Alternative Materials Research Articles

Rapid iron extraction from nickel leaching residue by a hydrogen plasma smelting reduction

The processing of limonite-type lateritic nickel ore through sulfuric acid leaching generates leaching residue that requires careful handling and treatment. This residue, which contains over 38% iron, has the potential to be an alternative raw material for the iron and steel industry. However, the direct use of this residue as a burden material in the steel industry faces challenges due to the substantial presence of sulfur, which exceeds 1%. In the pursuit of sustainability within the iron and steel sector, researchers have increasingly focused on advancing hydrogen plasma technology. Laboratory tests were conducted on the treatment of the leaching residue exposed to hydrogen plasma smelting reduction. The results revealed that within just 5 s of exposure to hydrogen plasma, the transformation of the residue into metal was initiated. After 30 s of exposure, the formation of metal had already occurred, but the sulfur content remained above 0.5%. However, when the residue was exposed to hydrogen plasma for 180 s, the sulfur content in the metal decreased to less than 0.1%. The presence of nickel and chromium in the resulting metal products should be taken into consideration, especially when special steels or stainless steel are being produced.

Biochar-Derived Anode Materials for Lithium-Ion Batteries: A Review

Highly portable nanoelectronics and large-scale electronics rely on lithium-ion batteries (LIBs) as the most reliable energy storage technology. This method is thought to be both environmentally friendly and cost-effective. We provide a study of a low-cost, abundant, and renewable supply of carbon-based biomass with potential uses in LIBs. Renewable feedstocks have received significant attention in recent decades as promising tools for efficient and alternative anode materials for LIBs. Researchers can synthesise carbon-rich biochar through the pyrolytic process of biomass. Depending on the synthetic process, precise surface chemistry, and textural qualities such as specific surface area and porosity, this material can be customised to favour application-specific properties with a preferred application. In this research, we look at the performance of biochar in LIBs, its properties, and the biomass supply, and we discuss the prospects for these biomass-derived materials in energy storage devices.

Removal of Cu(II) by sodium hexametaphosphate and nano zero-valent iron modified calcium bentonite: characteristic, adsorption performance and mechanism

Cu (II) is a toxic heavy metal commonly identified in groundwater contaminants. Bentonite-based cutoff wall is the most used method in isolating and adsorbing contaminants, while the bentonite in it easily to fail due to Cu(II) exchange. This study synthesized a novel material through the modification of calcium bentonite (CaB) utilizing sodium hexametaphosphate (SHMP) and nano zero-valent iron (NZVI). The characteristics, adsorption performance, and mechanism of the NZVI/SHMP-CaB were investigated comprehensively. The results showed that SHMP can disperse CaB and reduce flocculation, while NZVI can be further stabilized without agglomeration. The best adsorption performance of NZVI/SHMP-CaB could be obtained at the dosage of 2% SHMP and 4% NZVI. The NZVI/SHMP-CaB exhibited an outstanding removal efficiency of over 60% and 90% at a high Cu(II) concentration (pH = 6, Cu(II) = 300 mg/L) and acidic conditions (pH = 3–6, Cu(II) = 50 mg/L), respectively. The adsorption of Cu(II) by NZVI/SHMP-CaB followed a pseudo-second-order kinetic model, and fitting results from the Freundlich isothermal model suggested that the adsorption process occurred spontaneously. Besides the rapid surface adsorption on the NZVI/SHMP-CaB and ion exchange with interlayer ions in bentonite, the removal mechanism of Cu(II) also involved the chemical reduction to insoluble forms such as Cu0 and Cu2O. The generated FePO4 covered the surface of the homogenized NZVI particles, enhancing the resistance of NZVI/SHMP-CaB to acidic and oxidative environments. This study indicates that NZVI/SHMP-CaB is a promising alternative material which can be used for heavy metal removal from contaminated soil and water.

Computational studies on hyper velocity impact of spherical projectiles on whipple shield with hybrid Newtonian fluid-filled core

Satellites orbiting in low Earth orbits face potential threats from space debris. To mitigate this risk, a Whipple shield is employed to shield satellites from potential hyper-velocity impacts caused by debris of varying sizes and speeds. Typically, these protective systems use spaced aluminum plates affixed to the satellite’s exterior. Ongoing advancements in this field include exploring alternative materials such as foam, cellular cores, and ceramics to replace aluminum in plate construction. This study introduces a hybrid configuration featuring a Newtonian fluid-filled, high-performance fiber-reinforced polymer core positioned between the aluminum alloy plates, aiming to enhance the Whipple shield’s overall shielding effectiveness. The analysis of hyper-velocity impacts was performed numerically using ANSYS Autodyn® computational software. Spherical projectiles made of stainless steel, ranging in diameter from 2 mm to 4 mm, were selected for direct collision simulations with the Whipple shield at velocities of 5 km/s, 7 km/s, and 9 km/s. The front and rear plates, each 1 mm thick, were constructed using AA6061-T6. The core, measuring 10 mm in thickness, incorporated multiple plies of Kevlar fiber-reinforced polymer (KFRP), with interplay spacing between successive KFRP plies filled with a Newtonian fluid (water). It was observed that spherical projectiles made of stainless steel with diameter ≥ 3 mm penetrated the rear plate of the whipple shield at the lower velocity of 5 km/s, with enhanced damage as the initial velocity of the projectile was increased from 5 km/s to 9 km/s. The debris cloud was found to scatter the fluid droplets, rupture the successive KFRP layers, with the initial kinetic energy playing a significant role in the severity of the damage.

Experimental analysis of building components with paper and textile waste

The fast growth of building constructions industry and of the universal population is the main cause of increase in global energy consumption. Therefore, the improvement of the building envelope encourages the scientific community to investigate the use of alternative materials that assure indoor comfort conditions and at the same time promote the reduction of energy consumption by adopting energy saving strategies in the manufacturing process. The present research contribution aims to focus on the potential use of innovative building materials developed with waste paper, classified as urban non-hazardous discard component. The use of paper pulp originated from recycled paper and cardboard with the addition of textile fibers from industrial by-products was explored. Here, an effort has been made to realize sustainable insulating panel for internal use, considering different mix design and recycled components in various percentages. The research focuses on hygric, thermal, and physical performances of recycled waste based panels, measuring physical aspects as bulk porosity and bulk density and testing hygrothermal performances as the dry-state thermal conductivity, thermal diffusivity, volumetric heat capacity, and water vapour permeability. Furthermore, in order to assess the hygrothermal behaviour of the building envelope, a numerical simulation, carried out by WUFI® Plus in a Mediterranean context, was developed using as inputs the results collected from the measurement campaign in laboratory.

Recycled tire rubber materials in the spotlight. Determination of hazardous and lethal substances

One way of recycling end-of-life tires is by shredding them to obtain crumb rubber, a microplastic material (<0.5 mm), used as infill in artificial turf sports fields or as playground flooring. There is emerging concern about the health and environmental consequences that this type of surfaces can cause. This research aims to develop an analytical methodology able to determine 11 compounds of environmental and health concern, including antiozonants such as N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine (6PPD) or N, N´-diphenyl-1,4-phenylenediamine (DPPD), and vulcanization and crosslinking agents, such as N-cyclohexylbenzothiazole-2-sulfenamide (CBS), 1,3-di-o-tolylguanidine (DTG) or hexamethoxymethylmelamine (HMMM) from tire rubber. Ultrasound assisted extraction followed by liquid chromatography coupled to tandem mass spectrometry (UAE-LC-MS/MS) is validated demonstrating suitability. The methodology is applied to monitor the target compounds in forty real crumb rubber samples of different origin including, football pitches, outdoor and indoor playgrounds, urban pavements, commercial samples, and tires. Several alternative infill materials, such as sand, cork granulates, thermoplastic elastomers and coconut fibres, are also collected and analysed. All the target analytes are identified and quantified in the crumb rubber samples. The antiozonant 6PPD is present at the highest concentrations up to 0.2 % in new synthetic fields. The tire rubber-derived chemical 6PPD-quinone (2-((4-methylpentan-2-yl)amino)-5-(phenylamino)cyclohexa-2,5-diene-1,4-dione), recently linked to acute mortality in salmons, is found in all types of crumb rubber samples attaining concentrations up to 40 μg g−1 in football pitches. The crosslinking agent HMMM is detected in most of the playing surfaces, at concentrations up to 36 μg g−1. The tested infill alternatives are free of most of the target compounds. To the best of our knowledge, this study is the largest study considering the target compounds in tire rubber particles and the first to focus on these compounds in playgrounds including the analysis of HMMM, 6PPD-quinone and DTG in crumb rubber used as an infill material.

Cytotoxic Potential of Berunok Sea Cucumber (Paracaudina australis) Against Breast Cancer Cells (T47D)

Background Sea cucumbers can be explored as alternative raw materials by the pharmaceutical and fishery industries as anticancer agents because they contain potential bioactive compounds. Methods This study aimed to determine the anticancer activity of Paracaudina australis extract against breast cancer cells (T47D) using an MTT assay. The secondary metabolites found in P.australis are steroids, terpenoids, saponins, and phenolics. The Thin-Layer Chromatography test results are indicated by Rf values, and steroid compounds in the ethyl acetate fraction are included in the standard Rf values. The isolates obtained were identified by Gas Chromatography-Mass Spectrometry, Fourier-Transform Infrared Spectroscopy, High-performance liquid chromatography, and UV-Visual spectrophotometry. Results The isolated compounds were Dihydrocholesterol and Cholestan-3-ol, with a molecular formula (C27H48O). The ion weight and molecular mass of the compound were m/z 388,7. Conclusions This compound may be responsible for the anticancer activity of P.australis. The IC50 of Isolate F4 was 25,3 μg/ml, and IC50 of Isolate F7,8 was 13,76 μg/ml.

Evaluation of mechanical properties of paver blocks by replacing cement with fly ash and marble waste

Paver blocks (PB) play a pivotal role in various construction and infrastructure works providing aesthetically and durable pleasing surfaces for various applications such as pavements, walkways, and driveways. These blocks can be used for heavy vehicle loads instead of low-strength clay bricks and tiles. PB gained focus in the construction industry due to its multi-advantages like high strength, durability, and low maintenance cost. However, due to the usage of cement, its application is limited, which releases a huge amount of carbon dioxide into the ecosystem. Thus, it leads to global warming and climate change. In addition, cement is one of the expensive materials used in PB, which further reduces the interest of the construction industry and end-users of PB. Marble waste as its excessive amount of generation from stones in industry and fly ash as a byproduct from coal combustion immediate opportunities to use these materials and reduce the impact of waste material on the environment. Therefore, this study aims to reduce cement consumption by partially replacing marble waste and fly ash combinedly. The study contributes practically to the use of alternative materials in the construction industry. Three types of samples namely M1 (replacement with marble waste), M2 (replacement with fly ash), and M3 (replacement with both fly ash and marble waste) were used. Various proportions were added as a partial replacement, the replacement varying from 5 to 30%, which was 5%, 10%, 15%, 20%, 25%, and 30%. Statistical analyses were carried out for interpretations of the data. The result concluded that all three mixes achieved their maximum compressive strength on different days of curing. M1-15 and M3-20 mixes achieved maximum compressive strength related to control specimens at 56 days. However, the M2-20 mix achieved maximum compressive strength at 7, 28, and 56 days, The maximum flexural strength was recorded by the M1–15 mix at 7 and 56 days, while the M2–20 and M3–20 mix achieved maximum flexural strength at 7, 28 and 56 days. ANOVA tests by one-way indicate that there is no difference in the mean of compressive strength however, there is a difference in the mean of flexural strength. The Tukey post hoc analysis shows a statistically significant difference between all levels of days of compressive and flexural strength, except for some levels of compressive strength. The correlation test results indicate a positive and strong association between all three mixes.

Conceptual framework for identifying polymers of concern

With the increasing global concern over plastics' environmental and human health impacts, the urgency for effective regulatory measures is evident. The UN Environment Assembly's initiative to establish an international, legally binding instrument via the Intergovernmental Negotiating Committee (INC) on Plastic Pollution marks a significant step toward addressing this issue. However, the vast diversity of plastic types and their myriad applications present a complex challenge in pinpointing the most critical targets for regulation. This study builds on the existing body of literature to outline potential key criteria for identifying Polymers of Concern (PoC). We recommend a dual-focused definition of PoCs considering both (1) the type of the plastics and (2) their domain of applications based on the environmental and human health impacts throughout the polymer's life cycle. Recognizing the current gaps in our understanding of the full spectrum of plastics' impacts across their life cycles, we suggest adopting a precautionary approach that factors in the volume of plastics entering natural ecosystems alongside their life cycle impacts as reported in the literature. We then bring forward existing data on the assessment of some of the main polymer types and applications. We propose that policymakers examine a wide spectrum of strategies including not only bans and phaseouts but also economic incentives, innovation, and the redesign of plastic materials and products to mitigate the adverse impacts of PoCs. We further emphasize the importance of thoroughly assessing the feasibility, costs, and environmental, social and economic implications of alternative materials to avoid “regrettable substitution.” We conclude by identifying existing knowledge gaps and emphasizing the need for further research to refine the proposed criteria for identifying PoCs.

Investigation of metabolic processes of alcohol yeast during the fermentation of buckwheat-corn wort

To expand the range of competitive alcoholic beverages with original organoleptic properties, it is promising to study the use of new types of plant raw materials in grain distillate technologies. The purpose of this work was to establish the influence of the characteristics of the composition of grain wort prepared with the joint use of an alternative raw material source — buck- wheat and corn, which is widely used in alcohol production, on the metabolic processes of the yeast Saccharomyces cerevisiae 985-T and alcoholic fermentation. The objects of the study were buckwheat and corn; enzyme preparations — sources of amylases, xylanases, β-glucanases and proteases; samples of grain wort, mash and mash distillates. The prospects of introducing mixed grain media prepared using non-traditional buckwheat raw materials into the technology of original alcoholic bever- ages are substantiated. It was shown that the use of buckwheat as a source of biocomplete protein, essential amino acids and minerals together with corn containing a high level of starch and a low level of non-starch polysaccharides contributed both to an increase in the yield of alcohol and a change in the quantitative content of secondary metabolites in the composition of volatile impurities. It was found that an increase in the concentration of soluble carbohydrates in the wort and a decrease in its viscosity by 15.5–40.3% occurred due to the inclusion of corn in the composition of the grain mixture, and the enrichment of the wort with nitrogen assimilated by yeast by 19.0–41.8% — as a result adding buckwheat. The optimal ratio of corn and buckwheat in the composition of the grain mixture (7:3) was selected, which made it possible to improve the biochemical and technological parameters of grain must, increase the efficiency of the vital processes of yeast and alcoholic fermentation, ensure an increase in the yield of alcohol by 1.8%, reduce the formation of side metabolites, especially higher alcohols, and change their composition in the direction of increasing the proportion of aldehydes and esters, which can have a positive effect on the organoleptic characteristics of the distillate.

Multi-criteria decision making tool for sustainable concrete production using waste polyethylene terephthalate bottle cap aggregates

The widespread use of concrete has raised concerns about the consumption of its raw materials. To address this issue, researchers are actively exploring alternative waste materials to reduce the environmental impact of the construction industry. With this objective current study aims to investigate potential use of waste polyethylene terephthalate (PET) bottle cap aggregates on the characteristics of concrete, both in its fresh and hardened states. Three variations of modified waste PET aggregates (PETA): full (F), half (H), and quarter (Q), with the aim of evaluating their suitability as replacements for conventional coarse aggregates (CCA) was examined. The research assesses the effects of different PETA proportions (3%, 5%, and 8%) on concrete workability, compressive strength, splitting tensile strength, and flexural strength. The findings reveal that PETA-F and PETA-H adversely affect workability, primarily due to their larger surface area and difficulty in achieving homogeneous blending with other ingredients. In contrast, PETA-Q exhibits superior workability. The use of PETA-Q results in reduced compressive strength due to its smaller size and limited load-bearing capacity. Notably, PETA-H demonstrates improved compressive strength after 28 days. Interestingly, PETA-Q shows enhancements in splitting tensile and flexural strength, making it the top-performing alternative for fresh and hardened concrete properties. Overall, this research indicates that PETA-Q is most suitable for sustainable concrete production. Furthermore, the application of a multi-criteria decision-making tool validates our findings and determines that a 5% replacement of CCA with PETA is optimal, as higher replacements result in strength reduction. The utilization of PETA not only minimizes CCA consumption but also contributes to the development of eco-friendly, sustainable concrete. This study underscores the potential of environmentally conscious concrete and encourages the adoption of sustainable solutions for plastic waste management.

Production and investigation of water absorbent fibre pellets from unutilised lignocellulosic biomass pre-processed in a twin-screw extruder

Organic livestock farming requires all resource input to be organic as well. Competition for raw materials as bedding increases the demand for alternative bedding materials. The production of absorbent fibre pellets from underutilized lignocellulosic plant material is therefore a research area that needs further attention. Precise research on processing methods and absorbent quantity is essential for the development of sustainable, high-quality absorbent bedding pellets. Twin-screw extruded fibre from eight different raw materials were processed into absorbent pellets. These pellets were investigated for physical properties including absorbency, mechanical durability, particle-size distribution and bulk density in accordance with relevant standards. Due to the absence of a standardised method for assessing absorbency, a testing method was devised. This involved submerging the produced pellets in deionized water for durations of 30 s, 300 s, and 1200 s. This research analysed various raw materials for suitability in absorbent pellet production. Poplar pellets performed good in absorbency (130 %, 172 %, 194 % respectively) and mechanical durability (95 %). As a result, larger quantities of absorbent pellets could be produced from poplar if needed since poplar wood chips are of higher availability due to existing short rotation coppices. This article emphasised producing absorbent bedding pellets, prioritising, using twin-screw extruded lignocellulosic fibre, revealing significant raw material influence on absorption properties.

River-sourced Cladophora glomerata macroalgal biomass as a more sustainable and functional feed raw material for growing rabbits

Animal scientists actively seek strategies for ensuring the sustainable viability of animal ecosystems, with a focus on exploring alternative feed raw materials to reduce reliance on traditional ones. So, this study aims to analyse the impact of river-sourced Cladophora glomerata macroalgal biomass on the growth, slaughter performance, and physiological development of rabbits. Thirty weaned (52 days of age) Californian rabbits were assigned to three dietary treatments: standard compound diet (SCD), SCD enriched with 4% C. glomerata (CG4), and SCD enriched with 8% C. glomerata (CG8). Growth performance was recorded throughout the feeding trial, and at its conclusion (122 days of age), rabbits were euthanized, slaughtered, and subjected to intestinal analysis. Incorporation of CG diets showed no significant impact on body weight or average daily gain (p > 0.05); however, CG8 significantly lowered daily feed intake and feed conversion ratio (p < 0.05). The SCD resulted in a significantly higher lung percentage (p < 0.05), while CG diets had minimal effects on remaining slaughter performance traits. In duodenal content, CG-enriched diets increased acetic and propionic acid levels but reduced lactic (p < 0.05). Duodenal villus height remained stable, while in the ileum, CG4 inclusion resulted in a significantly higher villus (p < 0.05). Duodenal crypt depth increased with biomass supplementation; conversely, in the ileum, increased biomass led to decreased crypt depth (p < 0.05). In general, recent research suggests that adding C. glomerata to rabbit diets can be an effective alternative without adverse effects on growth, slaughter performance, or physiologial development.

NON-WOODEN RAW AS A SOURCE OF CELLULOSE FIBERS. USE PROSPECTS, PROBLEMS AND SOLUTIONS (REVIEW)

The article discusses various non-wood plants as sources of fibrous raw materials for the pulp and paper industry. The authors cite the main categories of non-wood fibrous raw materials: agricultural waste, naturally growing plants and industrial crops. Information is provided on the position of fibers in the plant: fibers of the inner part of the stem, bast (outer part of the stem) fibers, leaf fibers and fruit fibers, as well as methods for their isolation. Of the variety of non-wood plants, the authors highlight industrial hemp as the most promising raw material, having strong fibers and a high cellulose content. The use of non-timber raw materials has been found to help reduce pressure on forest resources and improve the environmental sustainability of pulp and paper production. Technological aspects of the production of paper products from non-wood raw materials are also considered. The advantages and disadvantages of using alternative raw materials, as well as its prospects, are given. The need for further research and development of new methods and technologies to optimize the efficiency of using non-wood raw materials in the pulp and paper industry is pointed out. In conclusion, a conclusion is drawn about the importance of using non-wood raw materials to reduce the negative impact of paper production on the environment and ensure the sustainable development of this industry.

Effect of Strength and Durability of Sand Cement Brick Containing Recycled Concrete Aggregate and Cold Bottom Ash

Introduction The market price of brick has risen sharply due to the insufficient brick supply. Therefore, implementing RCA as one of the alternative materials for sand replacement is significant. The consumption of natural aggregate (NA) can be reduced by using the RCA. It is a good step to utilize recycled concrete to minimize the problem of excess waste materials. The results of using RCA and CBA as sand replacements contribute to better performance in compressive strength as compared to the normal brick. The density of the brick was also reduced by 4.95% as the RCA and CBA took place in the brick. Besides that, the water absorption was decreased when incorporating RCA and CBA in the cement brick due to less free water in the mix and fewer voids. Aims This study aims to ascertain the performance, strength, and durability characteristics of sand cement bricks incorporated with RCA and CBA as partial replacements for sand. Methods Percentages of 1.5%, 3.0%, 4.5%, and 6.0% of CBA and 15%, 30%, 45%, and 60% of RCA were chosen for partial sand replacement. The brick had dimensions of 215 mm in length, 65 mm in depth and 105 mm in width. Density, compressive force, and water absorption tests were undertaken after each of the three varied ratios of water to cement (1:5, 1:6, and 1:7). Results The finding indicates that with the optimum RCA and CBA replacement and the correct water to cement ratio, the performance of the new brick is better than the normal brick. Conclusion The optimum sand-to-cement ratio is 1:6, according to the overall results of selecting the optimal sand-to-cement ratio by density, compressive strength, and water absorption test. However, the result for the density value shows that the average brick density is inferior to the control brick. For all of the sample bricks, the compressive strength was best at a sand cement ratio of 1:6. However, as each of the samples complies with the British Standard criterion of less or equal to 15% absorption, it was determined that the sand cement brick's capacity for water absorption was sufficient.

Effects of soft chain materials on the tribological performances of thermosetting polyurethane under water-lubrication

Polyurethane elastomers are widely used as functional alternative materials in water-lubricated bearing materials. In this study, three kinds of polyurethane elastomers with different soft chains were prepared to investigate the influence of soft chain materials on their tribological properties. The test results show that the specimen with soft chain polyols as propylene glycol has the best wear resistance, and the friction coefficient is only 0.09 at 0.7 MPa. Due to the excellent buried property, the wear debris can be discharged in time, so the surface of the test specimen is relatively flat, which is conducive to the formation of lubricating water film. This study provides the experimental basis for polyurethane as an alternative material for water-lubricated bearings.

A 3D printed ultra-short dental implant based on lattice structures and ZIRCONIA/Ca2SiO4 combination

Additive Manufacturing (AM) enables the generation of complex geometries and controlled internal cavities that are so interesting for the biomedical industry due to the benefits they provide in terms of osseointegration and bone growth. These technologies enable the manufacturing of the so-called lattice structures that are cells with different geometries and internal pores joint together for the formation of scaffold-type structures. In this context, the present paper analyses the feasibility of using diamond-type lattice structures and topology optimisation for the re-design of a dental implant. Concretely, a new ultra-short implant design is proposed in this work. For the manufacturing of the implant, digital light processing additive manufacturing technique technology is considered. The implant was made out of Nano-zirconia and Nano-Calcium Silicate as an alternative material to the more common Ti6Al4V. This material combination was selected due to the properties of the calcium-silicate that enhance bone ingrowth. The influence of different material combination ratios and lattice pore sizes were analysed by means of FEM simulation. For those simulations, a bio-material bone-nanozirconia model was considered that represents the final status after the bone is integrated in the implant. Results shows that the mechanical properties of the biocompatible composite employed were suitable for dental implant applications in dentistry. Based on the obtained results it was seen that those designs with 400 μm and 500 μm pore sizes showed best performance and led to the required factor of safety.

Moisture and mould growth risk of cross-laminated timber basement walls: Laboratory and field investigation

Reinforced concrete is a commonly used material for constructing basements in low-rise buildings or residential houses in Canada, and as the use of cross-laminated timber (CLT) advances, the door to think of an alternative basement material to offset greenhouse gas emissions associated with reinforced concrete is open. However, the evaluation of CLT durability in below-grade environments, specifically concerning moisture and mould development, remains an unexplored field in research. Hence, this paper aims to analyze CLT's moisture response and mould growth risk in below-grade environments using field and laboratory experiments. A laboratory experiment was carried out to test a waterproofing membrane solution selected to compose the wall assembly in the field experiment. A large-scale experimental CLT basement was built at a cohesive soil site in Edmonton, Canada. The field experiment involved monitoring the relative humidity, temperature, and soil volumetric water content of the CLT panels, which measure 3 m by 6 m in plan and 2 m deep. Data was collected for an extended period from June 2022 to July 2023. The VVT model, developed by Hukka and Viitanen (1999) and updated by Viitanen et al., 2011 to estimate the mould growth level, was used to predict the risk of mould growth. The laboratory experiment showed that the waterproofing membrane is suitable for protection against moisture in a still-water setup. Field experiment results suggested that the primary moisture source was below the basement floor when the floor was finished inadequately. The moisture content of CLT walls was significantly increased by floor flooding and decreased by heating the basement interior. The acceptable mould index of three was surpassed during periods of abundant water below the basement floor due to flood events, showing that the CLT panels were at risk of mould growth development.

Development of low carbon concrete and prospective of geopolymer concrete using lightweight coarse aggregate and cement replacement materials

The use of Ground Granulated Blast-furnace Slag (GGBS) as an alternative cement replacement material in combination with conventional coarse aggregate have been successful in the production of near green concrete. Undoubtedly, GGBS has exhibited good cementitious attributes, however, there are concerns with slow strength development and workability owing to its non-pozzolanic activities as well as some degree of porosity notwithstanding the sustainability potential. Therefore, this study presents a lytag based geopolymer lightweight concrete with high strength development, improved mechanical properties and reduced embodied carbon. To further improve and enhance the potential production of green concrete, complete replacement of conventional coarse aggregate with a recycled lightweight aggregate from industrial waste was carried out. The geopolymer precursors consisted of sodium hydroxide, sodium silicate, GGBS and silica fume to optimize the performance of the concrete at 60–80% cement replacement for a target design mix of 20, 30, 40, and 50 MPa. The performance of lytag based geopolymer concrete was compared with that of non-geopolymer lytag based concrete (control samples). The results show a 42% increase in compressive strength for the geopolymer lightweight concrete and a 22% increase in ultimate compressive strain which is an indication of improved moment of resistance in structural design. The results also show a 46–61% reduction in embodied carbon for the use of non-geopolymer lytag based concrete and 69–77% reduction for lytag based geopolymer concrete. The geopolymer concrete between 7 and 63 days of loading increases by 0.55% in creep strain compared with increases of 2.81% for non-geopolymer lytag based concrete and reduction to 27.96% for the normal weight concrete. Modulus of Elasticity reduces with age of loading for the geopolymer concrete during creep at 0.39% compared to reduction of 1.93% for non-geopolymer lytag based concrete and increase of 12% for the normal weight concrete.

Research on mix design and mechanical performances of MK-GGBFS based geopolymer pastes using central composite design method

In order to alleviate environmental problems and reduce CO2 emissions, geopolymers had drew attention as a kind of alkali-activated materials. Geopolymers are easier access to raw materials, green and environment friendly than traditional cement industry. Its special reaction mechanism and gel structure show excellent characteristics such as quick hardening, high strength, acid and alkali resistance. In this paper, geopolymer pastes were made with metakaolin (MK) and ground granulated blast furnace slag (GGBFS) as precursors. The effects of liquid–solid ratio (L/S) and modulus of sodium silicate (Ms) on the performances of MK-GGBFS based geopolymer paste (MSGP) were characterized by workability, strength and microstructural tests. The regression equations were obtained by central composite design method to optimize the mix design of MSGP. The goodness of fit of all the equations were more than 98%. Based on the results of experiments, the optimum mix design was found to have L/S of 0.75 and Ms of 1.55. The workability of MSGP was significantly improved while maintaining the strength under the optimum mix design. The initial setting time of MSGP decreased by 71.8%, while both of the fluidity and 28-d compressive strength increased by 15.3%, compared with ordinary Portland cement pastes. Therefore, geopolymers are promising alternative cementitious material, which can consume a large amount of MK and GGBFS and promote green and clean production.