Replacement Ratio Research Articles

Physical model test study on strength characteristics of gravel pile composite foundation

In gravel pile composite foundation stability design, the shear strength of composite foundation is critically important. However, due to the size limitation of test equipment, it is difficult to obtain its shear strength in field. This study designs a laboratory shear model test to obtain the shear strength of gravel pile composite foundation, where a total of four group tests were carried out, including two nature soils and two gravel pile area replacement ratios. The shear strength parameters obtained by the shear model tests are compared with the results of empirical formula methods such as the Chinese Standard Method and Priebe Method to verify the accuracy of these two methods. It is demonstrated that for the Chinese Standard Method, the empirical formula's results are smaller than the shear model test results when the pile-soil stress ratio b is 1. When the pile-soil stress ratio b is 1.5, the results are close to each other. For the Priebe Method, the empirical formula results are all larger than the shear model test results, and it is especially unsuitable for the mud soil.

Failure criterion and elasto-plastic constitutive model of seawater concrete incorporating coral aggregate subjected to triaxial loading

Recently, there has been a growing interest in utilizing coral reef debris as a replacement for river sands and natural coarse aggregates (NA). A novel type of seawater concrete, designated as CAC, was developed to effectively utilise raw coral debris and reduce material transportation costs. This study aimed to examine the mechanical properties of CAC under both uniaxial and triaxial loading conditions. Consequently, 18 prism uniaxial specimens and 90 triaxial cylinder specimens were prepared, considering concrete strength (C20, C40), replacement ratio of coral coarse aggregate (CA) (50 %, 75 % and 100 %), and lateral stress ratio (0, 0.1, 0.2, 0.3 and 0.5). The results indicated that the increase in peak stress and strain is associated with the triaxial stress ratio and the cylinder compressive strength of coarse aggregate. Furthermore, the compressive meridian of CAC is lower than that of conventional concrete. Based on the test results in this study, a modified William-Warnke failure criterion for CAC was established. Additionally, an elasto-plastic model considering a modified hardening and softening law was suggested for CAC under tri-axial loading. The proposed models were found to be well verified by the test results.

Axial compression behavior of carbon fiber reinforced polymer confined partially encased recycled concrete columns.

Partially encased concrete (PEC) has better mechanical properties as a structure where steel and concrete work together. Due to the increasing amount of construction waste, recycled aggregate concrete (RAC) is being considered by more people. However, although RAC has more points, the performance is inferior to natural aggregate concrete (NAC). To narrow or address this gap, lightweight, high-strength and corrosion-resistant CFRP can be used, also protecting the steel flange of the PEC structure. Therefore, carbon fiber reinforced polymer (CFRP) confined partially encased recycled coarse aggregate concrete columns were studied in this paper. With respect to different slenderness ratios, recycled coarse aggregate(RCA) replacement ratios, and number of CFRP layers, the performance of the proposed CFRP restrained columns are reported. The RCA replacement ratio is analyzed to be limited negative impact on the bearing capacity, generally within 6%. As for the slenderness ratio, the bearing capacity increased with it. However, wrapping CFRP significantly increased the bearing capacity. Considering the arch factor, a simple formula for calculating the ultimate strength of CFRP-confined partially encased RAC columns is developed based on EC4 and GB50017-2017. By comparison with the experimental values, the error is within 10%.

Long-term and accelerated swelling of steel slag-glass powder and steel slag-fly ash mixtures as sustainable geo-materials

The volumetric instability of steel slag hinders its use in pavement layers and embankments. Accordingly, evaluating the swelling potential of steel slag and designing volumetrically stable steel slag mixtures is required to promote its sustainable utilization. This paper focuses on the comparison of the swelling response of basic-oxygen-furnace steel slag (BOFS), electric-arc-furnace steel slag (EAFS), BOFS-fly ash and BOFS-glass powder mixtures based on the results of three different types of tests: (i) long-term California bearing ratio (CBR) swelling, (ii) heated water bath swelling and (iii) autoclave tests. BOFS mixtures were prepared using glass powder or class F fly ash with 5%, 10%, and 20% replacement ratios. The compaction characteristics, permeability, and California bearing ratio (CBR) of steel slag and steel slag mixtures were also assessed within the framework of a detailed discussion of their swelling response. At the end of swelling tests, the measured maximum 1D strains of EAFS were all at negligible levels. Based on the test results, BOFS and BOFS-glass powder mixtures had ∼5.0–5.5% swelling strains after 20.5 months without signs of stabilization. 20% class F fly ash replacement stabilized the swelling strains of the mixture at about 0.75% after ∼3 months of monitoring in long-term tests. 1D swelling rates measured for all BOFS-class F fly ash mixtures decreased with increasing fly ash content. CBR and swelling response of BOFS-class F fly ash mixtures were more favorable compared to those of BOFS. The heated water bath tests provided higher estimates of the swelling strains compared to those obtained from autoclave tests for the steel slag mixtures that contain 15% or more fines. The results of this study showed that glass powder replacement is not effective in alleviating the swelling of BOFS. The volumetrically stable BOFS-class F fly ash mixtures indicated favorable mechanical properties for their use in pavement layers.

Effect of Composition Characteristics on Mechanical Properties of UHPMC Based on Response Surface Methodology and Acoustic Emission Monitoring.

Manufactured sand (MS) is a promising alternative aggregate to quartz sand (QS) in ultra-high-performance concrete (UHPC) in the preparation of ultra-high-performance manufactured sand concrete (UHPMC), which possesses the characteristics of high strength, low cost, and environmental friendliness. In this study, the effects of variable compositional characteristics including the water-binder ratio, the stone powder (SP) content, and the MS replacement ratio on the mechanical and flexural strength of UHPMC were compared and analyzed based on response surface methodology (RSM). Meanwhile, the damage characteristics of UHPMC during compressive and flexural stress were monitored and evaluated using acoustic emission (AE) technology. The results reveal that the compressive and flexural strengths of UHPMC are both negatively correlated with the water-binder ratio, while they are positively correlated with the MS replacement rate. They tend to firstly increase and subsequently decrease with the increase in the stone powder content. In the load-displacement curve of concrete with a high MS replacement ratio and a low water-binder ratio, the slope in the elastic stage is steeper, the stiffness is higher, and the bending toughness and ductility are also better. The specimens with a 10% to 0% stone powder content present a steeper elastic phase slope, a slightly higher stiffness, and superior ductility. The specimens with a low MS replacement ratio and a high water-binder ratio display earlier cracking and weaker resistance, and the destruction process is complex and very unstable. The damage mode analysis based on RA-AF shows that an increase in the MS replacement ratio and a decrease in the water-binder ratio can both reduce the tensile cracking of UHPMC specimens under a four-point bending test. Although 10% stone powder can marginally slow down crack growth, the failure mode is not significantly affected.

Effects of povidone-iodine wound irrigation on surgical site infection in gastroenterological surgery: A randomized controlled trial

BackgroundThe irrigation efficacy of a povidone-iodine solution to prevent surgical site infection is still controversial. We assessed the irrigation effect with a povidone-iodine solution on the incidence of surgical site infection after gastroenterological surgery. MethodsThis study is a single-center, prospective, randomized, blinded-end point superiority trial for surgical wound irrigation. Patients undergoing gastroenterological surgery were randomly assigned in a 1:1 replacement ratio using computer-generated randomization. Patients were grouped according to their surgical wound treatment into the control group using the normal sterile saline and the povidone-iodine group using 10% povidone-iodine solution after the NS solution. The main finding was 30-day surgical site infections assessed in the full analysis set. ResultsFrom November 2020 to December 2022, 697 of 894 patients were eligible for the study, among which 347 were in the povidone-iodine group and 350 in the control group. Thirty-day surgical site infections occurred in 100 (14%) patients—54 (16%) in the povidone-iodine group and 46 (13%) in the control group (odds ratio, 1.229; 95% CI, 0.800–1.889; P = .406). Superficial incisional surgical site infections occurred in 30 (9%) and 15 (4%) patients, respectively (odds ratio, 2.154; 95% CI, 1.134–4.090; P = .026). Only 3 patients (1%) in the control group developed adverse skin reactions. ConclusionThis study examined the irrigation efficacy of povidone-iodine for surgical site infection prevention compared to control in gastroenterological surgery. Povidone-iodine wound irrigation has shown no additional beneficial effect on the occurrence of surgical site infections.

Mining waste as an alternative aggregate in brick production for carbon capture and storage

Abstract Production of waste rocks and overburden from ore mining in open-pit mines can cause undesirable environmental impacts. Thus, this study aims to tackle the issue of waste production from mining areas by utilizing mining waste to sequester CO2 and to evaluate its potential for carbon capture in cementitious material. This study attempts to evaluate the effect of mine waste ratio and carbonation curing time on physico-mechanical behavior of bricks. The bricks were fabricated using different ratios of mine waste, i.e. 20 – 40 % in the mix design. Carbonation curing between 1 – 3 hours was applied during the brick fabrication to estimate CO2 capture of the brick product. The brick performances were evaluated based on the compressive strength, water absorption and carbon capture capacity. It was found that curing time at 28 days provided the greatest compressive strength of the brick and greater performance was observed at 40 % replacement with the mine waste. Carbonation curing improved the brick performance with higher compressive strength and lower water absorption at longer exposure time of 3-hour carbonation. The resulting CO2 uptake was found to increase with the increase of carbonation time and at higher ratio of mine waste replacement. The CO2 capture capacity was between 0.45 – 0.58 % for bricks containing 20 – 40 % of mine waste, which corresponds to 9.4 – 16.3 g CO2/brick. Therefore, it has been shown that the use of mining waste as partial replacement for cementitious material was capable in improving the brick performance with incorporation of carbonation curing process.

Behavior of reinforced concrete columns made with seawater and glass FRP bars and subjected to high temperatures

This study presents experimental and analytical investigations on the axial capacity of 12 heat-damaged glass fiber-reinforced polymer reinforced concrete columns. The columns were prepared with dimensions of 200 × 200 × 1000 mm and 3 replacement ratios of seawater for concrete mixing and curing (0%, 50%, and 100%). At the age of 3 months, the columns were subjected to an elevated temperature of 500 °C for 30, 60, and 90 min and subsequently cooled and tested. The experimental results demonstrated that the compressive strength of concrete increased by 35% and 45% at seawater replacement ratios of 50% and 100%, respectively. In addition, seawater-concrete mixes exhibited a lower rate of strength development compared to the reference mix. Moreover, 100% seawater concrete columns reported an increase of 28% in the cracking and ultimate loads. However, columns at seawater replacement ratios of 0%, 50%, and 100% exhibited a drop of 27%, 53%, and 50% in the cracking load after being exposed to 500 °C for 90 min. Additionally, the columns exposed to elevated temperatures showed a reduction of 5%–20% in the ultimate load. Furthermore, the analytical models of ACI 440.11–22 and CAN/CSA-S806-12 significantly underestimated the axial capacity of all columns. The most accurate prediction for the columns’ axial capacity was associated with the analytical model of Mohamed et al. with mean, standard deviation, and coefficient of variance of experimental-to-predicted ratios of 1.17, 0.12, and 9.98%, respectively.

Flexural behavior of RC beams incorporating recycled concrete aggregate and reclaimed asphalt pavement exposed to elevated temperatures

Reducing the environmental footprint of concrete is one of the most effective methods to mitigate climate change since cement production contributes to about 8 % of global CO2 emissions. This paper presents an experimental investigation into the strength and flexural performance of reinforced concrete (RC) beams incorporating natural aggregate (NA), recycled concrete aggregate (RCA), and reclaimed asphalt pavement concrete (RAP) at normal and elevated temperatures. The NA was replaced by RAP at three replacement ratios of 40 %, 60 % and 80 %. Additionally, there were four mixes of 80 % RCA-20 % RAP, 60 % RCA-40 % RAP, 40 % RCA-60 % RAP, and 20 % RCA-80 % RAP. A total of 16 beams (L: 1400 mm, W: 150 mm, H: 250 mm) and 128 cylinders (H: 200 m, D: 100 mm) were tested to evaluate the flexural capacity and material strength. Eight RC beams were tested after exposure to a temperature of 600 °C for 3 h. The compressive strength, ultimate flexural load, and mid-span deflection were measured. The results showed that temperature has an adverse effect on the s compressive strength, flexural load capacity, and deflection of RC beams. Specimens made with the RAP and RCA combination showed a significant loss in their load-carrying capacity under elevated temperature by (55 %–65 %), while the temperature effect was relatively less severe in specimens made with high RAP replacement of NA. Increasing the RAP percentage increased the reduction of flexural capacity in RCA-RAP mixes by (3 %–10 %), while in NA-RAP mixes, the effect is similar except for 60 % RAP, which has a smaller reduction compared to 40 % and 80 % RAP.

Experimental and numerical investigation of the bending, shear, and punching shear behavior of recycled aggregate concrete precast/prestressed hollow core slabs

AbstractAlthough it has been shown that using recycled concrete aggregate in new structural concrete is economical and sustainable, the use of this material for such applications is still not widespread. One of the reasons is that manufacturers, designers, engineers, owners, and other market players are not familiar with specifying and utilizing this material—although standards are starting to incorporate provisions for recycled aggregate concrete, successful, practical example projects are needed. The current paper describes the results of a partnership between universities and a precast concrete manufacturer of hollow core slabs. Seven hollow core slabs with volumetric replacement ratios of natural aggregate with recycled aggregate from 0% to 60% were tested to failure in both bending and shear, and then undamaged portions of the slabs were subjected to punching shear until failure. The results showed only mild differences in strength, with different replacement percentages of recycled aggregate under the various loading scenarios. Numerical simulations performed in Abaqus demonstrated the feasibility of analyzing recycled aggregate concrete structural elements and provided important insights into their behavior.

Use of shells for the mechanical stabilisation of sediments: a valuable geomechanical perspective?

The present study contributes to developing a novel eco-friendly solution for the mechanical stabilisation of dredged marine sediments by using mussel shells – another high-impact waste of marine origin – in the partial replacement of cements. What are the underlying chemo-mechanical interactions affecting the evolution of such mixtures? Can mussel shells replace cement without compromising useful geomechanical and geochemical properties of the stabilised sediments? Can such mixtures still be modelled as soils when it comes to their geotechnical design and analysis? The paper answers these questions by assessing the mechanical performance of mixtures formed by sediments stabilised with three types of cement and a mussel shell powder and comparing them with those of the same sediments treated with cement only. Multiple beneficial effects of the use of mussel shell powder, as a peculiar source of calcium carbonate from its biogenic origin, have been demonstrated: it acts as a void filler; enhances the electrolytic exchanges between sediment and cement, and increases the contact area between the mineral particles promoting the chemical hydration reactions. As a result, for fixed replacement ratios, the original mixtures still exhibit soil-like behaviour consistent with traditional geomechanics and even better performance than the control mixtures.

Development of bio-based lightweight and thermally insulated bricks: Efficient energy performance, thermal comfort, and CO2 emission of residential buildings in hot arid climates

This study explores the viability of using industrial wastewater sludge (IWWS), generated by the mycelium treatment of dyeing wastewater, for the fabrication of lightweight and thermally insulating bricks. The pulverized IWWS was used at various replacement ratios of 0, 5, 10, 15, and 20 wt% of clay. The mixture was subjected to firing temperatures of 700, 800, and 900 °C. The effect of applying IWWS to the brick characteristics is assessed through an examination of the physico-mechanical and thermal properties. The utilization of IWWS resulted in a significant enhancement in apparent porosity (34.4 %), cold water absorption (25.6 %), boiling water absorption (28.5 %), linear drying shrinkage (5.1 %), and linear firing shrinkage (7.9 %) using 20 % IWWS at 900 °C. Furthermore, the density, compressive strength, and thermal conductivity were reduced as the substitution IWWS ratio increased, reaching up to 1662.9 kg/m3, 11.56 MPa, and 0.198 W/m.K., respectively, using 20 wt% IWWS at 900 °C. The effect of fabricated fired bricks (FBs) on the thermal insulation, CO2 emissions, and energy consumption of residential buildings was tested. This is accomplished by using energy modeling tools, such as Honeybee, Ladybug, and Climate Studio (Grasshopper plugins), in addition to Galapagos for optimizing wall design. The suggested wall design is being used in a communal residential building located in two distinct climatic regions, namely Cairo in Egypt and Jazan in Saudi Arabia. According to the projected mean vote (PMV) and anticipated percentage of discontent (PPD) measures, the utilization of fabricated FBs as wall materials exhibits significant improvements in thermal comfort. Furthermore, they lead to a 6 % and 7 % drop in CO2 emissions in Cairo and Jazan cities, respectively, as well as a significant 38.8 % and 39 % reduction in energy consumption in Cairo and Jazan cities, respectively. Therefore, the use of fabricated FBs demonstrates itself as a feasible and environmentally friendly choice for building construction.

Utilizing Sweet Corn “Milk” Residue to Develop Fiber-Rich Pasta: Effects of Replacement Ratio and Transglutaminase Treatment on Pasta Quality

The rising demand for fiber-rich food products has fuelled the exploration of innovative approaches to enhance their dietary fiber content. Although adding dietary fiber-rich materials into pasta formula can increase the dietary fiber content, this approach counters several technological problems as the cooking and textural properties of the resulting pastas are usually negatively affected. This study is aimed at utilizing sweet corn “milk” residue (SCMR), a food by-product, and transglutaminase to develop fiber-rich pasta. Durum wheat semolina was replaced by SCMR powder at the ratio of 0 (control), 5, 10, 15, and 20% to make SCMR-fortified pasta. The chemical compositions and cooking and textural properties of the fortified pasta were then quantified. As the replacement ratio increased, the dietary fiber content, total phenolic content (TPC), and antioxidant properties of pasta were considerably improved while the cooking and textural attributes were negatively impacted. At 20% SCMR fortification, the dietary fiber content and TPC of the pasta were increased by 3.2 and 1.2 times, respectively, while the cooking loss increased by 73% as compared to those of the control pasta. Meanwhile, the chewiness, cohesiveness, tensile strength, and elongation rate at break of the 20% SCMR-fortified pasta were reduced by 19%, 26%, 21%, and 65%, respectively, compared to those of the control pasta. To improve the cooking properties and the textural properties of the fortified pasta, transglutaminase was added to the pasta dough with 20% SCMR. The effect of transglutaminase was enzyme-dose dependent. The cooking and textural qualities of pasta were improved as enzyme concentration increased 0 to 0.75 U/g protein and declined as the enzyme concentration increased from 0.75 to 1.25 g/U protein. At the optimal concentration of transglutaminase (0.75 U/g protein), the cooking loss reduced by 16% while the chewiness, cohesiveness, tensile strength, and elongation rate increased by 18%, 11%, 31%, and 32% compared to those without transglutaminase. Novelty Impact Statement. This study focuses on developing the dietary fiber-enriched pasta using sweet corn “milk” residue and transglutaminase enzyme. The results showed that replacing 20% durum wheat semolina with SCMR powder significantly enhanced the dietary fiber and total phenolic content of the pasta but negatively affect the cooking and textural properties of the pasta. Adding transglutaminase at 0.75 U/g protein to the SCMR-semolina blended dough successfully restored the adverse effects of SCMR on the cooking and textural properties. This study showed that dietary fiber-enriched pasta with improved cooking and textural properties can be prepared using the combination of SCMR and transglutaminase.

H2 promotes the premature replacement of CH4–CO2 hydrate even when the CH4 gas-phase pressure exceeds the phase equilibrium pressure of CH4 hydrate

Submarine CO2 sequestration via solid hydrate has been considered a promising strategy for controlling greenhouse gas emissions. The simultaneous replacement of CH4 from subsea natural gas hydrates through buried CO2 offers a win-win approach. Utilizing H2 as an enhancer to promote CH4–CO2 hydrate replacement, coupled with integrating the replacement products into CH4 steam reforming for cyclic H2 production, presents a potential pathway for CO2 geological storage and eventual H2 recovery. However, the enhancement mechanism of H2 in the hydrate replacement process remains unclear. Focusing on the critical replacement condition, this study investigates the effects of gas-phase partial pressures on hydrate replacement in CH4-rich systems to elucidate the H2 influence mechanism. Remarkably, the results indicate, for the first time, that H2 induces premature CH4 hydrate dissociation under conditions exceeding the corresponding CH4 gas equilibrium pressure in CO2/CH4/H2 ternary gas systems. The critical condition for hydrate replacement depends on the total system pressure, rather than CO2 gas partial pressure. Additionally, in the CH4-rich systems, the driving force for CH4 hydrate decomposition takes precedence over that for hydrate reformation in controlling replacement. The replacement ratio increases from 16.7 % to 24.5 % as the CH4 partial pressure decreases from 2.01 MPa to 1.11 MPa at 274.15 K, despite simultaneous declines in both CO2 partial pressure and total system pressure from 1.70 MPa to 0.97 MPa and from 6.10 MPa to 3.39 MPa, respectively. These findings can provide insights into the improvement of CH4–CO2/H2 hydrate replacement efficiency and the development of oceanic CO2 sequestration.

Applying Resistant Starch to Improve the Gel and Water Retention of Reduced-Fat Pork Batter.

Emulsified meat products contain high animal fat content, and excessive intake of animal fat is not good for health, so people are paying more and more attention to reduced-fat meat products. This study investigated the impact of varying proportions of pork back-fat and/or resistant starch on the proximate composition, water and fat retention, texture properties, color, and rheology characteristic of pork batter. The results found that replacing pork back-fat with resistant starch and ice water significantly decreased the total lipid and energy contents of cooked pork batter (p < 0.05) while improving emulsion stability, cooking yield, texture, and rheology properties. Additionally, when the pork back-fat replacement ratio was no more than 50%, there was a significant increase in emulsion stability, cooking yield, hardiness, springiness, cohesiveness, chewiness, and L* and G' values (p < 0.05). Furthermore, resistant starch and ice water enhanced myosin head and tail thermal stability and increased G' value at 80 °C. However, the initial relaxation times significantly decreased (p < 0.05) and the peak ratio of P21 significantly increased from 84.62% to 94.03%, suggesting reduced fluidity of water. In conclusion, it is feasible to use resistant starch and ice water as a substitute for pork back-fat in order to produce reduced-fat pork batter with favorable gel and rheology properties.

A Review on Utilization of recycled Aggregate in concrete: Examining the effects of incorporating recycled concrete aggregate or other recycled materials as substitute for natural aggregate in concrete mixtures

In developed countries, concrete is mostly observed as a valuable resource. Recycling efforts have highlighted the importance of maintaining the required compressive strength when using old concrete in new construction. Research shows that compressive strength depends on factors like adhered mortar, water absorption, abrasion resistance, aggregate size, original concrete strength, curing time, replacement ratio, transition zone between old and new concrete, moisture level, impurities, and environmental conditions. While some studies have suggested methods for adopting recycled aggregates into concrete mixes, there's a need for a simple and environmentally friendly approach that considers the percentage of adhered mortar. This project aims to review existing literature on using recycled concrete as aggregates, focusing on compressive strength, and propose a method for incorporating recycled concrete aggregate while maintaining strength. Keywords: Construction and demolished concrete, second generation concrete, Adhere, recycling, workability, recycle aggregate, compressive strength

An Experimental Study On Strength Characteristics Concrete by Partial Replacement of Coarse Aggregate with Bethamcherala Waste Stone

In the current research work, as per the best knowledge of the authors, for the first time Bethamcherla stones has been used as a partial replacement of coarse aggregate in concrete mix. The scarcity of natural aggregate as well as finding alternative materials that can maintain or enhance the properties of concrete is crucial for sustainable construction practices. Bethamcherla stones (BS), which mainly comprises by limestone can be a potential substitute for coarse aggregate. Limestone is a common material used in concrete production, and its use as an aggregate could offer advantages such as reducing the demand for traditional aggregates and utilizing local resources efficiently. The concrete specimens, casted using BS, were kept for curing for different durations (7, 21, and 28 days), and the mechanical property was assessed using the compressive strength test, a standard procedure for evaluating concrete performance. Compressive strength is a fundamental parameter that reflects the ability of concrete to withstand loads and pressures, making it an essential property to study. It would be interesting to see the results of this study, especially how the compressive strength of the concrete changes with different replacement levels of coarse aggregate with BS aggregates (10%, 20%, 30%, and 40%). This data would provide insights into the effectiveness of using BS as a substitute and help determine the optimal replacement ratio that balances cost and performance considerations. Additionally, while compressive strength is a critical mechanical property, other properties such as flexural strength, durability, and elevated temperature effect also need to be evaluated to understand how the BS aggregates influence the overall behavior of the concrete. If this experimental study proves successful, it could pave the way for more sustainable and cost-effective construction practices in the Kurnool district of Andhra Pradesh and other regions facing similar challenges with traditional aggregate availability. Remember that the success of this research will depend on the accuracy of testing methods, the representativeness of the specimens, and the relevance of the findings to real-world construction applications. Seeing such innovative efforts toward improving construction materials and practices for a more sustainable future is exciting.

Impact of neodymium oxide (Nd2O3) substitution in barium–boron-phosphate glasses: A pathway to superior mechanical, optical, and radiation shielding performance

This study delves into the impact of substituting Nd2O3 for Na2O in Barium–Boron-Phosphate glasses, aiming to enhance their mechanical strength, optical characteristics, and radiation shielding efficacy. Glasses with a composition of 50B2O3 + 20P2O5 + 20BaO + (10-x)Na2O + xNd2O3 (x = 0, 1, 2, 3, 4 mol%) were synthesized and characterized. The findings indicate that as the Nd/Na ratio increases, the density of the glass also rises within the range of 3.77–4.23 g/cm3. Moreover, the addition of Nd leads to notable alterations in the optical characteristics of the resulting glasses. Specifically, there is a shift observed in the UV absorption edges, coupled with a noticeable increase in absorption at visible wavelengths. Moreover, Nd2O3 addition reduced the Urbach energy (from 0.6018 to 0.2239 eV for Nd0-Nd4) and the optical band gap indicating improved electronic structure and decreased disorder. The mechanical properties studied using the Makishima-Mackenzie model show As the replacement ratio of Nd2O3 increases, there is a noticeable improvement in the glass's mechanical robustness. Importantly, Glasses with high Nd/Na ratio in their composition exhibit enhanced radiation shielding capabilities, evidenced by increased mass attenuation coefficients and effective removal cross-sections for photons and fast neutrons, respectively. These findings suggest that Nd2O3-doped glasses offer a promising pathway for developing superior radiation shielding materials with tailored properties for diverse applications in nuclear facilities, medical devices, and space exploration equipment.

Investigation of anionic group characteristics of PCEs on the behaviour of fly ash cementitious systems

The compatibility of polycarboxylate-based water-reducing admixtures (PCEs) having different carboxylate, phosphate and sulfonate anionic groups with paste and mortar mixtures containing fly ash (FA) was investigated. It was found that, with an increase in the FA content of the mixtures, the PCE requirement for the target flow decreased and the consistency retention performance was improved due to the decrease in the amount of hydrated cement. An improvement in rheological parameters was observed with an increase in FA content from 15% to 30%. However, increasing the FA replacement level beyond 30% caused stability problems in the mixtures. This problem was eliminated with the addition of PCE. In the paste and mortar mixtures, regardless of the FA substitution ratio, the best performance was obtained with PCEs containing 7% and 5% phosphate and sulfonate, respectively. The most suitable FA replacement ratio in terms of rheological parameters and 28-day compressive strength was 30% and 15%, respectively. It was observed that the PCE anionic group content did not have any significant effect for all FA substitution ratios.

Structural behavior of one-way slabs reinforced by a combination of GFRP and steel bars: An experimental and numerical investigation

Abstract Glass- fiber-reinforced polymer (GFRP) offers a significant alternative to steel in reinforced concrete, with superior corrosion and fire resistance. Though less ductile and more brittle in stress–strain behavior than steel, it is very helpful to combine GFRP with steel reinforcement that improves the structural behavior. This research investigates the flexural characteristics of a one-way slab reinforced by a combination of GFRP and steel reinforcement. Three identical concrete slabs ((1500 × 550 × 120) mm and 43 MPa) were tested under static load with GFRP replacement ratios of (0, 20, and 40)%. The experimental data were utilized to verify a numerical model. The experimental outcomes indicated a substantial impact of the GFRP replacement ratio on the failure mode. The failure mode was flexural, flexural-shear, and shear regarding the reference slab, 20%, and 40% replacement, respectively. GFRP replacement influenced ductility and ultimate load by (9.13 and 10.7)% and (−21 and 5.0)% for replacement ratio (20 and 40)%, respectively. Based on the numerical analysis, the parametric study (considerably affected the structural response. Failure mode changed to flexural, and shear-flexural concerning (20 and 40)%, respectively. The optimum load was characterized at 40%, while max toughness and ductility were achieved at 20%.