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Chemistry & Building Materials (SCE) Exam Preparation Summer 2024 Chemistry & Building Materials Introduction Why do we need to know chemistry in construction? Building materials technology is the study of the (chemical) processes that occur...

Chemistry & Building Materials (SCE) Exam Preparation Summer 2024 Chemistry & Building Materials Introduction Why do we need to know chemistry in construction? Building materials technology is the study of the (chemical) processes that occur in the production, processing and use of building materials. manufacturing processing use recycling 2 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) | Prof. Dr. O. Blask Chemistry & Building Materials Introduction Classification of metallic and inorganic non-metallic materials group metallic materials Inorganic, non-metallic materials Construction metals ceramic materials inorganic glasses hydraulically bound materials Examples density high medium strength tensile and compressive compressive tensile and compressive compressive Ductility tough and deformable brittle, not brittle, not brittle, not deformable deformable at RT deformable sensitive to Water, strong acids, strong alkalis strong alkalis weak acids weak acids strong alkalis Temperature up to ≈ 600 °C up to ≈ 250 °C sometimes well up to ≈ 600 °C up to ≈ 250 °C resistance over 1000 °C normal glass concrete Steel, aluminum, brick, glass, concrete. 3 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) | Prof. Dr. O. Blask Chemistry & Building Materials Introduction Classification of organic materials and composite materials group Organic materials Composites synthetic fossil re-growing mineral metallic- mineral synthetic- mineral mineral Examples density small amount high small amount strength tensile and little firm tensile and compressive tensile and compressive tensile and compressive compressive compressive compressive Ductility tough to not very firm tough brittle, not ductile ductile-brittle ductile brittle deformable sensitive to UV-light, O2 , UV-light, O2 , UV-light, weak acids weak acids weak acids UV-ight, O2 , solvents solvents humidity solvents Temperature low low medium medium medium medium low resistance Wood, brick masonry, glass fiber reinforced plastics, plastics, reinforced concrete, bitumen, concrete. 4 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) | Prof. Dr. O. Blask Chemistry & Building Materials Introduction Requirements for building materials Stress caused by external loads: pressure, tension, shear Stress caused by mechanical, physical, chemical and biological influences mechanical: wear physical: frost, fire, impact chemical: acids, oils, gases biological: biofilms, bacteria Impact Resistance => Lifespan (durability) 5 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) | Prof. Dr. O. Blask Chemistry & Building Materials Basics of general and inorganic chemistry Building 10 2 Structure of matter Components meter 10 0 10 -1 Stones deci milli 10 -3 particles micro 10-6 _ Crystals nano 10-9 _ molecule s Ato pico 10 -12 ms 6 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Basics of general and inorganic chemistry The Periodic Table – A Systematics of the Elements Each element has characteristic properties that result from the combination of protons, neutrons and electrons. If you sort the elements according to the number of protons and neutrons, a pattern of properties emerges. Smaller atoms have approximately the same number of protons and neutrons; in heavier atoms the number of neutrons increases significantly. 7 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Basics of general and inorganic chemistry Summary of binding types Binding type binding Appear Materials Special properties Ionic bonding Strong, In unit cells of crystals Salts, mineral Brittle, usually high not oriented materials melting points Metal binding Medium, In the metal grid metals Electricity and heat not oriented conductive, ductile Covalent bond Very strong, In organic molecules, Mineral Electrical oriented in elementary cells of materials, insulators crystals polymers Molecular bonds Weak, Between Layers of Mineral Mostly liquid or (van der Waals, not oriented crystals, intermediate materials, gaseous dipole) or intramolecular polymers interactions Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Lennard-Jones potential differentiate F W Force Work Lennard-Jones potential rejection 𝑊 𝑎 =− 𝐹 𝑎 𝑑𝑎 𝑙 𝐹 =+ 𝑎 a0 Attraction F AN a0 𝑘 𝐹 =− 𝑎 F(a) = F AN + F AB 9 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Strength of materials W W W a) Covalent bond: b) Metallic bond: c) Van der Waals bond: high-strength materials solid materials less strong materials e.g. ceramic materials e.g. metals , e.g. non-crosslinked plastics A low energy level (W curve) is a prerequisite for high strength. 10 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Melting point and thermal expansion W The atomic distance a0 only occurs when no external energy is supplied, i.e. at absolute zero at 0K. At higher temperatures, the atoms start to oscillate around the average distance am. The distance a m - a 0 corresponds to the temperature expansion, which is greater the more asymmetrical the function W(a). am When the temperature reaches the melting point (M.P.), there is no longer a certain a0 distance (a = ∞). T ( M.P.) T=0K The more asymmetric the W curve is, the greater the thermal expansion. 11 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Chemical reaction Driving force of chemical reactions: Reduction of internal energy = enthalpy Atoms spontaneously form bonds or break bonds when it leads to a reduction in their internal energy. The types of bonds are determined by the degree of filling of the outer electron shells. We have already learned about three types of bonds, all of which are made possible by the redistribution of electrons. a) Ionic bonding : Admission and submission of electrons b) Covalents Bonding : Formation of electron pairs (electrons are sharing an orbit) c) Metal bonding : Delocalization of electrons d) Van der Waals or Molecular: This bond is less a chemical bond than a physical effect that occurs between molecules, but it is still usually referred to as a bond. 12 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Chemical reaction Goal: Electron conformation of a Noble Gas Noble Gases (box) have fully filled electron shells, which reduces their inner enthalpy to a minimum. Elements at the left (metals) easily donate electrons to become similar to a noble gas. Elements at the right (non-metals) easily accept electrons to become similar to a noble gas. 13 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Chemical reaction Exothermic reactions Exothermal reaction In exothermic reactions Energy is released. The sum of the internal energies of the products is less Energy Transition state than that the reactants. Before the products form, a more energy-rich transition Activation energy state must be overcome. Starting materials (reactants) The difference between the sum of the energies of the reactants and the transition state is the activation energy. Released energy End products The activation energy determines the kinetics of the (products) reaction Reaction Source: www.chemiezauber.de 14 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Chemical reaction Endothermic reactions Endothermal reaction In endothermic reactions, Energy is absorbed. The sum of the internal energies of the products is greaterEnergy Transition state than that the reactants. Activation energy End products Before the products form, a more energetic transition state (products) must be overcome. Starting materials Required (reactants) energy The difference between the sum of the energies of the reactants and the transition state is the activation energy. The activation energy determines the kinetics of the reaction Reaction Source: www.chemiezauber.de 15 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Chemical reaction Rate (kinetics) of chemical reactions Van’t Hoff's rule: Temperature : With molecular movement, the probability that An increase in temperature by 10 K leads to two to reactive particles will meet increases. four times the reaction rate. Concentration : High concentrations speed up the process because they increase the probability that reactive particles will collide. Pressure : Accelerated when the reactants have a larger volume than the products. Catalysis : Catalysts lower the activation energy and thus increase the reaction rate. Reactive Surface : Increases the likelihood of reactive particles colliding. 16 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Chemical reaction Types of chemical reactions Red-ox reactions Equilibrium reactions Acid-base reactions Precipitation and complex reactions 17 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Chemical reaction In redox “reduction-oxidation” reactions, one reactant is oxidized and another is reduced. In redox reactions, the hypothetical oxidation numbers of the atoms are considered. The oxidation number corresponds to the number of electrons given off by an atom. Oxidation = oxygen absorption = electron release! In compounds, the electrons are assigned to the more electronegative element. Elements are generally assigned the oxidation number ZERO The sum of the oxidation numbers of all atoms in a compound equals ZERO 18 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Chemical reaction Equilibrium reactions Many chemical reactions, similar to the acid-base reaction, do not only proceed in one direction, but can also proceed “backwards”. The reactions are called equilibrium reactions. Most equilibrium reactions take place in aqueous solution, since reactants and products are dissolved in a medium. Example: Formation of carbonic acid 19 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Chemical reaction Acid-base reaction According to Brönsted, acids are compounds that can release H + ions, while bases are compounds that can absorb H + ions. Proton Emission Acid Base + Proton Proton Acceptance Protons are very reactive and therefore never appear free but always bound, for example in water: reversibel 20 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Chemical reaction Ionic product of water and pH value Acid Base If you write down the concentrations of the above reaction you get: If you form the negative logarithm of the concentration of the H + ions to base 10: 21 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Chemical reaction Ionic product of water and pH value The pH value is the negative 10 logarithm of the H + ion concentration. 𝑘 = 𝑐 𝑐 =1 10 𝑚𝑜𝑙 /𝑙 𝑝𝐻 = − log 𝑐 = 14 + log 𝑐 The pH scale goes from 0 to 14 from acidic to alkaline: acidic neutral alkaline pH = 0 7 14 22 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Chemical reaction Weak acids Weak acids do not dissociate completely and their degree of attack is therefore lower than that of strong acids. ( dissociation constant K S ) - + 𝑝𝐻 = (𝑝𝐾 − log 𝐶 ) H3C COOH H3C COO + H Question: Estimate the pH value of lemon juice, household vinegar and carbon dioxide acidic neutral alkaline pH = 0 2 3 4 7 14 lemon juice Vinegar carbonic acid 23 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Macro structure Homogeneous Inhomogeneous Isotropic Anisotropic Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Types of microstructure Crystalline Brine and gels Amorphous The substance has a 3-dimensional Consist of colloidal particles Amorphous materials are solidified periodic arrangement of atoms or with d < 100 nm. liquids; they have no distinct order. molecules. The particles themselves can be crystalline, amorphous or liquid. Unit cells with short-range order and Brine: Soft system without cross- Short-range order but not long-range long-range order linking of the particles order e.g. bitumen Defined melting point Gel: Rigid system made of cross- Softening instead of melting point, Often fissile linked particles, temperature dependence of Anisotropy possible e.g. cement stone mechanical properties Metals, some ceramic materials Inorganic glasses, many plastics, some alloys Size: For small particles surface forces are stronger than gravity, particles do not unit cells, but no sediment in suspensions 3-dimensional order 3-dimensional order of unit cells Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Important crystal structures Cubic primitive Body centered cubic Hexagonally dense Face centered cubic Filling ratio: 0.52 Filling ratio: 0.68 Filling ratio: 0.74 Filling ratio: 0.74 Coordination number: 6 Coordination number: 8 Coordination number: 12 Coordination number: 12 Layer sequence: AAA Layer sequence: ABAB Layer sequence: ABAB Layer sequence: ABCABC Examples: Examples: Examples: Examples: some ionic crystals α -iron, potassium, sodium, cobalt, magnesium, zinc,  -Iron, aluminum, lead, molybdenum titanium calcium, silver, gold, platinum, nickel, copper Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Dense Package cubic primitive cubically dense hexagonally dense cubic dense Filling ratio: 0.52 Filling ratio: 0.68 Filling ratio: 0.74 Filling ratio: 0.74 Coordination number: 6 Coordination number: 8 Coordination number: 12 Coordination number: 12 Layer sequence: AAA Layer sequence: ABAB Layer sequence: ABAB Layer sequence: ABCABC Examples: Examples: Examples: Examples: some ionic crystals α -iron, potassium, sodium, cobalt, magnesium, zinc,  -Iron, aluminum, lead, molybdenum titanium calcium, silver, gold, platinum, nickel, copper Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask OTHER CRYSTAL STRUCTURES Tetragonal diamond graphite similarly body- The covalent bonds between the The graphite structure consists of centered cubic carbon atoms are oriented at a layers of six-membered rings. a≠c tetrahedral angle of 109.5°, Covalent and metallic bonds exist Examples: which results in the special within the layers and van der martensite, tin crystal structure. Waals forces prevail between the layers. Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials The structure of metallic materials The structure of metallic materials The plastic formability of metals is based on sliding in certain distinguished planes. Slip planes are special planes in the closest packings. Within levels the bonds are particularly strong, while between levels the bonds are weaker. 29 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Phase diagrams Phase Diagrams - Not soluble in each other in the solid state L: Melt from components A and B 𝛼: Pure phase of A crystals 𝛽: Pure phase of B crystals L B : Melt of the pure component B T A : Melting point of component A T B : melting point of component B 30 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Phase diagrams Phase Diagrams – Full Solubility When a melt of two substances with the composition C 0 Liquidus-line with ideal miscibility is cooled, mixed crystals of both Melt, L substances form at the liquidus line. The composition of the melt and mixed crystals changes with the temperature, as does the proportion of melt and mixed crystals. During further cooling, only mixed crystals with the Solidus-line composition C0 are present at the solidus line. mixed crystals, α Phase diagram of two components with full solubility 31 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Phase diagrams Phase diagrams – example: composition at point c Phase diagram of two components with full solubility 32 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Phase diagrams Phase diagrams – calculation of composition Both the composition of the phases and the ratio of mixed crystals to the melt depend on the temperature. Melt: Copper content in %: 100 − 𝐶𝐿 Nickel content in %: 𝐶𝐿 Mixed crystals: Copper content in %: 100 − 𝐶𝑆 Nickel content in %: 𝐶𝑆 Proportion of melt and mixed crystals (lever law): 𝐶 −𝐶 𝐶 −𝐶 𝑓 = 100 = 100 𝐶 −𝐶 + 𝐶 −𝐶 𝐶 −𝐶 𝐶 −𝐶 𝑓 = 100 𝐶 −𝐶 33 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Phase diagrams Eutectic phase diagrams – How does the melt solidify? Mixed crystalline basic structure. T isolated mixed crystals associated mixed crystals mixed crystals with grain boundaries A 100% 0% B 0% 100% 34 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Phase diagrams Eutectic phase diagrams – How does the melt solidify? In the eutectic T A 100% 0% B 0% 100% 35 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Phase diagrams Eutectic phase diagrams – hypoeutectic or hypereutectic structure T A 100% 0% B 0% 100% 36 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Structural steel Production of raw iron (blast furnace process) Raw iron is produced by reducing iron ores with coke. Indirect reduction zone (400-800 o C ) Direct reduction zone (800-1600 o C ) Source: www.tec-science.com 37 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Structural steel Production of raw iron (blast furnace process) Carburizing zone (1200-1600 o C ) Due to the formation of cementite, the melting point drops from 1536 oC to 1200 oC. Tap zone (1500 oC ) high cooling rates/low silicon contents: metastable Fe3C-containing white raw iron low cooling rates/high silicon content: stable gray raw iron containing graphite Raw iron has a high carbon content of 4.5%. Source: www.tec-science.com 38 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Structural steel Production of cast iron (alternative process) Direct reduction process (up to 1000 oC )  Fe -rich “sponge iron” with approx. 2% carbon The direct reduction process is suitable for producing cast iron with hydrogen. This greatly reduces the CO2 emissions from steel production. Contamination must be removed! Electric steel process, electric arc process (up to 3000 oC ) Melting the sponge iron Addition of alloying elements Aggregates bind undesirable iron companions as slag Source: www.tec-science.com 39 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask  eutectic at max. solubility of C 4,3% C, 1147 °C 2,06% C, 1147 °C eutectic at cementit 6,67% C 0,8% C, 723 °C max. solubility of C 0,02% C, 723 °C 40 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask  Structures of a eutectoid steel T1 : T2 : T3 : T4 : 41 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Structural steel The Influence of carbon content on the strength of steel. At 0.8% carbon, a eutectic structure of ferrite and fine- laminar cementite forms. This ensures particularly high strength. Over 0.8% carbon, cementite is deposited at the grain boundaries and the steel becomes brittle. 42 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Structural steel Special steels - alloy components Alloy component Characteristic Some examples of alloy components and Carbon (C) Increases hardness and tensile strength their effects are: Chromium ( Cr ) increases hardness, wear resistance and corrosion resistance Stainless steels “stainless steels” Manganese ( Mn ) increases forgeability and weldability, Steels with a content of at least 10.5% chromium (up to a hardness and tensile strength maximum of 25%) and a maximum of 1.2% carbon. Vanadium (V) and increase wear resistance and tensile passivating mixed oxide layer with oxygen (Cr,Fe)2O3. tungsten (W) strength At high carbon contents, Cr is bound to chromium-rich Molybdenum (Mo) increases hardness, tensile and hot carbides, therefore in C-rich cast iron, Ni is used instead strength of Cr. Nickel (Ni) increases hardness, tensile strength and corrosion resistance Silicon (Si) increases tensile strength, wear resistance and acid resistance Source: Benedix (2017) Bauchemie 43 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Cast iron Cast iron is made in the same blast furnace process as steel. However, by not refining (decarburizing), a high carbon content of approx. 4.5% is retained. As we cool, we are therefore in the carbon-rich right-hand region of the iron-carbon diagram. In this region the system has a eutectic at 4.3% carbon and a temperature of 1147 oC. Source: www.tec-science.com 44 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Aluminum (Bayer process) Aluminum is obtained economically from bauxite: Mit Natronlauge Soluble bildet sich is sodium aluminate lösliches formed Natriumaluminat: with caustic soda Al(OH) 3 + NaOH Na[Al(OH) 4 ] Deposits: The largest bauxite deposits are in Australia, Hardly Aus soluble Eisen bildetiron sichhydroxide is formed schwerlösliches from iron Eisenhydroxid: Brazil, Guinea, India, China and Russia. Fe(OH) 3 + NaOH Na[Fe(OH) 4] In Europe there are occurrences in Greece, Hungary and Croatia. (Electrolysis, Hall-Héroult process) Production: extraction of 1. Separation of iron oxide (Bayer process) aluminum 2. Production of metallic aluminum by fusion electrolysis graphite electrodes (Hall-Héroult process) kryolith-aluminumoxide melt 2- - 3C+6O 3 CO2 + 12 e 3+ - liquid aluminum 4 Al + 12 e 4 Al brickwork electrode graphite tube Source: From 1993: Andreas SchmidtSVG implementation / modification : Cepheids - File:Schmelzflusselektrolyse.png , CC BY-SA 3.0, 45 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask https://commons.wikimedia.org/w/index.php?curid=7510010 Chemistry & Building Materials Aluminum Aluminum (Al) is amphoteric , meaning it is insoluble in neutral or weakly acidic or weakly alkaline solutions. Aluminum and its oxide layer dissolve in strongly acidic or strongly alkaline solutions. pH: 8.5 Aluminum is therefore sensitive to alkaline building materials such as concrete, alkaline plaster and lime. It must therefore be protected from contact, especially with fresh Al is amphoteric. mortar and plaster. Upon contact with more noble metals (Cu, Ag, Au, Pt but also iron and steel), the oxide layer is destroyed and contact corrosion occurs. 46 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Aluminum The natural oxide layer can be artificially reinforced to protect the surface; workpiece voltage source (anode) this is now done using the ELOXAL process. Here we strengthen the natural oxide layer of 0.1-0.5 µm up to 25 µm by anodization. In addition, metal oxides can be stored in the pores as color electrolyte pigments. 1. Anodization: Electrolysis in dilute sulfuric or oxalic acid formation of the oxide layer 2. Dyeing: Dipping into a bath of metal salts tub (cathode) 3. Sealing: Boiling in demineralized water and forming aluminum oxyhydrate, which closes the pores symbolic drawing of an eloxal layer pore Al2O3 unit barrier layer dye aluminum 47 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Cast iron and other construction metals Construction metals - life cycle assessments steel aluminum copper zinc Lead power consumption 32 MJ/kg 210 MJ/kg 113 MJ/kg 91 MJ/kg 34 MJ/kg (40% RC- Cu ) Raw material consumption approx. 3 t/t Fe * 145 t/t Cu 25 t/t Zn ? Recyclability Very good Good Very good Good Very good Wash-off rate Not relevant Very low 0.2 µm/year 0.5 µm/year 0.6 µm/year remark Stainless steel sheet *approx. 1.5 t red 0.04 µm/a for tinned 97 MJ/kg mud / t Al Cu Conclusion In many cases, Al should only be due to high erosion due to high erosion To be avoided in stainless steel sheets obtained from rates in exposed rates in exposed outdoor areas due to are an ecological sources that act outdoor areas. outdoor areas. high runoff rates. alternative. responsibly *https://aluminium-stewardship.org/ 48 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Cast iron and other construction metals Construction metals - durability Base metals in particular are attacked by alkaline mineral building materials. Mineral building Construction metals Even neutral building materials such as gypsum or material anhydrite can be alkaline stimulated to accelerate Al Cu Zn Pb Cr steel hardening (e.g. anhydrite screed ). Lime, cement mortar, The table on the right gives guideline values as to which - + - - + + concrete (alkaline) metals may be brought into direct contact with mineral building materials and which metals require protection. Gypsum, anhydrite - + - + + - binder , hemihydrate Magnesia binder - - - + + - + resistant - corrosive attack 49 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Cast iron and other construction metals Structural metals – mechanical properties metal, E G An important parameter of the mechanical properties is the alloy GPa GPa modulus of elasticity. It describes the relationship between Structural steel 210 80 the elastic stretch (compression) and the required tension: V2A steel 180 ∆𝑙 Al 70 26 𝜎=𝐸 =𝐸 𝜀 𝑙 Cu 120 48 In the case of shear stress or shear: Ti 120 40 𝜏=𝐺 𝛾 Mg 45 17 The following applies: Ag 80 27 𝐺 = 𝐸/(2 + 2𝑣) Glass 40..90 26 with 𝑣 = 1/3for ideal isotropic substances. Polyethylene 1.5 0.1 Source: Hornbogen(2019) Metals, Kuchling (2011) Taschenbuch der Physik 50 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials silicates and glasses Minerals and rocks The outermost layer of our earth is made up of a variety of different rocks. Rocks are heterogeneous mixtures of individual building blocks, the minerals. Minerals are chemically and physically uniform natural substances formed in the earth's crust; they are usually in crystalline form. An important subdivision of rocks concerns their cohesion. While solid rock can be used directly as a building material (natural stone), loose rock (sands, clays) must be solidified with the help of a binder. With regard to their formation, rocks are divided into 3 groups: igneous rocks, sedimentary rocks and metamorphic rocks. Igneous rocks were formed directly by the cooling of liquid magma. Sedimentary rocks are formed from other rocks through weathering processes. Metamorphic rocks are formed by the transformation of igneous or sedimentary rocks. 51 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials silicates and glasses A quarter of the earth's crust consists of silicon and oxygen.  Chain silicates (“pyroxenes”)  The basic building block of silcates is the The general formula for the chains is: [Si2O6]n4n- [SiO4 ]4- anion  Each silicon atom shares 2 of the 4 oxygen atoms in its neighbourhood. Orthosilicate is rarely found in nature.  The charge balance occurs through alkali or alkaline earth  Examples: metal ions between the chains. Olivine: (Mg,Fe)2 SiO4 Zircon: ZrSiO4 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Building material technology Silicates and glasses Silica and Silicates In silicates, silicon has the coordination number 4 and forms isolated silicates dimeric silicates cyclo silicates SiO4 tetrahedrons with oxygen. These are only linked via shared corners, not via faces and edges. The SiO4 tetrates are the building blocks of silicates, which are classified based on their arrangement into: isolated silicates group silicates ring silicates chain silicates (pyroxenes) double chain silicates (amphiboles) layered silicates (phyllosilicates) tectosilicates layered silicates (phyllosilicates) The negative charges in the structures are balanced out by alkali or alkaline earth metal ions (e.g. Na + or Ca 2+ ). chain silicates (pyroxenes) silicon oxygen Source: Haldar(2013) Introduction to Minaeralogy and Petrology 53 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials silicates and glasses Aluminosilicates Aluminosilicates are layered or framework silicates in which some of the Si atoms in the lattice are replaced by Al atoms. Since Al3+ only has 3 instead of 4 positive charges like SiO24-, each exchange requires an additional alkali metal ion to balance the charges. 54 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Sustainable building materials Sustainable mineral building materials Structure of the layered silicates Overview of clay minerals exchangeable ions and water molecules Source: Bergaya F., Theng BKG, Lagaly G., Brigatti MF, Galan E., Schoonheydt RA, et al. Handbook of Clay Science. 1 pc edition : Elsevier; 2006. 1225. 55 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Silicates and glasses Characteristic / Enthalpie Glasses When heated, glasses do not melt at a defined temperature, but rather gradually soften. The glassy state is metastable because it has a higher internal energy than the crystallized state. At higher temperatures and enough time, glasses can crystallize (e.g. quartz glass at 1100 oC). Temperature 56 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials silicates and glasses Glasses Ordinary glass (window glass, bottle glass) consists of SiO2, Na2O oxide Characteristic and CaO. Expansion coefficients and chemical resistance can be improved by K2O increased melting point adding K2O, Al2O3 and B2O3 (Jena glass, borosilicate glass, Pyrex glass). B2O3 Chemical resistance and strength Addition of PbO (lead crystal glass ) increases the refractive index Pure quartz glass has a low coefficient of expansion and is Al2O3 Chemical resistance, strength, transparent to UV light. devitrification tendency and expansion coefficient Coloring of glasses is achieved by adding soluble metal oxides. PbO Higher light refraction Enamel is a colored or clouded glass that is fused to metal for protection or decoration. SnO2 Turbidity 57 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials silicates and glasses Clay ceramic (Silicate ceramic) Clay ceramic products are substances with a clay content of characteri Fine ceramic Coarse ceramic > 20% in the raw mixture. stic products products The clay ceramic building materials include brick products grain size Crystalline structural Structural such as bricks and roof tiles as well as high-fired stoneware components components e.g. B. pipes and firebricks. < 0.2 mm Pores ≥ 0.2 mm Clay, earthenware Sintered ware, stoneware porosity Water absorption Water absorption > 2% < 2% Porous shard Dense shards 58 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders Classification of inorganic binders (1) Hydraulic Non-hydraulic Inorganic binders are generally divided into binders binders hydraulic and non-hydraulic binders. Hydraulic binders harden through the reaction with water and are resistant to water to a certain extent, for example C3S + 3 H  C-S-H (Note: cement notation) Portland cement Air limes CaSO4 ∙ ½ H 2 O  CaSO4 ∙ 2 H 2 O Hydraulic lime Magnesia binder Non-hydraulic binders harden through reaction with Gypsum, phosphate binder hemihydrate and air or with other substances, e.g. b. anhydride Ca(OH) 2 + CO2  CaCO3 + H2O Sand-lime brick 5 MgO + MgCl2 + 13 H2O  5 Mg(OH)2 ∙MgCl2 ∙8 H2O Alkaline activated materials (AAM) Latent hydraulic binders harden through the reaction Geopolymers with water, but require another substance to activate, such as. B. alkalis. 59 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders Classification of inorganic binders (2) Hydraulic Non-hydraulic binders binders Since the majority of calcium oxides are obtained from limestone, which releases CO 2 during calcination , a further classification into Ca-rich and Ca-poor makes sense. Ca-rich Ca-rich Ca-rich binders form solid Ca salts when hardening, Air limes Portland cement such as calcium silicate hydrates, gypsum Hydraulic lime CaSO4 ∙ 2 H2O or CaCO3 Gypsum, Ca-poor binders form frameworks made of hemihydrate and aluminosilicates, magnesium oxychloride or anhydride phosphates. Ca-poor Ca-poor Calcinated Clay Magnesia binder Alkaline activated materials (AAM) Phosphate binder Geopolymers 60 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders Hydration of the binder Hydration Dissolution of Formation of a The setting process of hydraulic binders is called supersaturated hydration. the binder solution During hydration, reactive energy-rich phases form more stable water-containing phases in which the water is part of the crystal structure. Absorption of Formation of long prismatic (needle-like) The hydration products usually form long prismatic crystal water crystals (needle-shaped) crystals with a high surface area. The high surface area strengthens the adhesion of the crystals to one another and ensures cohesion and thus Adhesion of Setting = transition the crystals to from plastic to solid strength. We call this process setting. each other As the crystals continue to grow, the pore space is filled and further solidification occurs. growth of Filling of the pore crystals space and solidification 61 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders - limes Lime (construction lime) Limestone After gypsum, lime is the oldest binding agent in human history. The main components of construction lime are: CaO and Ca(OH)2 construction lime contains small amounts of: hardening MgO and Mg(OH)2 (Carbonization) burning SiO2, Al2O3 and Fe2O3 Raw materials for the production of building lime are: slaked lime quicklime Limestone, lime marl and dolomite Classification of lime: Air lime Hydraulic lime Source: Benedix(2015) construction chemistry Puzzolanic lime 62 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders - limes Air limes CaCO3 (s)  CaO(s) + CO2 (g) Step 1: Burning Limestone quicklime carbon dioxide produced from limestone (CaCO3) by firing at temperatures between ≥ 900 and ≤ 1200 oC (calcination). The result is a highly porous material with a pore content of approx. 52% by volume. CaCO3: limestone, calcite CaO : quicklime If the temperature is too high, dense crystalline calcium oxide (sintered lime) is formed which only reacts incompletely with water. 63 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders - limes Air limes CaO (s) + H2O ( l )  Ca(OH) 2 (s) Step 2: Slaking quicklime water slaked lime In order for it to function as a binding agent, the lime must be slaked. When slaked, the burnt lime reacts with water in a CaO : quicklime, quicklime highly exothermic reaction to form calcium hydroxide Ca(OH)2: slaked lime , slaked lime, hydrated lime (Ca(OH)2) (slaked lime, hydrated lime). Dry slaking: slaking with the stoichiometric As the volume increases, the lime breaks down into amount of water  dry powder microcrystalline Ca(OH)2 particles, which are Wet slaking: slaking with a slight excess of responsible for the reactivity of the lime. water  lime paste Important: If the slaked lime contains coarser particles Slaking with a strong excess of water of sintered lime, this will result in subsequent slaking  milk of lime in the hardened mortar and driving phenomena (lime swelling) (reduction in strength, cracks). 64 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders - limes Air limes Ca(OH)2 + H2O + CO2  CaCO3 (s) + 2 H2O(l) Step 3: Hardening Slaked lime CO2 from air moisture During hardening, Ca(OH)2 reacts with CO2 from the air Water Calcium carbonate to form calcium carbonate (carbonatation). Carbonation only takes place in the presence of water, as chemically it is a neutralization. The pH drops from moisture: building moisture released 12-13 to approx. 9. CO2 : CO2 content of the air is 0.04% In addition, the lime mortar stiffens, which is based on The low CO2 content in the air leads to long curing times of the removal of water from the lime mortar through approx. 1 year. In the past, coke ovens were also used. Today, porous bricks. If to much water is removed, the lime gypsum plaster is primarily used indoors. mortar will not harden. 65 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders - limes SiO2 _ Hydraulic lime In contrast to air limes, hydraulic limes harden with water both in the air and under water. cement Raw materials for hydraulic lime are clayey limestone ( lime marl ) or mixtures of clay and limestone. CaO Al2O3 _ _ _ The composition of the raw materials from the following components is important for the properties of hydraulic air lime Hydraulic lime lime: CaCO3 , SiO2 , Al2O3 and Fe2O3 contents in % 66 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders - limes Hydraulic lime 2CaO + SiO2  2 CaO∙SiO2 Burning 3 CaO + Al2 O3  3 CaO∙Al2O3 In contrast to air lime, the firing of hydraulic lime takes place above the sintering temperature at around 1250 oC. 4 CaO + Al2O3 + Fe2O3  4 CaO∙Al2O3 ∙Fe2O3 hydraulic factors arise : SiO2 , Al2 O3 and Fe2O3 Above 900 oC they react with alkaline CaO to form: Tricalcium aluminate 3CaO∙Al2O3 Dicalcium silicate 2 CaO∙SiO2 Tetracalcium aluminate ferrate 4CaO∙Al2O3 ∙Fe2O3 67 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders - limes Hydraulic lime 2CaO∙SiO 2 + 3 H 2 O  CaSiO 3 ∙2 H 2 O + Ca(OH) 2 Hardening Just like the firing, the hardening process is similar to 3CaO∙Al2 O3 + Ca(OH)2 + 12 H2 O  Ca4 Al2 O7 ∙13 H2 O that of Portland cement. Various hydrate phases are formed from the calcium- rich mixed oxides with silicon, aluminum and iron. The strength of hydraulic lime is significantly higher than These hydrate phases largely correspond to those that of air lime, but lower than that of Portland cement: formed in Portland cement. Air lime: approx. 1-2 MPa Since hydraulic lime is only fired at 1250 oC, tricalcium silicate (C3S) cannot be formed. Since C3S is the main Hydraulic lime (HL5): 5-15 MPa after 28 days strength-forming substance in Portland cement, the strength of hydraulic lime is lower than that of Portland Portland cement (CEM I 42.5) 42.5 MPa after 28 days cement. 68 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders - gypsum binders Calcium sulfate binders Calcium sulfate exists in 3 different levels of hydration: CaSO4 ∙ 2 H2O CaSO4 ∙ 0.5 H2O CaSO4 There are also several modifications of crystals. CaSO4 ∙ 2 H2O gypsum 𝛼-CaSO4 ∙ 0.5 H2O 𝛼-hemihydrate 𝛽-CaSO4 ∙ 0.5 H2O 𝛽-hemihydrate CaSO4 anhydrite-II CaSO4 anhydrite-III In total there are 5 minerals in the system CaSO4 - H2O Gypsum (left) an Anhydrite (right) 69 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders - gypsum binders Overview of the manufacturing processes for calcium sulfate binders Proceedings wet temperature product Application dry Autoclave process wet 80 - 180°C 𝛼- Hemihydrate Slef leveling screeds and fillers Rotary kiln process dry 120 – 180°C 𝛽-Hemihydrate + Machine plasters Anhydrite III Plaster cooker dry 150°C 𝛽-Hemihydrate Plasterboard Roost belt process dry 300 – 700°C Anhydrite II Machine plasters, screed binders 70 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders - gypsum binders Hydration calcium sulfate binders In the case of calcium sulfate, the hydration takes place via the solution , ie CaSO4 ∙ x H2O must first go into solution in order to precipitate again as gypsum. Anhydrite changes into gypsum without an intermediate stage (e.g. hemihydrate. The rate of hydration depends on the solubility difference between the binder and dihydrate. β-Hemihydrate is more soluble than 𝛼hemihydrate, so the former crystallizes more quickly than dihydrate and sets more quickly. Anhydrite II does not have a significantly higher solubility than gypsum, above that it 30°𝐶 even has a lower solubility, therefore pure anhydrite II does not react, but requires a stimulator such as K2SO4. 71 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders - gypsum binders Influence of moisture on strength The influence of moisture on the compressive strength is particularly pronounced in plaster. Even 1% moisture based on the mass reduces the compressive strength to 70%. The reason for this is the reduction in the adhesion forces between the hydrate phases. 72 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders Reactions during cement production When burning cement clinker, stable carbonates and oxides are converted into oxides, silicates, aluminates and ferrates that are metastable at room temperature. Highly reactive alkaline oxides Dicalcium silicate 2CaO SiO2 = C2S Tricalcium silicate 3CaO SiO2 = C3S Starting materials: Tricalcium aluminate 3CaO Al2O3 = C3A Limestone CaCO3 Tetracalcium aluminate ferrate Burning process Quartz SiO2 4 CaO·Al2O3 ·Fe2O3 = C4AF at approx. 1250 – 1450 °C Clay minerals (e.g. Al2O3 ) Calciumoxide CaO = C Silica SiO2 = S Alumina Al2O3 = A Ironoxide Fe2O3 = F Sulfate SO3 = 𝑆̅ 73 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders Burning the cement clinker The burning of cement clinker takes place in several stages: from 600 - 950°𝐶 CaCO3 (limestone) CaO + CO2 ↑ Al2O3 ∙ 2 SiO2 (metakaolin) Al2O3 + 2 SiO2 Turnover [%] 800 – 1000°𝐶 2 C + S + A CS + CA 1000 – 1250°𝐶 CS + C  - C2S (Belite) CA + 2C C3A (Aluminate) CA + 3 C + F C4AF (Ferrate) 1250 – 1450°𝐶  -C2S + C C3S (Alite, more stable above 1250 °𝐶) Distance from the furnance inlet [m] Cooling the clinker to prevent a backwards reaction from C3S to C2S. 74 Technische Hochschule Ingolstadt – Campus Neuburg | Chemistry & Building Materials (SCE) Winter 2023 | Prof. Dr. O. Blask Chemistry & Building Materials Inorganic binders Phases of Portland cement clinker, function and typical contents Clinker phase Clinker phase Characteristics typical salary formula Designation M.-% 3CaO  SiO2 tricalcium silicate Strength of the cement stone 50 – 75% ("Alit") High early strength of the cement 2CaO  SiO2 Dicalcium silicate Strength of the cement stone 5 – 20% (“Belit”) Post-hardening over weeks and months 3CaO Al2O3 tricalcium aluminate Solidification of the cement stone 5 – 15% (“aluminate”) 4CaOAl2O3 Fe2O3 Tetracalcium aluminate