REVIEW OF LECTURE #2

COMPRESSION TENSION

TORSION THIRD POINT LOADING

SPLIT TENSILE

WE FINISHED STRENGTH OF MATERIALS REVIEW....

•Strain vs Strain Curves

•Deformation due to Thermal Expansion

WE REVIEWED (CON’T)

•Modulus of Rupture

•Elastic Modulus Formulas

•Aggregate Testing – Seven Test(Must See Video)

•Explained various drying condtions

•Reviewed Procedures for Lab

TERMS YOU SHOULD KNOW

•PROPORTIONAL LIMIT – It is the Last Point before the ratio between stress .vs. strain becomes non-linear

•Yield Point – the stress at which deformation continues without increase inin the load

•Young Modulus – Modulus of Elasticity found in tension and compression

•others… brittle behavior, plastic behavior,elastic behavior, ductile behavior, etc.

•Elastic Limit – Maximum stress at whichmaterial can recover its original shape

LECTURE#2 AGGREGATES

Overview

Definition: Usually refers to mineral particles but can relate to byproducts or waste materials. (i.e. vitrified soils)

Natural aggregates are formed from rocksor the decomposition and transport of rock(see fig 2-2)

Natural sources include underwater, land( stripping) , Glacier Outwash.

Note:Disadvantage of natural aggregate deposits is:• the content of impurities and dust. •Rounded shapes and smooth surfacesare found with natural aggregates which is undesirable. However in some locationsit may be more economical.

Advantage of crushed stones:•Size of the particle can be manufactured as needed•Also angular shapes and rough surfaces are formed which is better suited for industry

AGGREGATES TESTING (cont’d)

Rock TypesIgneous Rock - Volcanic Rock which was molten at one time and then cooledi.e. Granites(CG), Basalt(FG) & DiabaseTrap Rock is Basalt and Diabase•Pumice and Scoria are rock filled with bubbles which are good for lightweight aggregate•Trap Rock is an excellent aggregate

Sedimentary Rock - Shows a lot of stratification from its natural depositionIf it is a sand deposit formed rock it is known as sandstone or quartzite•If it is a gravel deposit formed rock it is known as a conglomerateNote: Shale is not a great aggregate becauseof cleavage

AGGREGATES TESTING (cont’d)

Metamorphic Rock - Formed from Sedimentary or Igneous under heat and pressure

•i.e Shale turns into slate•i.e. Limestone turns into marble

What qualities do we want in Aggregates?Weight- Prevents erosion of banks or for gabion retaining wallsResistance - •For weathering and freeze/thaw•To breaking and crushing•To resistance to abrasionAbility-•to transmit compressive forces as a mass•to adhere to a cement agentPermeability- potential as a filtering or drainage system

What is Aggregates Strength Characteristic?

See P. 40 Fig 2-12 in Text

See Sample Problem!!

Book Notes –Chapt. 2

Earthmoving Basics:SOILS:

SPSW

GP

GW

Book Notes –Chapt. 2

Earthmoving Basics:SOILS:

Gravel

Clay and Silt

Sand

Book Notes –Chapt. 2

VolumeBankWt

VolumeLooseWtFactorLoad

/.

/.

Earthmoving Basics:– Load Factor

swellFactorLoad

1

1

Spoil Banks and Spoil Piles: