Fj. Ulm et O. Coussy, COUPLINGS IN EARLY-AGE CONCRETE - FROM MATERIAL MODELING TO STRUCTURAL DESIGN, International journal of solids and structures, 35(31-32), 1998, pp. 4295-4311
Couplings in early-age concrete are the cross-effects between the hydr
ation reaction, temperature evolution and deformation which can lead t
o cracking. They involve complex chemo-physical mechanism that operate
over a broad range of scales, from nanometer to meter. This paper exp
lores these thermo-chemo-mechanical cross-effects from the macroscale
of engineering material modeling (the typical scale of laboratory test
specimens) to the level of structural design. Set within the framewor
k of chemoplasticity, the cross-effects in the constitutive model are
derived from Maxwell-symmetries, and characterize the autogeneous shri
nkage, hydrate heat and strength growth due to the chemo-mechanical, t
hermo-chemical and chemo-plastic couplings. These couplings at a mater
ial level can be determined from standard material tests. provided tha
t the order of coupling is known. This is shown by considering adiabat
ic calorimetric experiments and isothermal strength growth tests, whic
h lead to identify an intrinsic kinetics function that characterizes t
he macroscopic hydration kinetics of concrete. Finally, an example of
application of the model to large-scale finite element analysis of con
crete structures is presented, which clearly shows the consequences of
thermo-chemo-mechanical couplings for the engineering design of concr
ete structures at early ages. (C) 1998 Elsevier Science Ltd. All right
s reserved.