1. 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

2. 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)
Tel:

3. 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.

4. 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

5. 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

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

7. 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 – )
Szalkay F.
(1952)

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

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

10. 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

11. Photo of Combined Reo-tribometre Instrument

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

13. 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

14. 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]

15. Tipical Specific Deformation-Time Functions of Asphalt Mixtures

16. 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

17. 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]

18. 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]

19. Effective Viscosity as Function of Shearing Stress

20. Static Yield-point of Asphalt Mixture
Up to 75 N-there is no deformation
= 0, [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, [MPa]

21. 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.

22. MANY THANKS FOR YOUR KIND ATTENTION
László A. Gömze
Department of Ceramics and Silicate Engineering
(University of Miskolc)
Tel: Fax: