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Joe Dralle 4/19/10. Why Concrete? It’s common, it’s everywhere, it’s old Most people don’t know its technical aspects Concrete can be complex Different.

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Presentation on theme: "Joe Dralle 4/19/10. Why Concrete? It’s common, it’s everywhere, it’s old Most people don’t know its technical aspects Concrete can be complex Different."— Presentation transcript:

1 Joe Dralle 4/19/10

2 Why Concrete? It’s common, it’s everywhere, it’s old Most people don’t know its technical aspects Concrete can be complex Different types and uses Engineering material with problems and solutions

3 What is Concrete? Solid building material made from aggregate and cement Aggregate encompasses things like: Small stones Gravel Sand Cement is often Portland Cement, which is the “glue” that keeps concrete together

4 History ~ BC: used by ancient Babylonians, Egyptians and Chinese in several primitive forms 128 AD: the Romans build the Pantheon with an unreinforced concrete dome 1756: John Smeaton of Britain discovered modern hydraulic cement and pioneered modern use 1824: Joseph Aspdin of Britain patented Portland Cement for his mixture of crushed limestone and clay 1892: Reinforced concrete patented in France and became an industry standard soon afterward

5 Types of Concrete Reinforced Concrete Made with steel bars to provide tensile strength Shotcrete Concrete delivered by pressure hoses onto vertical or overhanging surfaces Refractory Concrete (high temperature) Uses specialty cement to withstand high temperatures in masonry ovens and production of metals Cellular Concrete Aerated, lightweight concrete Polymer Concrete Fast-setting concrete with polymers added as binding agent

6 Cement Classification Hydraulic Non-hydraulic Hardens when in contact with water Hydration reactions occur in the cement as it hardens Portland cement is hydraulic Cannot set when in contact with water Composed of non-hydraulic lime and other minerals Not widely used today

7 Common Make-Up Concrete and cement composition Mix component Rolled gravel (silica+limestone) 5/15 mm 1093 kg/m3 Sand 0/5 mm 734 kg/m3 Portland cement: OPC HP (high performance) 358 kg/m3 Water 179 kg/m3 Cement composition SiO2 Al2O3 Fe2O3 CaO MgO SO3 Na2O % Weight

8 Cement Production

9 Clinker

10 Properties of Concrete High compressive strength (6000 psi is common) and lower tensile strength Water/Cement ratio (W/C) determines strength High W/C = high workability, but lower strength Low W/C = less workability, but greater strength Curing pertains to the period of hydration as the concrete absorbs moisture and becomes dry Steady curing rates result in the best structure Cracks occur after repetitive expansion and shrinking, often due to temperature changes Creeping may occur over longer periods of time as the concrete deforms from internal stresses

11 Uses Buildings, roads, pavement, bridges Dams/breakwaters Columns and other decorations Fences/walls Foundations Tunnels and sewers Recreational surfaces

12 Worldwide Usage

13 CO 2 Emissions

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16 Asphalt Concrete Type of concrete held together by bitumen Bitumen is a thick, sticky substance made from mostly polycyclic aromatic hydrocarbons (PAH) Naphthalene, Anthracene, Napthacene, Pyrene PAH are most commonly found in oil, coal and tar deposits

17 Asphalt Asphalt is technically synonymous with bitumen, but often asphalt is referred to as the concrete structure that we call “black-top” Asphalt/bitumen is often considered a colloid with solids suspended within a viscous fluid

18 Modern Adjustments and Considerations Decrease the amount of lime in cement to curb carbon emissions Using recycled concrete and cement Using additives and replacement materials to adjust cost and properties Silica fume (high surface area silica) is used to make very high strength concrete Blast furnace cement uses slag as the primary material in cement

19 References issions issions eline/timeline.html eline/timeline.html Img&_imagekey=B6TWG-4PMYXPH-1- 17&_cdi=5562&_user=443835&_pii=S &_orig=search& _coverDate=11%2F30%2F2007&_sk= &view=c&wchp=dGLbV zb-zSkzk&md5=3edbf10071b6ad505ebf1095f005d8fa&ie=/sdarticle.pdf


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