorption capacity – asbestos cement Uses: Roofing, pipes, brake linings, gaskets

62. Mechanical mixture of alumina, lime, silica and asphaltic bitumen 4. Asphalt Remains in solid state at low temperature Black or brownish-black in colour Uses: Water proofing floors and roofs, DPC, Swimming pools, roads and pavements Types: Natural and Residual (Artificial) Becomes liquid at 50 o C to 100 o C Water/fire/sound/acid proof

63. Binding material present in asphalt 5. Bitumen (Mineral tar) Insoluble in water, but completely soluble in carbon bisulphide , chloroform, naphta , etc. It is chemically a hydrocarbon Uses: Water proofing floors and roofs, DPC, Swimming pools, roads and pavements Obtained by fractional distillation of crude petroleum Black or brown in colour

64. Obtained from bark of oak trees 6. Cork Uses: For preparing cork sheets & boards Bottle stoppers Packing gaskets Cork carpets as floor coverings (Churches, theaters, etc – noiseless covering)

65. Produced by heating gypsum to 150 o C 7. Plaster of Paris White colour and in powder form CaSO 4 .2H 2 O → CaSO 4 . H 2 O + 1.5H 2 O   Can be easily shaped when wet Uses: For aesthetic appearene Wall panels, casting works Ceiling works, acoustics

66. Sound absorbent materials used to proof sound 8. Acoustic materials Absorbs sound and prevents echo in the room Acoustics of rooms, studios, theatre halls Eg :- Acoustic plaster, perforated plywood, mats Uses: Acoustics of rooms Sound systems in studios Theatre halls Commercial centers

67. Composed of minute glass rods 9. Fibre glass Soft and flexible in nature Water/sound/fire/vermin/acids proof Uses: Thermal insulations Sheets Fibre Glass Reinforced Plastics (FGRP)

68. A type of plastic - Polystyrene 10. Thermocole Light weight and white colour Cushioning property Uses: Sound insulation in auditorium and theaters Cushion for various equipments Craftworks and model preparations Can be moulded to desired shape easily Used for acoustics in ceiling works

69. Wood products Major wood products are Veneer Plywood Particleboard Fibreboard Hardboard

70. 1. Veneer Thin sheets of wood of superior quality Thickness = 0.4 mm to 6 mm Obtained by rotating a log of wood against a shark knife of rotary cutter Dried in kilns to remove moisture

71. Process of preparing a sheet of veneer is known as veneering. Veneers are used to produce plywood's, batten boards, and laminboards . Glued on the surface of inferior wood to create an impression that whole piece is made of expensive timber

72. 2. Plywoods Ply means thin layer Veneers placed in both longitudinal and transverse directions  more strength Suitable adhesives are used to held in position Available in different commercial sizes

73. Used for: Ceilings Doors Furniture Partitions Paneling walls Formworks of concrete

74. 3. Particle board Formed by breaking down real wood residuals into wood fibers and glued back together with special resin by applying high temperature and pressure Light in weight Used for making readymade furniture

75. 4. Fiberboard (Pressed/reconstructed wood) Rigid boards Thickness = 3 mm to 12 mm Not able to take loads

76. Used for: Interior decorations Doors Partitions Panel works

77. 5. Hardboard Wood pulp is pressed under high temperature and water is removed. Sheets are smooth on one side and textured on other side Thickness = 3 – 9 mm