INVESTIGATION AND MODELING OF RHEOLOGICAL PROPERTIES OF CERAMICS AND SILICATE MATERIALS László A. GÖMZE University of Miskolc, Department of Ceramics and Silicate Engineering Miskolc 16-17 March 2006 Section: APPLIED MECHANICS microCAD 2006

STATE OF AFFAIRS 1. Rheology, rheological model and rheo-mechanical equation of different raw, semi-finished and finished materials are the fundamental questions in understanding crushing, mixing, forming and sintering processes and equipment both in technical ceramic and building materials industry. L. A. Gömze, Department of Ceramics and Silicate Engineering (University of Miskolc) femgomze@uni-miskolc.hu, Tel: +36-30-7462714

STATE OF AFFAIRS 2. Describe the rheological properties and build-up adequate rheological model and mechanical (mathematical) equation of ceramics and other silicate materials we can only after understanding the morphology, micro- and nano-structure of these materials.

The Aims and Goals Give a historical overview about interpretation of rheology in ceramic and silicate industry Show the relationship between microstructure and rheological properties of ceramics and other silicate materials Show the rheological models developed/applied by author for ceramics and other silicate materials

The used System of Notation r - actual elastic deformation m – viscous deformation (residual) k – delayed elastic deformation pl – plasticy-viscous deformation E1 – Hookean dynamic modulus E2 – elasticity modulus of Voigt-Kelvin body n – viscosity of the Newton’s element m – viscosity of the Maxwell elements 1 – viscosity of the plastic-viscous body 2 – viscosity of the Voigt-Kelvin body 0 – static yielo-point of the plastic-viscous body F – mechanical force acting on material tfr – Time interval of relaxation of mechanical stress in material structure/system of asphalt mixtures tr – Time of delay of elastic deformation in the material structure/system of asphalt mixtures

Pavlushkin-Niczhiporenkó HISTORICAL OVERVIEW Rheological Models of Ceramic Raw Materials and Fired Ceramic Grains and Granules Kirpiczhev-Kick (1885) Rebinder-Pavluskin (1937-1963) Pavlushkin-Niczhiporenkó (1963-1968)

Rebinder – Szalkay - Pavluskin (1937 – 1952 -1963) HISTORICAL OVERVIEW Rheological Models of Glasses as Function of Cooling Temperature Rebinder (1937) Pavluskin (1963) Szalkay F. (1952) Rebinder – Szalkay - Pavluskin (1937 – 1952 -1963) Szalkay F. (1952)

Gömze – Turenko - Nazarov (Építőanyag, 1974) HISTORICAL OVERVIEW Rheological Models of Clay Minerals for Brick Industry Gömze – Turenko - Nazarov (Építőanyag, 1974)

HISTORICAL OVERVIEW Rheological Models of Reinforced Concretes and Fibre Reinforced Cements Gömze A. László (Építőanyag, 1983)

Combined Reo-tribometre Instrument 1.table; 2. worm-gear; 3. electromotor; 4. cable-drum; 5. cable-way or ropeway; 6. Moveable car with shearing plate; 7. inductive measurer of moving; 8. force measurer; 9. heatable specimen-fixture; 10. pneumatic cylinder; 11. magnetic valve; 12. measurer of pressure; 13. compressor; 14. thermostat; 15. control panel; 16. spider; 17. computer

Photo of Combined Reo-tribometre Instrument

Typical Shearing-force -Deformation/displacement Diagrams, Measured on Marshall-Probes

Some Results of Shearing Tests Effective viscosity of asphalt mixtures can be determined as: e=  (H/v); [MPa s] T [°C] Fmax [N] max [MPa] e [MPa s] Fdny [N] dny [Mpa] d [MPa s] 100 974 0,1192 0,216 348 0,0426 0,0232 110 952 0,1165 0,198 294 0,0359 0,0191 120 845 0,1034 0,136 284 0,0348 0,0128 130 810 0,0991 0,119 262 0,0321 0,0074 140 775 0,0945 0,106 217 0,0265 0,0053

Relaxation Test of Asphalt Mixtures on Combined Reotribometre F1=var – shearing force [N] Pny=F2/A=var – pressure stress in body [MPa] A=const. – working surface of Marshall-probe; [mm2] Q=var – Materials in asphalt mixture T=const – temperature of asphalt mixture [°C]

Tipical Specific Deformation-Time Functions of Asphalt Mixtures

Rheological Model of Asphalt Mixtures with Bitumen Binders E1 – Hookean dynamic modulus E2 – Elasticity modulus of Voigt-Kelvin body 0 – Static yield point of the visco-plastic body 1 – Viscosity of the plastic-viscose body 2 – Viscosity of the Voigt-Kelvin’s body r - actual elastic deformation pl – plasticy-viscous deformation k – delayed elastic deformation

Reological material equation - First derive of specific deformation by time; - Second derive of specific deformation by time; 0 – Static yield-point of the material structure/system ; [MPa] tr – Time of delay of elastic deformation in the material structure/system of asphalt mixtures; [s] tfr – Time interval of relaxation of mechanical stress in material structure/system of asphalt mixtures; [s]

Effective Viscosity of Shattered and non-shattered material Structures - First derive of specific deformation by time; - Second derive of specific deformation by time; 0 – Static yield-point of the material structure/system ; [MPa] tr – Time of delay of elastic deformation in the material structure/system of asphalt mixtures; [s] tfr – Time interval of relaxation of mechanical stress in material structure/system of asphalt mixtures; [s]

Effective Viscosity as Function of Shearing Stress

Static Yield-point of Asphalt Mixture Up to 75 N-there is no deformation = 0,009178 [MPa] Between 75 N-95 N there is an elastic deformation Over 95 N- there is a residual deformation in the examined asphalt mixture = 0,010402 [MPa]

Conclusion Using the new reo-tribometre we could develop a new reological model for asphalt mixtures and determine the values of their mechanical and reological characteristics and coefficients like E, , ... The new reological model can be used by the engineers of road-building industry in wide range in development of asphalt mixtures with different microstructural and mechanical, reological properties.

MANY THANKS FOR YOUR KIND ATTENTION László A. Gömze Department of Ceramics and Silicate Engineering (University of Miskolc) femgomze@uni-miskolc.hu Tel: +36-30-7462714 - Fax: +36-46-565103