Strength Tests Research Articles

Impact of electron-beam and gamma-ray on the compressive strength, surface features and phase composition of β-Ni(OH)2-impregnating-geopolymer pastes

In the sol-gel method, nano-materials are obtained by the calcination of the produced hydroxide, which represents several drawbacks, such as high toxicity, high cost and high energy consumption. Therefore, for the first time, β-Ni(OH)2 was used instead of nano-NiO to develop green geopolymeric composites with high-dose radiation tolerance. The mix-design was formulated using slag and fly ash (1:1) activated with 5wt.% NaOH and modified with 0.5, 1 and 2wt.% β-Ni(OH)2. The fresh properties were investigated. It was found that increasing the β-Ni(OH)2 dose reduces workability (mini-slump test) with a slight increase in density. A compressive strength test was performed for all specimens before (cured for 28-days) and after exposure to different radiation doses (100, 200 and 300 KGy). Electron-beam and gamma-ray were used as various sources of radiation. The results demonstrated that incorporating β-Ni(OH)2 in the non-irradiated and irradiated composites enhanced their performance at all additional levels. The irradiation process by electron-beam and gamma-ray positively impacts the compressive strength at all radiation doses, especially at 200 KGy. The highest compressive strength was achieved by the specimen containing 0.5wt.% β-Ni(OH)2 (67.3MPa at 28-days, 88MPa at 200KGy/electron-beam and 76.5MPa at 200KGy/gamma-ray). The XRD, TGA/DTG and SEM analysis techniques proved that the synergistic impact of β-Ni(OH)2 (high reactivity and filling/catalytic impact) and irradiation process (activation unreacted precursors) motivate the formation of new binding phases such as NiAl2O4, CaNiSi2O6 and analcime as well as ordering zeolitic phases in cross-linked structure, causing improvement in the performance.

Study of the relationship between uniaxial compressive strength vs non-destructive testing and specific weight in bank rocks from the Seybaplaya Campeche Mexico

This research study focuses on analyzing the uniaxial compressive strength of rocks and its correlation with non-destructive testing (Schmidt hammer) and specific gravity. It is important to note that Seybaplaya, located in Campeche, Mexico, is known for its fishing, industrial, and commercial activities. Samples from one of the main active quarries in the state of Campeche were used for the investigation. As a result, equations were developed to predict the simple uniaxial compressive strength based on values obtained from the Schmidt hammer and specific gravity. It is relevant to highlight that these relationships are only valid for rocks with lithological characteristics similar to those used in this study. The results of the analysis and the conclusions demonstrate the non-linearity of the relationships between simple uniaxial compressive strength, non-destructive testing, and specific gravity.

Effect of adding natural coconut oil on the antifungal, flexural strength, and hardness properties of heat cure acrylic resin (an in vitro study)

Purpose. This study's objective was to estimate the effect of various quantities of the addition of natural coconut oil according to concentrations (1%, 2%, 3%) on the heat cured denture base material's anti-fungal, flexural strength, and hardness properties. Material and method. A total of 120 samples were created and (divided into three groups each groups contain forty samples) built regarding the attitude test: Candida albicans adherence test, flexural strength test, and hardness test. Next, each group was subdivided into three subgroups (control 0%, 1%, 2% and 3%) based on the various quantities of the added natural coconut oil, with (n=10 samples for each subgroup). Each group was assessed at 48 hours. One-way ANOVA and other statistical methods were used to analyze the data, Duncan and Dunnett’s tests for comparison means among all groups with control at p ≤0.05. Results. A One-way ANOVA showed a significant difference in the mean values of Candida albicans adherence, with the additive of natural coconut oil groups (1%, 2%) showing the highest antifungal effect compare with (3% additive groups). Adding 1% coconut oil had no significant difference on hardness and flexural strength, while adding 2% and 3% additive of coconut oil groups showed a significantly decrease than control groups at p ≤ (0.05). Conclusion. The antifungal properties of heat-cured acrylic resin are enhanced by the addition of coconut oil. However, when used in high concentrations (greater than 1%), it can result in a decrease in hardness and flexural strength.

Mechanical properties of recycled aggregate concrete containing brick particles

To investigate the mechanical properties of recycled aggregate concrete containing brick particles (RACB), compressive strength tests were conducted on RACBs with different water/cement ratios and recycled fine aggregate substitution rates. The changes in compressive strength, elastic modulus and peak strain of RACB were analysed as a function of the proportion of substituted recycled fine aggregate, and a stress–strain equation was established. A damage model was established using ultrasonic non-destructive testing technology to reveal the damage mechanism of RACB. Results show that the basic mechanical properties of RACB are best when the replacement proportion of recycled fine aggregate (r) is 30%. The model parameter a of the stress–strain curve equation is consistent with the change of elastic modulus with r. The model parameter b has a quadratic function relationship with r, reflecting the brittleness of RACB. The initial damage of RACB is relatively large, and cracks penetrate the recycled coarse aggregate, leading to specimen failure.

Acceptability, feasibility, and effectiveness of WE-SURF™: a virtual supervised group-based fall prevention exercise program among older adults

Conducted physically, supervised group-based falls prevention exercise programs have demonstrated effectiveness in reducing the risk of falls among older adults. In this study, we aimed to assess the acceptability, feasibility, and effectiveness of a virtual supervised group-based falls prevention exercise program (WE-SURF™) for community-dwelling older adults at risk of falls.MethodA preliminary study utilizing virtual discussions was conducted to assess the acceptability of the program among six older adults. Effectiveness was evaluated in a randomized controlled feasibility study design, comprising 52 participants (mean age: 66.54; SD: 5.16), divided into experimental (n = 26) and control (n = 26) groups. The experimental group engaged in a 6-month WE-SURF™ program, while the control group received standard care along with a fall’s prevention education session. Feasibility of the intervention was measured using attendance records, engagement rates from recorded videos, dropouts, attrition reasons, and adverse events.ResultsPreliminary findings suggested that WE-SURF™ was acceptable, with further refinements. The study revealed significant intervention effects on timed up and go (TUG) (η2p:0.08; p < 0.05), single leg stance (SLS) (η2p:0.10; p < 0.05), and lower limb muscle strength (η2p:0.09; p < 0.05) tests. No adverse events occurred during the program sessions, and both attendance and engagement rates were high (> 80% and 8/10, respectively) with minimal dropouts (4%). The WE-SURF™ program demonstrated effectiveness in reducing the risk of falls while enhancing muscle strength and balance.ConclusionIn conclusion, WE-SURF™ was demonstrated to be an acceptable, feasible, and effective virtual supervised group-based exercise program for fall prevention in community-dwelling older adults at risk of falls. With positive outcomes and favourable participant engagement, WE-SURF™ holds the potential for wider implementation. Further research and scaling-up efforts are recommended to explore its broader applicability.(Registration number: ACTRN 12621001620819).

Associations of upper- and lower-limb muscle strength, mass, and quality with health-related quality of life in community-dwelling older adults.

This study aimed to investigate the associations between upper- and lower-limb muscle strength, mass, and quality and health-related quality of life (HRQoL) among community-dwelling older adults. A cross-sectional study was conducted with 428 Brazilian community-dwelling older adults aged 60 to 80 years. Upper- and lower-limb muscle strength were evaluated through the handgrip strength (HGS) test and the 30-s chair stand test, respectively. Muscle mass was assessed by dual-energy X-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA). Muscle quality was evaluated using the muscle quality index (MQI). HRQoL was assessed using the World Health Organization Quality of Life Brief Version questionnaire. Lower-limb, but not upper-limb, muscle strength and quality were independently associated with HRQoL, particularly within the domains of physical capacity, environment, and overall HRQoL for both males and females (P < 0.05). DXA- and BIA-derived analyses provided similar results in relation to muscle mass and muscle quality. Lower-limb, but not upper-limb, muscle strength and quality were independently associated with HRQoL among community-dwelling older adults. Moreover, the results obtained from both BIA and DXA were similar, highlighting that BIA can serve as a viable surrogate method for estimating body composition in resource-limited clinical settings. Geriatr Gerontol Int 2024; ••: ••-••.

Effects of protein-enriched nutritional support on skeletal muscle mass and rehabilitative outcomes in brain tumor patients: a randomized controlled trial

Patients with brain tumors require extensive and prolonged rehabilitation efforts as they suffer from lesion-induced motor weakness as well as treatment-related side effects, often leading to a significant decline in function. Protein supplements have shown positive effects on promoting muscle strength and physical performance in various tumor etiologies. However, reports on their effects specifically in brain tumor patients remain scarce. This study aims to investigate the feasibility and efficacy of protein supplements in enhancing rehabilitative outcomes via muscle strengthening and functional gain in brain tumor patients with neurological demise. Sixty brain tumor patients were randomly assigned to either a protein supplement or a control group, receiving either protein supplements or a placebo for 6 weeks, in conjunction with conventional rehabilitation therapy. Assessments before and after the intervention included laboratory tests, anthropometric measures using bioimpedance analysis, and functional assessments, which included the MMSE, the modified Barthel Index, the Beck Depression Inventory, the Brief Fatigue Inventory, the Timed Up and Go test, the 6-min walk test, the isokinetic quadriceps muscle strength test, and the handgrip power. After the intervention, the levels of serum hemoglobin, protein, albumin, and C-reactive protein were improved in both groups, however, the change was significant only in the protein group. The muscle strength was enhanced in both groups, however, the significant increase in pinch grasp power was only noted in the protein group (P < 0.05). The distance on 6MWT was also significantly extended at follow-up in the protein group (P < 0.01). In the subgroup analysis according to nutritional status, the moderate malnutrition group showed greater augmentation of muscle mass than those with adequate nutrition (P < 0.05). Interestingly, the amelioration of malnutrition was observed only the in protein group. This study using protein supplements to promote the rehabilitative potential of brain tumor patients revealed a significant effect on improving hemodynamic nutritional indices, muscle power reimbursement, and functional improvement, especially in malnourished patients. The safety and feasibility of protein supplements in brain tumor patients were affirmative in this study. Further studies with more patients may help confirm the secondary functional gain resulting from increased muscle power.Trial registration: This study was retrospectively registered in the Clinical Research Information Service, CRIS no. KCT0009113 on Jan 12, 2024.

Artificial neural network evaluation of concrete performance exposed to elevated temperature with destructive–non-destructive tests

AbstractIn this study, it is aimed to predict the performance of concretes obtained by using supplementary cementitious materials (SCM) before and after high temperature using artificial neural network. Thus, in addition to contributing to sustainable development and circular economy by using waste materials in concrete production, predicting concrete strength using artificial neural network without the need for experimental studies will provide a great advantage in practice. In addition, it will also contribute to the literature in terms of determining the optimum amount of metakaolin to be used with fly ash in concrete production. Metakaolin, silica fume and fly ash were used as SCM in different proportions in concrete mixes. Accordingly, a total of 22 concrete series were prepared, one of which was the control series. Porosity, ultrasonic pulse velocity, pressure and tensile strength tests were applied to the series at the end of 7th, 28th and 90th curing periods before high temperature. In order to determine the strength losses after elevated temperature, porosity and compressive strength tests were applied at temperatures of 400, 600 and 800 °C. Mineral additive series showed positive mechanical properties up to 20%. However, it has been observed that the use of fly ash after a certain rate causes a decrease in strength. After elevated temperature, strength loss was observed in all series due to the increase in temperature, while it was observed that the rate of being affected by elevated temperature decreased as the percentage of metakaolin increased. Optimum mineral additive usage percentages were determined as 10% fly ash and 15% metakaolin. On the other hand, the use of mineral additives above the optimum level caused the performance of the concrete to decrease. Then, the concrete compression strengths obtained at 7th, 28th, and 90th days and at 400, 600 and 800 °C temperatures are taken as the outputs of the ANN. The artificial neural network provided the closest results to experimental data. Moreover, to prove the predictive performance of ANN, a comparative analysis was made with GPR, SVM and LR and the smallest value of the RMSE value is obtained with the ANN model. Finally, a fivefold cross-validation criteria was used to objectively present the performance of the model.

A Sustainable Revolution in Sisal Fiber with Enhanced Mechanical Properties of Concrete

Introduction This study provides a comprehensive comparative analysis of conventional concrete (CC) and Sisal Fiber Concrete (SFC) and incorporates sisal fiber into a concrete blend for the M25 grade concrete mix. Methods In order to evaluate the efficacy of both variations of concrete, mechanical and durability parameters were examined. As compared to CC, the results indicated that SFC had a substantially greater compressive strength. The average compressive strength of SFC at the 28-day was 29.47 N/mm2, which signified a significant incremental percentage growth of 9.58% in comparison to CC. In the same way, SFC exhibited an exceptional flexural strength, as evidenced by its mean value of 7.81 N/mm2, which represented a significant 34.42% improvement in comparison to CC. The Bayesian factor independent sample test yielded a t-test value of 12.495 for compressive strength, accompanied by a p-value below 0.001. These results suggest that the observed difference was statistically significant. Conversely, a t-test value of 19.380 and a p-value below 0.001 were produced by the Bayesian factor independent sample test for flexural strength, both of which further supported the existence of a significant difference. The mean disparity in compressive strength between CC and SFC was 5.1522 N/mm2, with a 95% confidence interval encompassing values between 4.2856 and 6.0188 N/mm2. In a similar manner, the mean discrepancy in flexural strength was 2.0000 N/mm2, accompanied by a 95% confidence interval that varied between 1.7831 and 2.2169 N/mm2. Results The obtained results provide further evidence that SFC is stronger than CC in both compressive and flexural strength, which is consistent with the results obtained from the frequentist statistical analysis. Conclusion With its eco-friendly properties, sisal fiber concrete could indeed play a significant role in the future of sustainable construction.

Variation of SARA fractions of crumb rubber modified asphalt binder-aggregate interface system and its correlation with adhesion properties

The incorporation of rubber powder leads to a high degree of complexity in the CRMA binder-aggregate interfacial properties, which directly affects the interfacial adhesion performance. The objective of this study is to investigate the variation of SARA fractions of CRMA binder during the adhesion process and to explore the intrinsic relationship between the components and the adhesion properties. To this end, the staged extraction tests were performed to extract CRMA binder layers on the aggregate surface. After each extraction, the binder layer was evaluated in terms of its SARA fraction contents and molecular weight distribution. Additionally, the pull-off tensile strength (POTS) was used to assess the adhesion of the binder-aggregate interface through the binder bond strength (BBS) test. Finally, the correlation between the SARA fractions of CRMA binder and interface adhesion of CRMA binder-aggregate system was analyzed. The results showed that the CR tends to absorb the lighter components of base asphalt, the variations in SARA fractions and molecular weight distribution during the aggregate adhesion to CRMA binders occurred mainly in the third and fourth elution layers. Pen 70 CRMA binder and limestone show the best adhesion properties among all the binder and aggregate types. The increase in CR size and the decrease in CR dosage are favorable for the adhesion of CRMA binders to aggregates. Furthermore, asphaltenes and resins are positively correlated with adhesion, while aromatics and saturants are negatively correlated with adhesion. The correlation between SARA content and adhesion varied depending on the aggregate type.

Analysis of the synergistic effects of micro silica on the mechanical and durability properties of geopolymer concrete incorporating phosphogypsum

Geopolymers are developed by activating aluminosilicates with alkali solutions, stand as inorganic cementitious materials. Their distinct advantages over Portland cement render them highly attractive in the pursuit of carbon neutrality. Moreover, the manufacturing of geopolymers results in notably lower CO2 emissions when contrasted with conventional cement production methods. The industrial byproducts fly ash (FA), phosphogypsum (PG) and micro silica (MS) contained the alumna and silica which can be used for the development of the geopolymer concrete (GPC). This study presents the various proportions of PG content, ranging from 8 % to 40 %, were utilized as a partial substitute for FA, along with MS proportions ranging from 2 % to 10 %, in the preparation of GPC. The alkaline solution was standardized at 12 M of NaOH, and the alkali-to-binder ratio was set at 0.45. The compressive strength, RCPT, sorptivity, water absorption and porosity tests have been conducted for the GPC. The maximum compressive strength of the GPC was 61.53 MPa obtained for FPM8. The compressive strength of the GPC rose with the increasing percentage of MS, peaking at 8 %. The porosity, sorptivity and water absorption were also resulted minimum for the mix FPM8. The scanning electron microscope (SEM) images show the presence of calcium alumino silicate hydrate (C-A-S-H) gel in the specimens, resulting in enhanced mechanical properties and heightened strength of the blended cement paste. The environment impact assessment analysis of the GPC also show that the developed specimens emit less carbon in comparison to the conventional concrete. Hence, the developed GPC from the FA, PG and MS can be used in the application of the sustainable construction work.

Standardization use of the international classification of functioning, disability and health in the determination of health status in patients with post-acute COVID-19 syndrome

Purpose To propose a standardized method for the use of the International Classification of Functioning, Disability and Health (ICF) to describe the health status in Post-Acute COVID-19 Syndrome (PACS) and investigate interrater agreement in the linking process in instruments and clinical exams using the ICF categories. Materials and Methods Cross-sectional and interrater agreement study that followed the Guidelines for Reporting Reliability and Agreement Studies. Two raters performed the linking coding process in instruments of quality of life, anxiety and depression, fatigue and pulmonary function, inspiratory muscle strength and cardiopulmonary exercise testing. The codes were qualified by standards defined to each instrument and exams. Results The instrument with the lowest Cohen’s Kappa coefficient was anxiety and depression (k = 0.57). Forty ICF codes were linked to clinical instruments and exams. The fatigue instrument presented a higher degree of disability by the qualification process, from severe to complete, in the linked codes. Conclusion The study presents a standardized method for the assessment of the health status of patients with PACS through ICF. Restriction in work performance, socialization and family relationships as well as disabilities in physical endurance, fatigue and exercise tolerance were found in the sample. The agreement between the raters was moderate to perfect, demonstrating that the method can be reproducible.

The Effect of Using Jute on the Compressive Strength of Concrete

Background Concrete comprises cement, fine aggregates, coarse aggregates, and water, making it the most widespread construction material globally. However, while producing cement as an important component of concrete, it generates significant CO2 emissions, worsening global warming and environmental challenges worldwide. Objective This study aims to investigate the impact of incorporating jute fiber into concrete mixes of varying proportions to enhance compressive strength. Methods Concrete mixes of three grades were prepared, with varying percentages of jute (0.5%, 1.0%, 1.5%, and 2%) by weight of cement. Compressive strength tests were conducted at 7 and 28 days of curing. Results It shows notable enhancements in strength, improvement of 15.07 % (for Nominal mix 1:1:2) and 20.29% (for Nominal mix 1:1.5:3 ) is at the addtion of 1% jute but 6.72% (for Nominal mix 1:2:4) is at addtion of 2% jute mix. Conclusion Findings suggest that adding jute fiber, particularly with higher cement content, significantly enhances concrete strength, emphasizing its potential as a reinforcing material for sustainable construction.

Assessment of physical fitness among people over 60 years of age

Introduction: An ageing of population is becoming more and more common. With age, the functionality and efficiency of the body decreases. As a result, the time spent by seniors on physical activity is shortened and physical fitness decreases. For this reason, the physical fitness of seniors should be regularly checked and they should be encouraged to take up physical activity. There are many proven and reliable tests used to assess physical fitness. Materials and methods: The study group consisted of 40 people (31 women and 9 men), aged 60-78 years. The tests used in following study were: the SPPB questionnaire, handgrip strength test, and arm and calf circumference measurements. An attempt was made to find sociodemographic factors that could influence the level of physical fitness. It was checked whether physical fitness and physical activity depend on age, gender and BMI. It was checked how much time older people spend on physical activity during the day and week. The study confirmed that physical fitness decreases with age. Results: Tests and interviews have shown that people who spend more than 60 minutes a day on physical activity achieve higher scores on the SPPB questionnaire. These results were applicable to both women and men. Studies in a larger and more diverse population would need to be repeated in order to further confirm these results and draw more conclusions.

Engineering properties of pozzolanic cement-stabilised organic soil

In this study, the engineering properties of organic soil (OS) stabilised with pozzolanic cement (PC) were investigated. In tests, 10%, 15% and 20% proportions of PC were added to organic soil. Consistency limits, Proctor, unconfined compressive strength (UCS), triaxial (UU), swelling and compressibility tests were performed for OS stabilised with PC. The addition of PC to OS increased the minimum dry density (MDD) and optimum moisture content (OMC) values. The UCS values for OS stabilised with PC increased up to the 56 th day and then there was a reduction in unconfined compressive strength after the 56 th day. The internal friction angle value increased by 26% and the cohesion intercept value increased by 86% for OS stabilised with PC. With the increase in cement content in OS stabilised with PC, the UCS, internal friction angle and cohesion intercept values increased. Swelling of OS stabilised with PC rapidly reduced up to the 10th day and this reduction slowed after the 10th day. The compressibility of OS stabilised with PC increased until the 10 th day and this increase slowed after the 10th day. With the increase in cement content in OS stabilised with PC, swelling and compressibility values reduced. As a result of the study, it appears that pozzolanic cement is an effective stabiliser for organic soil.

Effect of Simultaneous Application of Glass Fiber Reinforcement and Polymer-Modified Asphalt Emulsion on DBST’s Resistance to Aggregate Loss Using Laboratory Investigation

Double bituminous surface treatment (DBST) has been a widely utilized pavement maintenance material due to its capability to restore the surface roughness of existing pavement and provide a layer of protection against weathering, aging, and moisture. However, DBST is highly prone to aggregate loss at an early stage, which is a very common problem experienced by surface treatment. Therefore, to lessen the aggregate loss and prolong the service life of DBST, fiber additive can be incorporated to strengthen the adhesion between the asphalt emulsion and aggregates. This study investigated the performance of glass fiber-reinforced polymer-modified DBST against aggregate loss by conducting laboratory tests using typical DBST as the benchmark of the test results. Four laboratory tests were chosen to represent different loading applications on the surface of the pavement: the bitumen bond strength (BBS) test, the sweep test, the Hamburg wheel-track test (HWT test), and a one-third-scale model mobile load simulator (MMLS3) model. Furthermore, the curing time of the asphalt emulsion was considered in the BBS test and sweep test. Based on all results from the conducted laboratory tests, polymer-modified DBST with glass fiber reinforcement presented an increased resistance to aggregate loss compared with typical DBST. Moreover, it was found that a longer curing time of the asphalt emulsion, whether it was typical or modified, strengthened the surface treatment’s resistance to aggregate loss.

Freeze-Dried β-Glucan and Poly-γ-glutamic Acid: An Efficient Stabilizer to Strengthen Subgrades of Low Compressible Fine-Grained Soils with Varying Curing Periods.

The freeze-drying of biopolymers presents a fresh option with greater potential for application in soil subgrade stabilization. A freeze-dried combination of β-glucan (BG) and γ-poly-glutamic acid (GPA) biopolymers was used to treat low compressible clay (CL) and low compressible silt (ML) soils in dosages of 0.5%, 1%, 1.5%, and 2%. The California bearing ratio (CBR) test for the treated specimens was performed under three curing conditions: (i) thermal curing at 60 °C, (ii) air-curing for seven days followed by submergence for 4 days, and (iii) no curing, i.e., tested immediately after mixing. To investigate the influence of shear strength on the freeze-dried biopolymer-stabilized soil specimens and their variations with aging, unconfined compressive strength (UCS) tests were conducted after thermal curing at 60 °C for 3 days, 7 days, and 7 days of thermal curing followed by 21 days of air curing. The maximum CBR of 125.3% was observed for thermally cured CL and a minimum CBR of 6.1% was observed under soaked curing conditions for ML soils. Scanning electron microscopy (SEM), infrared spectroscopy, average particle size, permeability, and adsorption tests revealed the pore filling, biopolymer adsorption and coating on the soil surface, and agglomeration of the soil along with the presence of hydrogen bonds, covalent amide bonds, and Van der Waals forces that contributed to the stiffening of the stabilized soil. Using three-dimensional (3D) finite element analysis (FEA) and layered elastic analysis (LEA), a mechanistic-empirical pavement design was carried out for the stabilized soil and a design thickness catalog was prepared for the maximum CBR. The cost reductions for a 1 km section of the pavement were expected to be 12.5%.

Effect of glass fibre on the strength and durability of artificially cemented alluvial clay

ABSTRACT Using cement with fibers is a cost-effective way to improve soft clays’ engineering properties. This study investigates the strength, stiffness, and durability of artificially cemented alluvial clay stabilized with glass fiber. Unconfined compressive strength and shear wave velocity tests were used, along with microstructural analysis via scanning electron microscopy and energy-dispersive spectroscopy. Durability and resistance to harsh weather were evaluated using wet-dry cycles. The combination of cement and glass fiber improved the mechanical response, with 0.4% glass fiber being the most effective. A blend of 0.4% glass fiber with 13% cement showed the highest strength and stiffness improvement and reduced mass loss. This mixture, supported by unique power functions forecasting its properties, is suitable for various civil engineering projects, such as unbounded sub-layers, highway barriers, stone columns, and ground improvement.

Mechanical strength and low-velocity impact behavior of glass fiber reinforced filament wound pipes with different number of layers after hydrothermal aging

Composite pipe is preferred over metal and other materials for water supply, liquid chemical transport, and fuel and gas transport. This is because composite pipes are more corrosion resistant, have a high strength/density ratio, high stiffness/density ratio, and more durable than metal pipes. The properties of the composite pipes employed may differ based on the operating environment. Therefore, determining the properties of the composite pipe according to the working environment is extremely important for its lifespan. The thickness of the samples is increased in line with different needs (such as increased strength). Increasing the thickness of samples, especially those exposed to different environmental conditions, and investigating the changes that will occur in the physical and mechanical properties of the samples are another important situation. In this investigation, glass fiber (GFRP) reinforced epoxy composite pipes have been examined, which were manufactured using the filament winding method with different layers [±55°]. To determine their properties in different working environments, the GFRP composite pipes were subjected to hydrothermal aging in pure water at 80°C for several days (7, 14, 21, and 28). The changes in their mechanical properties under working conditions were determined through hoop tensile strength tests and low velocity impact tests applied at different energy levels. The experimental results show that the tangential stress values increased by 10.59% as the number of layers increased. As the aging time increased, the durability of the 6-layer composite pipe decreased by 17.69%. Furthermore, the ability of the aged pipes to withstand damage was evaluated, revealing that the aging process exacerbated the damage within the pipes.

Properties of Biocomposites Made of Extruded Apple Pomace and Potato Starch: Mechanical and Physicochemical Properties.

This paper presents research results on biocomposites made from a combination of extruded apple pomace (EAP) and potato starch (SP). The aim of this work was to investigate the basic properties of biocomposites obtained from extruded apple pomace reinforced with potato starch. The products were manufactured by hot pressing using a hydraulic press with a mould for producing samples. The prepared biocomposites were subjected to strength tests, surface wettability was determined, and a colour analysis was carried out. A thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and cross-sectioning observed in a scanning electron microscope (SEM) were also performed. The obtained test results showed that the combination of apple pomace (EAP) and starch (SP) enabled the production of compact biocomposite materials. At the same time, it was found that each increase in the share of starch in the mixture for producing biocomposites increased the strength parameters of the obtained materials. With the highest share of starch in the mixture, 40%, and a raw material moisture content of 14%, the material had the best strength parameters and was even characterised by hydrophobic properties. It was also found that materials with a high content of starch are characterised by increased temperature resistance. The analysis of SEM microscopic photos showed well-glued particles of apple pomace, pectin, and gelatinised starch and a smooth external structure of the samples. Research and analyses have shown that apple pomace reinforced only with the addition of starch can be a promising raw material for the production of simple, biodegradable biocomposite materials.