BY:Prof. Dr. Hossam Ibrahim El dossoky El – Shorouk Academy The Higher Institute of Engineering Chemical Engineering Department Engineering Chemistry BY:Prof. Dr. Hossam Ibrahim El dossoky

Today’ Agenda CEMENT

CEMENT 1- Hydraulic cement 2- Air Cement Types: Natural cement, Pozzolanic cement, Portland cements, Super sulphate cement ……. Classification: Hydraulic cement Air cement 1- Hydraulic cement What is meant ? Cement + H2O Hardening Example:- ( N.P.C) 2- Air Cement Cement + H2O Hardening Example:- limestone , gypsum CEMENT Air

Clay + Limestone Clinker Clinker + Gypsum portland cement (P.C) Chemistry:- Clay + Limestone Clinker Clinker + Gypsum portland cement (P.C) Raw Materials for portland cement (P.C) Limestone (CaCO3) Clay (SiO2, Fe2O3, Al2O3) Gypsum (CaSO4.2H2O) Burning 1500 الطمى الحجر الجيرى كلنكر Cooling Grinding كلنكر الجبس الاسمنت البروتلاندى العادى 1- Hydraulic cement

Raw Materials for portland cement Limestone

Raw Materials for portland cement Clay

Technology:- Manufacture process Mixing 2. Burning process (takes place in rotary kiln) الخلط الحرق

Technology:- Manufacture process Temperature (°C) Reactions > 100 Evaporation of water > 500 Removal of combined water from clay > 800 Decomposition of CaCO3, MgCO3. Formation of CA, C2F and C2S begins. 800 – 900 C12A7 forms. Decomposes to C3A at higher temperatures. 900 – 1100 Formation of C3A and C4AF commences, decomposition of CaCO3 completed, maximum CaO will be present. 1100 – 1200 Formation of C2S reaches maximum, major parts of C3A and C4AF form. 1250 – 1280 Formation of liquid phase C3A, C4AF dissolve and recrystallize on cooling. 1280 – 1450 Formation of C3S, free-lime content decreases.

Summary A = Al2O3, C = CaO, F = Fe2O3 S = SiO2 100 – 500°C (Removement of water( 500 - 800°C (Calcination) CaCO3 CaO + CO2 800 – 1500°C 3CaO + Al2O3 3CaO.Al2O3 3CaO + SiO2 3CaO.SiO2 2CaO + SiO2 2CaO.SiO2 4CaO + Fe2O3 + Al2O3 4CaO.Al2O3.Fe2O3 A = Al2O3, C = CaO, F = Fe2O3 S = SiO2

Technology:- Manufacture process 3- Grinding Clinker + Gypsum portland cement (N.P.C) - What is the function of Gypsum? Retarding agent الطحن

Manufacture of portland cementمخطط صناعة الاسمنت البورتلاندى Clay Crushed Lime stone Grinding Water Wet-grinding Raw material mill Slurry storage basin Clinker cooler Clinker Storage Clinker mill Cement silo packaging Flue gases stack Driving motor gypsum fuel slurry 1450 0C Hot air Rotary drum kiln blower Cooling air

Composition range of Portland cement Oxides Formula Per cent limit Lime CaO 60 – 67 Silica SiO2 17 – 25 Alumina Al2O3 3 – 8 Iron oxide Fe2O3 0.5 – 6.0 For a perfect balance of the various cement constituents, the following relation should be satisfied. C = 1 2.8 S + 1.1A + 0.7F

Setting and Hardening الـتـصـلـب Initial setting Final setting 3CaO.Al2O3 + 6H2O 3CaO.Al2O3.6H2O + heat. 3CaO.Al2O3 + CaSO4.2H2O + XH2O 3CaO.Al2O3. CaSO4.YH2O Final setting 3CaO.SiO2 + XH2O 2CaO.SiO2.(X-1)H2O + Ca(OH)2 + heat Hardening 2CaO.SiO2 + XH2O 2CaO.SiO2.XH2O

Metastable Colloidal gel Crystalline products Cement + Water Plastic mass Metastable Colloidal gel Crystalline products Stable gel Crystalline Products of Coarser dimensions

Weathering of Cement and Concrete and its Prevention Ca(OH)2 + CO2 CaCO3 + H2O CaCO3 + H2O + CO2 Ca(HCO3)2 Ca(HCO3)2 + Ca(OH)2 2CaCO3 + 2H2O to overcome this problem by coating the surface with: Drying oils like linseed oil or Bituminous rubber or epoxy resin paint. The surface can also be treated with SiF4 when insoluble CaF2 is formed. Insoluble soluble

Weathering of Cement and Concrete and its Prevention Ca(OH)2 + CO2 CaCO3 + H2O CaCO3 + H2O + CO2 Ca(HCO3)2 Ca(HCO3)2 + Ca(OH)2 2CaCO3 + 2H2O to overcome this problem by coating the surface with: Drying oils like linseed oil or Bituminous rubber or epoxy resin paint. The surface can also be treated with SiF4 when insoluble CaF2 is formed. Insoluble soluble

2- Air cement CaCO3 CaO + CO2 Setting and hardening of lime CaO + H2O Ca(OH)2 + Heat Ca(OH)2 + CO2 CaCO3 + H2O CaO + CO2 CaCO3 Δ

Classification of lime Fat Limes 95-98% CaO and the rest are SiO2, Al2O3 and MgO Lean Limes 70-80% of CaO and the rest MgO, SiO2 and Fe2O3 Hydraulic Limes 70-80% CaO MgO < 2%. Dolomitic Limes dolomite (CaCO3.MgCO3)& (30-40%) MgO

Gypsum(CaSO4.2H2O) CaSO4.1/2H2O + 1 ½H2O CaSO4.2H2O Hardening 150°C CaSO4.2H2O CaSO4.1/2H2O CaSO4 CaO + SO3 Gypsum plaster of Paris anhydrite Hardening CaSO4.1/2H2O + 1 ½H2O CaSO4.2H2O 600°C >800°C

MODEL Questions

For any problem, Please contact me: Prof. Dr. Hossam Ibrahim El dossoky Head of department of chemical engineering High Institute of Engineering Shorouk Academy E-mail: hosam61@yahoo.com Coordinator : Eng. Amr Atef E.Mail : Amr_ae99@yahoo.com “If You can not build your dreams in the atmosphere, You won’t build that in any other place”