Strength Absorption Research Articles

Characterization and thermal analysis of metalworking sludge as a partial substitute for clays in ceramic production

This study evaluates the feasibility of using sludge from the metalworking industry (SMWI) as a partial substitute for clays in producing red ceramics for civil construction. The analysis of the white goods production process predicted the components of SMWI, potentially reducing the need for additional chemical analyses. According to the chemical analyses provided, SMWI is a non-hazardous solid waste, but not inert, due to the presence of aluminum, chlorine, and phenols, by Brazilian standards. The oxide composition of SMWI showed compatibility with the studied clays and data from the literature, suggesting its potential as an additive in ceramics. Rich in CaO and Al2O3, SMWI can enhance the mechanical strength of ceramics, although excessive addition may increase water absorption. Loss on ignition tests, thermogravimetry, and SEM-EDS analyses on SMWI and pure and 5% SMWI-added clays revealed the loss of volatile compounds and the formation of thermostable clay minerals. However, its distinct composition, with lower levels of Fe2O3 and SiO2, and the need for adequate homogenization, requires caution to avoid impacts on the final properties of the ceramic products, such as water absorption and mechanical strength. Thus, the use of SMWI as a ceramic additive presents itself as a sustainable and viable alternative, although further studies are necessary to validate its application in compliance with Brazilian technical standards.

An Experimental Study of the Properties of Bamboo Particle Reinforced Epoxy Matrix Biocomposites

Production of biodegradable polymer matrix biocomposites that are cost effective, sustainable, and environmentally friendly with desirable properties using particles as discontinuous phase (filler) is a welcome development. In this study, bamboo particle reinforced epoxy resin matrix biocomposites were developed by stir casting method. Varied weight percentages (5 to 30 wt. %) of 100 µm bamboo particles were added separately and blended with an epoxy resin – hardener matrix. The blends were fed into a fabricated wooden mould and allowed to cure at room temperature. After 24 hrs, the specimens were removed from the mould and subjected to microstructural examination using a Scanning Electron Microscope (SEM). Furthermore, the physical and mechanical properties characterisation of the specimens were also carried out. The results obtained from the experiments showed the presence of pores in the microstructure of the specimens and the distribution of reinforcing particles in the epoxy matrix. The reinforced composites (S2 to S6) demonstrated an appreciable increase in density when compared with the unreinforced control specimen (C1). Specimens (S2 to S6) demonstrated lower water absorption than C1. The composites demonstrated increased ultimate tensile strength with filler addition up to 25 wt. %. Similarly, the reinforced specimens demonstrated improved hardness as the weight percent (wt. %) of bamboo particles increased up to 25 wt. %. However, the composites demonstrated a reduction in impact energy as filler content increased when compared with the control specimen. Specimen S5 formulation, which contained 25 wt. % of reinforcing particles demonstrated the best properties in terms of density, water absorption, hardness, and ultimate tensile strength. These findings highlight the effectiveness of bamboo particles in enhancing the physical and mechanical properties of the developed ecofriendly biocomposites.

Olive Pomace Fly Ash as an Alternative Alkaline Activator for Electric Arc Furnace Slag for Sustainable Cementitious Materials

This study analyzes the potential of olive pomace fly ash (OPFA) as an alternative alkaline activator for electric arc furnace slag (EAFS) in the manufacture of sustainable cementitious materials. Cements were prepared by replacing 30–50 wt% of EAFS with OPFA and compared with control cements activated with potassium hydroxide (KOH) at concentrations of 4 and 8 M. Cements were characterized by bulk density, water absorption, total porosity, compressive and flexural strength, as well as analytical techniques such as XRD, FTIR and SEM-EDS. The results reveal that the incorporation of 40 wt% OPFA provides optimum properties, reaching maximum compressive and flexural strengths of 20.0 MPa and 5.7 MPa, respectively, after 28 days of curing. These improvements are attributed to the increased formation of C,K-A-S-H gel, which incorporates Fe, the main reaction product that densifies the matrix and reduces porosity. However, 30 wt% OPFA provides insufficient alkali content, which limits the reaction, while excess alkali at 50 wt% OPFA reduces mechanical performance due to unreacted residues and increased interconnected porosity. Compared to KOH-activated cements, which achieve maximum flexural and compressive strengths of 4.4 and 9.5 MPa (EAFS/KOH-8M binders), the results confirm the potential of OPFA as an alternative activator, with significant sustainability advantages.

Physical and mechanical properties of a tile produced with Burkina Faso clay

This study proposes an approach for manufacturing wall tiles from raw clayey material from Burkina Faso for use in the local ceramic industry. To this end, a clay sampled of Kodeni (KOD), primarily composed of kaolinite (62 wt.%), quartz (31 wt.%), and goethite (3 wt.%), with contents of 60.79 wt.% SiO₂ and 24.36 wt.% Al₂O₃ was used for wall tile manufacture. All the results of the physico-mechanical tests on the tiles developed at temperatures of 1150°C, 1200°C, and 1250°C show that these tiles meet the standards for mechanical strength of water absorption and thermal conductivity for ceramic applications. The formulation of the samples enriched with feldspar (25 wt.%) and fired achieved maximum flexural strengths of 22.58 MPa at 1250°C for the formulation containing no feldspar (F0) and 25.69 MPa at 1200°C for the formulation containing 25 wt.% feldspar (F1), confirming the densifying effect of feldspar at moderate temperatures. In addition, the water absorption and porosity of the tiles decreased progressively with increasing temperature, ensuring properties in line with ISO 13006 for wall use. The tiles also exhibited low thermal conductivity (≤ 1 W/(m.K)), limited and controllable linear shrinkage, and reduced deformation. These results suggest that KOD clay, amended with 25 wt.% feldspar at 1200°C temperature, is suitable for manufacturing wall tiles. Scanning electron microscopy analysis is planned to explore the evolution of the microstructure and viscous phase as a function of firing temperature to understand better the sintering processes and the interactions between the different stages.

Production of mortar with calcined alum sludge as partial cement replacement

Alum sludge is a largely generated and disposed waste from water treatment plants. This study aimed to produce mortar using alum sludge calcined at different temperatures (600 – 900 ºC). After the optimal calcination temperature was selected, the calcined alum sludge was used to replace 5, 10, and 15 % of cement by mass in mortar. The performance of the mortars was evaluated based on the workability, compressive strength, flexural strength, porosity, and percentage of water absorption. Mortars with alum sludge calcined at 800 ºC had the highest strength as compared to the other temperatures. The mechanical strength of mortars reduced while the porosity and percentage of water absorbed increased with increasing calcined alum sludge content. Although replacing 5 % of cement with calcined alum sludge would reduce the mechanical strengths by 13 – 15 %, it was still acceptable as it had negligible influence on the porosity and water absorption value of the mortar. In short, the partial substitution of cement with calcined alum sludge should be limited within 5 % to maintain the performance of the mortar.

Efeito da cura por carbonatação e do teor de sódio em geopolímeros submetidos ao ataque por sulfatos de sódio e magnésio

Abstract Geopolymer cement stands as an alternative to Portland cement to reduce the impacts associated with its production. This material is also affected by ions that can damage its mechanical properties and reduce its durability. Therefore, this research aims to evaluate metakaolin geopolymer concretes attacked by sulfates, both sodium and magnesium. The samples were made by varying the sodium oxide (Na2O) content in the activators on the metakaolin, the curing type, and the water/metakaolin ratio. The specimens were exposed to sodium sulfate, magnesium sulfate, and reference solutions (water) for 10 weeks. The analyses were performed using water absorption (by capillarity and immersion) and compressive strength tests. The results showed that sodium sulfate attack was more aggressive than magnesium sulfate in geopolymer concretes, 91.67% of the samples submitted to sodium sulfate degraded during absorptions tests while 8.33% were degraded by magnesium sulfate. A sodium content of 22% in metakaolin achieved greater resistance to magnesium sulfate attack and curing by carbonation did not improve the properties of the mixtures.

Development of porous concrete pavements with waste materials for flood control

An inventive design for porous concrete pavement slabs was established in this study. Following the "circularity" agenda and zero waste principles, the design of the permeable concrete mix was founded on several waste/byproduct raw materials, including solidified wastewater treatment sludge (SWS), modified solidified wastewater treatment sludge (MWS), and waste from the desulfurization process (WFDP). Porous concrete was made using cement, waste resources, admixtures, and natural and/or artificial aggregates as component materials. Bulk density, water absorption, compressive and flexural tensile strength, load-bearing capacity, resistance to frost and salt, and abrasion resistance were assessed. Changes in durability and mechanical qualities were tracked as the amount of waste material increased. This study provides a deeper understanding of the properties and possible uses of environmentally modified (green) porous concrete pavement slabs, or pavers, to lower the danger of flooding in urban settings. This concrete is considered environmentally friendly material for sustainable construction because of its porous structure, which significantly assists in regulating stormwater runoff, ensuring infiltration, and reducing the number of pollutants before they reach the groundwater. It has been demonstrated that a specific percentage of recycled materials may be incorporated into porous concrete without compromising the long-term viability or usefulness of permeable concrete, therefore complying with the Zero Waste Agenda and Circular Economy principles.

The basic monochromatic photovoltaic properties of a photodiode for laser power conversion

Abstract We studied the photovoltaic properties of a conventional silicon photodiode under monochromatic illumination conditions to clarify the loss mechanisms that are important for application as a laser power converter. While the short-circuit current increases linearly with the excitation power, the power dependence of the open-circuit voltage consists of two regions with different slopes as a result of the Joule heating. At higher excitation power densities, thermal effects play a key role in the current–voltage characteristics, and therefore the maximum conversion efficiency is achieved at a certain excitation-power density. Furthermore, the optimum excitation wavelength shifts towards longer wavelengths as the excitation power density increases, because the optimum value is determined by a trade-off between the optical absorption strength and the excitation power density.

Pengaruh Penambahan Abu Tempurung Kelapa dan Serbuk Cangkang Telur Terhadap Kuat Tekan dan Daya Serap Paving Block

Egg production, which increases yearly, produces large amounts of eggshell waste. Meanwhile, the coconut shell waste is also underutilized and piling up. Eggshell contains calcium carbonate (CaCO3), which is used as a cement composition material. Coconut shell ash contains silica, also used as a composition material for cement. The use of waste eggshell powder and coconut shell ash as a partial substitute for cement in the manufacturing of paving blocks is a solution to reduce waste and greenhouse gas (CO2) emissions during the cement production process. This study aimed to determine the percentage composition of eggshell powder and coconut shell ash that was suitable for producing paving blocks with optimal characteristics and to assess the effect of adding coconut shell ash with variations (0% ATK : 0% SCT); (6% ATK: 2,5% SCT); (3% ATK: 5% SCT); (6% ATK: 5% SCT); (3% ATK: 2,5% SCT) amount of cement, regarding the water absorption and compressive strength testing of paving blocks. The sample was 30 test objects. The experimental method used was a brick-shaped paving block with dimensions of up to 21 cm x 10,5 cm x 6 cm, referring to SNI 03-0691-1996, and testing was carried out after 21 days of age. The research results on the compressive strength of paving blocks with Quality B, the average compressive strength value is 20 MPa.

An Experimental Investigation on Geopolymer Bricks Using Quarry Dust as Fine Aggregate

Environmental pollution in the construction industry is mostly caused by the manufacture of Portland cement, which releases pollutants like CO2. In this study, geopolymer bricks constructed with fly ash, GGBS, and quarry dust as fine aggregates have undergone experimental work. An activator used in the mixture of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) is also used. For each combination, the molarity of sodium hydroxide was kept constant at 1M, while the ratios of sodium silicate to sodium hydroxide solution varied between 0.25, 0.5, and 1. Brick samples of 230 mm by 110 mm by 70 mm are collected. Tests on the test specimens were performed on the brick qualities, including efflorescence, water absorption, and compressive strength.

Enhancing concrete sustainability with spent diatomaceous earth from the wine industry: Long‐term experimental and statistical analysis

AbstractSpent diatomaceous earth, a by‐product of wine filtration, holds significant promise for use in concrete mixtures due to its pozzolanic properties, which enhance concrete performance. This research explores the application of spent calcined diatomaceous earth (SCDE), heat‐treated at 700°C to remove organic content, as a partial substitute for cement or sand in concrete. The high silica content of SCDE contributes to the formation of additional calcium silicate hydrates during the hydration process, leading to improvements in mechanical strength over time. The study includes a preliminary analysis of cement replacements ranging from 5% to 10% and sand replacements from 2.5% to 15%, assessing their effects on workability, density, water absorption, and compressive strength at 7 and 28 days. The testing program focuses on three key compositions: the reference concrete and optimal mixtures with 10% cement and 5% sand replacements. Compressive strength tests are conducted at 7, 28, 90, 180, and 360 days. The results, validated through ANOVA, demonstrate the influence of SCDE on concrete strength over time, with distinctive behavior patterns identified for different mixtures. The strength of concrete with replacements correlates with the reference strength, with a multiplicative factor that varies from 7 to 90 days and then. When SCDE replaces cement, the factor is less than one before 28 days due to the slow pozzolanic reaction, whereas for sand replacement, it always exceeds one because of the initial filler effect. After 90 days, the strength multiplicative factors are 1.13 for cement replacement and 1.30 for sand replacement, demonstrating the potential of SCDE for sustainable concrete manufacturing and its positive long‐term impact on mechanical performance.

Utilizing Rice Husk Ash And Coconut Shell As Partial Replacement Materials In Concrete

The global demand for concrete, a predominant construction material, has risen significantly. Key components in concrete are cement and aggregate, are crucial, but their continual extraction poses a threat to the environment, leading to a potential ecological imbalance. Consequently, current trends in concrete technology focus on exploring sustainable alternatives to reduce dependence on natural resources and mitigate environmental degradation. This study aimed to produce concrete using rice husk ash and coconut shell as partial replacement materials for cement and coarse aggregate, respectively. The mix ratio is 1:2:4 (cement: fine aggregate: coarse aggregate) for grade 20. Rice husk ash replaced 10% and 20% of cement, while coconut shell replaced 5% and 10% of coarse aggregate by weight. Samples were tested for workability, water absorption, and compressive strength. According to the slump test, every sample exhibits collapse and a true slump meanwhile in water absorption showed less than 8% according to standard value. The control sample showed good compressive strength (>20 N/mm²), while among the modified samples, the concrete mixture with 10% rice husk ash and 5% coconut shell achieved the highest compressive strength at 15 N/mm² after 28 days.

Effect of Water-to-Binder Ratio on Density, Compressive Strength and Morphology of Fly Ash/Ladle Furnace Slag Blended One-Part Geopolymer

Water-to-binder (W/B) ratio has a great influence on the bulk density, compressive strength and morphology of fly ash/ladle furnace slag (FA/LFS) blended one-part geopolymer. The objective of this work is to evaluate the effect of W/B ratio on the performance of the one-part geopolymer. The one-part geopolymer were prepared at W/B ratio of 0.20-0.30 and cured at room temperature for 28 days. The bulk density, water absorption, apparent porosity and compressive strength were determined, while the morphology was examined by scanning electron microscopy (SEM). The results showed that the one-part geopolymer with W/B ratio of 0.25 had highest compressive strength (39 MPa) with denser (2.1 g/cm3) structure as well as low water absorption (3.97%) and low apparent porosity (8.33%). The micrograph showed the optimal one-part geopolymer has less agglomeration of FA and LFS particles.

The Effects of CaO and MgO on Thermal, Mechanical and Optical Properties of Porcelain Tiles by Utilizing Blast Furnace Slag

In this study, the Blast Furnace Slag (BFS) of Zonguldak Eregli Iron and Steel Factories was used as a recycling raw material for the porcelain tile samples. A kind of clay with high MgO content was also used in the porcelain tile recipes. Maximum 10% of BFS was used instead of Na-feldspar. Sintering temperature for all samples was 1205°C for 50 minutes in the industrial roller kiln. Technological properties such as shrinkage, water absorption, colour measurement, and flexural strength were investigated as well as sintering properties and microstructures of the green and the sintered samples. As a result of the study, the addition of BFS did not adversely affect the technical properties of porcelain tile bodies. Particularly, the addition of BFS up to 3% contributed to an increase in flexural strength, and whiteness values of all samples increased because of the formation of anorthite and diopside compared to the reference body. The phase transformations and crystal formations such as anorthite and diopside resulted in a decrease in the firing shrinkage. Although the anorthite formation and diopside formation in the investigated samples had an adverse effect on condensation, it was found that they showed similar sintering behaviours compared to the reference body. This study showed that an industrial waste material can be converted into an environmentally friendly raw material that can create added value and provide energy efficiency.

Sulfate freeze–thaw resistance enhancement of cement mortar via a developed hydrophobic mica powder

This study developed hydrophobic mica powder (HMP) using mica powder and stearic acid through high-temperature stirring to enhance cement mortar’s resistance to freeze–thaw (F–T) cycles in sulfate environment. Initially, the impact of HMP content on water absorption and compressive strength was assessed. Further tests on cement mortar with varying HMP dosages evaluated sulfate resistance under F–T cycles, including mass loss rate, relative dynamic modulus of elasticity (RDME), and compressive strength. Results indicated that HMP modified mortar reduced water absorption by 62.75% and compressive strength by 5.43% compared to unmodified mortar. After 125 F–T cycles, HMP modified mortar showed minimal damage, with a 7.33% RDME reduction and a 9.12% compressive strength decline. Detailed stress–strain curve analysis led to an axial compression constitutive model incorporating the effects of F–T cycles and HMP contents. This paper elucidates the hydrophobic mechanism of HMP, demonstrating its potential to improve F–T resistance through experimental and microscopic analysis.

Design of Cf/SiCf/Si3N4f multifiber layered composite with enhanced electromagnetic wave absorption properties

AbstractTraditional fiber‐reinforced composites with single‐layered electrical conductivity (EC) face limitations with respect to electromagnetic wave absorption (EWA) bandwidth and strength. This study introduces a novel Cf/SiCf/Si3N4f layered composite (multifiber layered composite, MFLC), prepared via fiber alignment and curing, which capitalizes on the distinct ECs of carbon fibers (Cf), silicon carbide fibers (SiCf), and silicon nitride fibers (Si3N4f) to address these limitations. The Si3N4f layer enhances the impedance matching, deepening EW penetration and curtailing reflection. The conductive Cf and SiCf layers lead to substantial energy dissipation through conduction loss. Electric field simulations confirmed the regulatory effect of Si3N4f layer on EC, thereby facilitating the optimization of impedance matching. MFLCs achieved a minimum reflection loss of −68.52 dB and an effective absorption bandwidth of 8.23 GHz in the X–Ku band. The optimally matched composites demonstrated exceptional EWA performance, attaining the radar cross section reduction of up to 149.9%. The MFLCs hold significant promise as a novel class of lightweight, highly efficient, and wide‐bandwidth EW absorbers.

Static modeling of thermal properties and influence of soda hydroxide treatment on biomaterial behavior

In this work, a mathematical analysis carried out by an advanced statistical approach using the JMP software was adopted to deal with a complex problem involving several parameters. This method was applied to optimize the thermal insulation characteristics of a biocomposite. Following a precisely designed experimental program, the study focuses on analyzing the impact of different concentrations of treated date palm fibers (DPFT) on the thermophysical and mechanical properties of composite materials. The samples were prepared with different weight percentages of date palm fibers (0% to 20%), treated with NaOH and having a fiber length of 7 cm. Water absorption, density, flexural and compressive strength, thermal conductivity and diffusivity were taken into account. The results indicate that the incorporation of treated fibers has a beneficial effect on the thermal, mechanical and physical properties of the composite compared to the use of raw fibers. Additionally, higher proportions of DPF result in decreased thermal conductivity, diffusivity, and flexural and compressive strength, highlighting the positive impact of DPFT on the thermophysical and mechanical attributes of the composite.

Increasing the strength of alkali activated mortars prepared without cement by adding lime and crushed brick

Alkali-activated concretes, which aim to reduce cement, have received the most attention in recent years. By activating cementless geopolymer mortar samples with lime, blast furnace slag [BFS], fly ash [FA], crushed brick, sodium hydroxide, and sodium silicate, the study aims to produce more affordable and environmentally materials. Hydrated lime and crushed brick mortars, which have been utilized in ancient structures for thousands of years, have endured to the present day because of their toughness and appropriate construction techniques. However, the biggest disadvantage of ancient mortars is that their setting time is long due to the lime they contain and therefore their strength properties cannot be developed at an early age. In order to improve these properties of the mortars, 7.5 mole NaOH was used in fixed ratios and Na2SiO3 in variable ratios. On the mortar’s characteristics, the impacts of lime, crushed brick, BFA, and FA were examined. Tests on the generated samples included flow-table, setting-time, density, water absorption, porosity, flexural and compressive strength tests, as well as SEM, XRD, and FTIR studies. The reference ancient mortar sample has the lowest compressive strength value at 1.47 MPa, while the Y4 sample, which has a high BFS content at 22.5 MPa, has the highest compressive strength value. The YS4 sample comprising BFS, NaOH, and Na2SiO3 had the fastest setting time, at 20 minutes. In comparison to the reference samples, the samples’ workability was also enhanced. The reference sample had the highest water absorption value, 26.8%, while the other samples’ values stayed below 2%. In this case, activators contributed to the improvement of the mechanical qualities of traditional lime mortars.

Styrene-Butadiene Rubber Latex Modified Mortars Prepared with High Early Strength Portland Cement.

The increased early hydration rate of high early strength cement has economic advantages in many civil engineering fields (faster formwork removal or earlier demoulding of precast elements). Styrene-butadiene rubber (SBR) latex is the most common polymer in aqueous dispersions suitable for admixing in cement-based materials. It allows the designing of structures with specific properties for a variety of applications. The analysis of literature sources has shown that different properties of SBR latex-modified cement-based material samples reported were usually measured at 3, 7, 14, and 28 days of hardening. In this research, the authors decided to investigate a combined effect of high early strength Portland cement, characterized by an increased hydration rate, and SBR latex able to retard this process for a prolonged hardening period-up to 90 days in modified mortar samples. This study covers the results of the effect of different amounts of SBR latex (5%, 10%, 15%, and 20%) on the properties of modified mortar samples with a constant water-to-cement ratio prepared with high early strength Portland cement 42.5 R. The mortar samples were prepared from local raw materials produced by the Lithuanian companies. The properties, such as dry bulk density, ultrasonic pulse velocity, capillary water absorption, compressive and flexural strengths, and toughness, after three different hardening periods (7, 28, and 90 days) of the mortar samples were investigated. The applied mathematical-statistical methods allowed a detailed prognosis of the dependence between the dry bulk density and the strength properties of modified mortar samples. The combination of 42.5 R strength class Portland cement with the SBR latex in amounts ranging from 5% to 20% seems to be suitable for designing durable structures with specific properties.

Shielding the Hägg carbide by a graphene layer for ultrahigh carbon efficiency during syngas conversion

Fischer-Tropsch synthesis represents a key endeavor aimed at converting nonpetroleum carbon resources into clean fuels and valuable chemicals. However, the current state-of-the-art industrial FTS employing Fe-based catalysts is still challenged by the low carbon efficiency (<50%), mainly attributed to the prominent formation of CO2 and CH4 resulting from the nonregulated side water gas shift reaction. Herein, we describe a shielding strategy involving the encapsulation of the active Hägg carbide (χ-Fe5C2) by a graphene layer, exhibiting excellent resilience under reaction conditions and exposure to air, thereby eliminating the need for reduction or activation before the Fischer-Tropsch synthesis reaction. The graphene layer helps to stabilize the Hägg carbide active phase, and more importantly, greatly suppresses the side water gas shift reaction. Theoretical calculations suggest that graphene shielding inhibits the water gas shift reaction by reducing the absorption strength of OHx species. Remarkably, the optimum χ-Fe5C2@Graphene catalyst demonstrates a minimized CO2 and CH4 formation of only 4.6% and 5.9%, resulting in a high carbon efficiency (ca. 90%) for value-added products. These results are expected to inspire unique designs of Fe-based nanocomposite for highly efficient FTS with regulated carbon transfer pathways.