IMOS Module 5 - Concrete

UF IDS2935: Impacts of Material Science Fall 2024

Cement v. concrete

• cement is binder for concrete

• concrete is the composite (clinker + sand + rock)

Clinker process

• <700C = water is lost

• 700-900C = calcination (CaCO3 = CaO + CO2)

• 1150-1200C = liquid phase

• 1250-1450C = clinker nodules form

• after cooling = add gypsum to control setting

• clinker is ground into Portlad Cement

Bitumen

various mixtures of hydrocarbons with nonmetallic derivatives that occur naturally after heat-refining natural substances

Properties of Bitumen

• polymeric material (carbon, nitrogen, oxygen, hydrogen, sulfur)

• not a unique molecular composition

• found as natural surface deposits

• easily collected

• easily processed

• compositionally stable at <300F

Uses for Bitumen

• applied as coating/adhesive

• used for paving and roofing

Advantages of concrete

• can be mixed offsite

• cures at room temp.

• moldable into any shape

• cheap

Disadvantages of concrete

• relative durability

• CO2 emission (7% of worldwide release)

  • 1 ton of concrete = 1 ton of CO2

Future for concrete

• use non-fossil fuels for heating (solar power)

• green cement uses recycled material

• zerocrete uses 100% recycled Flyash based cement

• self-healing concrete uses bacteria and calcium lactate and heal cracks

Steel v. concrete

• compression: good v. good

• tension: good v. bad

• thermal expansion coefficient is the same

• alkaline environment reduces corrosion

Composites

a material constructed from two or more components in greater physical or chemical properties are derived from the combination of compositions or structures

Properties of composites

• componenets remain physically seperated

• not naturally occuring

• matrix and dispered phase

• dependent on concentrartion, size, shape, distribution, orientation

concrete history

• Ancient Greece used lime and pebbles

• Romans use Roman concrete

• Roman Empire falls and roman concrete recipe is lost

• Middle Ages concrete is weak

• John Smeaton discovers how to make cement hydraulic

• USA uses cement for the Erie Canal

• Portland Cement is invented

• reinforced concrete is invented

• first reinfoced concrete bridge is built in San Fransisco

Portland Cemenet

C + A + S + H + water + sand + rock

Roman concrete

• used for compression structures (cantenary)

• used different varieties for the dome of Parthenon

• used for roads, buildings, aqueducts

• sets underwater

• self-healing properties

Roman concrete composition

• quick lime formed from limestone and heat (CaCO3 = CaO + CO2)

• fine pozzolana (volcanic ash replaces sand (Al2O3 + SiO2)

• Water (H2O)

• C+ A + S + H

Greek v. Roman architecture

• doric

• ionic

• corinthian

Class order of Romans

colessium seating reinforces class order