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Break Down of Concrete Components

Break Down of Concrete Components. AIR. Cement. Water. Fine Aggregate. Coarse Aggregate. Mineral Admixtures : Pozzolans & Cementitious. Fly Ash Slag Cement Silica Fume Benefits Higher strengths at later age (over 28 days) Higher impermeability Improved workability

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Break Down of Concrete Components

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  1. Break Down of Concrete Components AIR Cement Water Fine Aggregate Coarse Aggregate

  2. Mineral Admixtures: Pozzolans & Cementitious Fly Ash Slag Cement Silica Fume • Benefits • Higher strengths at later age (over 28 days) • Higher impermeability • Improved workability • Some may have cementitious value (Slag & Class C Fly Ash) • Environmental

  3. Fly Ash particle shape

  4. Silica Fume or Microsilica • Used to reduce the permeability of a concrete mixture • Very fine material with High water demand (finer than cigarette smoke) • Produces a very dense concrete with excellent late age strength • Difficult to finish because of little or no bleed water • Usually have to use High Range Water Reducer • Typical dosage between 3 to 10% of total cementitious weight Silica Fume grains Cement grains

  5. Fine Aggregates • Types • Natural Sand • Crushed Stone Sand • Manufactured Sand • Natural sand 35% to 38% voids • > 40% void = high water demand • ACI: for every 1% voids > 40% add 1 gallon of water • Size • less than 0.2 in. (#4 sieve)(95-100 % passes #4) • fineness modulus (FM) used to describe the quality • usually consist of 35 to 45% of the concrete volume

  6. Coarse Aggregates • Types • Crushed Limestone • Gravel • Crushed Granite • Size • up to 3½ in. to #4 sieve • most concrete will use a #57 stone, ranging from 1 in. to #4 sieve • other examples are: • #467 (11/2” to No.4) • #67 (3/4” to No. 4) • #7 (1/2” to No. 4) • #8 (3/8” to No. 8)

  7. “Gradation is the particle size distribution of an aggregate as determined by sieve analysis (ASTM C 136)” What is Gradation?

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