Strength Characteristics Research Articles

Anisotropic Characteristic Strength and Energy Evolution of Irregular Columnar Jointed Rock Masses Before and After Excavation

Anisotropic Characteristic Strength and Energy Evolution of Irregular Columnar Jointed Rock Masses Before and After Excavation

Bending Strength Evaluation of Japanese Wooden Cultural Heritage Building Columns Based on a Non-Destructive Testing Method

ABSTRACT Column failure assessment is essential for seismic diagnosis of Japanese wooden cultural heritage buildings. Achieving accurate column failure assessment depends on accurately estimating the bending Young’s modulus (E b ) and characteristic bending strength (F b ) of columns. This study extends the application of a non-destructive testing (NDT) method to estimate E b and F b of Japanese cedar columns generally used in wooden cultural heritage buildings. For this purpose, a correlation between the dynamic bending Young’s modulus (E p ) and E b of Japanese cedar columns is established and the variations in the E p –E b relationship across different wood provenances and species are clarified. Using the proposed method, a statistical analysis of the estimated E b of Japanese wooden cultural heritage buildings is provided. Furthermore, estimated E b is used to determine F b of the columns using the mechanical grade classification system. The results show that most Japanese cypress and Japanese cedar columns feature higher F b than those used in conventional seismic diagnosis. Conversely, two-thirds of the Japanese red pine columns feature a lower F b than that used in conventional seismic diagnosis. The proposed F b evaluation method offers an NDT method that can be widely applied to Japanese wooden cultural heritage buildings to assess column failure more accurately.

Efficacy of Admixtures on Compressive Strength of Concrete

This report investigates the impact of reducing cement proportion in concrete by adding varying percentage of silica fume and glass fibre. The aim is to evaluate the compressive strength of modified concrete mix with varying percentage. The experiment involved varying levels of cement replacement with silica fume and the addition of glass fibre to determine the optimal combination for enhancing concrete performance. Testing methodologies included compressive strength tests of concrete cube. The results provide insights into the feasibility and effectiveness of utilizing silica fume and glass fibre to improve the strength characteristics of concrete while reducing cement content, contributing to sustainable and durable construction practices.

Establishing the Characteristic Compressive Strength Parallel to Fiber of Four Local Philippine Bamboo Species

Bamboo is considered a sustainable construction material due to its ability to grow quickly and its mechanical properties that are comparable to timber. Contributing to the current effort to establish structural bamboo standards in the National Structural Code of the Philippines (NSCP), this study establishes the characteristic compressive strength of four bamboo species: Bambusa vulgaris (36 samples), Dendrocalamus asper (36 samples), Bambusa blumeana (94 samples), and Guadua angustifolia Kunth (30 samples). The samples were subjected to compressive loading following ISO 22157-1 (2017). The characteristic compressive strength values obtained, according to ISO 12122-1 (2014), were 40.35 MPa for B. vulgaris, 40.21 MPa for D. asper, 46.63 MPa for B. blumeana, and 36.99 MPa for G. angustifolia Kunth. Simple linear analysis, one-way ANOVA, and Welch’s t-test were used to analyze the correlation models and establish a comparative analysis of the effects of nodes and geometric and physical properties on the compressive strength of bamboo samples. In comparisons of the characteristic compressive strengths obtained from this study to the strengths of unseasoned structural timber of Philippine woods, all bamboo species showed higher strength values than did other woods, and bamboos thus have great potential as an alternative construction material to timber.

Dingo optimization algorithm-based random forests model to evaluate the compressive strength of the concrete at elevated temperatures

The qualities of the materials employed to manufacture concrete are significantly impacted by high temperatures, which results in a noticeable decrease in the material’s strength characteristics. Concrete must be worked very hard and allowed to reach the required compressive strength (fc). Nevertheless, a preliminary estimation of the desired outcome may be made with an outstanding degree of reliability by using supervised machine learning algorithms. The study combined the Dingo optimization algorithm (DOA), Coot bird optimization (COA), and Artificial rabbit optimization (ARO) with Random Forests (RF) evaluation to determine the fc of concrete at high temperatures. The abbreviations used for the combined methods are RFD, RFC, and RFA, respectively. Remarkably, removing the temperature (T) parameter from the input set leads to a remarkable 1100% improvement in the effectiveness index (PI) and normalized root mean squared error (NRMSE), while causing a significant fall in the coefficient of determination (R2). The findings suggest that all RFD, RFC, and RFA have substantial promise in properly forecasting the fc of concrete at high temperatures. More precisely, the RFD algorithm demonstrated exceptional precision with R2 values of 0.9885 and 0.9873 throughout the training and testing stages, respectively. Through a comparison of the error percentages for RFD, RFC, and RFA in error-based measurements, it becomes evident that RFD exhibits an error rate that is about 50% smaller compared to that of RFC and RFA. This prediction is crucial for various industries and applications where concrete structures are subjected to elevated temperatures, such as in fire resistance assessments for buildings, tunnels, bridges, and other infrastructure. By accurately forecasting the compressive strength of concrete under these conditions, engineers and designers can make informed decisions regarding the material’s suitability and performance in high-temperature environments, leading to enhanced safety, durability, and cost-effectiveness of structures.

SPT approach for assessing mechanical properties of materials

The Round Robin Test of the Small Punch Test (SPT) method represents a critical step in establishing its reliability and applicability for assessing the mechanical properties of materials used in power plants. The mechanical properties of materials, such as strength and deformation characteristics, are of paramount importance in ensuring the structural integrity and safety of power generation facilities. The SPT method, a widely adopted in-situ testing technique, holds promise as a cost-effective means of evaluating these properties. However, its precision and consistency in different geological and operational contexts remain subjects of investigation. This study presents the results and findings from a comprehensive Round Robin Test aimed at rigorously assessing the SPT method's performance and suitability for characterizing materials within power plants. Multiple testing campaigns were conducted across diverse sites and material conditions, encompassing varying geological formations, moisture content, and temperature ranges. The objective was to evaluate the SPT method's repeatability, reproducibility, and accuracy in different operational environments

Investigation on Interfacial Bond Strength Characteristics of Concrete Filled in Galvanized Steel Tubes Utilizing Statistical Analysis and Advanced Prediction Techniques

Investigation on Interfacial Bond Strength Characteristics of Concrete Filled in Galvanized Steel Tubes Utilizing Statistical Analysis and Advanced Prediction Techniques

Artificial intelligence-based prediction models of bio-treated sand strength for sustainable and green infrastructure applications

As a sustainable, environmentally friendly, and green solution, biomineralization/bio-treatment process has recently emerged for enhancing the strength characteristics of loose sands by inducing cementation material commonly referred to as microbially induced calcite/cementation precipitation (MICP). To date, existing research on the unconfined compression strength of MICP-treated sands (UCSmicp) relies heavily on experimental data, with predictions primarily based on linear or curvilinear models that consider calcite (CaCO3) as the main influencing factor. However, there is limited exploration into the application of artificial intelligence (AI) and machine learning (ML) methods for UCSmicp prediction involving multiple influencing factors and their validation on unseen laboratory data. Therefore, this study intends to propose new prediction models of UCSmicp using four advanced ML techniques: Gaussian Process Regression (GPR), Adaptive Neuro Fuzzy Inference System (ANFIS), Artificial Neural Network (ANN), and Gene Expression Programming (GEP). The models incorporate various factors affecting UCSmicp, including sand uniformity coefficient (Cu), initial void ratio (e), mean grain size (D50), optical density at 600 mm wavelength (OD600), urea concentration (U), calcium concentration (Ca), and calcite content (C). Performance evaluation of models involved statistical assessments, error analysis, cross validation on laboratory data, and sensitivity and monotonicity studies. Results indicate that the proposed models exhibit exceptional precision across training, testing, and validation data in predicting UCSmicp, with ANN demonstrating the highest accuracy, followed by GPR, ANFIS, and GEP. Sensitivity analysis identifies CaCO3 as the main influencing factor on UCSmicp, while monotonicity analysis confirms alignment with physical processes. This work advocates for MICP as an eco-friendly solution and highlights the efficacy of advanced ML techniques in fostering sustainable infrastructure.

Strength and Compressibility Characteristics of An Expansive Soil with addition of GGBS and Alkali Activated Slag

Abstract: The phenomenal development in civil engineering infrastructure in developing countries like India, soil stabilization has emerged as à key problem in the engineering industry. Engineers have been attempting to enhance the engineering properties of low-quality soil due to their negative impact on project performance. With increasing awareness of environmental issues, there has been a remarkable shift towards green and sustainable technologies. Reuse of waste materials have been advocated for quite a while to improve the properties of poor soils open up to new avenue and double advantage of waste management. In the project investigation an attempt to evacuate the Plasticity characteristics, Strength characteristics and Compressibility characteristics were conducted on selected soil as per Indian Standards using GGBS and Alkali Activated Solution (AAS) with different percentages and curing for 0,3,7,14, and 28 days to analyze the variation of engineering properties. From the results combination of (GGBS + AAS) proved to increase of strength and reduce compressibility characteristics. The combination of GGBS + AAS is cost effective, non-destructive, low energy demanding and ecofriendly than GGBS to the selected expansive soil.

Effects of oil palm mesocarp fibers on the physical and mechanical properties of expansive soils

Palm fiber is one of the favorable materials used in stabilization of soft soil in geotechnical engineering projects, nowadays due to its sustainability, less damage of environment, biodegradability, availability and cost-effectiveness in a context of widespread appeal to the world for return to nature by protecting the earth. On the other hand, expansive soils are renowned for their swelling-shrinkage property and these volumetric changes resultantly cause huge damage to civil infrastructures. Likewise, subgrades consisting of expansive soils instigate serviceability failures in pavements across various regions worldwide. This paper presents results of the laboratory evaluation of expansive soils stabilized with oil palm mesocarp fiber (OPMF), with a view to determine its suitability as flexible pavement construction material. The mixtures were subjected to British Standard heavy (modified Proctor) compaction energy to determine their strength characteristics. The samples were subjected to different tests to ascertain their index properties. Varying proportions of OPMF from 1% to 4% were incorporated into the soil samples and the effects were observed based on compaction and California Bearing Ratio (CBR) results. The control samples without inclusion of OPMF achieved the highest Maximum Dry Densities (MDD), the MDDs reduced linearly as the OPMF content increased. Consequently, the CBR values decreased with increase in OPMF. The reduction in MDD ranged from 20.28g/cm3, 18.5 g/cm3, 15.65 g/cm3, 12.53 g/cm3 as the OPMF increased from 1%, 2% to 3%, 4%. and the optimum moisture content remained almost unaffected due to high-absorbent nature of the fibers. With the inclusion of the OPMF, the CBR value under soaked conditions dropped from 5% to 1.8% rendering them very unsuitable for pavement subgrade. It was concluded that the presence of fiber depreciated the engineering properties of the earth materials. Direct application of OPMF in any part of road pavement has been dissuaded.

Material extrusion additive manufacturing of zirconia: from filament characterisation to Weibull statistics

Purpose This study aims to investigate the performance of filament-based material extrusion additive manufacturing (MEX), combined with debinding and sintering, as a novel approach to manufacturing ceramic components. Design/methodology/approach A commercial ZrO2 filament was selected and analysed by infra-red (IR) spectroscopy, rheology and thermo-gravimetry. The influence of the print parameters (layer thickness, flow rate multiplier, printing speed) and sintering cycle were investigated to define a suitable printing and sintering strategy. Biaxial flexure tests were applied on sintered discs realised with optimised printing strategies, and the results were analysed via Weibull statistics to evaluate the mechanical properties of printed components. The hardness and thermal conductivity of sintered components were also tested. Findings Layer thickness and flow rate multiplier of the printing process were proved to have significant effect on the density of as-printed parts. Optimised samples display a sintered density >99% of the theoretical density, 20% linear sintering shrinkage, a characteristic flexural strength of 871 MPa with a Weibull modulus of 4.9, a Vickers hardness of 12.90 ± 0.3 GPa and a thermal conductivity of 3.62 W/mK. Gyroids were printed for demonstration purposes. Originality/value To the best of the authors’ knowledge, this work is the first to apply biaxial flexure tests and Weibull statistics to additively manufactured MEX zirconia components, hence providing comparable results to other additive technologies. Moreover, fractography analysis builds the connection between printing defects and the fracture mechanism of bending. This study also provides guidelines for fabricating high-density zirconia components with MEX.

Sustainable Production of Self Compacting Concrete by using Fly Ash and Granite Waste

The development of sustainable concrete has gained plenty of awareness in recent years. Researchers have conducted many experimental investigations for the manufacture of different forms of concrete by using numerous low carbon footprint materials, such as granite waste and fly ash. The using of low carbon footprint materials in construction industry will minimize the exploitation of natural raw materials and promote sustainability in construction industry. This research thus aimed to investigate the influence of granite waste (GW) and fly ash on the production of self-compacting concrete (SCC). The preliminary investigation was carried out for finding the maximum adding percentage of GW and fly ash in the successful production of SCC. The GW was used in the proportion of 10,20 and 30% as an alternative to fine aggregate (i.e. sand) by weight, while, fly ash was substituted with cement in the proportion of 10,20 and 30% by weight. The fresh characteristics (slump flow, V-funnel, and L-box), mechanical characteristics (compressive strength) were evaluated. The findings revealed that the combined use of GW (up to 30%) and fly ash (up to 30%) in SCC has the potential to considerably enhance the fresh and water absorption properties (without adversely affecting strength characteristics

Investigation of the Additional Powder Effect on the Strength of Joined Aluminum Alloy Plates in Friction Stir Welding Using the Topsis-Game Theory Model

Friction stir welding (FSW) is a process that can join many materials by causing minimal internal stress without the need for a direct electric current, contrary to traditional welding methods. The effects of SiC and Al2O3 reinforcing powders on the joining of AA6061-T6 and AA7075-T6 plates, which are difficult to join with conventional welding methods by FSW, are investigated in this study. The metallurgical properties of the combined samples are examined in terms of strength characteristics to investigate the effects of the reinforcement powder. In addition, elemental analysis is carried out for the mixing behavior of the powders. Finally, we used the TOPSIS method to select the most appropriate powder types to improve welding quality. Furthermore, a game theory application is presented to determine which powder type is suitable considering the joined aluminum plate’s strength expectations.

Evaluation of bond strength between zirconia milled ceramic material and veneered dental porcelain.

This study aimed at examining the bond strength between zirconia and ceramic veneer, following the ISO 9693 guidelines. A total of fifty specimens of zirconia/ceramic-veneer system were produced using two commercial zirconias (VITA YZ-HTWhite and Zolid HT+ White, referred to as Group A and Group B, respectively) and a ceramic-veneering material (Zirkonia 750). The microstructure (via x-ray diffraction analysis, XRD) and the mechanical properties (via 3-point bending tests) of the two groups were assessed. Then, experiments were conducted according to the ISO 9693 and conventional protocols applied for producing zirconia/ceramic-veneer restorations. Bond strength values, measured by 3-point bending tests, were 34.42±7.60MPa for Group A and 31.92±6.95MPa for Group B. SEM observations of the cohesively fractured surfaces (on the porcelain side) and the examination for normality using the Shapiro-Wilk test suggested the use of Weibull statistical analysis. Median strength (σ50%) for Group A and Group B was 34.76 and 32.22MPa, while the characteristic strength (σ63.2%) was 35.78 and 33.14MPa, respectively. The Weibull modulus disparity between groups (12.69 and 13.07) was not significant. Bond strength exceeded the ISO 9693 minimum of 20MPa, suggesting satisfactory strength for clinical use.

Microstructure and deterioration mechanism of hydraulic concrete under variable temperature dry-wet cycles

In the variable water level area, hydraulic concrete structures are susceptible to variable temperature and alternating dry-wet cycles, especially for thin-walled structures. To elucidate alterations in the microstructure and strength of hydraulic concrete subjected to variable temperature dry-wet cycles, this paper firstly conducted a durability test on hydraulic concrete. Subsequently, CT scan images of the specimens are acquired during the variable temperature dry-wet cycle. Secondly, in view of the shortcomings of existing threshold methods for CT image pore segmentation, a new image segmentation method (RASLPSO-TV-Top-hat) is proposed by using Tensor voting and Top-hat technology, combined with a Reverse Adaptive Particle Swarm Optimization algorithm with Self-Learning ability. The evolution process of pore structure (microcracks) of hydraulic concrete under the variable temperature dry-wet cycles is captured. Thirdly, an in-depth analysis is conducted on the compressive strength and acoustic emission characteristics. The analysis shows that with the number of cycles increases, there is a discernible interconnection among the pore structures. This interconnection leads to a noteworthy reduction in the compressive strength of the concrete. Additionally, the cumulative number of Acoustic Emission ringing events exhibits an initial rise followed by a subsequent decline. The study successfully identifies the patterns governing the deterioration of strength and microstructure evolution in hydraulic concrete. The mechanism underlying the decline in performance of hydraulic concrete under variable temperature dry-wet cycles is elucidated. It provides a reliable and valuable basis for the safety assessment of hydraulic concrete structures in the variable water level area.

Experimental substantiation of the technology for manufacturing composite parts based on a viscous metal-polymer

ABSTRACT The article deals with an experimental study of the technological process of obtaining a composite ABS, a metal-polymer part. As the title implies the article describes a method and device for the manufacture of composite parts based on the method of vacuum suction of a viscous metal-polymer into a shell form. Recommendations are given on the technological modes of filling the mould, taking into account the presence of vibration in the process of filling the mould with a metal-polymer, as well as the Reynolds number parameter for establishing a laminar flow of the metal-polymer in the technological mould cavities. The study of the strength of the designed composite part has been carried out using the finite element method of the APM FEM module. The calculations of the strength and stiffness of parts made of ABS, metal-polymer and metal make it possible to compare the strength characteristics of parts made by various methods. Relevant recommendations are given on the use of a composite part reinforced with a metal-polymer in the field of mechanical engineering.

Experimental Investigation of Sustainable Concrete Production using Blast Furnace as A Cement Substitute- A art of Review

The pursuit of sustainable construction practices has led to a growing interest in alternative materials that can reduce the environmental impact of traditional concrete production. This experimental study focuses on the utilization of blast furnace slag as a substitute for cement in concrete, aiming to assess its mechanical properties, environmental impact, and overall sustainability. The primary objectives of this research are threefold. Firstly, the study seeks to evaluate the mechanical properties of concrete by varying the content of blast furnace slag in the mix, with a specific emphasis on strength, durability, and structural performance. This involves conducting a comprehensive analysis of the concrete's compressive strength, flexural strength, and other relevant mechanical characteristics. Secondly, a life cycle assessment (LCA) will be employed to analyze the environmental impact of the concrete mixtures. This assessment will compare carbon dioxide (CO2) emissions, energy consumption, and overall sustainability of the concrete produced with varying percentages of blast furnace slag. The LCA will provide valuable insights into the environmental implications of using slag as a cement substitute, aiding in the identification of eco-friendlier concrete production practices. Lastly, the research aims to assess the environmental impact of blast furnace slag itself when employed as a cement substitute. This involves examining the production, transportation, and incorporation of blast furnace slag into the concrete mix, providing a holistic view of its sustainability across the entire life cycle. The experimental approach involves the meticulous design of concrete mixes with different percentages of cement replaced by blast furnace slag. The varying mix designs will be tested for mechanical properties, and the data obtained will be used to draw correlations between slag content and concrete performance. In summary, this research endeavors to contribute to the body of knowledge surrounding sustainable concrete production by exploring the mechanical, environmental, and sustainability aspects of utilizing blast furnace slag as a cement substitute. The findings of this study are anticipated to provide valuable insights for the construction industry to adopt more environmentally friendly practices while maintaining or enhancing concrete performance.

Exploring the geotechnical and microstructural properties of composite mixtures for landfill liner materials: an experimental investigation.

The present study directs the need for the development of an economical composite mix comprised locally available soil and industrial waste which satisfy the design parameters of the municipal solid waste (MSW) landfill. The local soil, bentonite, and fly ash mixtures are mixed in different proportions to evaluate the geotechnical and microstructural characteristics for suggesting an optimum composite mix that fulfills the design parameters of landfill liners. The curing periods of different mixes are also considered while evaluating the unconfined compressive strength (UCS) characteristics. The microstructure of the mixtures is examined using advanced imaging techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDAX) to gain insights into the changes at the microscale level due to the inclusion of fly ash. It is observed that soil-bentonite-fly ash composite mix in a ratio of 65:15:20 aligns with the optimal design characteristics required for a landfill liner. Notably, for this composite mix, both liquid limit (LL) and plastic limit (PL) show a significant increase of 48.57% and 32.33% respectively, while the optimum moisture content (OMC) rises by 11.25%. Conversely, maximum dry density (MDD) experiences an 8.79% decrease. Moreover, the free swell index (FSI) escalates by 113%, whereas hydraulic conductivity (HC) records a substantial reduction of 96.04%. Moreover, the UCS exhibited a notable increase of 209% after a 28-day curing period. The highest strength is achieved initially by soil mixed with 20% fly ash, followed by a blend containing 15% bentonite. Therefore, proper fly ash content in filler and other binder materials is an effective and sustainable approach that not only solves the disposal issue but also enhances the material's engineering characteristics, justifying its suitability to be used as a landfill liner.

Simulation of tensile strength for polymer hydroxyapatite nanocomposites by interphase and nanofiller dimensions

AbstractSeveral models have been used in literature studies to describe the mechanical behavior of hydroxyapatite (HA) polymer nanocomposites. However, previous models have often overlooked the size of HA and the properties of the interphase. In this study, we further develop an equation originally proposed by Kolarik. This advanced equation predicts the tensile strength of polymer/HA nanocomposites by considering the interphase parameter (A), rod‐like HA size, HA concentration, and interphase properties, including depth and strength. We validate our method using experimental data from various examples and through parametric inspections. Both the strength and the depth of the interphase directly affect the ‘A’ value and, consequently, the strength of the nanocomposites. For instance, an HA radius (R) of 6 nm yields the highest ‘A’ value of 4.97, enhancing the nanocomposite strength by up to 250%. In contrast, ‘R’ value of 20 nm fails to reinforce the samples effectively. Additionally, the thickness of the interphase (t) and the concentration of HA directly handle the nanocomposite strength. The strength of the samples significantly improves by 137% and 160% with an interphase thickness of 50 nm and an HA volume fraction of 0.2, respectively. Generally, the length of HA and interphase characteristics (thickness and strength) directly control the strength of samples, but the HA radius has an inverse relationship with nanocomposite strength.Highlights Kolarik equation is developed to predict the tensile strength of polymer HA nanocomposites. Interphase parameter, HA size, HA concentration and interphase properties are considered. HA radius of 6 nm produces the maximum enhancement of nanocomposite strength by 250%. Interphase properties and concentration of HA directly control the nanocomposite strength. All parameters reasonably influence the strength of samples confirming the developed model.

Pozzolanic potential of sustainable precursors for engineered geopolymer composites (EGC)

Abstract Confirming the pozzolanic activity is crucial to ensure their compatibility and performance in geopolymer composite (GC) applications, as it improves the geopolymerization process and optimizes the strength characteristics of GCs. This work evaluates the pozzolanic properties of Fly ash (FA), Basic Oxygen Furnace (BOF) slag, and Iron Ore Tailings (IOT) for their potential use in the development of Engineered Geopolymer Composites (EGC). IOT partially substitutes fine aggregate, while FA and BOF slag are the major precursors. Pozzolanic properties of the aforementioned materials were assessed through the Frattini, saturated lime test (SLT), and strength activity index (SAI). The Frattini test values recorded were 90, 47, and 30 % of CaO removal, denoting their degree of pozzolanicity respectively for BOF Slag, FA, and IOT. In the SLT, the formation of stable calcium silicate hydrates and aluminates are verified by the reaction of the test pozzolans with lime, thereby conforming their pozzolanicity. The results from the Frattini and SAI tests showed a significant correlation, indicating an effective pozzolanicity measure of the test materials. However, the results from the SLT did not align with the outcomes from the Frattini and SAI tests. This contradiction suggests that the SLT is ineffective compared to the other two test methods in measuring the pozzolanic activity of the test materials. The research findings provide valuable insights into the potential usage of these materials (pozzolans) as sustainable building materials in the construction industry.