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Note for CONCRETE TECHNOLOGY - CT By Amity Kumar

  • CONCRETE TECHNOLOGY - CT
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  • Amity University - AMITY
  • Civil Engineering
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COOLING & GRINDING • Rapid cool - glassy • Grinding – Starts at golf ball size – ends about 2-80 microns, 300 m2/kg – depends on application • Typical plant: 1 MT/y • Portland cement is manufactured by inter grinding the portland cement clinker with some (3 to 6 %) Gypsum rock. QUANTITIES • Worldwide: ~2 GT/y – China: 860 MT/y US: 100 MT/y – India: 200 MT/y UK: 12 MT/y • CONCRETE: ~15 GT/y – cf. steel ~1 GT/y, wheat ~0.6 GT/y, rice ~0.4 GT/y – 2.5 T for each of us! – 2mm Earth surface ECONOMIC IMPORTANCE • Availability & price crucial to national development – Cement: 1-2% of total construction costs – Construction: 5-10% of GDP – Demand for cement is key economic indicator APPLICATIONS • Structural – Reinforced concrete • Structuro-functional – bone/dental cements • Functional – waste immobilisation, land remediation • Sculptural • Improbable CONCRETE Concrete is a mixture of Cement paste and aggregate • Compression: up to 120 MPa – Comparable to Al • Tension: <10 MPa • Tension reinforcement – steel bars 4

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THE RC COINCIDENCES: 1 • Reason why RC bonds together is, • Coefficient of thermal expansion – Steel: 12µ/°C – Concrete: 7-12µ/°C – else RC would fall apart after a day Supplied by Dr THE RC COINCIDENCES: 2 • Fe Passivation – alkaline environment (pH 11-14) – oxide layer 5nm – prevents rusting – corrosion only when disturbed WASTE IMMOBILISATION • e.g. Nuclear waste – solidifies waste – nanostructure holds certain ions in place: less leaching – cement chemistry tailored to particular waste DENTAL CEMENT • Glass-ionomer cements – Al2O3/SiO2 glass + phosphoric acid • Replacing traditional mercury amalgam CPC BONE CEMENTS • Calcium phosphates – Hydrate to form hydroxyapatite – Ca10(PO4)6(OH)2 – natural bone (and tooth) mineral – bond & bioactivity – Add water. Supplied LAND REMEDIATION • Stabilisation/solidification – reaction between cement and soil immobilises contaminants – also adds structural strength SCULPTURE • Achievement of forms not possible in other media 5

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IMPROBABLE Improbable,but true • Foamed concrete – void filling – Fire fighting (cement foams based on ettringite) • Weather control – “bomb rainy clouds with cement” SUSTAINABILITY • Wealth creation, environmental protection and social justice going hand in hand” • “development which meets the needs of the present without compromising the ability of future generations” NEGATIVE • 5% of global CO2 emissions – ~1 w/w CO2/cement – limestone: CaCO3 @ 600°C ⇒ CaO +CO2 – fuel: 100 kg oil & 100 kWh per tonne • Quarrying – resource use: 1.6 t/t – landscaping 6

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