Strength Tests Research Articles

The effect of leachates on the physical and engineering properties of subsoil varies across different rock types and depth layers

Waste disposal on land is a major environmental issue that affects groundwater through soil. The aim of this study is to evaluate and compare the physical and engineering properties of subsoil at varying depths from different dumpsites and to determine the effects of leachates and parent rock types on these soil properties. Thirty-six subsoil samples were obtained from twelve trial pit profiles at depths of 0.5 m, 1.0 m and 1.5 m respectively. These soil samples were subjected to both geotechnical index and strength tests. Grain size analysis, linear shrinkage, CBR and compaction tests revealed that many of the soil samples from dumpsites and their environs met the criteria of a good landfill material. All the soil samples have low permeability that ranges from 2.07 × 10–6 to 1.49 × 10–4. Liquid limit, plasticity index and MDD values were higher in the control samples while the dumpsite soils became more permeable. The results of grain size analysis, linear shrinkage and CBR revealed that there was no significant difference in the properties of dumpsite and control soils. All the soil samples have TDS and EC values below 1000 ppm and 1000 µS/cm, except for trial pit 1, suggesting that the soil has a low risk of leaching contaminants into groundwater. For analysis of variance and Pearson’s correlation coefficient, the P values of some parameters such as pH, EC, TDS, CBR, OMC, MDD, SG, LS, PI and LL were significant at a 0.05 level of significance. The following pairwise parameters: pH-MDD, TDS-CBR, EC-CBR, OMC-MDD and TDS-EC recorded strong positive correlation values for the three dumpsites. The statistical analyses reveal that the soil's properties were only slightly influenced by parent rock types and can be used to limit contaminant flow into the groundwater in the short term.

Effect of Vinyl Acetate, Glass Fibers Contents, and Buffer Space on EVA's Mechanical Property and Shock Absorption Ability.

The aim of the study was to evaluate the mechanical properties and impact absorption capacity of prototype materials comprising ethylene vinyl acetate (EVA) of different hardness reinforced using different amounts of glass fibers (GFs), considering a buffer space. Six prototype materials were made by adding E-GFs (5 and 10 wt%) to EVA with vinyl acetate (VA) contents of 9.4 wt% ("hard" or HA) and 27.5 wt% ("soft" or SO). Durometer hardness and tensile strength tests were performed to evaluate the mechanical properties of the materials. Moreover, an impact test was conducted using a customized pendulum impact tester to assess the impact absorption capacity (with or without a buffer space) of the specimens. The mechanical properties of the prototypes, namely, durometer hardness, Young's modulus, and tensile strength, were significantly higher in the HA group than in the SO group, regardless of the presence or added amount of GFs. The addition of GFs, particularly in a large amount (10 wt%), significantly increased these values. In terms of the impact absorption capacity, the original hardness of the EVA material, that is, its VA content, had a more substantial effect than the presence or absence of GFs and the added amount of GFs. Interestingly, the HA specimens with the buffer space exhibited significantly higher impact absorption capacities than the SO specimens. Meanwhile, the SO specimens without the buffer space exhibited significantly higher impact absorption capacities than the HA specimens. Moreover, regardless of the sample material and impact distance, the buffer space significantly improved impact absorption. In particular, with the buffer space, the impact absorption capacity increased with the added amount of GFs. The basic mechanical properties, including durometer hardness, Young's modulus, and tensile strength, of the EVA prototype were significantly increased by reducing the amount of VA regardless of the presence or added amount of GFs. Adding GFs, particularly in large amounts, significantly increased the values of aforementioned mechanical properties. Impact absorption was significantly affected by the hardness of the original EVA material and enhanced by the addition of the buffer space. The HA specimen had a high shock absorption capacity with the buffer space, and the SO specimen had a high shock absorption capacity without the buffer space. With the buffer space, impact absorption improved with the amount of added GFs.

Experimental study on the punching failure model of soft red rock subgrade by BPT-BVM methods and it’s assessment of the load bearing capacity

The recommended bearing capacity of medium weathering mudstone foundation is less than the capacity of the rock structure to withstand loads in Southwest China. A comprehensive failure characterization of medium weathering mudstone in Chengdu has been performed including bearing plate test (BPT), binocular vision measurement (BVM) test, uniaxial compressive strength test, trial trench test of shallow rock surface and 3D imaging in this paper. Failure behavior of rock has been modeled with 3D imaging algorithm that utilizes Zhang’s calibration method in BVM system combination with trial trench test of shallow rock surface. The bearing capacity of medium weathering mudstone foundation were extracted from uniaxial experiments and BPT-BVM test by fitting relevant material properties to the data. The results revealed that: Bearing capacity of medium weathering mudstone of layered isotropic in Chengdu is undervalued. Specifically, the characteristic load carrying value is in the range 1500–2500 kP, that is 50% higher than in the local standard system. Failure process is different from Hoek–Brown Failure Criterion, presenting a wave peak transfer phenomenon of the increment displacement into the distance. Thus, it can be reduced to that of punching failures for thin bedded structures of Moudstone foundations. Compressive strength of soft rock proves to be main factor limiting the bearing capacity, a clear correlation between the uniaxial compressive strength reduction coefficient and the bearing capacity has been used to establish, leading to the proposal of a load bearing capacity prediction model.

Italian Canyoning Guides: Physiological Profile and Cardiometabolic Demand during Rope Activities

Canyoning activities require physical effort, highlighting the importance of maintaining a proper physical fitness. Canyoning guides emerge as key figures, not only to ensure safety during the experience but also to handle unforeseen situations promptly. This study aims to assess the physiological profile of canyoning guides and the cardiorespiratory demands experienced during rope activities by means of oxygen uptake and heart rate measurements. Seventeen canyoning guides (42.6 y ± 10.78; BMI of 24.0 kg/m2 ± 2.95) carried out coordinative and conditional tests. The participants showed good values in strength tests (27.3 cm ± 5.97 and 23.3 rep ± 8.06 in SJ and PUp tests, respectively), while the flexibility of males and females was below and well above the average, respectively. A noteworthy result was observed in the reaction test, in which a better performance was recorded with the non-dominant hand (168.1 ms vs. 202.0 ms). All subjects exhibited a low aerobic capacity by means of an RD test (10.6 ua ± 6.62). During rope activities and emergency/support simulations, metabolic and cardiovascular data indicated that a moderate/high effort was exerted, confirmed by an oxidative stress analysis. In conclusion, this study demonstrated how canyoning guides face significant physical requirements, but their physiological profile regarding aerobic power was not appropriate. Therefore, these findings could offer valuable insights into the development of specific training to ensure an appropriate aerobic fitness to perform canyoning safely.

Comparison of perlite and pumice effects on the geotechnical properties of saline silty soil

ABSTRACT This research mainly sought to evaluate the sediments of the Urmia lake bed to prevent their erosion and the possibility of improving the problematic saline fine soils in the region by the geo-polymerisation process. For this purpose, perlite and pumice materials, with pozzolanic properties and weight percentages of 3, 5, and 7, were separately mixed with soil, along with the calcium hydroxide (Ca(OH)2) solution as a catalyst with 2%, 5%, and 7%. Then, the samples were cured for one day. Uniaxial compressive strength (UCS), direct shear, and consolidation tests were performed to assess the geotechnical properties of improved soil compaction. The results revealed that, compared to pumice, perlite could improve the behavioural properties of the studied soil. The inclusion of perlite and pumice, along with calcium hydroxide, increased the flexibility of the stabilised soil, as indicated by the brittleness index. Similarly, combining 3% perlite with 2% Ca(OH)2 could increase UCS at failure by 3.27 times. In addition, the mixture of 5% perlite with 7% Ca(OH)2 could enhance the shear strength by 3.3 times. Finally, combining 3% perlite with 5% calcium hydroxide reduced the swelling of the improved soil by 82%, and the consolidation settlement was decreased by 64% on average.

Effects of Geological and Geotechnical Characteristics on Cut-Slope Stability of Residual Formations in the Hilly Terrain of Sri Lanka A Case Study from Central Expressway (Section 3)

Residual formations consist of residual soils and parent rocks of different levels of weathering due to physical, chemical and biological processes. Existence of residual soils on the hilly slope surface and weathering of parent rocks of the residual formations can cause slope instability problems. Cutting on the hilly slopes during development projects have aggravated the problems. Sri Lankan residual soil formations are formed by weathering of the metamorphic rock and have inherited significant abrupt variations in engineering characteristics. Basic characteristics of these residual formations such as unsaturated shear strength (geotechnical) and variation of geological features (geological) are essential parameters in slope stability analyses. Therefore, a study for effects of geological and geotechnical characteristics on cut slope stability of residual formation was done by selecting major cutting sections on hilly terrain in Central Expressway Project (CEP 03) trace where degree of weathering of the parent rock units, their petrography, physical, mechanical properties and various structural features as well as series of index properties, engineering properties and strength tests on residual soils were performed.This paper highlights the need for detailed experimental studies and presents preliminary studies that have been conducted to establish the geological and geotechnical characteristics of unsaturated Sri Lankan residual formation. The results indicate that the variation in geotechnical as well as geological characteristics of the residual formation are related to cut slope stability in hilly terrain.

Evaluation of long-term properties and life cycle assessment of alkali-activated concrete with varying fiber inclusions

The potential for using alkali-activated concrete (AAC) as a sustainable substitute for Portland cement (PC) concrete is a topic of ongoing research interest. The uncertainties in the raw material composition, the reportedly low tensile strength of AAC, and the lack of relevant standard codes of practice further inhibit wider industrial usage of AACs. Fiber inclusions reportedly enhance the tensile properties of traditional PC concrete. However, there is no long-term data available for fiber-reinforced alkali-activated concrete (FRAAC) mixtures. Hence, the present study is aimed at investigating the long-term mechanical properties of ambient-cured FRAAC with GGBS as the sole precursor. Four different types of fibers, viz., steel (SF), polyvinyl alcohol (PVAF), polypropylene (PPF) and glass (GF) are used in this research as reinforcements in AAC. Tests for compressive strength (fc′), splitting tensile strength (fsp) and flexural strength (fr) are conducted for FRAAC containing varying fiber contents of 0.1–0.3%. The findings demonstrated that fiber additions do not have any noticeable influence on the compressive strength of AAC. However, relative to the plain mix, the fsp and fr of FRAACs were enhanced by up to 32% and 29%, respectively. The formation of the hardened calcium aluminosilicate matrix and evolution of the fiber-matrix bonding over time was evident from the scanning electron microscopy (SEM) images. The related molecular bonds over a period of 7-d to 360-d was identified through mineralogical and chemical analyses. Furthermore, to validate its environmental sustainability, life cycle assessments were conducted. The AACs exhibited at least 43% lesser impacts than PC concrete on the ecosystem. FRAACs had only slightly higher (≤ 7% increase across all fiber types) impacts than plain AAC.

Mechanical characteristics of structural concrete using building rubbles as recycled coarse aggregate

Abstract The aim of this research is to investigate whether construction rubbles may be utilized as coarse aggregates in concrete. Experimentally, the slump, unit weight, compressive, tensile, and flexural strength tests were applied on concrete samples with varying percentages of recycled coarse aggregate (RCA) and compared with reference concrete produced with natural coarse aggregate. This research conducted 96 concrete samples with RCA replacement percentages of 0, 35, 65, and 100%, respectively. The control mixture produced with natural aggregate showed better results than the mixtures containing recycled aggregate; thus, compressive, tensile, and flexural strengths reduced as the amount of the recycled aggregate increased. Using 100% RCA, the compressive, tensile, and flexural strength reduction reached up to 64, 29, and 38%, respectively.

Experimental study on long-term impermeability of recycled aggregate concrete mixed with crystalline admixture and waste glass powder

The impermeability of recycled aggregate concrete (RAC) presents challenges for underground engineering, particularly concerning its larger pore. Combining crystalline admixture (CA) with waste glass powder (WGP) offers a feasible solution to enhance impermeability. To understand the collaborative mechanism of CA and WGP in improving RAC impermeability and establish an accurate mixture ratio, we conducted compressive strength tests and a series of permeability tests on WGP and CA modified recycled aggregate concrete (WRC). These tests involved different CA contents (0%, 1%, and 2%) and varying WGP replacement rates (0%, 10%, 20%, and 30%). Our findings indicated that when the WGP substitution rate exceeds 10%, the strength of the WRC decreases by approximately 23%. In contrast, the overall decline is about 5% when the CA content increases from 0% to 2%. Therefore, the WGP emerges as the primary factor influencing the compressive strength of WRC. Meanwhile, The WGP and CA play a major role in enhancing the short-term and long-term impermeability of WRC, respectively. Additionally, When the WGP substitution rate increases from 0% to 30% on same CA content, the RC increases by approximately 2%, indicating that elevated WGP content enhances the effectiveness of CA. Finally, the optimal combination to improve the impermeability of WRC is 10% WGP substitution and 1% CA content. Microscopic tests analyses show that under the influence of CA and WGP, C–S–H gel, C-A-S-H gel, and Ettringite are produced inside the WRC, effectively blocking pores and cracks, thus improving the specimen's impermeability. This research not only holds the potential to elevate impermeability but also offers a solution to the issue of waste glass accumulation, contributing to global sustainable development.

Comparison of digital nerve repair techniques: a systematic review

Introduction: Digital nerves are the most injured upper limb peripheral nerves [1]. There are numerous different methods of repair, with no standardised treatment options or guidelines. This systematic review aims to evaluate literature that investigated thebiomechanical strength of digital nerve repairs through varying methods in cadaveric models.Aims/Hypothesis: The aim of the study is to evaluate the literature available for digital nerve repairs and directly compare which surgical method yields the best results. The primary outcome is maximum load to failure of the repaired digital nerve following biomechanical (tensile) strength testing. We postulate that out of all the repair methods, augmentation of repair with fibrin glue or additional conduit will increase the load to failure compared to suture only repair.Methodology: We utilised the PRISMA methodology to conduct the systematic review. The following databases were searched: Embase, Medline, Cochrane, and Web of Science. Studies were reviewed and screened by two researchers following an inclusion and exclusion strategy to retrieve relevant papers.Results: A total of seven papers were included in the final review; these papers reported biomechanical data on cadaveric digital nerve repairs. Due to heterogenicity of methods between papers, a combination of quantitative and qualitative analysis of the results was made.Conclusion: The use of minimal suturing with conduit or glue or both has the ability to increase the maximum load to failure of digital nerve repairs compared to suture only methods. This has additional benefits to decrease the number of sutures required for repair. This thereby reduces potential scarring and inflammation.

Mix Design and Field Detection of Large-Particle-Size Graded Crushed Stone Mixtures for Pavement Reconstruction

Large-particle-size graded crushed stone mixtures (LPS-GCSMs) can improve the shortcomings of conventional graded crushed stone, such as low strength, high deformation, and a low modulus of resilience. At present, there is no systematic research on the gradation design and field evaluation of the LPS-GCSMs. In this study, compaction and California bearing ratio (CBR) tests and field construction conditions were combined to design six kinds of gradation of LPS-GCSM, and the optimum gradation was revealed. In order to improve the mechanical properties of LPS-GCSM, 2.5% cement was added to the mixture to prepare a low-content cement-modified LPS-GCSM (LCC-LPS-GCSM) based on the suggested gradation. The mechanical properties of the LCC-LPS-GCSM were investigated through unconfined compression strength (UCS) and compression rebound modulus (CRM) tests. Moreover, the compaction and deflection properties of LPS-GCSM and LCC-LPS-GCSM were examined through the test battery. The results showed that the optimum gradation of LPS-GCSM can be achieved with a combination of aggregate sizes of 20–40 mm, 10–20 mm, 5–10 mm, and 0–5 mm at a ratio of 44:20:10:26. The passing rates of 19 mm and 4.75 mm should be approximately at the median value of the gradation in view of field construction uniformity and a coarse aggregate interlocking effect. The UCS and CRM values of LCC-LPS-GCSM increased rapidly from 0 day to 28 days while they slowed after 28 days, which was similar to those of cement-stabilized materials. The field detection suggested that LPS-GCSM exhibited favorable compaction and that the addition of cement improved the stability of the field compaction of the mixture. Adding a subbase course of LPS-GCSM between the old pavement and the LCC-LPS-GCSM base can lead to more uniform stress on the base. The results of this study provide a reference for the gradation design of LPS-GCSM and optimization of the design indicators.

Measurement of true tensile strength from Brazilian tensile strength laboratory tests

Brazilian tensile strength (BTS) testing in standard practice is a practical method to approximate tensile strength for rock core using the conversion of axial compressive vertical and diametral loading to horizontal tensile stress in the centre of the core disk. The method, however, routinely inflates tensile strength, using peak tensile stress calculated from the BTS, versus true tensile stress (TTS) from direct tensile strength (DTS) tests. This study presents a novel technique to measure TTS directly from the BTS test via the onset of nonlinearity in horizontal strain response. TTS is equivalent to the peak strength of a DTS test. While not yet standardized, the modification to achieve TTS measurements is to instrument the BTS specimen with a horizontal strain gauge on each flat side. Over 100 BTS specimens of varying lithologies were instrumented, tested, and analyzed to measure their TTS and compare to peak BTS. Results demonstrate the average measured TTS is 0.81BTS, 0.75BTS, 0.85BTS for granitoid, carbonate, and metamorphic rocks, respectively. This concurs with previous studies, validating the proposed novel TTS measurement method. We recommend measurement of TTS be adopted into standard practice for BTS laboratory testing to improve accuracy of tensile strength data in rock engineering design.

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 with recycled fine aggregate substitution rates were analyzed, and a stress–strain equation was established. A damage model was established using ultrasonic nondestructive testing technology to reveal the damage mechanism of RACB. Results show that the basic mechanical properties of RACB reach the best when the replacement rate of recycled fine aggregate (r) is 30%. The model parameter a of the stress–strain curve equation is consistent with the change rule 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 the cracks penetrate the recycled coarse aggregate, and lead to specimen failure.

Evaluating flexure properties, hardness, roughness and microleakage of high-strength injectable dental composite: an in vitro study

BackgroundRecently, a new generation of high-strength flowable dental composites has been introduced by manufacturers. The manufacturers claim that these materials have enhanced mechanical and physical properties and are suitable for use in a wide range of direct anterior and posterior restorations, even in high-stress bearing areas.AimThe objective of this study was to assess certain physical and mechanical properties of these recently introduced high-strength flowable composites in comparison to conventional multipurpose dental composites.MethodsFour types of high-strength flowable composites (Genial Universal FLO, Gaenial Universal Injectable, Beautifil Injectable, and Beautifil Flow Plus) were tested in experimental groups, while a nanohybrid conventional composite (Filtek Z350 XT) was used as the control. For flexure properties, ten rectangular samples (2 × 2 × 25 mm) were prepared from each composite material and subjected to 5000 cycles of thermocycling. Samples were then subjected to flexural strength testing using the universal testing machine. Another twenty disc-shaped specimens of dimensions (5 mm diameter × 2 mm thickness) were fabricated from each composite material for surface roughness (Ra) (n = 10) and hardness (VHN) test (n = 10). All samples underwent 5000 cycles of thermocycling before testing. Additionally, microleakage testing was conducted on 60 standardized class V cavities prepared on molar teeth and divided randomly into five groups (n = 12). Cavities were then filled with composite according to the manufacturer’s instructions and subjected to thermocycling for 1000 cycles before testing using methylene blue solution and a stereomicroscope.ResultsAll tested materials were comparable to the control group in terms of flexural strength and surface roughness (p > 0.05), with Gaenial Universal FLO exhibiting significantly higher flexural strength compared to the other flowable composite materials tested. However, all tested materials demonstrated significantly lower elastic modulus and surface hardness than the control group (p < 0.05). The control group exhibited higher microleakage scores, while the lowest scores were observed in the Gaenial Universal FLO material (p < 0.05)ConclusionThe physical and mechanical behaviors of the different high-strength flowable composites investigated in this study varied. Some of these materials may serve as suitable alternatives to conventional composites in specific applications, emphasizing the importance of dentists being familiar with material properties before making material selections.

Martian Regolith Simulant-Based Geopolymers with Lithium Hydroxide Alkaline Activator

As humanity envisions the possibility of inhabiting Mars in the future, the imperative for survival in the face of its challenging conditions necessitates the construction of protective shelters to mitigate the effects of radiation exposure and the absence of atmospheric pressure. The feasibility of producing geopolymers using the Martian regolith simulant MGS-1 (as precursor) for potential building and infrastructure projects on Mars in the future is investigated in this paper. Various alkaline activators, such as sodium hydroxide (NaOH), lithium hydroxide (LiOH·H2O) and sodium silicate (Na2SiO3), are employed to investigate their efficiency in activating the precursor. The influence of alkali type and concentration on the mechanical performance of the synthesized geopolymers is examined. Geopolymer samples are oven-cured for 7 days at 70 °C before a compressive strength test. It is found that through the hybrid use of LiOH·H2O and NaOH with optimal concentrations, metakaolin and milled MGS-1 as precursors, geopolymer mixtures with a compressive strength of 30 ± 2 MPa can be developed. The present test results preliminarily demonstrate the potential of Martian regolith simulant-based geopolymers as suitable construction and building materials for use on Mars.

Prevalence and associated factors of locomotive syndrome in young Japanese adults: a cross-sectional study

BackgroundThe onset of locomotive syndrome (LS) precedes that of frailty. Therefore, the first step in extending healthy life expectancy is to implement measures against LS in young adults. The aim of this study was to investigate the prevalence of LS and its associated factors in young adults for early detection and prevention of LS.MethodsThe participants of this study comprised 413 university students specializing in health sciences (192 males and 221 females) with an average age of 19.1 ± 1.2 years. All participants voluntarily participated in the study and reported no serious health problems. The presence or absence of LS was evaluated using the stand-up test, two-step test, and the 25-question Geriatric Locomotive Function Scale. Additionally, musculoskeletal assessment (one-leg standing, squatting, shoulder elevation, and standing forward bend), body composition analysis (weight, body mass index, body fat mass, body fat percentage, skeletal muscle mass index (SMI), and phase angle), handgrip strength test, physical activity assessment, and nutritional assessment were conducted. Sex-stratified analyses were performed, comparing groups with and without LS. Factors associated with LS were explored using binomial logistic regression.ResultsOf the 413 young adults studied, 86 individuals (20.8%) were found to have LS. When stratified by sex, LS was observed to have a considerably higher prevalence in females (55, 24.9%) than in males (31, 16.1%). In males, the notable differences between the groups with and without LS were observed in one-leg standing and phase angle, whereas in females, differences were identified in body fat mass, body fat percentage, SMI, musculoskeletal pain, and handgrip strength. Two types of binomial logistic regression analysis revealed that the inability to perform one-leg standing was associated with LS in males, while the presence of musculoskeletal pain and a high body fat percentage were identified as factors associated with LS in females.ConclusionsOne in five young adults were found to have LS in this study, underscoring the necessity for early intervention and LS health education. Furthermore, effective management of musculoskeletal pain is also crucial.

Investigating the role of steel and polypropylene fibers for enhancing mechanical properties and microstructural performance in mitigating conversion effects in calcium aluminate cement

Fiber reinforcement is widely employed in numerous industries due to its exceptional mechanical properties; however, its specific role in enhancing the strength of calcium aluminate cement (CAC) composites remains inadequately understood. This study investigates the influence of fiber addition on the mechanical characteristics of CAC composites during curing. Two types of fibers, steel and polypropylene, were incorporated into CAC composites, and their mechanical properties, chemical composition, and microstructural performance were evaluated using various methods. Assessments including flowability, bulk density, volume of permeable voids, water absorption, and mechanical strength tests were conducted, alongside X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), and Field Emission Scanning Electron Microscopy (FESEM) analysis. Results reveal a significant enhancement in mechanical strengths with the inclusion of fibers in CAC composites. The addition of 1% fibers to the composites resulted in significant improvements. Steel fibers (SF) led to notable enhancements of approximately 19.7%, 68%, and 26.4% in compressive, direct tensile, and flexural strengths, respectively, while polypropylene fibers (PF) resulted in enhancements of 1.9%, 20%, and 16.7%, respectively. Microstructural analysis revealed that SF and PF contribute to pore refinement, enhancing strength and durability. Findings suggest that SF addition effectively mitigates strength loss induced by the conversion effects of stable phase C3AH6 in CAC, thereby fostering the development of an environmentally friendly, quick-setting, high-performance concrete system. This research offers valuable insights for the design and potential enhancement of CAC-based composites to improve performance and durability under severe conditions.

Comparative Study between Multiwall Carbon Nano Tube and Carbon Waste from Aluminium Production in the Preparation of Thermally Stable Cementitious Mortar

Objective: The objective of this study is to conduct a comparative investigation into the performance of multiwall carbon nanotube (MWCNT) and carbon wastes (C-waste) derived from the aluminum industry in the creation of thermally stable cementitious mortar. Specifically, the research aims to assess their impact on compressive strength and thermal stability, with a focus on identifying the superior additive for enhancing the properties of cement mortar. Methods: Cement mortar is produced using a blend of CEMIII cement and sand passing through a 1 mm sieve. Various ratios of MWCNT and C-waste, ranging from 0.1% to 0.7%, are incorporated into the mixture. Compressive strength tests are conducted at different intervals, up to 90 days, to evaluate the effects of additives on strength enhancement. Additionally, the resistance to high temperatures is examined by subjecting the mortar samples to firing temperatures up to 700 degrees Celsius. Results: The inclusion of both MWCNT and C-waste leads to improvements in compressive strength values, with the most significant enhancement observed at 0.1% concentration, resulting in approximately 70MPa and 75MPa at 90 days, respectively. Notably, C-waste demonstrates superior physical and mechanical properties compared to MWCNT, along with a lower production cost. Moreover, both additives exceed the specified limits for thermal resistance in mortar, achieving measurements of about 60MPa for MWCNT and 63MPa for C-waste when exposed to firing temperatures of 700 degrees Celsius. These results highlight the higher thermal stability of C-waste relative to MWCNT. Conclusion: In conclusion, this study confirms the efficacy of utilizing C-waste as an additive in cementitious mortar production, showcasing its superior performance over MWCNT in terms of compressive strength enhancement and thermal stability. The findings underscore the potential of repurposing industrial by-products such as C-waste to improve material properties while also addressing environmental concerns and reducing production costs in construction applications.

Laboratory assessment of the impact of modified asphalt binder on mechanical properties of grouted macadam mixtures under various performance conditions

ABSTRACT Grouted Macadam (GM) mixtures are used for pavement coatings due to their strong load-bearing capacity and rutting resistance. However, weak asphalt-cement interface bonding reduces crack resistance performance of these mixtures. This study aimed to enhance this adhesion through implementing TEGO Addibit L300 additive at concentrations of 0.2, 0.3, and 0.4% by weight of asphalt binder. Various tests assessed additive’s impact on asphalt binder properties, including penetration, softening point, and kinematic viscosity. Adhesion properties were evaluated through sessile drop and semi-circular bending bonding strength tests. Additionally, GM mixture performance was assessed with mechanical tests such as 3-point bending strength, indirect tensile strength, and Marshall stability, considering two conditions: samples tested immediately after a 28-day curing period (non pre-conditioned samples), and samples tested after the same period followed by exposure to 60 ℃ for 16 h (pre-conditioned samples). Results revealed that the adhesion capacity of the asphalt binder significantly affected GM mixture performance in both conditions. Addition of TEGO Addibit L300 enhanced ductility and fracture energy by 53.9% and 45.2%, respectively, in non pre-conditioned samples. In pre-conditioned samples, the additive increased indirect tensile strength by up to 12.1%. The optimal dosage for improving GM materials performance was determined to be 0.3%.

An Experimental Investigation Use of Waste Plastic and Waste Glass Together as Coarse Aggregate in Paver Block

Waste has become a major problem these days. Glass and plastic are found in municipal solid waste (MSW), and are of the most used daily materials. The amount of glass and plastics consumed annually has been growing steadily. Its low density, strength, user- friendly design, fabrication capabilities, long life, lightweight, and low cost are the factors behind such phenomenal growth. As waste plastic and waste glass is non-biodegradable material it blocks drains, pollutes rivers and streams have on the environment. This project focus on partially replacement of waste plastic and waste glass together as coarse aggregate in concrete paver block. To evaluate the effects of including these wastes, mechanical test like compressive strength test is conducted. The aim of the project is to recycle the waste plastic and waste glass into a paver block and to reduce the cost of paver block. This can serve as environmental friendly.