Voids identification in rubberized mortar digital images using K-Means and Watershed algorithms

Investigation of mechanical properties of PVA fiber-reinforced cementitious composites under the coupling effect of wet-thermal and chloride salt environment

The limited availability of natural resources, such as sand, and the need to reduce CO2 emissions, which are produced in large quantities in the production of binding materials, indicate the need to look for alternative raw materials used in construction materials. At the same time, there is a strong need to utilise waste packaging materials, the global production of which is constantly increasing. This work aims to investigate the possibility of using recycled polyethylene terephthalate (PET), utilised as a partial substitute for fine aggregate, and waste glass, implemented as powder, serving as a partial substitute for cement in the manufacturing of the cementitious composites. An experimental study was carried out to evaluate the physical and mechanical properties of the resultant cementitious composites. The incorporated PET aggregate comprised 0%, 5%, and 10% by volume of silica sand and 0%, 10%, and 20% glass powder by weight of cement. The addition of waste raw materials augmented the flow of fresh mortars, predominantly subsequent to the introduction of PET recyclate. The deployment of artificial aggregate in mortars induces a decrease in the volumetric density. Concurrently, the mechanical properties of mortars enriched with waste materials exhibited a reduction, in terms of both compressive and flexural strength, with the detriment escalating in conjunction with the content of waste raw materials. An analysis of statistical significance of effects, grounded in an analysis of variance, is delineated within this document, pinpointing the quantities of waste raw materials that can be assimilated in mortars without inducing a substantial deterioration of strength properties. Through studies on phase composition, it has been demonstrated that the utilised glass waste, possessing a grain size analogous to cement, exhibited poor pozzolanic properties. The test results indicate that it is possible to partially replace cement with glass powder, up to 10%, and fine aggregate with PET waste, up to 5%, without a significant reduction in the mechanical properties of the material.

Cementitious composites are porous material having complex structure system consist of hydration products, un-hydrated cement particles and pore solutions of various scales. Calcium carbonate whisker is a new type of low cost micro-scale filler fiber gaining popularity in the field of construction materials. However, addition of whisker has effect on physical, mechanical and microstructural characteristics of cementitious composites. Also, the low production cost of whisker will make the use of micro fiber more extensive in large scale construction projects. In this study, the effect of calcium carbonate whisker on physical, mechanical and microstructural properties of cementitious composites with different fiber contents are investigated. The fluidity, drying shrinkage, pore structure, impact resistance, compressive, flexural and splitting-tensile strength of whisker-mortar are considered. The scanning electron microscopy analysis is also performed to examine the microstructural and toughening mechanism of whisker reinforced composites. It was concluded that the addition of calcium carbonate whisker up to 10 % improves the physical and mechanical properties of cementitious composites and is suggested to be the optimize content. The calcium carbonate whisker also resists the crack propagation at micro scale and showed the toughening mechanism with better interfacial properties between whisker and matrix.

The characterization of microstructures in medical electrode materials is crucial for understanding their performance and functionality. Imaging with a Scanning Electron Microscope (SEM) delivers visual data with high resolution. However, manual fiber measurement using ImageJ is time-consuming and prone to inconsistent calculations. This study explores and compares the potential of three Artificial Intelligence (AI) or Python-based techniques in image processing, including Otsu thresholding, K-means clustering, and the U-Net deep learning model, to automate the microstructure analysis of conductive polymer composite materials used in biomedical electrodes. The methodology applied involves applying each technique to SEM images and comparing fiber width measurements obtained from ImageJ and SEM scale. The results are then evaluated based on fiber count and fiber width comparison. Preliminary findings indicate that deep learning approaches such as U-Net offer superior segmentation performance and fiber width measurement accuracy, with a significantly lower mean value of 10.70 μm compared to 16.58 μm in ImageJ and 17.02 μm in SEM. Meanwhile, classical methods such as Otsu and K-means remain computationally efficient alternatives. This comparative analysis highlights the strengths and limitations of each method and provides a foundational assessment for the development of more robust and automated SEM image analysis pipelines in biomedical materials research.

The growing environmental concern over waste tire accumulation necessitates innovative recycling strategies in construction materials. Therefore, this study aims to develop and evaluate sustainable concrete by integrating waste tire rubber (WTR) aggregates of different sizes and recycled waste tire steel fibers (WTSFs), assessing their combined effects on the mechanical and microstructural performance of concrete through experimental and analytical approaches. WTR aggregates, consisting of fine (0–4 mm), small coarse (5–8 mm), and large coarse (11–22 mm) particles, were used at substitution rates of 0–20%; WTSF was used at volumetric dosages of 0–2%, resulting in a total of 40 mixtures. Mechanical performance was evaluated using density and pressure resistance tests, while microstructural properties were assessed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The findings indicate systematic decreases in density and compressive strength with increasing WTR ratio; the average strength losses were approximately 12%, 20%, and 31% at 5%, 10%, and 20% for WTR substitution, respectively. Among the WTR types, the most negative effect occurred in fine particles (FWTR), while the least negative effect occurred in coarse particles (LCWTR). The addition of WTSF compensated for losses at low/medium dosages (0.5–1.0%) and increased strength by 2–10%. However, high dosages (2.0%) reduced strength by 20–40% due to workability issues, fiber clumping, and void formation. The highest strength was achieved in the 5LCWTR–1WTSF mixture at 36.98 MPa (≈6% increase compared to the reference/control concrete), while the lowest strength was measured at 16.72 MPa in the 20FWTR–2WTSF mixture (≈52% decrease compared to the reference/control). A strong positive correlation was found between density and strength (r, Pearson correlation coefficient, ≈0.77). SEM and EDX analyses confirmed the weak matrix–rubber interface and the crack-bridging effect of steel fibers in mixtures containing fine WTR. Additionally, a hybrid prediction model combining physics-informed neural networks (PINNs) and CatBoost, supported by data augmentation strategies, accurately estimated compressive strength. Overall, the results highlight that optimized integration of WTR and WTSF enables sustainable concrete production with acceptable mechanical and microstructural performance.

This study investigated Microbially Induced Calcite Precipitation (MICP) technology to improve the mechanical properties of cementitious composites containing incinerated sugarcane filter cake (IFC) using a calcifying bacterium Lysinibacillus sp. WH. Both IFC obtained after the first and second clarification processes, referred to as white (IWFC) and black (IBFC), were experimented. This is the first work to investigate the use of IBFC as a cement replacement. According to the X-ray fluorescence (XRF) results, the main element of IWFC and IBFC was CaO (91.52%) and SiO2 (58.80%), respectively. This is also the first work to investigate the use of IBFC as a cement replacement. We found that the addition of strain WH could further enhance the strength of both cementitious composites up to ~ 31%, while reduced water absorption and void. Microstructures of the composites were visualized using a scanning electron microscope (SEM). The cement hydration products were determined using X-ray diffraction (XRD) followed by Rietveld analysis. The results indicated that biogenic CaCO3 was the main composition in enhancing strength of the IBFC composite, whereas induce tricalcium silicate (C3S) formation promoting the strength of IWFC composite. This work provided strong evidence that the mechanical properties of the cementitious composites could be significantly improved through the application of MICP. In fact, the strength of IFC-based cementitious composites after boosting by strain WH is only 10% smaller than that of the conventional Portland cement. While using IFC as a cement substitute is a greener way to produce environmentally friendly materials, it also provides a solution to long-term agro-industrial waste pollution problems.

Mucoadhesive polymeric (carbopol 934) suspension of ciprofloxacin was prepared by ultrasonication and optimized with the aim of developing an oral controlled release gastro-retentive dosage form. The qualitative analysis of the formulation was performed by fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray powder diffraction (XRD), and scanning electron microscopy (SEM) analyses. FTIR (400 cm-1 to 4000 cm-1 region) and Raman (140 to 2400 cm-1 region) Spectroscopic studies were carried out and the spectra were used for interpretation. XRD data of pure drug, polymer and the formulation were obtained using a powder diffractometer scanned from a Bragg's angle (2θ) of 10° to 70°. The dispersion of the particle was observed using SEM techniques. The particle size distribution and aspect ratio of particles in the polymeric suspension were obtained from SEM image analysis. The results from FTIR and Raman spectroscopic analyses suggested that, in formulation, the carboxylic groups of ciprofloxacin and hydroxyl groups of C934 undergo a chemical interaction leading to esterification and hydrogen bonding. The XRD data suggested that the retention of crystalline nature of ciprofloxacin in the formulation would lead to increase in stability and drug loading; decrease in solubility; and delay in release of the drug from polymeric suspension with better bioavailability and penetration capacity. The SEM image analysis indicated that, in the formulation maximum particles were having aspect ratio from 2 to 4 and standard deviation was very less which provided supporting evidences for homogeneous, uniformly dispersed, stable controlled release ciprofloxacin suspension which would be pharmaceutically acceptable.

This study explores the potential of using sustainable materials in brick manufacturing by designing a novel brick mix in the laboratory, incorporating sand, lime kiln dust (LKD) waste, tyre rubber, and ground granulated blast furnace slag (GGBFS) waste. These cementless bricks blended LKD–GGBFS wastes as the binder agent and fine crumb rubber from waste tyres as a partial replacement for sand in measured increments of 0%, 5%, and 10% by volume of sand. Ordinary Portland cement (OPC) and fired clay bricks were sourced from the industry, and their properties were compared to those of the laboratory bricks. Tests performed on the industry and laboratory bricks included compressive strength (CS), freeze-thaw (F-T), and water absorption (WA) tests for comparison purposes. Additionally, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were performed on the bricks to assess the morphological and mineralogical changes responsible for the observed strengths and durability. The CS and WA values of the engineered bricks were 12, 6, and 4 MPa, and 7, 12, and 15%, respectively, for 0, 5, and 10% crumb rubber replacements. The industry bricks’ average CS and WA values were 13 MPa and 8%, respectively. From the results obtained, the green laboratory bricks passed the minimum strength requirements for load-bearing and non-load-bearing bricks, which can be used to construct small houses. Lastly, the engineered bricks demonstrated strength and durability properties comparable to those of the industry-standard bricks, indicating their potential as a sustainable alternative to help divert waste from landfills, reduce the pressure on natural fine sand extraction, and support eco-conscious brick production for a sustainable environment.

At present the disposal of waste tyre rubber (WTR) has become a major waste management problem in the world. Therefore in this study, polymer blended based on Polyethylene which is Low Density Polyethylene (LDPE) or High Density Polyethylene (HDPE), with Renewable Polymer (RP) and waste tyre rubber (WTR) is prepared via injection molding. Blended polymer such as LDPE/RP/WTR and HDPE/RP/WTR is known as LRT and HRT respectively. The preparation of polymer blend steps start with the preparation of RP. The RP is prepared by crosslinking the renewable monomer with Polymethane Polyphenyl Isocyanate (MDI) at composition ratio of 1:0.5. The second steps involved by adding 10 gm of liquid RP prepared earlier on with fixed amount of LDPE and HDPE of 100 gm. Then the blended LDPE/RP or HDPE/RP namely as LR or HR respectively is further added with WTR with different percentages ratio of 5 %, 10 % and 15 %. The manually blended polymer mixture and filler is then melt mixing using injection moulding to fabricate the tensile specimen for mechanical tensile test and physical determination such as density, distribution of WTR in polymer blend and surface fracture morphology using scanning electron microscope. The samples were then exposed to UV irradiation exposure in UV Accelerated Weathering for 500, 1000, 1500, 2000, 2500 and 3000 hours to evaluate the photostability of the polymer blends. The optimum amount of WTR ratio composition is at 5 % for both LRT and HRT blends which indicate the stability of polymer blends towards UV irradiation exposure at 1000 hours.

The utilization of waste rubber as a viable option for manufacturing building materials holds great significance for the sustainable development of the construction industry. This study explores the addition of two additives, fly ash (FA) and glass fiber (GF), to rubberized mortar in order to improve its performance. The impact of different waste rubber powder (RP) replacement rates and modified additive dosages on the performance of rubberized mortar, including fluidity, mechanical properties, drying shrinkage, impact resistance, and thermal insulation properties, was investigated. Furthermore, the analytic hierarchy process (AHP) was adopted to study the priorities of the rubberized mortar modified by FA and GF. The results indicate that the addition of RP leads to a decrease in mortar fluidity, mechanical properties, and drying shrinkage. However, it can enhance its impact resistance and thermal insulation properties. The additives, FA and GF, have a significant influence on the properties of rubberized mortar. By means of AHP method analysis, this study concludes that the optimal comprehensive properties of FA- and GF-modified rubberized mortar can be achieved by replacing 10% of sand with RP and using 10% FA and 0.4% GF. This study presents a configuration method for modified thermal insulation rubberized mortar, and it may lead to FA and GF being considered potential candidates for developing environmentally friendly building materials.

This paper presents a study on the mechanical properties of rubber mortar with the inclusion SBRL (butylbenzene latex) and PP (polypropylene) fiber and the microstructures of SBR latex modified mortar were analyzed. The results proved for specimens with 20 vol.% of rubber, when the P/C of SBR latex was 10%, the compressive and flexural strength of SBR latex modified rubber mortar was optimal. Besides, for specimens with 20 vol.% of rubber, the compressive and flexural strength of SBR latex and polypropylene fiber modified rubber mortar increased with the inclusion of polypropylene fiber, especially when the P/C of SBR latex was 10%. Through scanning electron microscope (SEM), it was founded that polymer has formed a consecutive reticulate film which has a toughening effect on cement matrix.

Theoretical analysis of dimensional measurements made using a scanning electron microscope (SEM) requires a raw image to be corrected for the probe shape of the incident electron beam. In this paper, an effective electron beam shape (EEBS), which differs from the Gaussian profile conventionally assumed in SEM image analysis, was studied using a Monte Carlo simulation method. A model of a focusing electron beam with finite width due to aberration was used in simulating the SEM image of gold particles on a carbon substrate. It was found that the EEBS is local to the electron beam landing position and deviates significantly from the Gaussian profile; it is strongly dependent on both the sample topography and the electron beam focusing condition.

Valorization of agricultural wastes is important both economically and environmentally. This study aimed to investigate the use of biochar as a filler to improve the mechanical properties of mortar and to help sequestrate CO2. The biochar was produced by pyrolysis of apricot kernel shell at 500 °C. Nanobiochar particles with dimensions less than 500 nm were obtained by high-energy ball milling process. Scanning electron microscope was used for determining the morphology of nanobiochar. The nanobiochar at different volume percentages [0.00-0.04-0.06-0.08-0.12-0.15%] was added to mortar. The mortar was casted into 40x40x160 mm molds. After water curing at 20°C for 28 days, compressive strength and flexural strength tests were performed. The mixture containing 0.04% nanobiochar by volume had an increase in flexural and compressive strengths by 5% and 15% respectively, while its fracture energies for flexure and compression increased by 98% and 38% respectively compared to the reference mortar. Furthermore, the mixture having 0.12% volume had an increase in flexural and compressive strengths by 32% and 11%, respectively, while the increase in fracture energies for flexure and compression was 52% and 25%, respectively, compared to the reference mortar. The mechanisms of nanobiochar effect on flow, strength, and fracture energy were enlightened. The nanobiochars bridge the cracks, divert the cracks, act as hydration nucleation sites, enhance the matrix by its porous structure, and developed internal curing that led to increase in strength and fracture energy. This study suggests that the biochar produced from the apricot kernel shell has the potential to be used as a carbon sequestering mixture to improve performance of mortar and thereby utilizing waste as a construction material, contributing to the economy and environment.

The increasing production of solid waste and the scarcity of natural aggregates as a matter of fact have made waste recycling a necessity. One such waste, which is generated in large quantities, is slag. However, slag from incineration plants may contain harmful elements that adversely affect the physical, chemical and mechanical properties of cement composites. This study presents laboratory research results on the effect of slag from the Poznan Municipal Waste Thermal Conversion Plant (Poland) on the physicochemical properties of cement composites. The samples were analyzed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It was shown that the slag analyzed contained significant amounts of aluminum, which had a direct effect on the structure of the concrete. An example of this influence is the release of hydrogen during reactions, which causes swelling and cracking of the concrete and reduces its mechanical strength. The authors emphasize that waste aggregate (slag) can be effectively used in the production of concrete after appropriate processing that reduces the risk of adverse effects.

Sustainability is becoming a priority for developers and the use of environmentally friendly materials is increasing. Nowadays, the application of raw materials from renewable sources to building materials has gained a significant interest in this research area. Lignocellulosic aggregates and cellulosic fibers are coming from many different sources such as wood, plants and waste. They are promising alternative materials to replace synthetic, glass and asbestos fibers as reinforcement in inorganic matrix of composites. Natural fibers are renewable resources so their cost is relatively low in comparison to synthetic fibers. With the consideration of environmental consciousness, natural fibers are biodegradable so their using can reduce CO<sub>2</sub> emissions in the building materials production. The use of cellulosic fibers in cementitious matrices have gained importance because they make the composites lighter at high fiber content, they have comparable cost - performance ratios to similar building materials and they could be processed from waste paper, thus expanding the opportunities for waste utilization in cementitious materials. The main objective of this work is to find out the possibility of using different wastes: hemp hurds as waste of hemp stem processing and recycled fibers obtained from waste paper for making cement composite products such as mortars based on cellulose fibers. This material was made of cement mortar containing organic filler based on hemp hurds and recycled waste paper. In addition, the effects of fibers and their contents on some selected physical and mechanical properties of the fiber-cement plaster composites have been investigated. In this research organic material have used to mortars as 2.0, 5.0 and 10.0 % replacement of cement weight. Reference sample is made for comparison of physical and mechanical properties of cement composites based on recycled cellulosic fibers and lignocellulosic aggregates. The prepared specimens were tested after 28 days of curing in order to investigate density, compressive strength and water absorbability. Scanning Electron Microscopy examination was also carried out.