Materials science and civil engineering materials

1. Materials science and civil engineering materials Assistant Professor Dr. Tayfun Altuğ Söylev

2. Historical Perspective • Historically, the development of societies have been tied to the ability to produce materials. In fact, early civilizations have been designated by the level of their materials development (Stone Age, Bronze Age, Iron Age)

3. Historical Perspective • The earliest humans had access to only a very limited number of materials, those that occur naturally: stone, wood, clay, and so on. • With time they discovered techniques for producing materials that had properties superior to those of the natural ones; these new materials included pottery and various metals.

4. Historical Perspective • Furthermore, it was discovered that the properties of a material could be altered by heat treatments and by the addition of other substances. • It was not until relatively recent times that scientists came to understand the relationships between structural elements of materials and their properties (approximately the past 100 years)

5. Materials science and engineering • Materials science involves investigating the relationships that exist between the structures and properties of materials (to develop new materials) • In contrast, materials engineering is designing or engineering the structure of a material to produce a predetermined set of properties (to create new products using existing materials)

6. Properties of materials • All important properties of solid materials may be grouped into six different categories: mechanical, electrical, thermal, magnetic, optical, and deteriorative • Mechanical properties relate deformation to an applied load or force; ex: elastic modulus and strength

7. Mechanical properties

8. Properties of materials • Electrical properties, ex: electrical conductivity and dielectric constant • Thermal behaviour: heat capacity and thermal conductivity • Magnetic properties demonstrate the response of a material to the application of a magnetic field

9. Properties of materials • For optical properties, the stimulus is light radiation • Deteriorative characteristics relate to the chemical reactivity of materials

10. Classification of materials • Solid materials have been conveniently grouped into three basic classifications: metals, ceramics, and polymers. • Metals: Composed of one or more metallic elements (such as iron, aluminum, copper, titanium, gold, and nickel), and often also nonmetallic elements (for example, carbon, nitrogen, and oxygen) in relatively small amounts

11. Metals

12. Metals • Relatively stiff and strong, yet ductile (capable of large amounts of deformation without fracture), resistant to fracture, which accounts for their widespread use in structural applications. • Good conductors of electricity and heat, not transparent to visible light.

13. Metals

14. Fracture a) Highly ductile; b) moderately ductile c) brittle

15. Ceramics • Ceramics: compounds between metallic and nonmetallic elements. • Some of the common ceramic materials include aluminum oxide (or alumina, Al2O3), silicon dioxide (or silica, SiO2), and, in addition, what some refer to as traditional ceramics-those composed of clay minerals (i.e., porcelain), as well as cement, and glass.

16. Ceramics • Relatively stiff and strong-stiffnesses and strengths are comparable to those of the metals. Typically very hard. Extremely brittle (lack ductility), highly susceptible to fracture. • Typically insulative to the passage of heat and electricity (i.e., have low conductivities), and more resistant to high temperatures and harsh environments than metals and polymers.

17. Polymers • Polymers: Plastic and rubber materials. Many of them are organic compounds that are chemically based on carbon, hydrogen, and other nonmetallic elements. • Some of the common familiar polymers are polyethylene (PE), nylon, polyvinyl chloride (PVC), polycarbonate (PC), polystyrene (PS), and silicon rubber.

18. Polymers • Not as stiff nor as strong as the metallic and ceramic materials. However, low density.Extremely ductile. Low electrical conductivities • Composites: One of the most common and familiar composites is fiberglass, in which small glass fibers are embedded within a polymeric material

19. Selection of materials • Why do we study materials? An engineer, whether mechanical, civil, chemical, or electrical, will at one time or another be exposed to a design problem involving materials. • Many times, a materials problem is one of selecting the right material from the many thousands that are available.

20. Selection of materials • There are several criteria. On only rare occasions does a material possess the maximum or ideal combination of properties. Thus, it may be necessary to trade off one characteristic for another. • The engineer must consider the fitness of the material for the purpose of the structure being designed.

21. Selection of materials • The fitness-for-purpose: ensuring that the material will perform adequately both during construction and in subsequent service. • Principal criteria: strength, deformation and durability • For particular applications: water-tightness or speed of construction, aesthetics, environmental impact

22. Selection of materials • For instance, members carrying tension can be made of steel or timber, facing panels can be fabricated from fibre composite, metal, timber or masonry. • The matter may be resolved by the engineer making a choice based on his or her judgement, with often some help from calculations

23. Selection of materials • Timber is outstanding in terms of stiffness and strength at both minimum weight and minimum cost. • minimum cost: the highest scoring materials other than timber are steel and concrete.

24. Selection of materials • Other properties, such as ease of construction, durability and toughness should be taken into account. • The cost of the energy used in manufacturing the material and its transport and fabrication must also not be overlooked, either in simple economic or in environmental terms.

25. Selection of materials

26. Materials applied in civil engineering • Civil engineering - the art of construction of all kinds of buildings • Dwelling as well as public buildings, industrial buildings, bridges, viaducts, tunnels, roads and railways, highways and airports, liquid reservoirs and loose-material containers, weirs, dams, offshore structures, TV towers etc.

27. Materials applied in civil engineering Engineering works had to have • reliability • durability • functionality but also • harmony and beauty

28. Materials applied in civil engineering Development of civil engineering  struggle with • available materials • spans or height • active loads • and the forces of nature: water, fire, wind and earthquakes

29. Stone and brick First of all, ancient communities: natural materials such as stone and timber In the course of time: clay to form bricks In the main civilisation centres, the hot climate  the elimination of timber

30. Stone and brick • Stone and brick: from stone pyramids in Egypt 3000 years B.C.E. until Industrial Revolution in England (18th and 19th centuries) • Brittle materials: suitable for walls and columns • Problems in horitonzal elements due to their low tensile bending strength

31. Arch • Structures of larger span  semicircular elements: arch • In the course of time: lighter and less massive • Greater ratio of span-to-width

32. Arch • No development during the early Middle Ages • New ideas in Gothic and the Renaissance • However still based in the forms of arches: from semicircular to segmental and elliptical

33. Old bridges A single arch of the Pont Neuf Paris Ponte Santa Trinita crosses the Arno River in Florence, Italy

34. Old bridges The most famous bridge in Florence and also the oldest, dating from 1335-45, Ponte Vecchio with its three stone arches. Florence, Italy Pont du Gard Roman aqueduct near Nimes in France

35. Steel Steel: basic construction material of the 19th and 20th centuries • Steel and cement are two relatively new building materials • First cast iron, then puddled and cast steel, finally refined high strength steel proved to be very good construction materials

36. Steel • Ductile materials, high tensile and compressive strength  spans that some years ago were beyond consideration

37. Akashi-Kaikyo Bridge The largest span from 1998 to the present – span length = 1991 m

38. Great Belt Bridge Span length = 1624 m

39. Messina Straits Bridge Span length = 3300 m – expected opening 2012

40. Steel • Despite such progress, steel bridges are reaching the limits of their possibilities. • What can the high strength steel cables be replaced to make them much lighter but as strong as the steel cables?

41. CFRP Carbon fibre reinforced polymer: structural material of the future • Carbon fibre reinforced polymer used in space and aviation thechniques and professional sport • Composed of very thin fibers with a diameter of 5-10 m, embedded in polyester resin

42. Boeing 787 Boeing 787 Dreamliner ․Largest passenger aircraft ․Made of largest amount of carbon fibers

43. SR-71 "Blackbird”

44. B-2 bomber Extensive use of carbon fibre composites to make them undetectable by radars

45. CFRP

46. CFRP First applied in strengthening of a bridge in 1991. CFRP cables were applied for the first time in 1996 Ibach Bridge near Lucerne in Switzerland

47. Ibach Bridge, Switzerland 1991

48. Laroin Foot Bridge, 2002 1st bridge ever built in France using carbon composite cables

49. CFRP • With very high resistance to axial tension exceeding even twice that of high tensile strength steel, the elastic modulus is not much lower, whereas the mass density is about five times lower. • Material of the future: durable, fatigue resistant, and non-corrosive

50. Concrete Concrete: basic construction material of the 20th century • The other invention of the First Industrial Revolution that caused progress in civil engineering was cement. • Portland cement (excellent hydraulic binder) was patented in 1824. It was used for the production of a new material – concrete.