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2. SIVA By Prof. Dr. Attaullah Shah 2 Fine and Coarse aggregates

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5. Aggregates: Aggregates make up 60-75%of total volume of concrete. Aggregate: the inert filler materials, such as sand or stone, used in making concrete.  Coarse Aggregates  Fine aggregates 80-90%of Asphalt Volume 95%of Polymer Concrete 5

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8. Mineral Identification 8

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11. Aggregates Manufacturing 11

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13. Natural Aggregates 13

14. Types of Aggregates 14

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20. Specific Gravity (Relative density)  Absolute: the ratio of the weight of the solid to the weight of an equal volume of water (both at a stated temperature)  Refers to volume of the material excluding all pores  Apparent: ratio of the weight of the aggregate (dried in an oven at 212- 230ºF for 24 hours) to the weight of water occupying volume equal to that of the solid including the impermeable pores  Used for calculating yield of concrete or the quantity of aggregate required for a given volume of concrete 20

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39. Suggested Quality Control Programme for aggregates 39

40. Aggregates Quality Assurance Plan 40

41. PRODUCTION OF AGGREGATE To produce quality aggregate, rock or gravel must be excavated, loaded, and transported to an aggregate processing plant (crushing plant). Here the raw material is washed if necessary, crushed, screened, sorted, and blended if necessary, and stored or loaded into haul units. Sands are not crushed but often require washing and dewatering before use. FIGURE 7-1. Aggregate processing plant. (Courtesy of Cedarapids, Inc.)

42. PRODUCTION OF AGGREGATE Rock Crushers  Jaw crushers utilize a fixed plate and a moving plate to crush stone between the two jaws. Jaw crushers are principally used as primary crusher  Impact crushers: Use breakers or hammers rotating at high speed to fracture the input stone. There are various types of impact crushers including impact breakers, horizontal and vertical shaft impactors, hammermills, and limemills  Cone or gyratory crushers use an eccentrically rotating head to crush stone between the rotating head and the crusher body. - Roll crushers produce fracturing of stone by passing the material be­tween two or more closely spaced rollers

43. PRODUCTION OF AGGREGATE To produce quality aggregate, rock or gravel must be excavated, loaded, and transported to an aggregate processing plant (crushing plant). FIGURE 7-1. Aggregate processing plant. (Courtesy of Cedarapids, Inc.)

44. PRODUCTION OF AGGREGATE Rock Crushers Feeders and Screens The Crushing Cycle Washers and Other Equipment

45. PRODUCTION OF AGGREGATE FIGURE 7-2. Portable cone crusher. (Courtesy of Kolberg-Pioneer, Inc., and Johnson Crushers International)

46. PRODUCTION OF AGGREGATE Table 7-1. Principal types of rock crushers and their characteristics

47. PRODUCTION OF AGGREGATE Major types of rock crushers.

48. PRODUCTION OF AGGREGATE Table 7-2. Gradation of jaw crusher output (percent passing—open circuit)

49. PRODUCTION OF AGGREGATE Table 7-3. Gradation of roll crusher output (percent passing—open circuit)

50. PRODUCTION OF AGGREGATE FIGURE 7-4. Apron feeder. FIGURE 7-5. Three-deck vibrating screen. Feeders and Screens are used to supply gravel or stone to a crusher. Types of feeders include apron feeders, reciprocating plate feeders, vibrating feeders, and belt feeders. An apron feeder consists of a hopper box mounted above a plate feeder which operates like a conveyor to feed stone into a crusher. Apron feeders often incorporate a grizzly to remove oversize stone from the crusher input. A grizzly is simply a set of widely spaced bars or rods which serve to remove oversized material which might jam the crusher.

51. A reciprocating late feeder is somewhat similar to an apron feeder but is smaller and used mainly to feed secondary or tertiary crushers. A vibrating feeder uses vibratory action to move material from the receiving hopper into the crusher. Belt feeders combine a receiving hopper with a conveyor belt to move material to the crusher. Screens: Screens are used at a number of points in the aggregate processing cycle to separate aggregate by size for storage, blending, or re- crushing. There are a number of types of screens including horizontal and inclined vibrating screens and rotating screens. Screens are often placed into a deck consisting of two or more screens placed one above the other. A scalping screen is simply a screen used to remove oversized particles from the aggregate stream.

52. The capacity of a screen is determined by a number of factors including screen size and screen opening size; slope of the screen; position in the deck; amount of oversize and half-size material; and material condition, shape, and weight factors. Washers and Other Equipment  Common types of washing equipment include scrubber drums, wet screens, log washers, sand dehydrators, and classifying tanks.  Scrubber drums consist of an inclined revolving drum equipped with agitator fins and water spray nozzles.  Log washers utilize revolving auger pad of water to wash off undesirable material as the aggregate is moved through the tub by the auger blades.  Sand dehydrators consist of rotating auger screws mounted in an inclined trough. Water and material to be cleaned are piped into the bottom of the trough.

53. PRODUCTION OF AGGREGATE. Aggregate flow through crushers.