H’mida Hamidane, Ayman Ababneh, Ali Messabhia and Yunping Xi
The purpose of this paper is to develop a method for predicting the chloride ingress into concrete structures, with an emphasis on the low temperature range where freeze-thaw…
Abstract
Purpose
The purpose of this paper is to develop a method for predicting the chloride ingress into concrete structures, with an emphasis on the low temperature range where freeze-thaw cycles may cause damage.
Design/methodology/approach
The different phenomena that contribute to the rate and amount of transported chlorides into concrete, i.e., heat transfer, moisture transport and chloride diffusion are modeled using a two-dimensional nonlinear time dependent finite element method. In modeling the chloride transport, a modified version of Fick’s second law is used, in which processes of diffusion and convection due to water movement are taken into account. Besides, the effect of freeze-thaw cycles is directly incorporated in the governing equation and linked to temperature variation using a coupling term that is determined in this study. The proposed finite element model and its associated program are capable of handling pertinent material nonlinearities and variable boundary conditions that simulate real exposure situations.
Findings
The numerical performance of the model was examined through few examples to investigate its ability to simulate chloride penetration under freeze-thaw cycles and its sensitivity to factors controlling freeze-thaw damage. It was also proved that yearly temperature variation models to be used in service life assessment should take into account its cyclic nature to obtain realistic predictions.
Originality/value
The model proved promising and suitable for chloride penetration in cold climates.
Details
Keywords
Mashal Sheban, Muna Abu‐Dalo, Ayman Ababneh and Silvana Andreescu
The aim of this research was to develop corrosion protection systems for reinforced concrete structures under chloride attack. Benzotriazole (BTA) and BTA derivatives were used as…
Abstract
Purpose
The aim of this research was to develop corrosion protection systems for reinforced concrete structures under chloride attack. Benzotriazole (BTA) and BTA derivatives were used as corrosion protection materials for the steel.
Design/methodology/approach
The effect of BTA and four other BTA derivatives on the corrosion resistance of steel in simulated concrete pore (SCP) solutions was studied. BTA derivatives were used as two separate protection systems: inhibition and pickling protection systems. The experiments were performed in SCP solutions which simulated concrete with and without severe chloride attacks. Electrochemical techniques, i.e. potentiodynamic polarization and electrochemical impedance, and Fourier transform infrared spectroscopy (FTIR) were used to assess the steel corrosion protection systems.
Findings
The potentiodynamic polarization studies showed an increase in the pitting potential for all protection systems tested. In addition, a large increase in the steel solution interfacial resistance was observed by electrochemical impedance studies (EIS) due to the formation of steel‐BTA derivatives complex on the surface. This film was formed on the steel surface with either mono‐or bi‐dentate bonds between the triazolic nitrogen ring and the steel surface as shown by the FTIR.
Research limitations/implications
BTA derivatives provided good protection for steel in SCP solutions, indicating their applicability in reinforced concrete structures. However, tests using reinforced concrete samples are required to study possible interactions between steel, BTA derivatives and concrete constitutes, e.g. sand, gravel, cement and chemical admixtures. These BTA‐based systems also should be studied under carbonation attack.
Originality/value
BTA derivatives provided a good protection for steel in the SCP solutions, and this indicates the applicability to use them in reinforced concrete structures.
Details
Keywords
Naim Nusair, Raed Ababneh and Yun Kyung Bae
The purpose of this empirical study is to provide a deeper understanding of how transformational leadership relates to followers' innovative behavior in the Jordanian public…
Abstract
Purpose
The purpose of this empirical study is to provide a deeper understanding of how transformational leadership relates to followers' innovative behavior in the Jordanian public sector.
Design/methodology/approach
Perceptual data were collected from 358 employees working in different public sector organizations located in the Northern region of Jordan.
Findings
Results demonstrate that transformational leadership accounted for 47 percent in the variation of followers' innovative behavior in the Jordanian public sector. Additionally, the findings showed that place of work variable had significant impact on the attitudes of the respondents toward the transformational leadership behavior of their managers and their innovative behavior.
Practical implications
Organizations should invest in transformational leadership training and in the selection of supervisors with this leadership style before initiating the implementation of innovations.
Originality/value
The paper is one of the first to investigate the relationship between transformational leadership and followers' innovative behavior in developing countries.