Journal of Materials and Engineering Structures
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Enhancing Mechanical Properties of High Strength Concrete with Nanomaterials, Copper Slag, and Steel Fibers: Experimental Study and Predictive Modeling
Full text linkThis research investigates methods to improve the performance of high-strength concrete (HSC) using advanced and sustainable materials. Nanomaterials such as Nano silica and Nano alumina were incorporated as partial replacements for cement, while copper slag was utilised to partially substitute fine aggregate. Additionally, steel fibers were added to assess their influence on the mechanical properties of HSC. The study developed three concrete mixtures: a control mix (CO) containing 30% Ground Granulated Blast Furnace Slag (GGBS) with a water-cement ratio of 0.38, a mix with varying copper slag replacements (CCS) at levels between 10% and 50%, and an optimised mix (CCSNSA) combining 2% nanomaterials with the most effective copper slag proportion. Steel fibers were introduced into all mixtures in varying amounts, ranging from 0–2% by volume. Experimental results demonstrated that including steel fibers significantly enhanced the compressive, tensile, and flexural strengths of concrete. Furthermore, predictive models were developed for the strength characteristics of all mixes, and their outputs showed a strong correlation with experimental data. This study highlights a sustainable and effective approach to enhancing the mechanical performance of HSC by integrating copper slag, nanomaterials, and steel fibers
Reviewing the degradation of environmental pollution in cement concrete structures using Nano-Titanium Dioxide
Full text linkThe rising levels of pollution globally affect cement concrete structures and historical monuments by making them fade, stained, and dull due to settling of dust particles. Titanium Dioxide (NT) is a naturally occurred photocatalytic material when used with construction materials (CM), offers benefits such as environmental pollution degradation and self-cleaning action. Moreover, its application supplements in enacting the original appearance of the structure for longer times. The main aim of this review study is to summarize the current information available primarily on ‘environmental pollution degradation and self-cleaning effect’. The standard tools for effective summarization of existing data like a) PRISMA analysis, b) VOSviewer, and c) Citespace were used. Further, the major research gaps, environmental impacts, concept of sustainability in relation to utilization of NT and future trends are incorporated. This review successfully concludes the potential application of NT in cement concrete structures for possible reduction of environmental pollution
Performance comparison of hyperbolic paraboloidal shell footing with its flat counterpart
Full text linkWhile traditional flat footings are commonly used in construction, hyperbolic paraboloidal shell footings present potential benefits in load distribution and settlement reduction. The study encompasses two primary aspects: the design of both footing types in accordance with Indian standard practices, followed by a comparative analysis of their performance utilizing finite element methodology. Performance comparison is carried out concentrating on vertical settlement, stress distribution, and the amount of concrete required under centric gravity loads. The hyperbolic paraboloidal shell footing was modeled with curved surfaces, and the underlying soil was treated as nonlinear using the Mohr-Coulomb yield criteria. The amount of concrete required for a hyperbolic paraboloidal shell footing is significantly less, calculated to be 0.61 times that of a flat footing.
Mechanical and microstructural properties of high strength concrete with manufactured sand and recycled coarse aggregates
Full text linkThe influence of manufactured sand (M-sand) and Recycled Coarse Aggregates (RCA) on the fresh, mechanical and microstructural properties in the high strength concrete is focused in order to promote sustainable materials in the high strength concrete. Therefore, there are four proposed mixes such as conventional concrete, RCA replaced by 25% coarse aggregate, MS replaced by river sand 100% and combination of MS (100%) and RCA (25%) replaced together are designated as CM, RC, MS and MSRC, respectively. The proposed mixes were evaluated through the mechanical tests such as compression and tension tests as well as the microstructural analysis such as microstructure as well as elements and phase formations through the SEM, XRD and EDX analysis. It was concluded that the inclusion of RCA and M-sand in concrete has reduced the workability because of their higher water absorption capacity. The compressive strength of mix RC and MS was reduced by 12.9 and 8.24%, respectively as compared to CM. Also, the compressive strength of mix MSRC was reduced by 13.3% compared to the control mix. It was observed that the tensile strength of mix RC and MS individually was reduced by 7.7 and 7.17%, whereas the same on mix MSRC was further reduced by 16% as compared to mix CM. The microstructure of the MS was relatively denser as compared to the RC, however the microstructure of mix MSRC was found to be weaker due to untreated silica particles present in the interface of mortar as compared to the control mix CM. The CM mix revealed that the brownmillerite and calcite act as an activator in the early hydration of concrete and as an inert filler. The RC mix mostly showed the presence of quartz and small peaks of hatrurite and the mineral phase on MS mix has strong peaks of quartz and albite, whereas the mineral phases in MSRC show both hatrurite and albite along with quartz are the hydration products of C3S. The presence of higher Sulphur content in a mix of RC, MS and MSRC also indicates lower durability to water penetration and brittle microstructure
Towards Greener Skies: Natural Fibres for Aeronautical Applications
Full text linkChoosing materials mostly involves taking their sustainability into account. The material selection for airplane internal product design is heavily influenced by the enormous demand, knowledge of the ecological effect, and appropriateness among a material’s performance, properties, and adequacy for the part to be utilized. In this study, natural fibres for aeronautical applications were chosen using a step-by-step methodology. To have a better understanding, data about the mechanical, physical, and chemical features of bio-fibres were gathered and subjected to a hierarchical analysis prior to the start of the selection process. For this purpose, three physical subcriteria (crystallinity index, density, and moisture content), three mechanical subcriteria (young’s modulus, tensile strength, and “elongation at break”), and three different chemical subcriteria (lignin, hemi-cellulose, and cellulose) were taken into consideration. Subsequently, hierarchy strategies were applied to identify the weights assigned to the attributes based on the notional significance of each attribute
Use of Microgrid Fiber type new Additives to Improve Load Bearing and Energy Absorption Capacities of Shotcrete Mixes
Full text linkIn this study, different polypropylene type polymer fiber additives were comparatively examined carrying out a series of EFNARC plate (slab) loading test, which is a popular test for evaluation of the shotcrete liner performances. A new fiber type called microgrid fiber (MGF) was compared with the conventional polypropylene fiber (PPF) additives. Shotcrete mixes were tested to determine their load bearing, deformability and energy absorption capacity properties. Additionally, indirect (splitting) tensile strength (ITS) values of specimens were determined to compare influences of different fiber types. According to the slump test findings, the workability of the fresh mixes decreased with an increase in fiber content. It was determined that the workability properties of conventional PPF and MGF added specimens were similar. However, it was found that the MGF type additive reduced the fresh mix workability more than the PPF additive due to the increase in the fiber content. It was found that MGF additive was found to supply better improvements in ITS values, load bearing and energy absorption capacity properties of slabs in comparison with the conventional PPF additive. The new MGF type additive was assessed to be usable to effectively improve the shotcrete performances
Sustainable Concrete Innovation: Crumb Rubber as a Partial Fine Aggregate Replacement
Full text linkThe exponential growth of the automobile industry contributes a significant accumulation of waste tires, presenting a substantial environmental challenge due to their non-biodegradable nature. This study investigates the potential of using crumb rubber produced from waste tires as a partial replacement for natural fine aggregates of concrete, aiming to enhance the material's properties while mitigating environmental impact. The mechanical and durability characteristics of concrete introducing 5%, 10%, and 15% crumb rubber were determined through various tests, including compressive strength, stress-strain behavior, and impact resistance. Results indicate that while there is a slight decrease in compressive strength with increased rubber content, the post-cracking behavior and impact resistance improve significantly, with energy absorption capacities increasing by 75%, 125%, and 158.4% for 5%, 10%, and 15% replacements, respectively. Additionally, durability tests reveal that rubberized concrete shows reduced chloride ion penetration and improved resistance to acid attack, with 30% reduction in chloride penetration at 15% rubber content. The findings suggest that incorporating crumb rubber can enhance the ductility and durability of concrete, making it a viable and sustainable alternative in construction, particularly in applications such as road pavements where impact resistance is crucial. This study contributes to the ongoing research on sustainable construction materials and emphasizes the importance of recycling waste materials to reduce environmental impact
Enhancement of Mechanical Properties of Unfired Clay Bricks Using Rice Husk Ash and Fibre Reinforcement
Full text linkThis study investigates the production of unfired clay bricks incorporating cement and rice husk ash (RHA) as a binder, with rice husk (RH) serving as fiber reinforcement. The need for eco-friendly building materials is critical, as cement production contributes 7-8% of global CO₂ emissions, and while fired clay bricks are stronger, their high production cost due to significant energy requirements makes them less sustainable. Providing lower-cost building materials can reduce rural-to-urban migration and make housing more affordable for low-income earners. RH fibers were added in varying volumes (0, 5, 10, 15, 20, and 25 vol%) while maintaining a constant RHA and cement content of 10 vol.%. The mixed clay bricks were dried for seven days and cured at room temperature (22°C to 28°C) for 21 days, totalling 28 days of curing. Mechanical properties, including compressive strength, flexural strength, and fracture toughness, were evaluated alongside the chemical composition and textural characteristics of the clay and RHA. Particle size distribution (PSD) analysis classified the clay as sandy clay with higher sand content, determined using sieve analysis and the hydrometer method. X-ray fluorescence (XRF) confirmed that the RHA met NIS/ASTM standards, with a minimum of 70% combined SiO₂, Al₂O₃, and Fe₂O₃, qualifying it as a pozzolanic material. Optimal mechanical performance was observed at 5% RH fiber content, with fibers 2-4 mm in length, achieving compressive strength of 7 MPa, flexural strength of 2.1 MPa, and fracture toughness of 2.15 MPa√m, while fiber content beyond 5% resulted in gradual declines, particularly significant after 20%. The study concludes that RH fiber-reinforced composites are suitable for lightweight, durable building materials, promoting environmental sustainability and improved performance
Strengthening of Deficient Drop-in-ends with Near Surface Mounted (NSM) Steel Bars under static and repeated loading
Full text linkThe present research work, presented the results of eight drop-in-ends specimens tested experimentally to investigate the efficiency of the NSM steel bars technique in strengthening the drop-in-ends including internal miss detailing, under static and repeated loading. Two values of shear span/depth (a/d) ratios was considered, namely are 1.0 and 1.5. Several variables were considered including (a/d) ratio, effect of deficient nib reinforcement (by about 40%) and the type of loading. The behaviour has been discussed in terms of cracking load, failure load, cracking pattern, load-deflection curve and failure mode. Results revealed that increasing a/d ratio from 1.0 to 1.5 yielded a reduction in capacity and the corresponding deflection by 33% and 5%.Moreover, capacity reduced by 11% and 5% for the two values of a/d respectively, when the nib steel reduced by (40%).Furthermore, it was found that the strengthening by NSM steel bars resulted in increasing capacity by 15% and 14% for the two a/d ratio respectively. Regarding the repeated loading tests, it was found that capacity and corresponding deflection reduced by 25% and 42% for a/d =1.0 relative to the strengthened specimen and tested under static loading ,while the respective values for a/d =1.5 were 5% and 3%. In addition, it was obtained that the capacity was reduced by 16% when increasing a/d ratio from 1.0 to 1.5
A Comprehensive Analysis of the Influence of Fly Ash on the Bond Properties between Reinforcing Steel and Concrete
Full text linkThis paper examines the possible use of fly ash to make concrete greener. Because cement manufacturing adds to CO₂ levels, using fly ash instead is becoming more popular. This study seeks to find out how bond strength changes for 0–30% fly ash replacement, study the effects of microstructure, and establish the best ratios for use in structures. For this experiment, we used Grade 53 OPC concrete, which was made to meet a target strength of 20 MPa with a water-binder ratio of 0.5. On-center compressive strength (ASTM C39), tensile strength (ASTM C496), and bond strength (ASTM C900) were tested. The study showed that using a 10% fly ash replacement resulted in the best outcome, raising the concrete’s compressive strength by 7.3% (from 22.3 to 23.6 MPa), tensile strength by 5% (4.2 MPa), and bond strength by 3% (13.9 MPa) by pozzolanic reactions at the interface between aggregates and cement. When the quantity of added fly ash was increased to 20–30%, the concrete became weaker and difficult to work with (slump: 0–0.9 in.), again due to fly ash diluting the binder. We found out that 10% is the most sustainable amount of fly ash for construction. We had used superplasticizers with silica fume when we were going to replace the amount of cement. In the future, experiments with added salt, carbonation, and earthquake loads could extend how widely this approach is used