CONSTRUCTION MATERIALS and CONCRETE

2. CONSTRUCTION MATERIALS and CONCRETE

3. CONCRETE WHAT IS CONCRETE? • Constructionmaterial • Mixture of portland cement, water, aggregates, and in some cases, admixtures. • The cement and water form a paste that hardens and bonds the aggregates together. • Often looked upon as “man made rock”. • Versatile construction material, adaptable to a wide variety of agricultural and residential uses. • Strong, durable, versatile, and economical. http://www.inlandcanada.com/NR/rdonlyres/F0EBC912-01A0-4D58-AE7D-6F9FD7DE0FF7/0/ConcreteRecycler3.jpg

4. CONCRETE • Can be placed or molded into virtually any shape and reproduce any surface texture. • The most widely used construction material in the world. • In the United States almost twice as much concrete is used as all other construction materials combined. • The ready-mix concrete producer has made concrete an appropriate construction material for many applications.

5. Composition of concrete • Water • Aggregates • Chemicaladmixtures • Cement http://www.bu.edu/sjmag/scimag2008/images/Texture__Concrete_Cracked_by_ivelt_resources.jpg

6. WATER • Good water is essential for quality concrete. • Should be good enough to drink--free of trash, organic matter and excessive chemicals and/or minerals. • The strength and other properties of concrete are highly dependent on the amount of water and the water-cement ratio. http://pure-perfection.net/custom/Water-Droplet-1039X761.jpg

7. AGGREGATES • Aggregates occupy 60 to 80 percent of the volume of concrete. • Sand, gravel and crushed stone are the primary aggregates used. • All aggregates must be essentially free of silt and/or organic matter. http://www.bondedaggregate.co.uk/images/select-aggregate-driveway.jpg

8. CHEMİCAL ADMİXTURES • Materials in the form of powder or fluids that are added to the concrete to give it certain characteristics not obtainable with plain concrete mixes. • In normal use, admixture dosages are less than 5% by mass of cement, and are added to the concrete at the time of batching/mixing.

9. CHEMİCAL ADMİXTURES Themostcommontypes of admixturesare: • Accelerators : - Speedupthehydration (hardening) of theconcrete. - Typicalmaterialsusedare CaCl2andNaCl. • Acrylicretarders : -Slowthehydration of concrete, andareused in largeordifficultpours. - Typicalretarder is tablesugar, orsucrose (C12H22O11).

10. CHEMICAL ADMIXTURES • Air Entraining agents: -The most commonly used admixtures for agriculturalconcrete. -Produce microscopic air bubbles throughout the concrete. -Entrained air bubbles: • Improve the durability of concrete exposed to moisture and freeze/thaw action. • Improve resistance to scaling from deicers and corrosive agents such as manure or silage.

11. CHEMICAL ADMIXTURES • Water-reducingadmixtures -Increase the workability of plastic or "fresh" concrete, allowing it be placed more easily, with less consolidating effort. -High-range water-reducing admixtures are a class of water-reducing admixtures • Increaseworkability • Reducethewatercontent of a concrete. • Improvesitsstrengthanddurabilitycharacteristics.

12. REINFORCEMENT • Strong in compression, as the aggregate efficiently carries the compression load. • Weak in tension as the cementholding the aggregate in place can crack, allowing the structure to fail. • Reinforced concrete solves these problems by adding eithermetal reinforcing bars, steel fibers, glass fiber, or plastic fiber to carry tensile loads. http://www.eurocode2.info/images/reinforcement.jpg

13. CEMENT • Crystalline compound of calcium silicates and other calcium compounds having hydraulic properties. • Considered hydraulic because of their ability to set and harden under or with excess water through the hydration of the cement’s chemical compounds or minerals http://img.alibaba.com/photo/11654315/Portland_Cement_42_5_N_R.jpg

14. CEMENT • Uses Main use is in the fabrication of concrete and mortars • Modern uses -Building (floors, beams, columns, roofing, piles, bricks, mortar, panels, plaster) -Transport (roads, pathways, crossings, bridges, viaducts, tunnels, parking, etc.) -Water (pipes, drains, canals, dams, tanks, pools, etc.) -Civil (piers, docks, retaining walls, silos, warehousing, poles, pylons, fencing) -Agriculture (buildings, processing, housing, irrigation)

15. CEMENT • HYDRAULIC CEMENTS: • Hydraulic lime: Only used in specialized mortars. Made from calcination of clay-rich limestones. • Natural cements: Misleadingly called Roman. It is made from argillaceous limestones or interbedded limestone and clay or shale, with few raw materials. Because they were found to be inferior to portland, most plants switched. • Portland cement: Artificial cement. Made by the mixing clinker with gypsum in a 95:5 ratio.

16. CEMENT • Portland-limestone cements: Large amounts (6% to 35%) of ground limestone have been added as a filler to a portland cement base. • Blended cements: Mix of portland cement with one or more SCM (supplementary cemetitious materials) like pozzolanic additives. • Pozzolan-lime cements: Original Roman cements. Only a small quantity is manufactured in the U.S. Mix of pozzolans with lime.

17. CEMENT • Masonry cements: Portland cement where other materials have been added primarily to impart plasticity. • Aluminous cements:Limestones and bauxite are the main raw materials. Used for refractory applications (such as cementing furnace bricks) and certain applications where rapid hardening is required. It is more expensive than portland. There is only one producing facility in the U.S.

18. PORTLAND CEMENT • Mostactivecomponent of concrete • The greatest unit cost in concrete, • Its selection and proper use are important in obtaining most economically the balance of properties desired for any particular concrete mixture. http://www.cement.org/decorative/images/overview2.jpg

19. PORTLAND CEMENT • The production process for portland cement first involves grinding limestone or chalk and alumina and silica from shale or clay. • Type I/II portlandcementsarethemost popular cementsusedbyconcreteproducers -TypeI cement is the general purpose cement and most common type. Unless an alternative is specified, Type I is usually used. -Type II cement releases less heat during hardening. It is more suitable for projects involving large masses of concrete--heavy retaining walls

20. Types of Portland cement

21. PORTLAND CEMENT PhysicalProperties of PortlandCements • Fineness, • Soundness • Consistency • Setting time • Compressive strength • Heat of hydration • Loss of ignition

22. Concrete production • This process develops physical and chemical properties like mechanical strength, low moisture permeability, and chemical and volumetric stability. A properly proportioned concrete mix will provide • Mixing concrete • Workability • Curing

23. Mixing concrete • Essentialfor • The production of uniform concrete, • Highqualityconcrete. • Equipmentandmethodsshould be capable of effectivelymixing http://en.yujianjx.com/upload/Concrete-Mixing-Plants-HZS50.jpg

24. Workability • The ease with which freshly mixed concrete can be placed and finished without segregation. • Difficult to measure but ready-mix companies usually have experience in determining the proper mix. • Important to accurately describe what the concrete is to be used for, and how it will be placed.

25. Curing • Concrete that has been specified, batched, mixed, placed, and finished "letter-perfect" can still be a failure if improperly or inadequately cured. • Usually the last step in a concrete project and, unfortunately, is often neglected even by professionals. http://www.eagleind.com/piclib/324.jpg

26. Curing • Curing has a major influence on the properties of hardened concrete such as durability, strength, water-tightness, wear resistance, volume stability, and resistance to freezing and thawing. • Proper concrete curing for agricultural and residential applications involves keeping newly placed concrete moist and avoiding temperature extremes (above 90°F or below 50°F) for at least three days. • A seven-day (or longer) curing time is recommended.

27. Curing • The best curing method depends on: • Cost, • Application equipment required, • Materials available, • Size and shape of the concrete surface. • Prevent the loss of the mixing water from concrete by sealing the surface. • Can be done by: • Covering the concrete with impervious paper or plastic sheets, • Applying membrane-forming curing compounds.

28. Curing • Begin the curing as soon as the concrete has hardened sufficiently to avoid erosion or other damage to the freshly finished surface. • Usually within one to two hours after placement and finishing. http://epg.modot.mo.gov/files/thumb/b/b2/1055.jpg/400px-1055.jpg

29. Properties of concrete • Strength • Elasticity • Cracking • Shrinkagecracking • Tensioncracking

30. Strength Concrete has relatively • High compressive strength, • Low tensile strength • Fair to assume that a concrete sample's tensile strength is about 10%-15% of its compressive strength • The ultimate strength of concrete is influenced by - water-cementitious ratio -the design constituents - the mixing -placement -curing methods

31. Elasticity • Function of themodulus of elasticity of theaggregatesandthecementmatrixandtheirrelativeproportions • TheAmericanConcreteInstituteallowsthemodulus of elasticityto be calculatedusingthefollowingequation: where wc = weight of concrete (poundspercubicfoot) andwhere f'c = compressivestrength of concrete at 28 days (psi)

32. Cracking • All concrete structures will crack to some extent. • Cracks due to tensile stress induced by shrinkage or stresses occurring during setting or use

33. Shrinkage cracking • Occurwhenconcretemembersundergorestrainedvolumetricchanges (shrinkage) as a result of eitherdrying, autogenousshrinkageorthermaleffects. • The number and width of shrinkage cracks that develop are influenced by -the amount of shrinkage that occurs -the amount of restraint present -the amount and spacing of reinforcement provided. http://epg.modot.org/files/thumb/3/39/216_Removal_of_existing_expansion_joint.jpg/550px-216_Removal_of_existing_expansion_joint.jpg

34. Tension cracking • Most common in concrete beams where a transversely applied load will put one surface into compression and the opposite surface into tension due to induced bending. • The size and length of cracks is dependent on - The magnitude of the bending moment - The design of the reinforcing in the beam at the point under consideration.

35. Types of concrete • Glass concrete • Asphalt concrete • Rapid strength concrete • Rubberized concrete • Polymer concrete • Geopolymer or green concrete • Limecrete • Refractory Cement • Concrete cloth • Innovative mixtures • Gypsum concrete • Regular concrete • High-strength concrete • Stamped concrete • High-performance concrete • Self-consolidating concretes • Vacuum concretes • Shotcrete • Pervious concrete • Cellular concrete, • Cork-cement composites • Roller-compacted concrete

36. Concrete testing Compression testing of a concrete cylinder Same cylinder after failure http://www.antouncivil.com.au/vca/Images/testing.jpg http://www.concrete-curb.com/wp-content/uploads/BreakageCylinder.jpg

37. General test methods • Compaction Factor Test(Compacting Factor Test,Glanville) • Compaction Test • Free Orifice Test (Orimet Test) • K-Slump Tester • Free Flow Test Methods • Slump Test • Modified Slump Test • Slump Rate Machine • Kelly Ball Test • Ring Penetration Test • Cone Penetration Test • Moving Sphere Viscometer • Flow Trough Test • Delivery-Chute Torque Meter • Delivery-Chute Depth Meter • Surface Settlement Test

38. Concrete recycling • increasingly common method of disposing of concrete structures • recycling is increasing due to -improved environmental awareness - governmental laws -economic benefits • Recycling concrete provides -environmental benefits -conserving landfill space

39. Construction materials • Asphalt • Aggregate • Brick • Gypsum

40. ASPHALT • Also known as bitumen • Dark brown to black • Highly viscous • Hydrocarbon produced from petroleum distillation residue.  • At least 80% carbon, which explains its deep black color. • Sulphur is another ingredient. • Primarily used as a sealant for rooftops and a durable surface for roads, airport runways, playgrounds and parking lots. http://www.ekocozum.com/blog/wp-content/uploads/2008/05/asfalt.jpg

41. ASPHALT • Asphalt can be separated from the other components in crude oil • By the process of fractional distillation, usually under vacuum conditions. http://www.cranedigital.com/case_studies/oil_and_gas/fractional_distillation_column2.jpg

42. TYPES OF ASPHALT • The major types of asphalt used in construction are ; • Rolled asphalt • Mastic asphalt. http://www.pkeenanroads.com/wp-content/gallery/stone/rolled.jpg http://www.highwaysmaintenance.com/JPEGsurf/smisSMA.jpg

43. Rolled Asphalt • Made of aggregate, or solid materials such as sand, gravel, or recycled concrete, with an asphalt binder. • Used to make roads and other surfaces, such as parking lots, by being applied in layers and compacted. • Different types of rolled asphalt are distinguished according to the process used to bind the aggregate with the asphalt.

44. TYPES OF ROLLED ASPHALT • Hot mix asphalt concrete (HMAC) - Produced at 160 degrees Celsius. -This high temperature serves to decrease viscosity and moisture during the manufacturing process, resulting in a very durable material. -HMAC is most commonly used for high-traffic areas, such as busy highways and airports. http://www.crossroadspaving.com/images/asphalt-paving-repair.jpg

45. ROLLED ASPHALT • Warm mix asphalt concrete (WAM or WMA) -Reduces the temperature required for manufacture by adding asphalt emulsions, waxes, or zeolites. -Benefits both the environment and the workers, as it results in less fossil fuel consumption and reduced emission of fumes. http://www.wispave.org/images/iStock_000007064664XSmall.jpg

46. ROLLED ASPHALT • Cold mix asphalt concrete, -Emulsified in soapy water before mixing it with the aggregate, eliminating the need for high temperatures altogether. -The asphalt produced is not nearly as durable as HMAC or WAM -Typically used for low traffic areas or to patch damaged HMAC. http://www.dykespaving.com/wp-content/themes/classic/images/coldmix.jpg

47. ROLLED ASPHALT • Cut-back asphalt concrete -Illegal in the United states since the 1970s, but many other countries around the world still use it. -The least environmentally friendly option, resulting in significantly more air pollution than the other forms. -Made by dissolving the asphalt binder in kerosene beforemixing it with the aggregate, reducing viscosity while the concrete is layered and compacted.

48. MASTIC ASPHALT • Also called sheet asphalt. • Lower bitumen content than the rolled asphalt. • Used for some roads and footpaths. • Used also in roofing and flooring . http://www.e-470.com/images/newsSMAfullsized.jpg

49. MASTIC ASPHALT • Stone mastic asphalt (SMA), is another variety. • Becoming increasingly popular as an alternative to rolled asphalt. • Benefits include -Anti-skid property -The absence of air pockets But if laid improperly -May cause slippery road conditions.

50. PHYSICAL PROPERTIES OF ASPHALT • Durability -  A measure of how asphalt binder physical properties change with age. - Sometimes called age hardening .  - In general, as an asphalt binder ages, its viscosity increases and it becomes more stiff and brittle.