Papers by Keyword: Durability

Abstract: This paper deals with the multi-criteria optimization of reinforced concrete floor structures in terms of environmental impacts, costs, and durability. A software tool was developed and applied to three structural systems: one-way slabs with beams and girders, slabs supported by beams on all edges and flat slabs. The implemented optimization algorithm is presented, and the influence of span and imposed load on the environmental impacts and costs of the optimal solutions is analyzed. Selected scenarios illustrate the process of identifying the most suitable structural variant. Finally, the discussion highlights practical aspects of structural system selection, where additional criteria such as layout flexibility, acoustic performance, and construction time must be considered.

Abstract: This study evaluates the effect of acid attack on the behavior of concrete containing bentonite and fly ash. The concrete mixes contain varying dosages of bentonite mixed with a constant ratio of 10% fly ash. The concrete mixes include A0, A1, A2, A3, A4, and A5, which contain 0%, 10%, 20%, 30%, 40%, and 50% bentonite, respectively. Experimental results reveal that the addition of 10% fly ash along with 10% bentonite can show significant resistance toward acid attack. The concrete mix A1, containing 10% fly ash and 10% bentonite, loses only 1.1% of its mass as compared to the controlled mix of concrete, which shows a significant loss of its mass up to 8.4%. Microstructural analysis of concrete specimens reveals significant changes in hydration products using scanning electron microscopy (SEM). The addition of 10% bentonite along with fly ash creates a denser microstructure due to the formation of calcium silicate hydrate gel and refines the internal pores of the concrete, which provides a significant resistance towards acid attack. In addition, higher dosages of bentonite lead to a porous and loose microstructure, which becomes susceptible to microcracking and spalling.

Abstract: This review utilizes bibliometric analysis to examine global research trends and the chronological development of studies on the incorporation of mine wastes and tailings in concrete. A total of 345 publications were extracted from the Web of Science (WOS) database, and their analysis revealed a clear upward trajectory in scientific output since 2000. Respectively, China, India, Canada, and the USA were identified as the countries contributing the most to this research area. Among the 1139 author keywords extracted from the collected papers, 103 keywords with a minimum of three occurrences were analyzed using the VOSviewer software. VOSviewer further supports identifying research gaps and emerging trends by visualizing relationships among authors, publications, and keywords, facilitating a deeper understanding of the dynamics within the field. The analysis of keyword occurrences shows convergence towards research that focuses on the development of sustainable and high-performance materials that equate environmental responsibility with industrial economy demands. The current review also uses Biblioshiny, a web-based tool that explores topic timelines. It reflects that, in recent years, research focuses have shifted toward more sustainability, advanced materials, and performance optimization in the use of mine tailings in concrete.

Abstract: In Lima, many concrete structures experience accelerated deterioration due to physical and chemical factors, limiting their durability. This study evaluates the effect of recycled glass powder (RGP) and a nanosilica additive (1.5 %) on concrete with f’c = 27.5 MPa (280 kg/cm²), focusing on optimizing its mechanical properties, durability, and economic feasibility. Mixtures with 10 %, 15 %, and 20 % cement replacement by RGP were prepared, assessing compressive, tensile, and flexural strength, as well as permeability and water absorption. The mixture with 10 % RGP (RGP-10) showed the best early age mechanical performance, increasing compressive strength by 39.1 %, tensile strength by 12.7 %, and flexural strength by 26.2 % compared to the concrete control. Mixtures with 15 % and 20 % RGP showed lower initial strength, although future gains are expected due to delayed pozzolanic reactions. Regarding durability, RGP-10 reduced permeability by 9.02 % and water absorption by 6.45 %, while RGP-15 and RGP-20 achieved even greater reductions, with permeability decreasing by 11.48 % and 9.84 %, and water absorption by 8.68 % and 10.56 %, respectively. Although the nanosilica additive increases the initial cost, its combination with RGP produces significant improvements in mechanical properties and durability, contributing to a reduction in maintenance related costs, resulting in a durable, sustainable, and economically viable material.

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: Retracted paper: 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.