78
T. Krykowski
Many models can be used to predict the time of damage in concrete cover. They
include the traditional models [8], models including the time of filling pore voids
[9], or models including the additional loss related to solubilisation of reinforcing
steel due to electrode reaction on the rebar surface [6]. Finally, there are models that
additionally include the possibility of micro-damage formation at the early stage of
concrete degradation [7, 10]. Another group of publications focuses on numerical
modelling of issues related to cracking of concrete covers. Some of them discuss the
propagation of damage in covers [11–13] and other papers also describe the effect of
many various processes (diffusion, transport of moisture, heat) [14] on propagation
of that type of damage. The majority of such papers develop existing concepts of
corrosion in covers by including additional physical and chemical phenomena.
The basic drawback of many models presenting aspects of cover damage is their
deterministic nature and uncertainty of parameters describing corrosion. The evaluation of characteristics of material parameters for microstructure of ITZ and chemical
composition of corrosion products seems to be difficult. Considering such parameters
for models as random variables can solve the above difficulties. Corrosion parameters
regarded as uncorrelated random variables at uniform distribution were described,
inter alia, in the paper [11].
That paper presents the application of the Monte Carlo method to evaluate the
cracking time of cover in concrete specimens subjected to accelerated corrosion
testing. Parameters of the model were assumed to be random variables at Gaussian
distribution. The probabilistic approach was used to determine boundary coordinates
for the tensor of volume strains that was produced by deposition of corrosion products
in the steel-concrete in f
ε
V
i j
and sup
ε
V
i j
interfacial transition zone.
2 Model of Reinforcement Corrosion
Initiation of reinforcement corrosion time and activation of mechanical damage in
the cover are not identical. In the initial stage filling of empty pore spaces in the
transition zone with higher porosity can be only observed [5]. Next along with the
increasing of mechanical interactions the micro-cracks formed in the cover bordered
with the transition zone between steel and concrete are being fulfilled [7]. Kinetics
of such changes related to the impact of corrosion products on concrete was defined
in the paper [2] in accordance with the following relationship
˙
V e f f = ˙
V ekw − ˙
V por − ˙
V tran , ˙
V ekw = ˙
V R − ˙
V Fe 2+ , ˙
m
2+
Fe = k I.
(1)
where ˙
V e f f , ˙
V ekw are respectively the effective (equivalent) rate of change in volume
of corrosion products, ˙
V por —the rate of volume change of corrosion products
penetrating into micro-cracks in the ITZ layer, ˙
V tran —the rate of change of volume
of corrosion products transferred into deeper layers of concrete, ˙
V R , ˙
V Fe 2+ —are
T. Krykowski
Many models can be used to predict the time of damage in concrete cover. They
include the traditional models [8], models including the time of filling pore voids
[9], or models including the additional loss related to solubilisation of reinforcing
steel due to electrode reaction on the rebar surface [6]. Finally, there are models that
additionally include the possibility of micro-damage formation at the early stage of
concrete degradation [7, 10]. Another group of publications focuses on numerical
modelling of issues related to cracking of concrete covers. Some of them discuss the
propagation of damage in covers [11–13] and other papers also describe the effect of
many various processes (diffusion, transport of moisture, heat) [14] on propagation
of that type of damage. The majority of such papers develop existing concepts of
corrosion in covers by including additional physical and chemical phenomena.
The basic drawback of many models presenting aspects of cover damage is their
deterministic nature and uncertainty of parameters describing corrosion. The evaluation of characteristics of material parameters for microstructure of ITZ and chemical
composition of corrosion products seems to be difficult. Considering such parameters
for models as random variables can solve the above difficulties. Corrosion parameters
regarded as uncorrelated random variables at uniform distribution were described,
inter alia, in the paper [11].
That paper presents the application of the Monte Carlo method to evaluate the
cracking time of cover in concrete specimens subjected to accelerated corrosion
testing. Parameters of the model were assumed to be random variables at Gaussian
distribution. The probabilistic approach was used to determine boundary coordinates
for the tensor of volume strains that was produced by deposition of corrosion products
in the steel-concrete in f
ε
V
i j
and sup
ε
V
i j
interfacial transition zone.
2 Model of Reinforcement Corrosion
Initiation of reinforcement corrosion time and activation of mechanical damage in
the cover are not identical. In the initial stage filling of empty pore spaces in the
transition zone with higher porosity can be only observed [5]. Next along with the
increasing of mechanical interactions the micro-cracks formed in the cover bordered
with the transition zone between steel and concrete are being fulfilled [7]. Kinetics
of such changes related to the impact of corrosion products on concrete was defined
in the paper [2] in accordance with the following relationship
˙
V e f f = ˙
V ekw − ˙
V por − ˙
V tran , ˙
V ekw = ˙
V R − ˙
V Fe 2+ , ˙
m
2+
Fe = k I.
(1)
where ˙
V e f f , ˙
V ekw are respectively the effective (equivalent) rate of change in volume
of corrosion products, ˙
V por —the rate of volume change of corrosion products
penetrating into micro-cracks in the ITZ layer, ˙
V tran —the rate of change of volume
of corrosion products transferred into deeper layers of concrete, ˙
V R , ˙
V Fe 2+ —are