Microprestress-Solidification Theory for Concrete Creep. I: Aging and Drying Effects
Publication: Journal of Engineering Mechanics
Volume 123, Issue 11
Abstract
A new physical theory and constitutive model for the effects of long-term aging and drying on concrete creep are proposed. The previously proposed solidification theory, in which the aging is explained and modeled by the volume growth (into the pores of hardened portland cement paste) of a nonaging viscoelastic constituent (cement gel), cannot explain long-term aging because the volume growth of the hydration products is too short-lived. The paper presents an improvement of the solidification theory in which the viscosity of the flow term of the compliance function is a function of a tensile microprestress carried by the bonds and bridges crossing the micropores (gel pores) in the hardened cement gel. The microprestress is generated by the disjoining pressure of the hindered adsorbed water in the micropores and by very large and highly localized volume changes caused by hydration or drying. The long-term creep, deviatoric as well as volumetric, is assumed to originate from viscous shear slips between the opposite walls of the micropores in which the bonds or bridges that cross the micropores (and transmit the microprestress) break and reform. The long-term aging exhibited by the flow term in the creep model is caused by relaxation of the tensile microprestress transverse to the slip plane. The Pickett effect (drying creep) is caused by changes of the microprestress balancing the changes in the disjoining pressure, which in turn are engendered by changes of the relative humidity in the capillary pores. Numerical implementation, application, and comparison with test data is relegated to a companion paper that follows in this issue.
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References
1.
Bažant, Z. P.(1970). “Constitutive equation for concrete creep and shrinkage based on thermodynamics of multi-phase systems.”Mat. and Struct., Paris, France, 3, 3–36.
2.
Bažant, Z. P.(1972). “Thermodynamics of interacting continua with surfaces and creep analysis of concrete structures.”Nuclear Engrg. and Design, 20, 477–505.
3.
Bažant, Z. P.(1977). “Viscoelasticity of porous solidifying material—concrete.”J. Engrg. Mech. Div., ASCE, 103, 1049–1067.
4.
Bažant, Z. P. (1979). “Discussion of `Viscoelasticity of porous solidifying material—concrete.”' J. Engrg. Mech. Div., ASCE, 725–728.
5.
Bažant, Z. P. (1988). Chapter 2. Mathematical modeling of creep and shrinkage of concrete. John Wiley & Sons, Inc., New York, N.Y.
6.
Bažant, Z. P. (1995). Internal research note on solidification—microprestress theory, Northwestern University, Chicago, Ill.
7.
Bažant, Z. P., and Baweja, S. (1995). “Creep and shrinkage prediction model for analysis and design of concrete structures—model B3.”Mat. and Struct., Paris, France, 28, 357–365, 415–430.
8.
Bažant, Z. P., and Carol, I. (eds.). (1993). “Current status and advances in the theory of creep and interaction with fracture.”Proc., 5th Int. RILEM Symp. on Creep and Shrinkage of Concrete (ConCreep 5), E&FN Spon, London, U.K., 291–307.
9.
Bažant, Z. P., and Chern, J. C.(1985). “Concrete creep at variable humidity: constitutive law and mechanism.”Mat. and Struct., Paris, France, 18(103), 1–20.
10.
Bažant, Z. P., and Chern, J.-C.(1987). “Stress-induced thermal and shrinkage strains in concrete.”J. Engrg. Mech., ASCE, 113(10), 1493–1511.
11.
Bažant, Z. P., and Gettu, R.(1992). “Rate effects and load relaxation: static fracture of concrete.”ACI Mat. J., 89(5), 456–468.
12.
Bažant, Z. P., Hauggaard, A. B., and Baweja, S.(1997). “Microprestress-solidification theory. II: Numerical algorithm and verification.”J. Engrg. Mech., ASCE, 123(11), 1195–1201.
13.
Bažant, Z. P., and Jirásek, M.(1993). “R-curve modeling of rate and size effects in quasibrittle fracture.”Int. J. Fracture, 62, 355–373.
14.
Bažant, Z. P., and Kaplan, M. (1996). Concrete at high temperature. Longman-Addison Wesley, London, U.K.
15.
Bažant, Z. P., and Moschovidis, Z.(1973). “Surface diffusion theory for the drying creep effect in Portland cement paste and concrete.”J. Am. Ceramic Soc., 56, 235–241.
16.
Bažant, Z. P., and Najjar, L. J.(1972). “Nonlinear water diffusion in nonsaturated concrete.”Mat. and Struct., Paris, France, 5(25), 3–20.
17.
Bažant, Z. P., Osman, E., and Thonguthai, W.(1976). “Practical formulation of shrinkage and creep of concrete.”Mat. and Struct., Paris, France, 9(54), 395–406.
18.
Bažant, Z. P., and Prasannan, S.(1989a). “Solidification theory for concrete creep. I: Formulation.”J. Engrg. Mech., ASCE, 115(8), 1691–1703.
19.
Bažant, Z. P., and Prasannan, S.(1989b). “Solidification theory for concrete creep. II: Verification and application.”J. Engrg. Mech., ASCE, 115(8), 1704–1725.
20.
Bažant, Z. P., and Thonguthai, W.(1979). “Pore pressure in heated concrete walls—theoretical prediction.”Mag. of Concrete Res., 31, 67–76.
21.
Bažant, Z. P., and Wu, S. T.(1974). “Creep and shrinkage law of concrete at variable humidity.”J. Engrg. Mech. Div., ASCE, 100, 1183–1209.
22.
Bažant, Z. P., and Xi, Y.(1994). “Drying creep of concrete: constitutive model and new experiments separating its mechanisms.”Mat. and Struct., Paris, France, 27, 3–14.
23.
Bažant, Z. P., and Xi, Y.(1995). “Continuous retardation spectrum for solidification theory of concrete creep.”J. Engrg. Mech., ASCE, 121(2), 281–288.
24.
Carol, I., and Bažant, Z. P.(1992). “Viscoelasticity with aging caused by solidification of nonaging constituent.”J. Engrg. Mech., ASCE, 119(11), 2252–2269.
25.
Damkilde, L. (1983). “Stability of plates of elastic-plastic material,” PhD thesis, Rep. No. 187, Department of Structural Engineering, Technical University of Denmark, Denmark.
26.
Deryagin, B. V.(1933). “Elastic form of thin water layers.”Z. Phys., 84, 657–670.
27.
Deryagin, B. V.(1940). “On the repulsive forces between charged colloid particles and the theory of slow coagulation and stability of lyophole sols.”Trans. Faraday Soc., 36, 203, 730.
28.
Deryagin, B. V. (ed.). (1963). Research in surface forces. Consultants Bureau, New York, N.Y.
29.
Feldman, R. F., and Sereda, P. J.(1968). “A model for hydrated portland cement paste as deduced from sorption-length change and mechanical properties.”Mat. and Struct., Paris, France, 1, 509–520.
30.
Hansen, T. C. (1960a). “Creep and stress relaxation in concrete.”Proc. No. 31, Swedish Cement and Concrete Institute, Royal Institute of Technology, Stockholm, Sweden.
31.
Hansen, T. C. (1960b). “Creep of concrete: the influence of variations in the humidity of ambient atmosphere.”6th Congr. of the Int. Assoc. of Bridge and Struct. Engrg. (IBASE), Stockholm, Sweden, 57–65.
32.
Hauggaard, A., Damkilde, L., and Krenk, S. (1996). “An energy based numerical approach to phase change problems.”DCAMM Rep. No. 528, Technical Univ. of Denmark, Lyngby, Denmark.
33.
Pickett, G.(1942). “The effect of change in moisture content on the creep of concrete under a sustained load.”ACI J., 38, 333–355.
34.
Powers, T. C. (1965). “Mechanism of shrinkage and reversible creep of hardened cement paste.”Proc. Int. Conf. on the Struct. of Concrete, Cement and Concrete Association, London, U.K., 319–344.
35.
Powers, T. C.(1968). “The thermodynamics of volume change and creep.”Mat. and Struct., Paris, France, 1(6), 487–507.
36.
Powers, T. C., and Brownyard, T. L. (1946–1947). “Studies of the physical properties of hardened portland cement paste.”ACI J., 42 (1946) 101–132, 249–366, 469–504; 43 (1947) 549–602, 669–712, 854–880, 933–992.
37.
Schmidt-Döhl, F., and Rostásy, F. S.(1995). “Crystallization and hydration pressure or formation pressure of solid phases.”Cement and Concrete Res., 25(2), 255–256.
38.
Wittmann, F. H. (1974). “Bestimmung physikalischer Eigeschaften des Zemmentsteins.”Deutscher Ausschuss für Stahlbeton, Heft 232, W. Ernst & Sohn, Berlin, Germany, 1–63 (in German).
39.
Wittmann, F. H. (1980). “Properties of hardened cement paste.”Proc., Int. Congr. on Chem. of Cement, Paris, France, Vol. I, Subtheme VI-2.
40.
Wittmann, F. H. (1982). “Creep and shrinkage mechanisms.”Creep and shrinkage of concrete structures, Z. P. Bažant and F. H. Wittmann, eds., John Wiley & Sons, Inc., New York, N.Y., 129–161.
41.
Wittmann, F. H., and Roelfstra, P. E.(1980). “Total deformation of loaded drying concrete.”Cement and Concrete Res., 10, 211–224.
Information & Authors
Information
Published In
Journal of Engineering Mechanics
Volume 123 • Issue 11 • November 1997
Pages: 1188 - 1194
Copyright
Copyright © 1997 American Society of Civil Engineers.
History
Published online: Nov 1, 1997
Published in print: Nov 1997
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