A new meta-model to calculate carbonation front depth within concrete structures

Abstract

Carbonation processes cannot be ignored as regards durability and service-life of new concrete structures, and their correct understanding and quantification are essential for maintenance and repair works on existing structures. This paper initially presents a new meta-model developed to calculate carbonation front depth based on the analytic solution of Fick's first law. The only input data required by this non numerical model are: (i) material variables (concrete mix design, maximum nominal aggregate size, cement type, and chemical composition of cement type CEM I and cement density); (ii) technological parameters (initial curing period (t(c))); (iii) environmental parameters (ambient temperature (1), relative external humidity (RH) and CO2 concentration in the air ([CO2](ext)). Consequently, this model is fully suitable for the prediction of carbonation depth in the case of new reinforced concrete structures, for which these required parameters are well-known. The meta-model is validated using data from the literature on short and long-term natural carbonation exposure conditions. Most of the experimental data concern CEM I, CEM II, CEM III cement types, and CEM I additives (fly ash (FA)) with various water to cement (W/C) ratios and t(c). The meta-model is also compared with two already available models: Papadakis' model and Yang's model. The three model predictions are compared with the corresponding values found in the literature. The results confirm that the prediction of the new meta-model proposed here for estimation of carbonation depth is the most accurate in every case

Experimental Investigation on Carbonation Behavior in Lime-Stabilized Expansive Soil

“…Carbonation starts from the surface and propagates to the center of the material; therefore, the deep understanding of carbonation front and propagation rate, namely, the carbonation depth and rate, is critical in assessing the extension in service life of stabilized soil or a concrete structure [18,19]. Based on literature review, Ta et al [20,21] summarized that the factors affecting carbonation depth and rate were chemical compositions and mix proportions in porous materials, along with temperature, relative humidity, concentration, and partial pressure of CO 2 in the external environment [19,[22][23][24]. Cui et al [17] performed accelerated carbonation tests to study the effect of CO 2 concentration on concrete carbonation, where four stages were identified based on the CO 2 concentration ranging from 2% to 100%.…”

Application of sensitivity analysis in the life cycle design for the durability of reinforced concrete structures in the case of XC4 exposure class

“…The service life considered here is predicted using the carbonation model recently developed by Ta et al [28] ( Figure 3). This carbonation model is validated using data from the literature on short and long-term natural carbonation exposure conditions.…”

“…In the carbonation model proposed by Ta et al [28], The characteristics of these cements are presented in Appendix (Table A1).…”

Aplicação de modelagem matemática para fins de previsão de vida útil de estruturas de concreto sujeitas à ação de CO2

“…Por meio de pesquisa bibliográfica foram encontrados na literatura 19 diferentes modelos destinados à estimativa da profundidade de carbonatação do concreto ao longo do tempo, os quais estão descritos em detalhe nos trabalhos de Carmona [9], Pauletti [11], Possan [7], Possan et al [12], Possan, Dal Molin e Andrade [13], Ta et al [14] e Ekolu [9]. Para análise comparativa no presente estudo, foram selecionados os modelos propostos por Ekolu [9] e Possan [7], uma vez que apresentam variáveis de entrada de fácil obtenção, os quais são apresentados em detalhe na sequência.…”