Papers by Keyword: Mechanical Strength

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: Additive Manufacturing (AM) is considered a vital ingredient in Industry 4.0. Its manner of production is depositing material on a layer-on-layer basis. However, this manner of production normally generates undesirable layer lines. A common solution used to address this is a technique known as Vapor Smoothing (VS). VS is a modern process where chemical vapor is produced to contact the surface of Fused Deposition Modelling (FDM) fabricated parts. This would result in the disruption of part’s outer layers resulting in smoothening of its surface. This type of study has abundant Acrylonitrile Butadiene Styrene (ABS)-based research but currently lacks Polylactic Acid (PLA). Roughness is only one of the common criteria for a good FDM fabricated PLA part. Mechanical strength should also be considered as an acceptance criterion. Having said this, characterization such as Optical Microscopy with ImageJ processing; and tensile testing via Universal Testing Machine (UTM) were utilized. This research introduced a calculated response where good roughness can be attained without sacrificing too much strength in the form of an S/R ratio. It was identified that optimum vapor smoothing parameters are 55 degrees C with an exposure time of 4-min, where we were able to attain a roughness from 10.600 to 3.999 um roughness while having a reduction of strength from 46.1 to 42.7 MPa. As part of our recommendation, it would enhance the study if other characterization methods may also be applied to cite the effects of VS on mechanical properties such as fatigue, and flexural and compressive testing.

Abstract: The crucial role of hybridization in composite research lies in combining different materials to leverage their strengths, creating superior properties and functionalities, leading to enhanced performance and diverse applications. In this research, MWCNTs are chosen as fillers due to their well-known attributes of high mechanical strength. The Hand layup technique was employed to develop the hybrid composite, incorporating MWCNT particles at four different weight fractions (0.5%, 0.75%, 1%, and 2%) it was observed that 1wt% provided optimal properties, beyond which a decline occurred. Mechanical strength analysis was carried out experimentally, focusing on tensile, flexural, and impact strength of the composite. This study examines the impact of filler weight percentage and fiber orientation on mechanical properties of jute-glass-epoxy composites .The results demonstrated a notable impact of increasing reinforcement weight % on the composite's mechanical performance. Specifically, the tensile strength showed a remarkable improvement of 25%, while flexural strength saw a significant increase of 30%, and the impact strength exhibited a notable enhancement of 18.2%.Microstructural analysis using SEM is employed to understand the dispersion of MWCNTs within the jute-glass epoxy matrix and their influence on the composite's mechanical behaviour. These findings highlight the potential of MWCNT reinforcement to improve mechanical properties of jute and glass-based hybrid composites, making them attractive candidates for various engineering applications.

Abstract: This study investigates the dual benefits of Phase Change Material (PCM) incorporation in concrete for pavement construction, focusing on both performance enhancement and energy efficiency. Through extensive mechanical testing and thermal analysis, the effects of PCM content on concrete strength and temperature stress mitigation were evaluated. Results indicate that while PCM addition led to reductions in compressive and flexural strengths, mixes containing 8% PCM maintained feasible strengths for pavement applications. Furthermore, thermal analysis demonstrated significant reductions in temperature and curling stresses with increasing PCM content, highlighting the potential for enhanced pavement durability and energy efficiency. Multi-criteria decision-making (MCDM) analysis identified the 8% PCM mix as the optimal choice due to its balanced performance across critical parameters. This research underscores the efficacy of PCM-enhanced concrete in improving pavement performance and energy efficiency, emphasizing the importance of careful PCM content selection in achieving sustainable pavement solutions.

Abstract: Magnesium phosphate cement concrete (MPCC) has high early strength, which is conducive to achieving rapid repair of winter concrete pavements under no-maintenance conditions. In this paper, we investigated the influence mechanism of four cement antifreeze components on the mechanical and durability properties of MPCC under the severe cold environment, focusing on the development law of the performance of MPCC as a rapid repair material for pavements. The results show that the antifreeze effect of MPCC antifreeze components under severe cold environments is contrasted as MgCl₂ > Mg (NO₃)₂ > Ethylene glycol > Mg (NO₂) ₂. However, the addition of antifreeze components, especially inorganic salt antifreeze components, will also have an adverse effect on the antifreeze resistance of concrete during the service period.

Abstract: We report the fabrication of porous hydrophobic flat sheet membranes composed of polyvinylidene fluoride-co-hexafluoropropylene (PVDF-co-HFP), which is incorporated with graphene (GNP) concentrations of (0.2, 0.5, and 0.8 wt.%) as the hydrophobic filler. FTIR, XRD, and SEM results were used to analyze the composites' functional groups, crystallinity and surface morphology. The water contact angles were 116 ±1.2°; 120 ±0.9°; 126 ±0.7°; 130 ±0.6° for pristine, 0.2 wt%, 0.5 wt%, and 0.8 wt% of GNP membranes, respectively. Moreover, the graphene incorporation enhanced the fabricated polymer's ultimate tensile strength (UTS). The UTS was as follows 2.4±0.01, 5.43±0.02, 7.485±0.015 and 6±0.01MPa for pristine, 0.2 wt% GNP, 0.5 wt% GNP and 0.8 wt% GNP respectively. The highest UTS was (7.485 ±0.015 MPa) for the 0.5 wt% GNP. Graphene incorporation (0.5 wt%) enhanced the membranes’ porosity (78 ±1.9%). This study explored the effect of graphene to improve the flat sheet membranes' mechanical strength, hydrophobicity, and porosity, which can then be applied in desalination using membrane distillation to mitigate clean water shortages and crises.

Abstract: Utilizing local materials and recycling waste has the potential to yield both ecological and economic advantages in the field of construction materials. In this context, the object of this work is to apply Taguchi's design of experiments on cement eco-mortar, which were designed using an L-9 orthogonal array, to optimize and model the effect of dune sand of the El Oued region, rubber aggregates, and crushed clay brick waste on the mechanical strength at 28 days. The different interactions were also investigated between the factors targeted in our study, namely: dune sand (DS) content, rubber aggregates (RA) content, and brick waste (BW) content. The results of the analysis of variation (ANOVA) as well as the mathematical models developed in this study showed that the BW factor content has a positive effect on compressive strength and a negative effect on flexural strength. In addition, the interactions between DS and BW contents and between RA and BW contents have a negative effect on the compressive strength of eco-mortar. With regard to flexural strength, the results showed that the interaction between the factors DS and RA contents has a negative effect on flexural strength, in contrast to the interaction between the RA and BW contents, which has a positive effect.

Abstract: Due to economic, sustainable, and aesthetic benefits, academia and the construction industry are exploring the use of earth in modern construction is being widely studied. Unfortunately, earth as a construction material has low mechanical, poor water durability resistance, and the potential to swell and crack. Therefore, this paper evaluates chitosan and potato starch, natural biodegradable polymers, as stabilizers to improve mechanical strength and water durability resistance of printable earth-based matrix reinforced with sisal fibers. Although the test results indicated that the chitosan had a better performance as an earth stabilizer than potato starch, adding both stabilizers resulted in earthen composites with higher compressive strength and lower water permeability. These results demonstrate the feasibility of using natural stabilizers to improve the performance of earth-based materials for 3D printing without affecting their printability capacities.

Abstract: A rammed-earth technique has been echoed worldwide due to being conceived not only as an environment-friendly method of construction but also standing as an alternative method to arguably replacing cement. The technique however shows several pitfalls. One concerns the lengthy process of curing upon erecting the rammed-earth walls due to the low process of a chemical reaction occurred throughout the curing stage. A second bias followed from the slow curing and concerns the degradation accentuated at the outer wall’s texture, particularly at the edges, due to effects of the weather cycle. These drawbacks have been observed while accomplishing a funded research project. This article has at its stake remedying the above pitfalls. A natural sandy limestone shows a low percentage of calcium carbonate needed for a cohesive mixture. The method suggested here is based on an experiment that uses minerals of the fruits’ and vegetables’ waste as a binding substance. Curing time in this method has been reduced to the half. It is also suggested here that each stage has its importance, including mixing the soil particles dry and wet, compacting the moistened soil mixture, a well-made formwork and curing, towards remedying the above pitfalls.

Abstract: The present work investigates the use of an alumino-silicate material, the pyrophyllite as cement substitution, synthetic polypropylene fibers and binder to create an unusual ultra-performance fiber concrete; new composite, which offers a wide field of possible use in construction industry. Effect of pyrophyllite on the physical-mechanical properties is analyzed. One reference fiber concrete without pyrophyllite and three fiber concretes containing 10%, 20%, 30% of pyrophyllite were elaborated. Results show that the pyrophyllite affects the characteristics of the concrete. Indeed, in the hardened state, the density of fiber concrete decreased with pyrophyllite rate increasing. Moreover, the use of pyrophyllite slows down the hardening process of concrete, consequently producing at early ages, compressive, flexural and tensile strengths and elastic modulus of concretes approaching without exceeding those of the reference fiber concrete. The fiber concretes are also considered to be of good quality. It seems that the rate of 10 % of pyrophyllite generates the best physical-mechanical performances that approach those of the reference fiber concrete. The use of pyrophyllite as a cement substitution is beneficial since it can help to decrease the production of cement; the amount of CO₂ released and protects the environment.