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UNIT-III CONSTRUCTION MATERIALS

BY Dr. P. K. Gaidhane GWCET ,Nagpur. UNIT-III CONSTRUCTION MATERIALS. CONSTRUCTION MATERIALS. Construction Materials are stones, bricks, steel, wood, sand, gravels, cement etc.,

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UNIT-III CONSTRUCTION MATERIALS

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  1. BY Dr. P. K. Gaidhane GWCET ,Nagpur UNIT-III CONSTRUCTION MATERIALS

  2. CONSTRUCTION MATERIALS • Construction Materials are stones, bricks, steel, wood, sand, gravels, cement etc., • The concrete is widely used as non metallic materials for construction. • Portland cement is the bonding materials in concrete, which is widely used as non metallic materials for construction in our industrial age.

  3. CHEMICAL COMPOSITION OF PORTLAND CEMENT

  4. Microscopic Constituents of Portland Cements P.C.+Water→The compounds in the cement undergo chemical reactions with the water independently, and results different products.

  5. Microscopic Constituents of Portland Cements

  6. PORTLAND CEMENT ROW MATERIAL FOR PORTLAND CEMENT • Calcareous Materials: • These material Supply Calcium Oxide (CaO). • Examples: Limestone, Marl, Chalk, Marine shell deposits etc. • Argillaceous Materials: • These material Supply Silica (SiO2) and Alumina (Al2O3). • Examples: Clay,slate, slag of blast furnace etc., • Gypsum: • It act as retarders in initial setting of cement.

  7. Parameters for the manufacture of Portland cement 1]Lime Saturation Factor: The ratio of lime saturation factor should be in the range of 0.66 to 1.02, which provide strength in cement concretes. 2]Silica and Alumina modules: Silica and Alumina modules express quality of cement. Silica modules should be about 2.81 and Alumina modules not should be less than 0.66. 4]MgO Content should be less than 6.0 % to soundness of cement. 3]Fine grinding of raw material help for kinetic reaction.

  8. MANUFACTURING OF PORTLAND CEMENT (Dry process & Wet process) • Construction: • Modern rotary kiln is long steel cylinder, line with fire bricks. • The length of kiln range from 30 to 150 m. • The kiln is slightly inclined i.e. 50 to 60 inclination to the horizontal and is downwards towards the exit end. • The kiln is slowly rotated at a speed about 1 R.P.M.

  9. MANUFACTURING OF PORTLAND CEMENT Working: • Crushing And Grinding: Raw material like Calcareous Materialsand Argillaceous Materials are crushed in gyrotatary crusher and dried, ground and mixed in proper proportion. • The current of dry air ( in dry process) or 30 to 40% water ( in wet process) passed over this dried material in ball mill. • Row Material added from the upper end of rotary kiln, and burning fuel and air is introduced from the lower end of kiln.

  10. REACTIONS IN THE KILN Drying Zone: • 400°C----Upper part of kiln • Moist slurry → Dry powder Preheating Zone: • 400-700°C----Upper central part of kiln • Argillaceous Material → Silica (SiO2) + Alumina (Al2O3). CalciningZone: • 700-1000°C----Lower central part of kiln • CaCO3 → Lime (Cao) + CO2

  11. REACTIONS IN THE KILN Clinkering Zone: • 1400-1500°C----Lower part of kiln (Hottest Zone) • 2Cao + SiO2→ 2 CaO SiO2 ----------------------------C2S • 3Cao + SiO2→ 3 CaO SiO2 ----------------------------C3S • 4Cao + Al2O3 + Fe2O2→ 4CaO.Al2O3.Fe2O2 --------C4AF • 3Cao + Al2O3→ CaO.Al2O3. ----------------------------C3A • These silicates and aluminates combine and produce Cement clinkers

  12. MANUFACTURING OF PORTLAND CEMENT Cooling of hot Clinker: • Hot clinkers are cooled in rotary steel coolers • Medium Rate: Formation of crystalline C3S • Slow Rate : Formation of powdered C2S • Fast Rate : Formation of C3A and C4AF are prevented Grinding of cooled clinkers: • Clinker is ground with gypsum (3%) in steel ball mill to get high strength to concrete. Store and Packing: • Cement coming out from grinding mill is stored in concretes storage and packed in jute bag containing 50 kg cement.

  13. CLINKER GYPSUM

  14. PROPERTIES OF PORTLAND CEMENT 1. Heat of Hydration • The Chemical reactions between compounds in cement with water to form crystalline gel along with evolution of some heat is called heat of hydration. • C3A + 6H2O → C3A:6H2O (Crystalline gel) + 880 KJ/Kg • C4AF+ 7H2O → C3A:6H2O + CF:H2O + 418 KJ/Kg

  15. PROPERTIES OF PORTLAND CEMENT 2. Soundness of Cement • When water is added to the cement, then cement undergoes hydration reaction, then hydration reaction produce very small change in volume of cement structure, it is called as soundness of cement. • Soundness of cement is directly related to the presence of amount of crystalline CaO&MgO, which contribute unsoundness. • Lechatelier Method: Only free CaO can be determined. • Autoclave Method: Both free CaO&MgO can be determined.

  16. PROPERTIES OF PORTLAND CEMENT • If amount of CaO is more, i.e., lime saturation factor is more than the range of 0.66 to 1.02., then such cement become unsound. so the strength of such cements concretes decreases. • If amount of MgO is more, i.e., more than 6. 0 %. In cement, then such cement become unsound, i.e., produce more change in the volume of cement structure during hydration reaction. • Dolomite is unsuitable, because it contain high amount of MgO ( More than 6. 0 %.)

  17. PROPERTIES OF PORTLAND CEMENT 3. Setting and Hardening of Cement • i] Initial set or Flash set: • When water is added to the cement, then it produce cement paste and form quite rigid structure within short time is called initial set or flash set. • Initial setting of cement is mainly due to hydration of C3A (1 day) and hydration of C4AF (1 day). • In order to retard this quick initial setting , 2-3 % gypsum is added in cement during its grinding, which produce calcium sulpho-aluminate. C3A + 6H2O → C3A :6H2O (Crystalline gel) + 880 KJ/Kg C4AF+ 7H2O → C3A :6H2O + CF:H2O + 418 KJ/Kg

  18. PROPERTIES OF PORTLAND CEMENT • ii] Final set or Initial strength: • After some days, quite rigid structure of cement converted in very hard rigid structure of cement is called as final set or initial strength. • Final setting and hardening of cement is mainly due to hydrolysis of C3S (7 days) and hydrolysis of C2S (28 days). • Thus during the setting and hardening of cement, constituents of cement undergoes hydration and hydrolysis. 2C3S + 6H2O + 3/2 O2 → C3S:3H2O (gel) + 3Ca(OH) 2 (Crystalline) + 502 KJ/Kg 2C2S + 4H2O + ½ O2 → C3S:3H2O (gel) + 3Ca(OH) 2 (Crystalline) + 251 KJ/Kg

  19. ADDITIVES OF CEMENT • Additives of cement: Compounds which are added in cement clinkers during grinding in ball mill to improve the properties of cement is called as additives of cement. 1]Accelerators: It increase the strength of initial setting of cement. E. g., NaCl, CaCl2, SiO3 etc., 2]Retarders: It reduce the strength of initial setting of cement. E.g., gypsum, Plaster of Paris etc., 3]Air entrainment material: It reduce the % of entrapped air in of cement concretes. E.g., Vinsol, Durex etc.,

  20. ADDITIVES OF CEMENT 4]Water repellants: It reduce moister loving character of cement. E.g., Ca and Al Stearate and Oleates etc., 5]Dispersing agent: It prevent the formation of lumps or cracks in cement. E.g., Na salt of Naphthalene or Sulphonic acid. 6]Workability agents: It increase the work ability of cement and decrease the heat of hydration of cement. E.g., Lime, Clay, Silica etc.,

  21. TYPES OF PORTLAND CEMENT High Alumina Cement: Constituents: Total alumina more than 32% and Alumina/Lime ratio is in the range of 0.85 to 1.30 Preparation: It is prepared by grinding the clinkers formed by calcining bauxite and lime. Advantages/ Properties/Uses : [1]. It allow time for mixing & placing operation of cement paste. [2]. Resistant to high temperature and action of acid. [3]. Lining of fire bricks in blast furnace. [4]. Evolved more heat. [5]. Set quickly & attain higher ultimate strength. Disadvantages : [1]. No contact with lime or ordinary cement, [2]. It is costly [3]. Not used in mass construction

  22. Low heat Cement : Constituents: C3A=5%, C2S=53%, C4AF=16% and C3S=20%. Preparation: It is prepared by grinding the clinkers formed by aluminates and silicates. Advantages/ Properties/Uses : [1].Initial setting time is 1 hrs and final setting time is 10 hrs. [2].It produce low heat of hydration. [3].Use for mass construction work. [4].Use for construction of piers and dams or allied monolithic mass concretes work. Rapid hardening cement : Constituents and Preparation: It is prepared by grinding the clinkers formed by high % of C3S i.e. about 56 %.

  23. Rapid hardening cement : Advantages/ Properties/Uses : [1]. Compressive strength at the end of first day is 11.5 N/mm2 and at the end of third day is 21 N/mm2 . [2]. Tensile strength at the end of first day is 2 N/mm2 and at the end of third day is 3 N/mm2. [3]. Its concretes is light in weight and not damage easily. [4]. Use for construction and repairing of borders road during emergency. White cement : Constituents and Preparation: It is prepared by grinding the clinkers formed by row materials which are free from coloring oxides like Fe, Mn & Cr.

  24. Advantages/ Properties/uses : [1].Setting time is more than 30 minute. [2].It superior aesthetic value. [3].It is costly. [4].Use for floor finish, ornamental work, statues etc., [5].Use for fixing marble and glazed tiles. Oil-Well Cement : Constituents and Preparation : It is prepared by grinding the clinkers formed by minimum amount C3A & maximum amount C2AF. It also contain retarders like sugars, cellulose and organic acids. Advantages/ Properties/uses : [1]. Setting time is more i.e. sets slowly. [2]. It is costly. [3]. Use for cementing steel coating of oil and gas wells

  25. Pozzolana cement : Pozzolana is a volcanic powder, it is found in Italy. pozzolana material does not have any hydraulic property but is activated in hydraulic material. Constituents and Preparation: It is prepared by grinding 10-30% pozzolana, 6% gypsum and ordinary cement. Advantages/ Properties/Uses : [1]. Compressive strength increases with increasing time. [2]. Tensile strength is high. [3]. It evolved low heat, [4]. It is cheap. [5]. Resistant to the action of sulphate dissolve in water. Disadvantages: [1]. Compressive strength is less in early days. [2]. Less resistant to errosion and weathering action.

  26. Ready Mix Concrete • RMC is a type of concrete, which is manufacture in a factory or batching plant, according to the requirement and then delivered to a work site by the transport. • Manufacturing Process: • Portland cement + Water = Cement paste • Cement paste + sand = Mortar • Coarse aggregates + Mortar = Concrete • Concrete + Steel = Reinforce Cement Concrete

  27. Ready Mix Cement • Workability of concrete depends on Cement paste, sand and coarse aggregates. • If there is insufficient cement paste, then the mixture will tends to harsh and unworkable i.e., lesser will be the net influence for paste shrinkage. • If there is too much cement paste, then mixture will tends to segregation i.e., fractions of coarse aggregates tends to separate out from mixture. • The total mixture water should be constant.

  28. Types of Reinforce Cement Concrete • Standard Ready Mix Concretes: Prepared for delivery at a concrete plant instead of concrete site. • Architectural and Decorative Concrete: Prepared for structural function, aesthetic or decorative finish and offer in verity of color. • Rapid Hardening Concrete: Prepared for rapid repair for job like road and airport runways and to provide early strength development. • Fiber reinforced concrete: Design with micro and macro fibers and can be potentially substitute steel rebar reinforcement or for reducing shrinkage. • Fluid Fill Concrete: Prepared for providing protection during setting or laying of pipelines. (Surrounding the pipe by concrete )

  29. Advantage / Application of RMC • By this technique better quantity of concrete is prepared and can be used at congested site or diverse work place. • Elimination of storage space for basic material at site, reducing in wastage of basic material. • Elimination of botheration, storage and handling of concrete material, procurement of plants and machinery and labour problem. • Reducing in time requirement, Noise and dust pollution at site. • RMC is used in home building site, commercial building site and government project such as bridges and highways.

  30. Disadvantagesof RMC • Traveling time of transportation from plant to site is critical over longer distance. • Generation of additional road traffic. • Concrete’s limited time span between mixing and transportation, RMC should be placed at working site within 90 Minutes of batching at the plant.

  31. Fly Ash As Cement Material • Fly ash is one of residue obtained after the burning of coal and comprises the fine particle that rise with flue gases. • The composition of fly ash is depends on the source and type of coal being burned. Main constituents of fly-ash are SiO2 and CaO2. • Worldwide 65% of fly ash produced from coal power station. • Application • In Concrete production. • For molding and other structural fills. • In cement clinkers production. • Stabilization of soft soils. • As aggregate substitute material.

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