Reduced Water Absorption Research Articles

Quality of complete feed wafer supplemented with different plant protein sources for small ruminants

<p class="MDPI17abstract"><strong><span lang="IN">Objective:</span></strong><span lang="IN"> This study aimed to assess the quality of complete feed wafers with different plant protein sources for a feed of small ruminants.</span></p><p class="MDPI17abstract"><strong><span lang="IN">Methods:</span></strong><span lang="EN">The research was conducted in May-September 2022. The research method used a completely randomized design (CRD) with 4 treatments and 4 replications. </span><span lang="IN">The method used in this study was Completely Randomized Design (CRD) with 4 treatments, namely R0 = Wafer with an animal protein source (Fish meal) (Control), R1 = Wafers with protein source <em>Sesbania grandiflora</em>, R2 = Wafers with protein source <em>Gliricidia sepium</em>. R3=Wafer with protein source <em>Leucaena leucocephala</em>.</span><span lang="EN">The research variables consisted of physical quality (moisture content, wafer density, specific gravity, water absorption) and nutritional quality (dry matter, organic matter, crude protein, crude fat, crude fiber, and nitrogen free extracts). Data analysis according to the Analysis of Variance procedure using SPSS version 21.</span></p><p class="MDPI17abstract"><strong><span lang="IN">Results:</span></strong><span lang="EN">The results showed that the use of plant protein sources had no significant effect (P>0.05) on water content and wafer density but had a significant effect (P<0.05) on specific gravity and water absorption capacity. The use of plant protein sources can increase the value of water content, wafer density, and specific gravity and reduce water absorption capacity. Meanwhile, the crude protein (CP) content of the wafer had no significant effect (P>0.05) and produced the same value as using fish meal. Other nutritional variables had a significant effect (P<0.05) such as DM, OM, EE and NFE which increased and CF decreased on the use of plant protein sources in making feed wafers compared to the use of fish meal.</span></p><p><strong><span lang="IN">Conclusions:</span></strong><span lang="IN"> It was concluded that the use of legumes <em>Sesbania grandiflora</em>, <em>Gliricidia sepium</em></span><em><span lang="EN-US">,</span></em><span lang="IN"> and <em>Leucaena leucocephala</em> as a source of vegetable protein in wafers could replace fish meal. The three types of legumes </span><span lang="EN-US">had</span><span lang="IN"> the same effect on the physical and nutritional quality of the resulting product</span><span lang="EN-US">.</span></p>

Sustainable road paving: Enhancing concrete paver blocks with zeolite-enhanced cement

Abstract The present investigation assesses the impact of zeolite-enhanced sustainable cement (ZESC), a product achieved through the blending and grinding of clinker, gypsum, and varying percentages of natural zeolite (6, 10, and 15%). While the existing research has mainly concentrated on substituting ordinary Portland Cement with natural or synthetic zeolite, a critical research gap persists in using this manufactured cement in nontraditional building materials. Addressing this gap, our investigation assesses the durability and mechanical properties of concrete paver blocks manufactured by ZESC, particularly crucial for road paving applications. Comprehensive evaluations of hardened properties were conducted, including compressive strength, splitting tensile strength, abrasion resistance, and water absorption. In addition, the impact of ZESC on the fresh properties of concrete paver blocks was examined. The findings reveal that a 15% N.Z. inclusion in ZESC production results in an optimal mix design, leading to a remarkable increase in compressive strength and splitting tensile strength by 24 and 25%, respectively. It reduces water absorption and abrasion resistance by 80 and 7.8%, respectively, compared to O.P.C. cement concrete paver blocks. It is noteworthy that the addition of natural zeolite to ZESC mixtures led to an increased water demand. Notably, the integration of natural zeolite significantly reduces the environmental impact of cement production, promoting a sustainable shift by minimizing cement clinker. The study employs microstructural analysis, supported by scanning electron microscopic images, revealing a significant reduction in microcracks and enhanced cohesiveness, particularly at the aggregate-cemented paste interface in ZESC mixes.

Effect of seawater aging on mechanical, buckling, structural, and thermal properties of nano Al2O3 and TiO2‐doped glass‐epoxy nanocomposites

AbstractEnsuring the stability of composite structures in the marine environment is crucial. The harsh and corrosive nature of marine conditions presents unique challenges, making maintenance a top priority. In this study, the impact of seawater aging on the mechanical, buckling, structural, and thermal properties of glass fiber‐reinforced polymer nanocomposites was investigated. Composites were produced using the VARTM method with 2% nano Al2O3 and 2% nano TiO2. Aging was conducted in a seawater environment at room temperature for 120, 240, and 360 days. Mechanical properties, including tensile, compressive, flexural, impact, and buckling tests, were performed, and water absorption was determined. Structural analysis was carried out using SEM images. The experimental results indicated that the presence of nanoparticles minimized the effect of seawater. TiO2 preserved tensile strength by 10.33%, impact energy by 6.8%, and critical buckling load by 3.06% compared to the pure composite. Al2O3 reduced water absorption to 0.594% and preserved tensile strength by 6.67%, impact energy by 4.02%, and critical buckling load by 2%. Thermal test revealed an increase in thermal conductivity with aging, with the TiO2‐doped composite exhibiting the smallest increase (14.66%). The significance of the obtained results was confirmed through ANOVA analysis.Highlights Glass fiber‐reinforced nanocomposite was produced with nano Al2O3 and TiO2. The effect of seawater aging was investigated. It showed that TiO2 nanoparticles are a good candidate against seawater aging. The experimental results showed statistical significance.

Improvement on Strength, Durability, and Crack Closure Behavior of Bacteria Concrete under Marine Soil Exposures

Abstract In the concrete industry, bacteria-precipitated calcium carbonate (CaCO3) can be used to repair cracks. If cracks in concrete are not repaired in a timely manner, other durability problems arise, necessitating expensive crack repair methods. Bacteria can be isolated from an appropriate physical environment so that they continue to function effectively in concrete. In this study, suitable self-healing bacteria are isolated from a concrete dump yard and incorporated into concrete specimens. After 3 days of normal curing, the specimens were pre-cracked and kept in marine exposure conditions for a period of 56 days. Strength and durability properties such as compressive strength regain, ultrasonic pulse velocity (UPV), and dynamic Young’s modulus were studied, and a water absorption test was carried out for cubes exposed in marine soil conditions. Marine soil treated with a bacteria and nutrient solution (1:9) exhibited improved crack-healing behavior as well as increased strength and durability. Compressive strength regain of 45.98 %, an increased modulus of 54.04 %, and crack healing of 83.05 % were reached with a 60 % reduction in water absorption and 32.49 % increment in UPV values. A microstructure study demonstrates the presence of CaCO3 compounds in healed crack surfaces and treated marine soil, which is primarily due to bacterial action under marine exposures conditions.

Effect of recycled aggregate treatment methods by pristine graphene on mechanical and durability properties of concrete

Using recycled concrete aggregates (RCAs) in concrete is a promising approach to minimise the environmental impacts associated with construction and demolition waste while simultaneously enhancing the sustainability of concrete. Improving the quality of RCAs is crucial for promoting confidence among materials suppliers and systematic utilisation of RCAs in construction. Pristine graphene (PG) suspensions (0.1% and 0.2% concentrations in water) were investigated for improving the properties of RCAs and thereby improving the mechanical and durability properties of concretes made with 100% RCAs as coarse aggregates. Two PG treatment methods were used – spraying and soaking. Nano-silica (NS) suspensions of the same concentrations were also used for comparison. Tests for axial compressive, splitting tensile and flexural strengths were performed; water absorption and drying shrinkage were also assessed. Microanalysis was conducted using scanning electron microscopy and micro computed tomography. PG was found to be more effective than NS for increasing strength properties and reducing water absorption and drying shrinkage of concrete due to its lower porosity. For a given nanomaterial concentration and type, concretes made with soaked RCA exhibited higher strengths and lower water absorption and drying shrinkage than concretes with sprayed RCA. The concretes made with soaked RCA also had lower porosity and fewer microcracks. The results are promising and indicate that treating RCAs reduces their water absorption, thereby improving concrete performance.

Sustainable Construction through Waste Transformation: An Investigation into Bricks Made from Biomedical Waste

Abstract: This study explores the innovative use of biomedical waste, including sterilization wrap, plastic syringe components, medical glass, and mixed biomedical waste, as alternative raw materials in the production of sustainable bricks. Given the environmental and health risks associated with the disposal of biomedical waste, repurposing these materials for brick manufacturing presents a viable solution for waste management and sustainability in construction. Through chemical analysis, particle size distribution evaluation, and testing of physical and mechanical properties, this research assesses the feasibility and impact of incorporating various ratios of biomedical waste into bricks. The results indicate that certain biomedical wastes, particularly medical glass, can enhance the bricks' compressive strength and reduce water absorption, making them comparable or superior to traditional bricks. This study not only highlights the potential for reducing landfill use and environmental pollution but also contributes to the development of eco-friendly building materials. Future work will focus on optimizing material mixtures, evaluating long-term performance, and assessing the environmental impact of these sustainable bricks. This research underlines the importance of interdisciplinary approaches in addressing environmental challenges, offering a promising avenue for waste management and sustainable construction practices.

Physical Properties of Polymer Concrete Utilizing Pahae Natural Zeolite, Corn Husk Fiber, and Polyurethane Resin Adhesives

This study aimed to determine the optimum composition in the manufacture of polymer concrete using Pahae natural zeolite, corn husk fiber, and polyurethane resin adhesives. This study used the hot-press method at 170℃ for 30 minutes. The compositions of zeolite and corn husk fiber tested were varied under three different additions of polyurethane resin of 15 g, 20 g, and 25 g, while the composition of sand was fixed at 60 g. The inclusion of corn husk fiber content reduces the density of the concrete and increases the porosity and water absorption. The physical properties analysis showed that the polymer concrete samples showed the highest density was 1.89 g/cm3 from 20 g of polyurethane resin and no addition of corn husk fiber; the highest porosity was 6.15% from 15 g of polyurethane resin and 10 g of corn husk fiber; and the highest water absorption was 5.85% from 15 g of polyurethane resin and 10 g of corn husk fiber. Because improved material quality and durability are linked to reduced water absorption rates in polymer concrete, the most favorable composition with minimal water absorption (0.51%) came from the sample utilizing 20 grams of polyurethane resin without incorporating corn husk fiber.

Experimental Study on Mechanical and Durability Behaviour of a Sustainable Masonry Block Incorporating Agricultural and Industrial Wastes

Objectives: The production of conventional cement blocks consumes significant amount of cement. The production of cement, involves significant energy consumption and releases carbon dioxide emissions, contributing to carbon footprint. However, advancements in sustainable masonry block production have been made to minimize these drawbacks. Hence, this research aims to develop a sustainable masonry solid block by incorporating Rice Husk Ash (RHA) and Flay Ash (FA). Methods: The manuscript discusses the mechanical and durability properties of sustainable masonry block and comparing the result with the conventional cement blocks. The materials used are FA, Lime, Gypsum, RHA, Marble Dust Powder (MDP), Stone Quarry Dust (SQD). The solid blocks tested for Compressive strength, Density, Water absorption, Initial rate of water absorption, efflorescence, and chemical resistance. Findings: The results showed that, the addition of RHA, FA, and MDP enhanced the compressive strength of the solid blocks upto 46% when compared to convention cement block. A density reduction of 2.5% was achieved. It also exhibited a reduction in water absorption of 29.2%. IRA tests evident that the sustainable solid blocks shows reduced water absorption levels at both the one-minute and two-minute time intervals in comparison to conventional cement solid blocks. At a one-minute time, the rate of absorption for M4 is 69% lower when compared to conventional cement solid blocks. The RHA, FA and MDP admixed blocks showed better durability properties in terms of efflorescence, and chemical resistance. Novelty : This solid block production method is an innovative methodology that supports the conservation of natural resources, reduces pollution, and preserves the environment. As a result, it encourages the advancement of eco-friendly technology. Keywords: Sustainable building blocks, Fly ash, Lime, Rice husk ash, Marble dust, Stone quarry dust

Novel multifunctional nanocomposites containing graphitic carbon nitride/silanized Nb2O5 nanofillers for the protection of steel surfaces in the automobile industry

The inorganic nanofiller niobium pentoxide (Nb2O5) was altered with [3-(2-aminoethylamino)propyl]trimethoxysilane (AEPS) and the resulting AEPS/Nb2O5 was encased with graphitic carbon nitride (GCN) in pure epoxy resin (EP). The protection performance of mild steel coated with epoxy in the presence of various concentrations of GCN encapsulated in silanized Nb2O5 was investigated using electrochemical techniques in a marine environment. A limiting oxygen index (LOI) test showed that GCN/AEPS-Nb2O5 considerably enhanced the flame retardancy properties of the epoxy coating. The PHRR and THR values for EP-GCN/AEPS-Nb2O5 significantly decreased by 81 % and 69 %, respectively, compared to those of pure EP, showing that the material is more flame-retardant. The results of salt spray tests showed that the addition of GCN/AEPS-Nb2O5 enhanced corrosion protection and reduced water absorption. Even after 960 h of exposure to seawater, epoxy-GCN/AEPS-Nb2O5 exhibited increased coating resistance of 8.99E9 Ω.cm2, according to the EIS measurements. According to SECM research, coated steel made of the EP-GCN/AEPS-Nb2O5 nanocomposite has the lowest degree of ferrous ion dissipation (1.0 I/nA). According to the FE-SEM/EDX results, the decomposition products of silanized GCN were enhanced, generating a sturdy inert nanolayered coating. To prevent ions from penetrating the specimen, EP-GCN/AEPS-Nb2O5 crystallizes into a strong, inert coating, has greater adhesive strength, and can endure prolonged immersion without losing its integrity. Therefore, the EP-GCN/AEPS-Nb2O5 nanocomposite could act as a viable coating component in the automobile industry.

Mechanical characterization of novel Parthenium hysterophorus and Jute reinforced polymer matrix composites for light weight medium load applications and application of MADM-VIKOR approach

This study explores the use of natural fibers in composite materials to enhance mechanical properties and reduce water absorption for lightweight medium load applications. The approach involves hybridizing Parthenium hysterophorus (PH) and Jute with epoxy L-12 matrix in different stacking sequences to create four tri-layer composites. Mechanical tests following ASTM standards revealed that composites with Jute fibers on top and PH fibers in the middle exhibit superior mechanical performance and reduced water absorption, making them suitable for such applications. The tensile strength of composite (CP4) with PH fiber at center and Jute fibers at extreme was found to be 1.7 times higher compared to composite with all three layers of PH fiber (CP1). Similarly, the flexural strength and compressive strength of CP4 is found to be 60% and 80.5% more compared to CP1. Shore D hardness of CP4 is found to be 1.29 times better compared to CP1. Whereas the energy absorption due to impact load of CP1 is better compared to its counter parts wit CP1 exhibiting 71.15 times better compared to CP4. Scanning electron microscope (SEM) analysis of fractured surfaces provides insights into fiber bonding and fracture mechanisms. Overall, this research underscores the potential of natural fiber hybrid composites for improved mechanical characteristics and water resistance in various applications, highlighting specific fiber combinations and stacking sequences.

Ultrasonic cavitation erosion of CFRP composites

To date, cavitation erosion of carbon fibre reinforced polymer (CFRP) composites has attracted only limited scientific attention. This paper investigates this knowledge gap through a series of experiments, in which unidirectional and bidirectional (2x2 twill) CFRP composites were exposed to cavitation clouds produced by an ultrasonic transducer in distilled water. Both composites were bonded with epoxy resin. Cavitation erosion tests were conducted according to the ASTM G32-16 standard using a stationary specimen method. The effect of water absorption on monitoring erosion damage was studied using saturated and dry specimens. Specimen mass loss measurements and microscopy observations were done at regular intervals throughout testing. Erosion imprint topographies were studied using X-ray computed microtomography. Three distinct erosion stages were identified from the erosion process observations. Nonuniformities in surface geometry and properties facilitated nucleation and accelerated local erosion. Surface epoxy thickness, fibre diameter and packing, and thickness and layup of fibre bundles influenced the erosion process. The erosion mechanisms included cracking and debonding of epoxy, and tunnelling and trenching in fibre bundles. Research findings indicated that the composite internal structure can potentially be designed for reduced water absorption and increased erosion resistance. Acoustic impedance was most efficient in predicting material response to cavitation erosion.

Comparative Analysis of Two Different Combinations of Pretreatment Methods for Treating Recycled Concrete Aggregates

Objectives: This research is aimed at comparing the performance of two sets of treatments. The first set of treatments tests the performance of heated, abrasioned, and fly ash-treated recycled concrete aggregates (RCA), while the other set of treatments examines the performance of heated, abrasioned, and silica fume-treated aggregates. Though previous research has examined the performance of the standalone treatment methods for enhancing RCA properties, there is a research gap that attempts to study the performance of the combinations of various treatments and their merits. To bridge the gap in the literature, this study compares the combination of two sets of treatment methods to investigate the relative effectiveness of the combination of the treatment methods that can improve RCA properties. Methods: The study was conducted using the concrete mix design procedure outlined in IS 10262-2019 in the laboratory. As part of the experimentation program, a total of 24 sample cubes were casted and tested. Findings: A 14.5% reduction in water absorption was observed for 10mm heated, abrasioned, and fly ash-treated aggregates, whereas a 15.2% reduction in water absorption was observed for 20mm heat-treated, abrasioned, and fly ash-treated aggregates compared to untreated aggregates. Similarly, for heat-treated, abrasioned, and silica fume-treated aggregates, a 41.7% reduction in water absorption was observed for 10mm aggregates, and a 45% reduction was observed for 20mm aggregates over untreated aggregates. A 133% increase in slump value was observed for heated, abrasioned, and fly ash-treated aggregates, whereas a 150% increase in slump value was observed in the case of heated, abrasioned, and silica fume-treated aggregates. Further, a 150 % increase in compressive strength was observed for heated, abrasioned, and fly ash-treated aggregates, and a 165% increase in compressive strength was observed for heated, abrasioned, and silica fume-treated aggregates over untreated aggregates. Novelty: This research addresses the ninth United Nations Sustainability Development Goal, i.e., Industry, Innovation, and Infrastructure, as it promotes the use of eco-friendly construction practices. Moreover, the present research offers a manifold contribution to the state-of-the-art literature on construction management and offers numerous implications for the construction industry. Keywords: Recycled concrete aggregates, Silica fume treatment, Fly ash treatment, Water absorption, Workability, Compressive strength

Enhancing Water Resistance in Foam Cement through MTES-Based Aerogel Impregnation.

The propensity of foamed concrete to absorb water results in a consequential degradation of its performance attributes. Addressing this issue, the integration of aerogels presents a viable solution; however, their direct incorporation has been observed to compromise mechanical properties, attributable to the effects of the interface transition zone. This study explores the incorporation of MTES-based aerogels into foamed cement via an impregnation technique, examining variations in water-cement ratios. A comprehensive analysis was conducted, evaluating the influences of MTES-based aerogels on the thermal conductivity, compressive strength, density, chemical composition, and microstructure of the resultant composites across different water-cement ratios. Our findings elucidate that an increment in the water-cement ratio engenders a gradual regularization of the pore structure in foamed concrete, culminating in augmented porosity and diminished density. Notably, aerogel-enhanced foamed concrete (AEFC) exhibited a significant reduction in water absorption, quantified at 86% lower than its conventional foamed concrete (FC) counterpart. Furthermore, the softening coefficient of AEFC was observed to surpass 0.75, with peak values reaching approximately 0.9. These results substantiate that the impregnation of MTES-based aerogels into cementitious materials not only circumvents the decline in strength but also bolsters their hydrophobicity and water resistance, indirectly enhancing the serviceability and longevity of foamed concrete. In light of these findings, the impregnation method manifests promising potential for broadening the applications of aerogels in cement-based materials.

Monitoring Changes in the Jakarta Flood Disaster with Using Sentinel 2A Imagery

DKI Jakarta Province is one of the provinces in Indonesia with a relatively high incidence of flooding since its establishment in the Dutch East Indies era because geomorphologically Jakarta is a floodplain area. On the other hand, land pressure by increasing urbanization in the city of Jakarta results in the increasingly limited availability of decent housing land for the community so that lands that should be water catchment areas and riverbanks are transformed into densely populated flying areas which ultimately reduces water absorption capacity in the Jakarta area. To obtain fast data in identifying flood-affected areas, the technique of identifying the potential extent and distribution of flooding by utilizing the remote sensing NDWI (Normalized Difference Water Index) method and/or using the Modified Normalized Difference Water Index (MNDWI) method from the free data Sentinel 2A satellite can be useful to provide data input to relevant parties in DKI Jakarta Province. Opportunities and constraints The application of NDWI and/or MNDWI techniques will greatly assist mapping activities and identification of the distribution of flood areas as an alternative input to policymakers for action and anticipation of areas with high flood potential. This research is one of the first steps and input to the DKI Jakarta Government in making strategies and roadmaps for flood mitigation in DKI Jakarta.

Durability, Capillary Rise and Water Absorption Properties of a Fiber-Reinforced Cement-Stabilized Fly Ash–Stone Dust Mixture

The management of unutilized fly ash poses challenges due to concerns about storage and its potential groundwater contamination. Within the road industry, where the bulk utilization of fly ash is feasible, its unsuitability for use in the base and sub-base layers of pavements due to its low strength and a high proportion of fine particles has been a limitation. The incorporation of stone dust alongside fly ash, treated with lime or cement, yields superior strength and stiffness. Apart from strength, the stabilized mix’s durability, capillary rise, and water absorption properties are crucial for determining its suitability for pavement applications. Observations from this study reveal that fiber-reinforced cement-stabilized fly ash–stone aggregate specimens treated with 4% and 6% cement, with and without fibers, met the limiting mass loss of 20%, as specified in IRC SP: 89. The mass loss decreases with an increase in cement and fiber content. However, the capillary rise in the mixes increases with a higher percentage of fly ash and fiber content but decreases with increased cement content. Cement addition results in a reduction in water absorption; however, the addition of fibers results in an increase in water absorption. A linear correlation has been established between mass loss and UCS and IDT, which can be used to evaluate the suitability of materials for the structural layer without conducting a wet–dry durability test, which typically takes one month. This study proposes that cement-stabilized fly ash and stone aggregate mixtures with 4% and 6% cement can be used as the subbase and base of pavement based on wet–dry mass loss criteria and water absorption criteria. Observations from this study reveal that fiber-reinforced cement-stabilized fly ash–stone aggregate specimens treated with 4% and 6% cement, with and without fibers, met the limiting mass loss of 20%, as specified in IRC SP: 89. The mass loss decreases with an increase in cement and fiber content. However, the capillary rise in the mixes increases with a higher percentage of fly ash and fiber content but decreases with increased cement content. Cement addition results in reduction in water absorption. However, the addition of fibers results in increase in water absorption. A linear correlation is established between mass loss and UCS and IDT, which can be used to evaluate the suitability of materials for the structural layer without conducting wet–dry durability tests, which take one month. This study proposes that cement-stabilized fly ash and stone aggregate mixtures with 4% and 6% cement can be used as the subbase and base of pavement based on wet–dry mass loss criteria and water absorption criteria.

Effect of vacuum–vibration–compaction molding on the properties and performances of polymer-modified cementitious material

The addition of polymers to cementitious materials can significantly enhance the water resistance of building structures operating under complex environments. The organic-inorganic cross-linked network established between the functional groups of polymers and inorganic materials significantly influences the properties of the matrix material. However, the gas-entrapping effect of polymers can have a detrimental effect on the pore structure of the paste, and the degree of organic-inorganic chemical reaction can impose a limitation on the use of polymers in cementitious materials. In this study, the vacuum-vibration-compaction (VVC) molding method was employed to improve the pore structure of the cement paste and to encourage organic-inorganic chemical reactions. The addition of the polymer did not significantly harm the pore structure compared to the paste obtained through the ordinary molding method. Consequently, in the VVC molding method, the addition of 5 wt% polymer significantly raised the content of Ca(COOH)2, a product of organic-inorganic chemical reaction, by 40.1 % and amplified the molecular chain length of the C–S–H structure by 39.0 % compared to the ordinary molding method. Furthermore, the polymer reduced water absorption by up to 66.0 %. Therefore, the VVC molding method can enhance waterproof of cementitious materials more efficiently with the use of polymers.

Laboratory evaluation of a complex treatment technology for reducing water absorption of the pavement subbase aggregate from the blast-furnace slag

When smelting each ton of pig iron, approximately 500 kg of blast-furnace slag is formed and requires recycling. Air-cooled blast-furnace slag can be used for the manufacture of slag aggregate for the pavement subbase layers, as an alternative to natural stone aggregate. The wide use of slag in this area is limited by its high water absorption. This paper proposes a complex technology to reduce water absorption of slag aggregate. This technology includes selective crushing, which allows separating low-porosity aggregate grains from high-porosity ones, and impregnation of selected low-porosity grains with hydrophobic agent (surface hydrophobization). The results of a laboratory evaluation of this technology effectiveness are presented. Article also contains optimal parameters of this complex technological process which allowed to reduce the water absorption of the slag aggregate from 4.54% to 1.05%.

Assessment of mechanical and durability performance of silica fume and metakaolin as cementitious materials in high-performance concrete

AbstractThe present study aims to determine the effects of blending cementitious materials on the mechanical and durability properties of high-performance concrete (HPC). Densified silica fume and fine-grounded metakaolin are used as supplementary cementitious materials (SCMs). A total of 16 mixes containing both binary and ternary blending of SCMs were chosen for w/b ratios of 0.4 and 0.3 respectively. The hardened properties tested for the HPC mixes were compressive strength at 7, 28, and 90 days, flexural strength at 28 days, and modulus of elasticity at 28 days. Maximum strength gains up to 15%, 38%, and 23% for compression, flexure, and elastic modulus were observed in ternary mixes compared to binary mixes. Stress-strain behaviour of ternary mixes indicates increased tolerance of stress for the least amount of strain in the specimens. Based on the experimental results, empirical relations were developed and checked with the existing codes and by earlier researchers. The durability properties tested for HPC were water absorption at 28 days, acid attack, and sulphate attack at 28, 56, and 90 days. Ternary mixes improved the pore structure of HPC, resulting in a 56% reduction in water absorption and a 34% reduction in compressive strength loss due to immersion in 5% H2SO4 at 90 days. The findings of the study endorse that ternary blending of SF and MK can improve the engineering properties of HPC, and a mix containing SF 10% and MK 10% is recommended for the best results.

Developments of terahertz metasurface biosensors: A literature review

Abstract Terahertz metasurface (THz-MS) biosensor is a hybrid technology that combines terahertz time-domain spectroscopy and metasurface for the detection of biomolecules and cells. Compared with traditional strategies, it is label-free, non-invasive, time-saving, and easy to operate. However, three fundamental issues, namely, low sensitivity, low specificity, and drastic water absorption, hinder the development of THz-MS biosensors for clinical application. Recently, numerous studies of THz-MS biosensors have been performed to solve these problems, and the results show great potential for the sensitive detection of nucleotides, proteins, and cells. Therefore, it is important to summarize the development of THz-MS biosensors in biomedical detection. In this review, we summarized the mechanism, manufacturing, and implementation of THz-MS biosensors. Then, strategies to improve the sensitivity, selectivity, and means to reduce water absorption are presented. Sensitivity can be improved by suppressing electromagnetic radiation and strengthening the interaction between target molecules and meta-atoms. Antibodies and aptamers are the most effective strategies for improving specificity. Microfluidics and hydrogels are two potential ways to reduce the water absorption. Subsequently, the applications of the THz-MS biosensors for the detection of nucleotide, proteins, and cells are summarized. Finally, the prospects for the future development of THz-MS biosensors are outlined.

Gamma radiation impact on dielectrics and RH sensitivity of nylon–carbon–GNP–epoxy composites

AbstractComposites of carbon–graphene nanoplatelets (GNP) epoxy with nylon‐66 interleaving were fabricated and investigated to understand the impact of γ‐irradiation on their dielectrics and relative humidity (RH) sensitivity by capacitance and water absorption measurements. The moisture sensitivity was investigated by measuring memory effect (hysteresis) and response time of the capacitance. Composites were γ‐irradiated at doses of 1000 and 3000 kGy and studied by the same set of measurements. X‐ray diffraction analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy were used to understand the impact of γ‐irradiation on the morphology and surface roughness of the composites. Results of these measurements suggest that 3000‐kGy dose γ‐irradiation produces good chain scission and cross‐linking, resulting in reduced water absorption and a 360% increase in capacitance values. The sensitivity of capacitance for 3000‐kGy γ‐irradiated composite was found to be highest at 40 pF/%RH, and hysteresis was 1.8% RH and not observed in non‐irradiated composites. Based on these observations, it seems that 3000‐kGy γ‐irradiated composite could be a potential candidate for moisture content diagnostics during condition monitoring of the carbon–epoxy structures in several industrial applications and needs to be further investigated.Highlights Composites of carbon–GNP epoxy with nylon‐66 interleaving were γ‐irradiated. 3000‐kGy dose γ‐irradiated composites exhibit 360% increase in capacitance. Sensitivity and hysteresis were higher than those of 1000‐kGy and non‐irradiated samples. Good chain scission and cross‐linking resulted in reduced water absorption.