Numerical analysis of concrete degradation due to chloride-induced steel corrosion

Ayinde, Olawale O.,Zuo, Xiao-Bao,Yin, Guang-Ji Techno-Press 2019 Advances in concrete construction Vol.7 No.4

Concrete structures in marine environment are susceptible to chloride attack, where chloride diffusion results in the corrosion of steel bar and further lead to the cracking of concrete cover. This process causes structural deterioration and affects the response of concrete structures to different forms of loading. This paper presents the use of ABAQUS Finite Element Software in simulating the processes involved in concrete's structural degradation from chloride diffusion to steel corrosion and concrete cover cracking. Fick's law was used for the chloride diffusion, while the mass loss from steel corrosion was obtained using Faraday's law. Pressure generated by steel corrosion product at the concrete-steel interface was modeled by applying uniform radial displacements, while concrete smeared cracking alongside the Extended Finite Element Method (XFEM) was used for concrete cover cracking simulation. Results show that, chloride concentration decreases with penetration depth, but increases with exposure time at the concrete-steel interface. Cracks initiate and propagate in the concrete cover as pressure caused by the steel corrosion product increases. Furthermore, the crack width increases with the exposure time on the surface of the concrete.

Bond behaviour at concrete-concrete interface with quantitative roughness tooth

Ayinde, Olawale O.,Wu, Erjun,Zhou, Guangdong Techno-Press 2022 Advances in concrete construction Vol.13 No.3

The roughness of substrate concrete interfaces before new concrete placement has a major effect on the interface bond behaviour. However, there are challenges associated with the consistency of the final roughness interface prepared using conventional roughness preparation methods which influences the interface bond performance. In this study, five quantitative interface roughness textures with different roughness tooth angles, depths, and tooth distribution were created to ensure consistency of interface roughness and to evaluate the bond behaviour at a precast and new concrete interface using the splitting tensile test, slant shear test, and double-shear test. In addition, smooth interface specimens and two separate the pitting interface roughness were also utilized. Obtained results indicate that the quantitative roughness has a very limited effect on the interface tensile bond strength if no extra micro-roughness or bonding agent is added at the interface. The roughness method however causes enhanced shear bond strength at the interface. Increased tooth depth improved both the tensile and shear bond strength of the interfaces, while the tooth distribution mainly influenced the shear bond strength. Major failure modes of the test specimens include interface failure, splitting cracks, and sliding failure, and are influenced by the tooth depth and tooth distribution. Furthermore, the interface properties were obtained and presented while a comparison between the different testing methods, in terms of bond strength, was performed.

Application of machine learning models and landsat 8 data for estimating seasonal pm <SUB>2.5</SUB> concentrations

Bashir Olasunkanmi Ayinde,Muhammed Rabiu Musa,Abdul-Afeez Olakunle Ayinde 환경독성보건학회 2024 환경독성보건학회지 Vol.39 No.1

Air pollution is a significant global challenge that affects many cities. In Europe, Bosnia and Herzegovina (BiH) are among the most highly polluted and are mainly affected by air pollution. In this study, we integrate open-source landsat 8 remote sensing products, topographical data, and the limited ground truth PM<SUB>2.5</SUB> data to spatially predict the air quality level across different seasons in Tuzla Canton, BiH by adopting three pre-existing machine learning models, namely XGBoost, K-Nearest Neighbour (KNN) and Naive Bayes (NB). These classification models were implemented based on landsat 8 bands, environmental-derived indices, and topographical variables generated for the study area. Based on the predicted results, the XGBoost model exhibited the highest overall accuracy across all seasons. The predicted model results were used to generate spatial air quality maps. Based on the classification maps, the PM<SUB>2.5</SUB> air quality level predicted for Tuzla Canton in the Winter Season is very unhealthy. The findings conclude that the PM<SUB>2.5</SUB> air quality concentration in Tuzla Canton is relatively unsatisfactory and requires urgent intervention by the government to prevent further deterioration of air quality in Tuzla and other affected cantons in BiH.

Interface Shear Behaviour between Precast and New Concrete in Composite Concrete Members: Effect of Grooved Surface Roughness

Erjun Wu,Olawale Olatunde Ayinde,Guangdong Zhou 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.6

A major condition for the quality performance of connected-concrete layers is enough shear strength at the interface. Research shows that the interface shear behaviour is highly dependent on the texture of its interface. Although, several research on the effect of surface roughness on the interface shear behaviour of concrete to concrete connection using different interface patterns exists; however, there is scant literature on studies using quantitatively controlled interface texture, especially studies considering the roughness tooth geometrical parameters. In this study, seven different interface roughness geometries were designed and utilised as the study parameters for the interface shear behaviour, as well as the initial confining pressure. The double-sided shear test was used to determine the shear behaviour, failure mode, shear transfer mechanism, alongside the friction and cohesion values for all the studied interface types. The test results showed that both the interface roughness geometry and the magnitude of the confining pressure have a significant effect on the interfacial shear behaviour. Using different formations of the interface geometry provided a 15.4% difference in interfacial shear strength. For most of the interface geometries, interface cracking load increases linearly with the increase of initial confining pressure, while for the shear strength, the increase in confining pressure is more effective at lower pressure values. The friction and cohesion coefficients are influenced by the roughness tooth angle and tooth distribution.

Characteristics of Wood Ash Cement Mortar Incorporating Green-Synthesized Nano‑TiO₂

Bolanle Deborah Ikotun,Akeem Ayinde Raheem 한국콘크리트학회 2021 International Journal of Concrete Structures and M Vol.15 No.3

This paper presents the findings of an investigation into the influence of green-synthesized nano-TiO₂ on the characteristics of wood ash (WA) cement mortar. Mortar specimens were prepared by partial replacement of cement with WA (10% by weight) and addition of 1, 2 and 3% nano-TiO₂ by weight of binder; using constant water-to-binder ratio (w/b) for all mixtures. The properties evaluated are setting time of the binder and flexural and compressive strength with water absorption of the mortar. The results indicated that addition of 1 and 2% nano-TiO₂ reduced setting times of WA cement paste. Also, the flexural and compressive strength of WA cement mortar were higher with the incorporation of up to 2% nano-TiO₂. The water absorption of WA cement mortar was reduced when nano-TiO₂ was added with 2% incorporation having the best result. The incorporation of NT in WA cement mortar improved its workability and strength characteristics.

Characterization of prepared eco-friendly biochar from almond (Terminalia catappa L) leaf for sequestration of bromophenol blue (BPB) from aqueous solution

Jabar Jamiu Mosebolatan,Owokotomo Ignatius Adekunle,Ayinde Yusuf Timilehin,Alafabusuyi Ayodele Modupe,Olagunju Gbolahan Olusayo,Mobolaji Victor Oluwafemi 한국탄소학회 2021 Carbon Letters Vol.31 No.5

Novel eco-friendly adsorbents were prepared through pyrolysis and acid activation of raw almond leaf (RAL) to form almond leaf biochar (ALB) and chemically activated almond leaf biochar (CAL), respectively. The prepared adsorbents were characterized using TGA, FTIR, SEM–EDX, BET and XRD techniques and their physicochemical properties investigated. RAL, ALB and CAL were utilized for adsorption of BPB dye from aqueous solution using batch technique under optimum conditions. The optimum dye adsorbed by RAL, ALB and CAL were 92.83, 93.21 and 94.89%, respectively at pH 3, dye initial conc. (100 mg/L), adsorbent dose (0.04 g/25 mL), 60 min contact time and 301 K adsorption temperature. Although, Langmuir maximum monolayer adsorption capacities were found to be 365.36, 535.62 and 730.46 mg/g for RAL, ALB and CAL, respectively, but isotherm conformed to Freundlich model. Kinetic study confrmed suitability of pseudo-second-order model with rate constant 9.33×10–4, 9.91×10–4 and 12.60×10−4 g mg−1 min−1 for RAL, ALB and CAL, respectively. Negative values of thermodynamic parameters (∆G and ∆H) established sequestration process to be spontaneous and exothermic. RAL, ALB and CAL were discovered to be highly efcient adsorbents that could be used in place of expensive commercial adsorbents.

Modeling of time-varying stress in concrete under axial loading and sulfate attack

Guang-Ji Yin,Xiao-Bao Zuo,Yu-Juan Tang,Olawale Ayinde,Dong-Nan Ding 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.2

This paper has numerically investigated the changes of loading-induced stress in concrete with the corrosion time in the sulfate-containing environment. Firstly, based on Fick’s law and reaction kinetics, a diffusion-reaction equation of sulfate ion in concrete is proposed, and it is numerically solved to obtain the spatial and temporal distribution of sulfate ion concentration in concrete by the finite difference method. Secondly, by fitting the existed experimental data of concrete in sodium sulfate solutions, the chemical damage of concrete associated with sulfate ion concentration and corrosion time is quantitatively presented. Thirdly, depending on the plastic-damage mechanics, while considering the influence of sulfate attack on concrete properties, a simplified chemo-mechanical damage model, with stress-based plasticity and strain-driven damage, for concrete under axial loading and sulfate attack is determined by introducing the chemical damage degree. Finally, an axially compressed concrete prism immersed into the sodium sulfate solution is regarded as an object to investigate the time-varying stress in concrete subjected to the couplings of axial loading and sulfate attack.

Sources of tolerance to low soil nitrogen in some Striga resistant and quality protein maize (Zea mays L.) varieties

Oloyede-Kamiyo Qudrah Olaitan,Olaniyan Amudalat Bolanle,Abdul-Waheed Jafar Ayinde,Akinseye Benson Akinloye 한국작물학회 2021 Journal of crop science and biotechnology Vol.24 No.5

Low soil nitrogen (N) is one of the major abiotic stresses reducing maize yield in Africa. Twenty-fve maize varieties which included quality protein maize (QPM), drought and Striga tolerant maize, and two low soil nitrogen (LN) tolerant maize as checks, were evaluated in two locations between 2017 and 2018 to identify varieties with tolerance to LN. The feld was mopped of nitrogen by planting maize twice without fertilizer and the soil was analyzed before the trial. The experiment was laid out in a randomized complete design in three replications. Urea fertilizer was applied in a split dose at 2 and 4 weeks after planting at rate of 30kgN/ha for low nitrogen (LN) and 90kgN/ha for high nitrogen (HN) plot. Data were collected on days to fowering, anthesis-silking interval, leaf death, grain yield, and other agronomic parameters. Data were subjected to analysis using SAS. Rank summation index (RSI) and cluster analysis were used to select the best varieties under LN. Apart from the two checks, varieties DT STR -Y2 SYN and TZE COMP3 DT had good yield of 1.99 tons/ha and 1.39tons/ ha, respectively, under LN, with yield gap of 0 and 44%, respectively. The top ranked varieties under LN using RSI either appear singly or in a group under cluster analysis. They included drought and Striga tolerant varieties along with the two LN checks, implying that Striga tolerant maize also possesses the ability to tolerate LN. The varieties could, therefore, be involved in a breeding program for improvement for low soil nitrogen. Low soil nitrogen (N) is one of the major abiotic stresses reducing maize yield in Africa. Twenty-fve maize varieties which included quality protein maize (QPM), drought and Striga tolerant maize, and two low soil nitrogen (LN) tolerant maize as checks, were evaluated in two locations between 2017 and 2018 to identify varieties with tolerance to LN. The feld was mopped of nitrogen by planting maize twice without fertilizer and the soil was analyzed before the trial. The experiment was laid out in a randomized complete design in three replications. Urea fertilizer was applied in a split dose at 2 and 4 weeks after planting at rate of 30kgN/ha for low nitrogen (LN) and 90kgN/ha for high nitrogen (HN) plot. Data were collected on days to fowering, anthesis-silking interval, leaf death, grain yield, and other agronomic parameters. Data were subjected to analysis using SAS. Rank summation index (RSI) and cluster analysis were used to select the best varieties under LN. Apart from the two checks, varieties DT STR -Y2 SYN and TZE COMP3 DT had good yield of 1.99 tons/ha and 1.39tons/ ha, respectively, under LN, with yield gap of 0 and 44%, respectively. The top ranked varieties under LN using RSI either appear singly or in a group under cluster analysis. They included drought and Striga tolerant varieties along with the two LN checks, implying that Striga tolerant maize also possesses the ability to tolerate LN. The varieties could, therefore, be involved in a breeding program for improvement for low soil nitrogen