Cost-effective design of reinforced concrete with use of self-terminated carbonation model

Piotr Woyciechowski,Joanna Sokołowska,V Andreev

doi:10.1051/matecconf/20168604016

Piotr Woyciechowski, Joanna Sokołowska + Show 1 more

Open Access

https://doi.org/10.1051/matecconf/20168604016

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Abstract

According to Eurocodes EC0 and EC2 designing of concrete structure durable in terms of carbonation is assured by selection of suitable thickness of reinforcement concrete cover. The selection is done on the basis of structure category and concrete strength class, regardless of the concrete material composition or technological type, thus selected value is an estimation, often exaggerated. The paper presents elaborated “self-terminated carbonation model” that includes abovementioned factors and enables to indicate the maximal possible depth of carbonation. The model, in contrast to parabolic models published in the literature, is a hyperbolic function of carbonation depth in time. The paper explains why such model describes the phenomenon of carbonation better than others. The paper contains an example of calculation of the cover thickness using that model.

Highlights

Durability is one of the important determinants of building material sustainability as well as sustainability of the structure
Providing the durability of reinforced concrete structure working under certain environment conditions depends on providing proper (1) durability of concrete, (2) proper thickness of the concrete cover, as well as taking into consideration serviceability limit states in terms of cracks, namely (3) calculating crack width which would not exceed the Eurocodes limits (EN 1991 Eurocode: Basis of structural design – “EC0” and EN 1992 Eurocode 2: Design of concrete structures – “EC2”)
The requirements in terms of the minimal thickness of the concrete cover due to durability formulated in Eurocode EC2 are different in case of reinforced concrete structures and pre-stressed concrete structures; they are different for each type of structure defined in Eurocode EC0 and exposure class defined in the standard EN 206

Summary

Introduction

Durability is one of the important determinants of building material sustainability as well as sustainability of the structure. In Polish Complement there are given recommendations for the use of cements in the conditions of carbonation exposure class. The requirements in terms of the minimal thickness of the concrete cover due to durability formulated in Eurocode EC2 are different in case of reinforced concrete structures and pre-stressed concrete structures; they are different for each type (category) of structure defined in Eurocode EC0 and exposure class defined in the standard EN 206. Knowing the structural class determined according to EC0 and EC2 (Fig. 1) and specific requirements for concrete exposure class XC given in standard EN 206 (Table 1), it is possible to determine the minimal thickness of concrete cover (cmin,dur, mm) required in case of reinforced concrete threatened by carbonation (Table 2). The given algorithm enables optimal choice of the concrete cover thickness, which minimizes the uncertainty occurring during designing the reinforced concrete structures according to the simplified approach discussed in the first part of this paper

Traditional approach to mathematical model of carbonation

Model of carbonation as the finite process

Findings

Conclusions