Lecture3_-_Agg_propoerties

Lecture3_-_Agg_propoerties - 1 Lecture 3: Aggregates...

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Unformatted text preview: 1 Lecture 3: Aggregates Construction Materials CM 3400 Toughness Resistance of coarse aggregate to abrasion and mechanical degradation during handling, construction, and use Los Angeles Abrasion Test (C 131) Aggregate at standard gradation is subjected to damage by rolling with prescribed number of steel balls in large drum for a rolling with prescribed number of steel balls in large drum for a given number of rotations Result expressed as % changes in original weight Requirements (Usually 40% or Less) Typical Values: Lowest (Basalt, 10) Highest (Gneiss, 60) Limestone, 19-30 LA Abrasion Test- Approx. 10% loss for extremely hard igneous rocks- Approx. 60% loss for soft limestones and sandstones 2 Soundness Estimates resistance to weathering (F/T) Sodium or Magnesium Sulfate Test Sample Submerged for 18 hrs/ Dried @ 110 + 5 C Process is Repeated Five Times One immersion and drying is considered one cycle Result is total percent loss over various sieve intervals for a prescribed number of cycles: Max. loss values typically range from 10 to 20% per 5 cycles Max. Loss is 12% (Sodium Sulfate) or 18% (Magnesium Sulfate) Soundness Soundness Before After 3 Percent Crushed Fragments in Gravels Quarried materials always 100% crushed Minimum values depended upon traffic Minimum values depended upon traffic level and layer (lift) Defined as % mass with one or more fractured faces Percent Crushed Fragments in Gravels 0% Crushed 100% with 2 or More...
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Lecture3_-_Agg_propoerties - 1 Lecture 3: Aggregates...

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