Papers by Keyword: Durability

Abstract: Rapid growth in infrastructure projects in Nigeria has led to indiscriminate river sand mining, causing river bank erosion, bed degradation, biodiversity loss, and poor water quality. Researchers have explored laterite as a substitute for river sand in concrete production. This study investigated use of lateritic soil from Akure (Lat. A), Ondo (Lat. B), and Ile-Oluji (Lat. C) for replacing fine aggregate with replacement levels of 0%, 10%, 20%, and 30% used in concrete cubes (150 × 150 × 150 mm). The physical, chemical, and mineralogical properties of the laterite, and the strength and durability of the resulting concrete, were investigated through Atterberg limits, X-Ray fluorescence, compressive strength, splitting tensile strength and sorptivity tests. Results revealed that concrete with 10% Lat. C achieved the highest compressive strength of 11.45 N/mm², while 20% Lat. B and 10% Lat. A attained strengths of 8.5 N/mm² and 10.77 N/mm², respectively. The optimal sorptivity values were 3.18 ×10⁻⁴ mm/min⁰^.⁵ for 10% Lat. A, 4.73 ×10⁻⁴ mm/min⁰^.⁵ for 20% Lat. B, and 5.66 ×10⁻⁴ mm/min⁰^.⁵ for 10% Lat. C. This suggests that laterite with predominantly silty fines is comparatively better in achieving satisfactory strength and durability than laterite with predominantly clayey fines. The laterite index properties showed a good relationship with the compressive strength models, but did not fit well with the sorptivity models. Hence, while the laterite index properties contribute to the compressive strength of lateritic concrete, they may not essentially affect its sorptivity.

Abstract: This work focuses on the design and the study of mechanical behavior of new adobe clay bricks material made from local ecological materials for use in construction. The hydraulic binder used is a clay mineral material from the Sibang district in Gabon, and the biomass consists of sawdust from tropical wood species (okoume) combined with additives such as sugar cane molasses and cassava starch. The sawdust comes from okoume, where the selected protocol is based on their availability and widespread use locally. Preleminary tests done on clay show detailed analyses using laser granulometry, chemical analysis of major elements in total rock, X-ray diffraction on total rock and oriented samples (normal and heated to 550°C and ethylene glycol), infrared spectroscopy, cation exchange capacities, and scanning electron microscopy. The mixture of sawdust from okoume, padouk, azobe specie and 85% Sibang clay allowed for the design of bricks with quality facades. The respective compression strength tests resulted in 6.44 MPa, 3.15 MPa and 3.13 MPa, where the mixture containing the okoume sawdust showed a resistance, of 6.44 MPa, two times higher than the others. The adobe bricks incorporating sawdust from okoume, padouk and azobe woods are in compliance with the French standard for compressed earth blocks. The sawdust-wood mixture combined with clay is an ecological material and an alternative to the use of traditional concrete blocks in Gabon.

Abstract: Evaporation of a saline solution from a porous medium often leads to the formation of salt efflorescence at the surface of the medium. We look at the special case where the medium is formed by the assembly of fine and coarse medium vertical columns perpendicular to the evaporation surface and where there is a continuous wicking of the solution into the medium in combination with evaporation. Experiments lead to distinguish two main cases depending on the development or not of the efflorescence at the surface of the coarse medium. On the contrary, the presented analysis suggests that the coarse medium surface colonization occurs when the evaporation flux is sufficiently high no matter what the type of efflorescence is on the fine medium surface. In addition, the analysis suggests that the colonization will always occur when the supersaturation is close to the solubility.

Abstract: The emission of greenhouse gases during its production, and the poor performance of cementbased concrete in marine environments has raised the need for alternative eco-friendly materials. This study investigated the strength and durability of Geopolymer concrete cured in marine water. The Slag/Metakaolin-based geopolymer concrete was used in this study. Two curing regimes were adopted; a sample was cured in marine water while the control was air-cured and designated as GPCW and GPCD respectively. Geopolymer beams, cubes, and cylinders were used for flexural, compressive, and tensile tests, respectively, at 7, 28, 90, 180, 270, and 365 days. Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS) were used to determine the microstructural and elemental compositions. Results showed an increase in compressive, flexural and tensile strengths between 7 to 180 days, with a gradual decrease at 365th days for the GPCD samples. The GPCW showed a 43% reduction in strength between the 7th and 28th days, with a further decrease of 11% from 28 to 365 days. The average strength of both samples was above C40 grade concrete. SEM revealed differences in GPCD and GPCW with the latter displaying less dense structures with larger voids, consistent with the reduction in compressive strength over time. The EDS analysis showed that there was <1% ingress of Sulphate into GPCW on average, this revealed its resistance to the deterioration-causing agent in cement-based concrete. This study concluded that GPC can be used for coastal marine concrete structures.

Abstract: With the continuous development of novel concrete formulations incorporating various materials, a prevalent issue is their susceptibility to deterioration, which often results in the formation of cracks within the internal structure. This study mainly explores the impact of liquid concrete deep-penetration sealer (CDPS) on the durability of concrete. The evaluation of durability included compressive strength tests, abrasion resistance tests, permeability tests, and rapid chloride ion penetration tests. Although compressive strength and permeability are conventionally regarded as the primary metrics for assessing concrete performance in the industry, abrasion resistance is often overlooked. To address this gap, this study incorporated abrasion resistance testing to ascertain the sealer's efficacy in mitigating surface wear. This barrier mitigates the ingress of deleterious external agents, thereby enhancing the overall durability of the concrete. Furthermore, the results highlight the potential of such treatments to significantly improve critical performance parameters, particularly in terms of wear resistance and resistance to chloride ion penetration, which are essential for prolonging the lifespan of concrete structures.

Abstract: Accurately predicting the water-binder ratio (W/B ratio) is crucial for achieving rice husk ash supplemented concrete structures' desired strength and durability. This study introduces an innovative approach for W/B ratio prediction, utilizing cutting-edge machine learning algorithms in combination with Explainable Artificial Intelligence (XAI) techniques. The research employs hybrid ensemble learning models, including Random Forest (RF), CATBoost (CB), Whale Optimization Algorithm-optimized RF (RF-WOA), and Moth Flame Optimization-optimized CB (CB-MFOA). The results indicate that these hybridized models significantly outperform the standalone models (RF and CATBoost) and traditional empirical methods (feret’s law, Abram’s law and bolomey’s method), with the CB-MFOA model achieving the highest accuracy, demonstrated by an R-value of 0.9984 during the calibration phase. In the verification phase, the CB model excelled with an R-value of 0.966. In addition to model performance, the study integrates XAI methods to explain the predictions and identify the key factors influencing the w/b ratio. Cement was found to be the most critical variable, enhancing the accuracy of the CB-MFOA model. The findings confirm that the proposed method improves prediction precision and provides engineers with a reliable tool to optimize concrete mix designs, thereby improving the durability and sustainability of concrete. This research contributes to the broader field of concrete technology by advancing the application of AI-based solutions in civil engineering and related fields.

Abstract: This study relates to the development of geopolymer concrete (GPC) and empirical models which can be used to predict strength and durability under different curing temperatures. The binders and alkaline activators used for the GPC production were characterized to determine their physical and chemical properties. The partial and pure geopolymer concrete samples were produced. The partial replacement of Geopolymer concrete (GPC) samples was done with cement at varying percentages of 0, 2.5, 5, 7.5, 10, 12.5, 15, 17.5 and 20% to determine the optimum cement stabilization. Fourier transform infrared spectroscopy (FTIR) results show key absorbance level at the zone between 950.1 and 3250.12 cm⁻¹. It means that enhancement of the laboratory-produced (bespoke) superplasticizer enhanced the performance of GPC by reducing the viscosity and enriching the flow behaviour of the concrete. The optimal geopolymer product showed substantial strength and durability enhancements at 70°C followed by declining values at temperatures above 70°C, indicating material deterioration. A positive correlation between hot-state temperature, strength and durability properties was also established. Furthermore, scrutiny of the model shows that overall dataset points for training and test sets are clustered close to the diagonal line, signifying that the model provides precise estimation of the strength and durability features. .

Abstract: In recent years, flexible strain sensors with high sensitivity and a wide sensing range have been developed for biosensors, wearable sensors, electronic skin, and soft robots. In this study, SR/CNT/SR composite-based sensors were fabricated using the sandwich manufacturing method. The sensors were then analyzed for electro-mechanical properties to test their performance. The flexible strain sensor showed a high sensitivity of 76.60 at 0-80% strain range. In addition, the sensor also showed a high linearity of 0.978 in one linear region. The sensor also constantly changes relative resistance at 10 cycles in the 0-40% range. While in the 45-80% strain range, the relative resistance value fluctuates. This is due to the large crack in the sensor when stretched. This sensor also has a fast response time of about 80 ms and a fast recovery of around 95 ms. This flexible strain sensor is also stable for durability testing at 500 loading and release cycles.

Abstract: Material abrasion is a critical consideration in product design, manufacturing, and maintenance because it has a high impact on several properties. When it comes to the abrasion of polymer yarns, insight into the behaviour of yarns due to constant abrasion is important for ensuring final product quality, performance, and customer satisfaction. For this study, a group of polymer yarns is selected. The yarns differ in raw material, as well as the yarn type. Within the experiment selected yarns in both single condition and within the fabric structure were conducted to different abrasion tests. The study findings reveal that yarn type, raw material composition, and additional treatments significantly influence abrasion resistance. Recycled polyester yarns demonstrate comparable, if not superior, abrasion resistance to conventional ones, making them viable for various applications.

Abstract: Limestone fillers are increasingly recognized as a sustainable alternative to cement and sand in mortar and concrete mixtures, driven by environmental concerns over the excessive use of natural resources and raw materials. This study investigates the potential exploitation of different limestone fillers, waste products of the quarrying industry, in the production of cementitious composites. The investigation includes the physico-mechanical characterization of a number of mixtures with different percentages of limestone fillers used as partial replacement to sand. The results show that increasing the limestone filler content negatively influences the mechanical performance of the hardened end-products, decreases their density and increases their open porosity. At the same time, increased clay particle content in the limestone filler decreases the workability of the fresh mixtures.