1. Lecture #2: Aggregate Composition and Grading

2. Aggregate Uses Rock like material that has many Civil Engineering applications: Road bases and fills PCC: 70% AC: 90% Ballast for railroads Foundations Plaster, mortar, grout, etc.

3. Considered to be inert, inorganic material 1) Naturally occurring: a)Gravels & Sands b)Crushed Washed and Sieved (Graded by size) 2) Normal Weight - BSG 2.6 3) Light Weight a)Blast Furnace Slag b)Expanded Shale, Clay, or Slate 4) Recycled Concrete

4. Use of Recycled or Aggregate Fines

5. Washing and Waste

6. Aggregate Composition & Structure Derived from rocks Single or multiple minerals 3 Types: Igneous, Sedimentary, & Metamorphic can be defined according to: 1) Chemical and mineral composition 2) Internal structure 3) Texture

7. Aggregate vs. Rocks and Minerals  Aggregate - fragments of naturally occurring rocks  Rock – combination of one or more minerals  Mineral - are naturally occurring inorganic substances of more or less definite chemical composition and crystalline structure

8. Rock and Mineral Identification To help gain an appreciation for aggregate characteristics and uses in certain applications. Also to understand why some rocks and minerals have desirable and undesirable characteristics as potential aggregates.

9. Three Type of Rocks According to Their Origin IgneousSedimentaryMetamorphic Origin solidification due to cooling from a molten magma weathering & erosion of the pre-existing rocks Transformation of the pre- existing by the process called metamorphism Process sequential crystallization of minerals from liquid with decreasing Temp. accumulation and consolidation of the products of weathering and erosion Transformation involves mineralogical, textural and structural change of the original rocks Commonly used as aggregates Granite, andesite, basalt, gabbro Limestone, Sandstone, gravel Marble, metaquartzite, gneisses, granulites

10. Minerals Type of mineralsNameChemical formulae SilicaQuartz, Chert, Opal etc. SiO 2 FeldsparsOrthoclase Albite Anorthite KAlSi 3 O 8 NaAlSi 3 O 8 CaAlSi 2 O 8 CarbonateCalcite Dolomite CaCO 3 Ca,Mg (CO 3 ) 2 Ferromagnesian silicates Pyroxene Olivine (Fe,Mg)SiO 3 (Fe,Mg) 2 SiO 4 OpaquesMagnetite Hematite Ilmenite Fe 3 O 4 Fe 2 O 3 FeTiO 3

11. Aggregates are combination of Different Type of Rocks and Minerals  Sandstone (quartzite) – contains mainly quartz  Limestone – contains mainly calcite  Dolomitic limestone – 10-30% dolomite, 90-70% calcite  Gravels – accumulation of different rock types SRG – mainly quartz-rich rock CRG – mainly calcite-rich rock  Granite – contains quartz, feldspar, biotite, amphibole, pyroxenes etc.

12. Properties of Rocks

13. Igneous Rocks

14. Sedimentary vs. Metamorphic Limestone Marble

15. Rock Identification Hardness HCI Reactivity Cleavage Other

16. Hardness Based on Mohs hardness scale Use a knife blade to scratch material Use a mineral to scratch the testing material

17. HCl Reactivity Serves to differentiate the carbonate minerals with react with HCl from other mineral types.

18. Cleavage On planes of breakage; a mineral may contain one or more planes of cleavage or none. Micas have cleavage in one direction Feldspars have two cleavage planes at right angles Quartz has no cleavage but does have a conchoidal fracture (shell like appearance).

19. Other Color: Used as supportive evidence Ability to Transmit Light: Material may be transparent, translucent, or opaque.

20. Crystal Properties  Structure - 3D network or lattice  Cleavage - between planes of most closely packed  Optical properties - refract/polarize  XRD  Symmetry

21. Braggs’s Law XRD

22. Bulk Chemical Analyses by XRF Aggr.No.Bulk chemical analyses (wt%) SiO 2 Al 2 O 3 Fe 2 O 3 CaOMgONa 2 OK2OK2OLOI SRG1 94.1700.9300.9401.7800.0000.2200.2801.68 CRG3 35.5701.2002.3032.2001.5000.0000.3026.46 Lst5 02.2800.4700.2453.7600.5200.0000.0542.53 Sst12 79.8408.4304.5101.0900.8501.4301.9501.67 Granite15 68.9713.4505.2102.1800.8003.7204.2300.21

23. Properties of Aggregates Physical Specific gravity Bulk density Porosity Voids Absorption Moisture Size Texture Shape Mechanical Modulus of elasticity Compressive strength Shrinkage Chemical

24. Mineralogy: Calcite Dolomite Hematite Quartz Feldspar etc Mineral CoTE Indirect Measurement and Correlation Oxide Analysis SiO 2 CaO Fe 2 O 3 etc Mineral Constituents

25. CoTE and MOE of Pure Minerals Minerals CoTE (10 -6 / o C) MOE (x10 6 psi) Calcite05.5820.42 Dolomite09.6229.07 Quartz13.0012.30 Microcline06.6009.50 Albite06.5210.50 Anorthite03.0017.60 Magnetite06.8638.30 Pyroxene12.1132.50

26. Model for Thermal Expansion of Concrete  Parallel Model  Series Model  Composite Model

27. Serial Model  1/E= V 2 /E 2 +V 1 /E 1  α c = α 2 V 2 + α 1 V 1 Mineral 1 Mineral 2

28. Parallel Model Mineral 1 Mineral 2

29. Hirsch’s Composite Model Mineral 1 Mineral 2

30. Validation of Aggregate CoTE Composite Model      

31. Standard Size Groupings Course aggregate 4.75mm to 50mm Fine aggregate 0.075mm to 4.75mm

32. Gradation Chart

33. Gradation Chart Calculation

34. 0.45 Gradation Chart

35. Aggregate Particle Size and Grading

36. Effect of Fines in Mixture

37. Grading Limits for Sand

38. Grading Limits for Coarse Aggregate

39. Calculation of Fineness Modulus

40. Calculate the Fineness Modulus Sieve #Wt Ret% Ret% Pass 1-1/20 3/4300 3/81010 41320 81220 16370 pan75 totals

41. COE Method

42. Aggregate Stocking Piling

43. Aggregate Proportions

44. Stock Pile Segregation

45. Fine Aggregate Splitter

46. Aggregate Sampling