CONCRETE
MATERIALS
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Aggregate Sieve Analysis: Particle Size Distribution, Slides of Reinforced Concrete Design
A sieve analysis of aggregates, detailing the weight retained on various sieve sizes and the cumulative percentage retained. It provides data on both coarse and fine aggregates, showing the distribution of particle sizes. This information is crucial for determining the suitability of aggregates for use in construction materials like concrete and asphalt, ensuring they meet specific gradation requirements for optimal performance. The analysis helps engineers assess the quality and consistency of aggregate sources, which directly impacts the strength, durability, and workability of the final product. Understanding aggregate gradation is essential for designing durable and cost-effective infrastructure projects. Useful for civil engineering students and professionals involved in material testing and quality control.
Typology: Slides
2024/2025
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CONCRETE
MATERIALS
CEMENT
Portland cements are hydraulic cements, meaning they react and harden chemically with the additional of water Cement contains limestone, clay, cement rock and iron ore blended and hated to 1200 to 1500 deg Celsius The resulting product โclinkerโ is then ground to the consistency of powder and gypsum is added to control setting time
CHEMICAL COMPOSITION
CEMENT CHEMISTRY
Short Hand Notation ๏ผ (^) C (CaO, Calcium Oxide) ๏ผ (^) A (Al 2
O
3 , Alumina) ๏ผ (^) S (SiO 2 , Silica) ๏ผ (^) S (SO 3 , Sulfate) ๏ผ (^) H (H 2 O, Water) Reactive Compounds ๏ผ (^) C3S (tricalcium silicate) ๏ผ (^) C2S (dicalcium silicate) ๏ผ (^) C3A (tricalcium aluminate) ๏ผ (^) CSH2 (gympsum) ๏ผ (^) C4AF (tetra-calcium alumina ferrite)
OTHER COMPOUNDS
๏ผ (^) Magnesium Oxide, MgO ๏ผ (^) Calcium Oxide, Lime CaO ๏ผ (^) Alkali, Na 2
O, K
2
O
AGGREGATES
Aggregate is a rock like material which used in many civil engineering and construction applications including: ๏ (^) Portland cement concrete ๏ (^) Asphalt concrete ๏ (^) Base materials for roads ๏ (^) Ballast for railroads ๏ (^) Foundations ๏ (^) Plaster, mortar, grout, filter materials, etc.
CLASSIFICATIONS OF AGGREGATES
CLASSIFICATION BASED ON SIZE
a. Fine Aggregates Aggregate passing the 3/8 โ in/ (9.5 mm) sieve and almost passing the 4.7 mm (No. 4) sieve and predominantly retained on the 75 โum (No. 200) sieve. The fine aggregate may be natural sand, crushed stone sand or crushed gravel sand. b. Coarse Aggregates Aggregate predominantly retained on the 4.75 mm (No. 4) sieve. The coarse aggregates may be crushed stone, uncrushed gravel and partially crushed stone or gravel.
CLASSIFICATIONS OF AGGREGATES
CLASSIFICATION BASED ON SHAPE
a. Rounded Aggregates ๏ (^) Aggregate with wounded particles (river or sea shore gravel) that has minimum voids ranging from 32 to 33% ๏ (^) It gives minimum ratio of surface area to the volume, thus requiring minimum cement paste to make good concrete ๏ (^) The only disadvantage is that the interlocking between its particles is less and hence the development of the bond is poor, making it unsuitable for high strength concrete and pavement
CLASSIFICATIONS OF AGGREGATES
CLASSIFICATION BASED ON SHAPE
c. Angular aggregates ๏ (^) Aggregate with sharp angular and rough particles (crushed rock) that has a maximum percentage of voids ranging from 38 to 40% ๏ (^) The interlocking between particles is good, providing a good bond ๏ (^) The aggregate requires more paste to make workable concrete of high strength ๏ (^) The angular aggregate is suitable for high strength concrete and pavements subjected to tension
CLASSIFICATIONS OF AGGREGATES
CLASSIFICATION BASED ON SHAPE
d. Flaky and Elongated Aggregates ๏ (^) An aggregate is termed flaky when the ratio of least dimension (thickness) to the mean dimension is less than three-fifth (0.6) ๏ (^) The particle is said to be elongated when the ratio of greatest dimension (length) to the mean dimension is more than nine-fifth (1.8 times)
CLASSIFICATIONS OF AGGREGATES
CLASSIFICATION BASED ON UNIT WEIGHT
b. Heavyweight Aggregates ๏ (^) Heavyweight concrete is produced from heavy weight aggregate, which is more effective as a radiation shield ๏ (^) The unit weight of concrete varies from 30 to 57 kN/m ๏ (^) The specific gravity is varies from 4 โ 6. ๏ (^) Example: Baryte (Gs = 4 to 4.6), Ferrophosphorus (Gs = 5.8 to 6.8), Hematite (Gs = 4.9 to 5.3), and Magnetite (Gs = 4.2 to 5.2),
CLASSIFICATIONS OF AGGREGATES
CLASSIFICATION BASED ON UNIT WEIGHT
c. Lightweight aggregates ๏ (^) The lightweight aggregates have unit weight up to 12 kN/m ๏ (^) These aggregates are obtained from pumice, volcanic cinder, diatomite, blast furnace slag, flay ash, etc. ๏ (^) The weight of concrete (structure) is reduced to a great extent and it provided better thermal insulation and improved fire resistance
EFFECT OF AGGREGATE PROPERTIES ON CONCRETE
C. Particle Surface Texture In general, sands with a rough surface texture will have a higher water requirement than sands with smooth particle surfaces D. Water Absorption All aggregates absorb water to a greater or lesser degree. The higher the water absorption the higher the water requirement will be, but the water absorbed into the aggregate will not affect the effective water: binder ratio or the strength. It will, however lead to rapid slump loss if absorption is excessive, say > 1% by mass. In general, it is preferable to avoid concrete aggregate properties with water absorptions of more than 1 or 2.5% by mass