CEMENT CONCRETE (1) (1)construction and materials

construction and materials

1. CEMENT CONCRETE

2. Add a Footer 2 INDEX Introduction Ingredients and market survey Properties Quality Control Concrete Mix Design Production of Concrete Factors affecting its strength Tests Storage of materials Concrete Chemicals Types(Plain and reinforced) Uses

3. INTRODUCTION Cement Concrete is a major building material used in modern building constructions. It is used in all parts of the building like foundations, superstructure and roofs. It is obtained by mixing cementitious materials, water, and aggregates(and sometimes admixtures) in required proportions which when mixed and allowed to cure hardens into a rock like mass known as concrete. 3

4. Add a Footer 4 Ingredients Concrete is a composite material comprising a matrix of aggregate and binder that hold the mixture together. The constituent are -: Cement Water Aggregates Admixture

5. Add a Footer 5 Cement is used as binding material in concrete. Portland cement is most commonly used cement in concrete. Cement when mixed with water will forms a paste that hardens into a strong material. This paste fills the voidS between aggregate particle and binds them together to form concrete. Cement

6. Add a Footer 6 water There are two main purposes of water in concrete that is to hydrate the cement and make concrete workable. There are certain things that should be kept in mind while using the water that is – Water used for mixing and curing should be clean and free form injurious amount oil, alkalis, acid, salt and organic materials. Ph value should not be less than 6 of the water used.

7. Add a Footer 7 Coarse aggregates Coarse aggregate is the portion of the concrete which is made up of the larger stones embedded in the mix.  Coarse Aggregates in concrete provides body and strength to the concrete and acts as a filler material which will give the homogeneous mass of the concrete. Fine aggregates Fine aggregate is the essential ingredient in concrete that consists of natural sand or crushed stone. Fine aggregates are the structural filler that occupies most of the volume of the concrete mix formulas. It provides dimensional stability and appropriate amount of it enhances the hardening of concrete.

8. Add a Footer 8 admixtures Admixture are the material in form of power or fluid that are added to concrete to give it certain characteristics that can’t be obtainable with plane concrete mixes. There are no. of type of admixture, some of the are : water reducing Plasticising Air entrainment Retarders Accelerators

9. Price Cement : 340 rupees – 380 rupees per bag of 50 kg ( depends on the quality) Sand : River sand – 50 rupees (per cubic feet) M sand – 55 rupees (per cubic feet) Aggregate : M ix aggregate - 52 rupees (per cubic feet) S mall aggregate ( jeera gitti ) – 40 rupees (per cubic feet) Market survey Add a Footer 9

10. Add a Footer It possesses a high compressive strength. It is a corrosion resistance material and atmospheric agent has no appreciable effect on it. It hardens with age the process of hardening continues for a long time after the concrete has attained sufficient strength. It is this property of cement concrete which gives it a distinct place among building materials. It is more economical than steel. It binds rapidly with steel and as it is weak in tension, the steel reinforcement is placed in cement concrete at suitable places to take up the tensile stresses. This is termed as the reinforced cement concrete or simply as R.C.C. Properties of cement concrete 10

11. Add a Footer properties of cement concrete are influenced by many factors mainly due to mix property of cement , aggregates and water. ratio of these materials control the various concrete properties which are discussed below. 1.compressive strength of concrete. 2.tensile strength of concrete. 3.shrinkage of concrete. 4.modular ratio. 5.poissons ratio. 6.durability of concrete. 7.creeps Factors affecting properties 11

12. Add a Footer Compressive strength of concrete is the most important properties of concrete. The characteristic strength that is in concrete grade is measured by 28 days cylinder/cube strength. Standard cylinder 150 x 300 mm or 1500x300 club with aggregate size of which is not exceeding 25mm is used to determine the strength. Compressive strength of concrete 12

13. Add a Footer the estimate of flexure tensile strength or the modulus of the rupture or the cracking strnegth of concrete from cube compressive strength from cube compressive strength is obtained by the relation. the tensile strength of he concrete in direct tension is obtained experimentally by split cylinder. its varies between 1/8 to 1/12 of the cube compressive strength. tensile strength of concrete 13

14. the property diminishing in volume during the process of drying and hardening causes shrinkage. it depends mainly on the duration of exposure. if this strain is prevented it produces tensile stress in the concrete and hence concrete develops crack. shrinkage of concrete 14 Poisson's ratio varies between 0.1 for high strength and 0.2 for weak mixes. It is normally taken as 0.15 for strength design and 0.2 serviceable criteria. Poisson’s ratio

15. Compressive Strength is determined by loading properly prepared and cured cubic, cylindrical or prismatic specimens under compression. The Factors Affecting the Compressive Strength of Concrete are - Water Cement Ratio Quality of cement and chemical constituents Storage of cement Aggregate Water Moisture in aggregate Slump Degree of compaction Temperature at the time of molding cubes Curing efficiency Curing temperature Moisture content at the time of cube tests Direction of loading Duration of loading Degree of lateral restraint Compression machine and operation factor Different concretes require different degrees of durability depending on the exposure environment and properties desired. The ability of concrete to withstand the conditions for which it is designed without deterioration for a long period of years is known as durability. concrete will remain durable if: The cement paste structure is dense and of low permeability Under extreme condition, it has entrained air to resist freeze-thaw cycle. It is made with graded aggregate that are strong and inert The ingredients in the mix contain minimum impurities such as alkalis, Chlorides, sulphates and silt. Following are the factors affecting durability of concrete- • Cement Content • Moisture • Aggregate Quality • Temperature • Water Quality • Abrasion • Concrete Compaction • Carbonation • Curing Period • Permeability • Carbonation • Wetting and Drying Cycles • Freezing and Thawing • Alkali-Aggregate Reaction • Sulfate Attack • Organic Acids durability 15 COMPRESSIVE STRENGTH

16. 16 workability Workability is the most important property of freshly mixed concrete. In simple words, workability means the ease of placement and workable concrete means the concrete which can be placed and can be compacted easily without any segregation. Workability is a vital property of concrete and related with compaction as well as strength. Factors Affecting Workability- Method and duration of transportation Quantity and characteristics of cementing materials Aggregate grading, shape and surface Texture Quantity and characteristics of chemical Admixtures Amount of water Amount of entrained air Concrete & ambient air temperature. 1. Larger maximum particle size (25mm) and 2. proportion of the larger particles. 3. High specific gravity of coarse aggregate. 4. decrease in the number of fine particles. 5. Particle shape and texture. 6. Water/cement ratio. Some of the factors affecting segregation . Consistency is the fluidity or degree of wetness of concrete. 1.It is generally dependent on the shear resistance of the mass. 2.It is a major factor in indicating the workability of freshly mixed concrete. segregation

17. Add a Footer 17 Concrete Mix Design Cement Fine Aggregate Water Air Coarse Aggregate Admixtures

18. 18 Concrete Mix Design means, determination of the proportion of the concrete ingredients i.e. Cement, Water, Fine Aggregate, and Coarse Aggregate which would produce concrete possessing specified properties such as workability, strength and durability with maximum overall economy. Concrete Mix Design

19. Add a Footer 19 The characteristic strength of concrete is defined as the strength of concrete below which not more than 5% of the test result are expected to fall . Grade of concrete For Example:- M 20 M refers to MIX. 20 refers to characteristic compressive strength of cube (150mm*150mmm*150mm) at 28 days in N/mm2 .

20. Add a Footer 20 Types of Mixes Nominal Mix:- The Wide use of concrete as construction material has led to the use of mixes of fixed proportions, which ensure adequate strength. These mixes are called Nominal Mix. Nominal mix concrete may be used for grade M 5, M 7.5, M 10, M 15, and M 20. Mix Design:- The concrete mix produced under quality control keeping in view the strength, durability, and workability is called the Mix Design.

21. Add a Footer 21 Mix Design FACTORS INFLUENCING THE CHOICE OF MIX DESIGN  Grade Of Concrete Type Of Cement Maximum nominal size of Aggregate Grading Of Combined Aggregate Maximum Water/Cement ratio Workability Durability Quality Control

22. Add a Footer 22 Mix Design METHODS OF CONCRETE MIX DESIGN I.S. Method (Indian Standard Method) A.C.I. Method (American Concrete Institute Method) Road Note-4 Method (U.K. Method) IRC-44 Method Arbitrary Method Maximum Density Method DOE (British Method)

23. Add a Footer 23 Indian standard method steps TARGET MEAN STRENGTH SELECTION OF W/C RATIO DETERMINATION OF WATER CONTENT CALCUATION OF CEMENT CONTENT CALCULATION OF MASS OF FINE AGGREGATE AND COARSE AGGREGATE

24. Add a Footer 24 Indian standard method Step 1: Target Strength for Mix Proportioning f’ ck = f ck + (t*s) f’ ck = Target Mean Strength at 28 Days f ck = Characteristic Strength at 28 Days t = Tolerance factor= 1.65 (I.S. 10262) s = Standard Deviation Step 2: SELECTION OF WATER CEMENT RATIO Different cements, supplementary cementitious materials and aggregates of different maximum size, grading, surface texture, shape and other characteristics may produce concretes of different compressive strength for the same free water-cement ratio.

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27. Add a Footer 27 Add a Footer 27 PRODUCTION

28. Batching is the process of measuring concrete mix ingredients by either mass or volume and introducing them into the mixer. To produce concrete of uniform quality, the ingredients must be measured accurately for each batch. Volume batching Weight batching BATCHING 28

29. Add a Footer 29 Volume batching :- This method is generally adopted for small jobs . • Gauge boxes are used for measuring the fine and coarse aggregate. • The volume of gauge box is equal to the volume of one bag of cement. Weigh Batching :- • Batching by weight is more preferable to volume batching ,as it is more accurate and leads to more uniform proportioning. • It does not have uncertainties associated with bulking. It’s equipment falls into 3 general categories : Manual :- In case of manual batching all weighing and batching of concrete are done manually. It is used for small jobs. Semi automatic:- In it, the aggregate bin gates are opened by manually operated switches and gates are closed automatically when the material has been delivered. Contains interlock which prevents charging and discharging. Fully automatic:- In it, the material are electrically activates by a single switch and complete autographic record are made of the weight of each material. The batching plant comprises 2,3,4 or 6 compartment bins of several capacities. T he weigh batchers and discharging are provided below the bins.

30. Add a Footer Mixing :- The mixing should be ensured that the mass becomes homogeneous , uniform in colour and consistency . Methods of Mixing : 1.Hands(using hand shovels) 2.Stationary Mixers 3.Ready mix concrete Hand Mixing:- Mixing by hands using ordinary tools like, hand shovels etc. This type of mixing is done for less output of concrete. MIXING 30

31. Add a Footer   Procedure 31 1. Measured quantity of sand is spread evenly on platform. 2. Spread the measured quantity of cement on this sand and mix it till the colour of concrete mixture is uniform. 3. Spread the measured quantity of coarse aggregate on the platform with sand and cement. Now spread the mixture of cement and sand on the stack of aggregate and mix it at least 3 times. 4. Add 3 quarters of total quantity of water required and turn the material towards the centre with spades.

32. Add a Footer 32 Add a Footer 32 Stationary Mixers :- Concrete is sometime mixed at jobsite in a stationary mixer having a size of 9 cubic meter . These mixers may be of : Tilting type mixer:- It consist a conical drum which rotates on an inclinable axis. It has only one opening. The drum charged directly and discharged by tilting and reversing the drum. Non tilting type mixer:- The mixing drum is cylindrical in shape and revolves two – horizontal axis. It has opening on both sides. The ingredients are charged in from one opening. For discharging concrete chute is introducing to other opening by operating a lever. Agitator Trucks :- A vehicle carrying a drum or agitator body, in which freshly mixed concrete can be conveyed from the point of mixing to that of placing, the drum being rotated continuously to agitate the contents. Non-agitating Trucks:- Used for: Transport concrete on short hauls(small distance) over smooth roadways. Truck-mixed concrete :- Used for: Intermittent (periodic) production of concrete at jobsite, or small quantities.

33. Add a Footer Mortar Pan : Concrete is carried in small Quantities Wheelbarrows and Buggies: The capacity of wheelbarrows varies from 70 to 80 litres. Suitable for concrete road construction where concrete is deposited at or below mixer level. Belt Conveyors: Conveying concrete horizontally or higher/lower level. Cranes and Buckets: • Used for Work above ground level , Buckets use with Cranes, cableways, and helicopters. Pumps: Conveying concrete from central discharge point to formwork. Transit Mixer: Used for transporting the concrete over long distance . Transporting 33

34. Add a Footer 34 Add a Footer 34 Foundation bed To construct a foundation we have to excavate earth trenches. After excavation of trenches we check the bed of the earth trench The bed of the trench should be free from roots, organic matters and loose earth Trenche is wetted by spraying water to avoid the loss of water from concrete The chutes are used for placing concrete in deep trenches. Columns and deep beams While placing of concrete in columns or deep beams it is not suggested to allow the free fall of concrete more than a meter unless the mix is designed to be dropped The free fall of concrete results in segregation. Then we use the tremie pipe to dropped cement concrete to the cover blocks and we also use the sloping board. It is a process of depositing a fresh concrete on its final position. Before placing concrete form work must be checked for its rigidity and cleanliness . Concrete should not be dropped from height as it causes segregation or piled up in heaps The wheel barrow or vibrating needle should not be allowed to run over the placed concrete. PLACING

35. Add a Footer Compaction is the process of removing entrapped air bubbles from the fresh concrete and improving the packing of aggregates to form dense concrete. If air bubbles present in structure or placed concrete Then honey combing or blow holes are caused in concrete. This effects the strength of concrete The approximate air content in fresh concrete is 25% which is reduced to 2-5% by compaction.   HAND COMPACTION It is a type of compaction done by manually. There are three types in this compaction process Rodding A single steel rod is used for pocking the fresh Concrete. Ramming A flat metal piece attached to a hammer is used to hit on the surface of concrete. Compaction process of this type is done in floor construction Tamping In thin cross sectional surface tamping is done tamping in the surface of the concrete with a wooden bar is used. COMPACTION 35

36. Add a Footer 36 Add a Footer 36 Add a Footer 36 Vibration takes place on the surface of the concrete. Form vibrator This is used for vibrating thin section of concrete members. Table vibrator Vibrating tables are used for the compaction of concrete in the production of precast member. P latform vibrator It is used in smaller thickness structures construction like slabs. The compaction of concrete is done by applying vibration at the surface the platform vibrator consists of metal platform attached with vibrating motors. Screed vibrator Screed is also used for the compaction of concrete up to a depth of 100mm the screed consists of a long beam attached to a frame and vibrating motor. Vibration takes place inside the concrete mix. Needle vibrator Poker vibrators essentially consist of vibrating needle which is inserted into the fresh concrete A loosely kept mass attached with the cable inside the needle hits on the inner surface of the hallow needle on rotation driven by a motor the hitting action generates vibration in the needle. The compaction of concrete takes place due to the vibration of the needle. EXTERNAL VIBRATOR INTERNAL VIBRATOR

37. Add a Footer • Curing can be defined as a procedure for insuring the hydration of the Portland cement in newly-placed concrete. • It generally implies control of moisture loss and sometimes of temperature. Need for curing:- • Causes Hydration reaction of cement with water. • Loss of water by evaporation can be prevented. • Maintain conductive Temperature . • For completing of Hydration reaction. • For capillary segmentation . Curing 37

38. Add a Footer 38 Add a Footer 38 Add a Footer 38 Add a Footer 38 There are two ways to cure:- Cure by applying water Use a fine spray of water over the concrete the concrete must be moist all of the time. Hosing it once or twice a day and letting it dry in between is no good this way can use a lot of water. Cure by keeping the moisture :- Overlap the sheets and hold them down with sand, rocks or timber Regularly check that the concrete is still moist under the sheets. Curing compounds:- Curing compounds can be applied to concrete soon after finishing. They are sprayed or painted on the surface and help slow the loss of water. They are effective but very expensive.

39. Add a Footer 39 Add a Footer 39 Add a Footer 39 Add a Footer 39 BLEEDING in concrete is a phenomenon in which free water in the mix rises up to the surface and forms a paste of cement on the surface known as “laitance” . BLEEDING Segregation is the cause of bleeding in the concrete mix. Segregation is the cause of bleeding in the concrete mix. Bleeding will be more frequent on the surface of concrete, when water to cement ratio is higher.  Causes Of Bleeding In Concrete Due to bleeding concrete loses its homogeneity. Bleeding is responsible for causing permeability in concrete. As far as safety is concerned, water that accumulates below the reinforcing bars, reduces the bond between the reinforcement and concrete. In the process of bleeding the accumulation of water creates a water voids and reduces bond between the aggregate and cement paste. Due to bleeding pumping ability of concrete is reduced. Increase in the water-cement ratio at the top. The accumulation of water at the top, results in delayed surface finishing. EFFECTS OF BLEEDING

40. Add a Footer 40 Add a Footer 40 Add a Footer 40 Add a Footer 40 Add a Footer 40 Segregation is the cause of bleeding in the concrete mix.  METHODS OF REDUCING BLEEDING 1) Add minimum water content in the concrete mix, use chemical admixtures to reduce demand to water for a required workability. 2) Design the concrete mix properly. 3) Use fly ash or other supplementary cementitious materials. 4) Using air entraining admixtures is very effective in reducing the bleeding. 5) Add more cement in the mix. 6) Increase the amount of fine aggregate if sand is coarser (fineness modulus of 2.5 to 2.8 best suited) in mix and reduce aggregate proportionally. FINISHING The finish can be strictly functional or decorative. Finishing makes concrete attractive and serviceable. The final texture, hardness and joint pattern on slabs, floors, sidewalks, patios and driveways depend on the concrete's end use.

41. Add a Footer 41 TEST

42. Add a Footer 42 SLUMP TEST It is to determine workability of the concrete. SLUMP MEAN Slump is the vertical settlement of fresh concrete after the mould has been withdrawn. It is measured as the difference between the height of the mould and highest point of the subsided concrete. NOT SUITABLE For very wet or very dry concrete mixes. Aggregate size is greater than 40 mm. SUITABLE For concrete of medium to high workabilities , ie slump value of 25 mm to 125 mm.

43. Add a Footer 43 COMPACTION FACTOR TEST It is to detemine workahility of the concrete. APPARATUS Hoppers with polished surface have hinged doors at the bottom. Cylindrical mould
Trowel
Rod NOT SUITABLE For very low workable concrete because such concrete cannot be fully compacted.

44. Add a Footer 44 VEBE TEST APPARATUS Vibrating table
Elastic supports
Cylindrical container
Metal cone open at both ends
Iron rod SUITABLE For concrete mixes with low or very low workability. NOT SUTTABLE For concrete of higher workability, i.e. Slump above 75 mm.

45. Add a Footer 45 HARDENED CONCRETE COMPRESSIVE STRENGTH It is conducted to determine the strength of the concrete. DIFFERENT TESTS FOR COMPRESSIVE STRENGTH Cube Test Cylinder Test

46. Add a Footer 46 Cylinder Test It is conducted to determine the strength of the concrete. Cylinder module of 150mm diameter x 300 mm height Compression testing machine
Weighing balance

47. Add a Footer 47 CUBE TEST It is conducted to determine the strength of the concrete. APPARATUS Iron Moulds 150 mm X 150 mm X 150 mm
Clamping Equipment’s
Mineral Oil / Normal Oil
Steel Rule
Trowel
Compression Testing Machine

48. Add a Footer 48 Storage of Material • Store construction materials in a building which is dry, leak proof and as moisture proof as possible. • There should be minimum number of windows in the storage building. Stack the chemical materials off the floor on wooden planks in such a way, so that it is about 150 mm to 200 mm above the floor.

49. Add a Footer 49 Concrete Chemicals CONSTRUCTION CHEMICALS Construction chemicals, as the name suggests are chemicals used in construction activities. These chemicals have an extensive functional scope in the field of construction. They can be used in ongoing construction projects for speeding up the work or in new construction ventures or for repairing and retrofitting existing buildings or for enhancing durability and providing strength to the structures. Construction chemicals are used along with various building materials at the construction site to improve workability, to increase efficiency, add effectiveness and to protect the part of any structure, or to accelerate the speed of construction work. 1. Admixtures, 2. Plasasticizersrs , 3.Superplasticizers, 4.Retarders and Retarding Plasticizers 5.Accelerators and Accelerating Plasticizers, 6.Air-entraining Admixtures 7.Pozzolan IC or Mineral Admixtures, 8.Damp-proofing and Waterproofing Admixtures 9.Gas forming Admixtures, 10.Air-detraining Admixtures, 11.Alkali-aggregate 12.Expansion Inhibiting Admixtures, 13.Workability Admixtures, 14.Grouting Admixtures, 15.Corrosionsion Inhibiting Admixtures, 16.Bonding Admixtures Fungicidal, Germicidal, Insecticidal Admixtures, 17.Colouring Admixtures

50. Add a Footer 50 ADMIXTURES An admixture is a substance which can be added to concrete to achieve or modify its properties. Admixtures are added to the concrete, in addition to cement, water and aggregate, typically immediately before or during the mixing process. Admixtures can be used to reduce the cost of building with concrete, or to ensure certain required properties or quality of the cured concrete. If problems arise with the concrete during the construction process, admixtures can be used as an emergency measure to try and prevent failure. Fig. Liquid admixtures, from left to right: antiwashout admixture, shrinkage reducer, water reducer, foaming agent, corrosion inhibitor, and air-entraining admixture.

51. TYPES OF CONCRETE Add a Footer 51

52. Add a Footer 52 LIGHT WEIGHT CONCRETE Made up of light weight aggregates(expanded shale, foamed slag, etc.) These aggregates can also be prepared artificially by heating special clays at 1000 which expands and becomes light weight. Used as filling-concrete in bathrooms, terraces, etc. It also acts as thermal insulation compared to normal concrete . FLYASH CONCRETE Concrete using flyash obtained from lignite or other materials is called flyash concrete. Flyash can replace cement or fine aggregates or both. The addition of flyash is said to improve the impermeability, corrosion resistance and sulphate resistance of concrete.

53. Add a Footer 53 HIGH STRENGTH CONCRETE/HIGH PERFORMANCE CONNCRETE Concrete with strength over 40N/mm sq. It satisfies the requirements which cannot be achieved by normal concrete. These performances can be high strength, low shrinkage, self compaction, high fire resistance, etc. They may have strength up to 80N/mm sq.. Materials used are- cement, coarse and fine aggregates In required quantity, water, superplasticizers(high water reducing agents) and supplementary cementing materials like silica fume, blast furnace slag, etc. SILICA FUME CONCRETE Silica fume is very finely divided silica obtained as a byproduct in industry. Concrete to which Silica Fume is added is called “silica fume concrete”. Silica fumes consist of very fine particles. Hence it is found that if we mix silica fumes with concrete the minute pore spaces can be reduced resulting in high strength concrete. Silica fume is also a pozzolana which will contribute to the strength.

54. Add a Footer 54 PLAIN CONCRETE The plain concrete will have no reinforcement in it. The main constituents are the cement, aggregates, and water. Most commonly used mix design is 1:2:4 which is the normal mix design. The density of the plain concrete will vary between 2200 and 2500 Kg/meter cube. The compressive strength is 200 to 500 kg/cm 2 . These types of concrete are mainly used in the construction of the pavements and the buildings, especially in areas where there is less demand of high tensile strength. The durability given by these type of concrete is satisfactory to high extent.

55. Add a Footer 55 PRECAST CONCRETE Various structural elements can be made and cast in the factory as per the specifications and bought to the site at the time of assembly. Such concrete units are called as the precast concrete. The examples of precast concrete units are concrete blocks, the staircase units, precast walls and poles, concrete lintels and many other elements. These units have the advantage of acquiring speedy construction as only assemblage is necessary. As the manufacturing is done at site, quality is assured. The only precaution taken is for their transportation.   AIR ENTRAINED CONCRETE It is a specially prepared plain concrete in which air is entrained in the form of thousands of uniformly distributed particles. The Volume of air thus, entrained may range between 3-6 percent of the concrete. The air entrainment is achieved by adding a small quantity of foaming or gas-forming agents at the mixing stage. Fatty acids, fatty alcohols, and resins are some common air entraining agents. Air entrained concrete is more resistant to Scaling Deterioration due to freezing and thawing Abrasion

56. Add a Footer 56 GLASS CONCRETE When the recycled glass is used as an aggregate in the concrete, this type of concrete is known as Glass Concrete. They provide better thermal insulation and also have a great appealing look as compared to other types .   This concrete will increase the aesthetic appeal of the concrete. RAPID STRENGTH CONCRETE As the name implies these concretes will acquire strength with few hours after its manufacture. Hence the formwork removal is made easy and hence the building construction is covered fastly . These have a wide spread application in the road repairs as they can be reused after few hours. This type of concrete is mostly used in underwater construction and in repairing of roads.  VACCUM CONCRETE In this type, more quantity of water is added to the concrete mix, and then the mixture is poured into the formwork. The excess water is then removed from the concrete with the help of a vacuum pump. That is why it is called vacuum concrete. This technique is used to attain the strength of concrete early. It will attain the compressive strength within the period of 10 days as compared to 28 days of ordinary concrete.

57. Add a Footer 57 REINFORCED CEMENT CONCRETE Reinforced  Cement  Concrete (RCC) is a composite building material consisting of structural concrete reinforced with a reinforcing material like steel. The most common reinforcement used is steel, due to its  complimentary properties  and it is called steel reinforced cement concrete or simply Reinforced Cement Concrete. Steel bars embedded in concrete are called as ‘reinforcing bars or reinforcement’. You can read what makes  steel suitable for reinforced concrete  here. Reinforcing bars are available in two major grades, mild steel and high yield strength steel. Steel fabric made from cold drawn steel wires welded to form a mesh are also used as reinforcement in RCC.

58. Add a Footer 58 Plain concrete is strong in compression, but it is weak in bending. Too weak that its tensile strength is around one tenth of its compressive strength. When plain concrete member is subjected to bending, it develops cracks and ruptures. For the same reason plain concrete is not used where bending action can occur. Tensile strength is defined as the ability to resist bending forces. Bending forces causes tensile stresses in flexural members like beams and columns. Plain concrete when reinforced with steel, which is more than hundred times stronger than concrete in tension, the overall capacity of plain concrete in  bending is enhanced . The steel bars compensate the concrete’s incapability for tensile resistance, effectively taking up all the tension, acting monolithically with concrete. So, when concrete and steel bars combine to act against forces result in good strength. Similar to how human bones reinforces the flesh and mass around it.

59. Add a Footer 59 ADVANTAGES OF USING REINFORCED CONCRETE Concrete and steel bars : Since RCC have both the elements with the properties of concrete which is strong in compression and steel good in tension it gives the advantage of both. Casted into any shape : Fresh concrete will be in the form of fluid and so it can be poured and casted into any shape. It gives easiness to the engineer to decide the shape of structure based on architectural aspects Resistant to fire and weather : RCC with proper cover will withstand to fire for about 3 – 4 hours. RCC will also survive any type of weather with proper quality control and durability considerations. Maintenance :   After the completion of work low maintenance is needed for  concrete structures  compared to the other (steel and timber) type of structures. Availability :  Steel and Concrete are a commonly used construction material and so it is easily available to  prepare  reinforced cement concrete. Economical :  It is economical compared to the other materials like steel structure. Rigidity :  Reinforced Concrete members are good in rigidity due to their stiffness.

60. Add a Footer 60 USES

61. Add a Footer 61 PLAIN CEMENT CONCRETE The objective of plain cement concrete alias PCC is to arrange a firm impermeable bed to RCC in the foundation where the soil is soft and flexible. It is mostly applied over brick flat soling or devoid of brick flat soling. Plain cement concrete is commonly used for foundations. As concrete on the bed flooring, under the column footings. As a solid to get a hard and uniform surface on the surface of the window and ventilator. Coping -To counter concrete on parapets and composite walls.

62. Add a Footer 62 PLAIN CEMENT CONCRETE To flag the area around the buildings. Pavement Making - it is used in rigid Pavement construction ( reinforced-less rigid pavements).The surface course can vary in thickness but is usually between 150 mm (6 inches) (for light loading) and 300 mm (12 inches) (for heavy loads and high traffic). For making tennis courts, basketball courts etc. Plinth protection reduces direct water entering into the soil close to the plinth wall. In other word , the area surrounding the building is usually known as the plinth protection. A plinth protection usually is done by pouring an approximate 75 – 100 mm layer of plain cement concrete along the edge of the building. 9. Storm / sewer on drains, small retaining walls and in small scale canal construction. 10.It is also used in some stone masonry works

63. Add a Footer 63 REINFORCED CEMENT CONCRETE R.C.C. is used as a structural element, the common structural elements in a building where R.C.C. is used are: Footings Columns Beams and lintels Chejjas , roofs and slabs. Stairs R.C.C. is used for the construction of storage structures like Water tanks Dams Bins Silos and bunkers. It is used for pre-casting Railway sleepers Electric poles

64. Add a Footer 64 REINFORCED CEMENT CONCRETE It is used for the construction of big structures like Bridges Retaining walls Docks and harbors Under water structures. R.C.C. is used for constructing tall structures like Multistorey buildings Chimneys Towers. It is used for paving Roads Airports. R.C.C. is used in building atomic plants to prevent danger of radiation. For this purpose R.C.C. walls built are 1.5 m to 2.0 m thick

65. Title: GROUP MEMBERS Shreya Chandra Shreya Singh Shrasti Gautam Shubham Kumar Shubhangi Sonkar Sudeep Srivastava Sunil Yadav Add a Footer 65

66. THANK YOU Add a Footer 66