Comprehensive Guide to Aggregate Production in Concrete Construction

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

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

8. Mineral Identification

11. Aggregates Manufacturing

13. Natural Aggregates

14. Types of Aggregates

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

39. Suggested Quality Control Programme for aggregates

40. Aggregates Quality Assurance Plan

41. FIGURE 7-1. Aggregate processing plant. (Courtesy of Cedarapids, Inc.) 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.

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

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

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

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

47. PRODUCTION OF AGGREGATE Major types of rock crushers.

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

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

50. FIGURE 7-4. Apron feeder. FIGURE 7-5. Three-deck vibrating screen. PRODUCTION OF AGGREGATE 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.