Green Construction Material Research Articles

Investigation of the optimum calcination temperature for water treatment plant sludge to develop a sustainable alkali activated concrete

Nowadays, Egypt is treating the Nile River Water to produce drinking water, and this process generates large amounts of waste, around 635 million m3 annually, which is called water treatment plant sludge (WTPS). This WTPS cost the government around 30 million US dollars to return it back to the Nile River in addition to negatively affecting the environment. Therefore, there is an urgent need to find environmentally friendly alternatives that reduce the impact of such an issue. This paper focuses on treating WTPS by drying, grinding and calcining to develop it as an alternative binder for use in alkali-activated concrete. This approach would not only provide green construction material but also reveal an environmental disposal route for the sludge produced in Egypt or in any country has the same issue. The treatment methodology used in this study was based on finding the optimum calcination temperature regime for WTPS after drying and grinding. Fifteen specimens of WTPS powder were used to investigate the optimum calcination temperature and duration by applying different temperatures ranging from 500 °C to 800 °C for various exposure durations of 30, 60 and 90 min. XRD and Chapelle tests were employed to chemically investigate the efficiency of the obtained calcined WTPS specimens, while strength activity index and compressive strength tests were used to mechanically verify the findings of the chemical tests. The results indicated that the calcination regime, which involved applying a maximum temperature of 650 °C for 90 min, achieved the best chemical characteristics and a strength activity index of 145%. Moreover, this regime resulted in a compressive strength of 21 MPa when WTPS powder was used as a precursor in alkali-activated concrete. Additionally, this paper presented a brief comparison of the production cost and energy consumption between cement and WTPS. The comparison demonstrated the efficiency of using WTPS as a replacement for cement, showing that the production of WTPS costs 50% less and consumes 92% less energy than cement.

Advances in TiO2-enhanced photocatalytic building materials: applications in cement and asphalt for environmental purification

AbstractTiO2 is the most popular semiconductor photocatalyst owing to its high quantum efficiency, chemical stability, low cost, and non-toxicity, making it an excellent photocatalyst with significant application potential. Integrating the environmental photocatalysis of TiO2 with traditional building materials offers the opportunity to develop green construction materials with advanced functionalities. These materials can facilitate the degradation of surface pollutants, enable self-cleaning, and contribute to environmental purification. This review provides a comprehensive overview of the advancements in photocatalytic cement and asphalt materials, explores various methods for incorporating TiO2, and delves into the underlying mechanisms of photocatalytic degradation. Furthermore, it addresses the limitations of current research, offering valuable insights and guidance for future studies in the field of photocatalytic building materials for carbon neutrality.

SEM analysis, durability and hardened characteristics of eco-friendly self-compacting concrete partially contained bentonite and waste walnut shells

Reusing waste materials as aggregate in self-compacting concrete (SCC) may reveal green construction materials. Walnut shell (WS) can be used in place of aggregate in SCC. This study utilized five dissimilar volume fractions of WS as fine aggregate ranging from 8% to 40%, containing bentonite clay powder constant as 10% of cement weight. The SEM analysis, fresh properties and hardened characteristics of all SCC mixtures were assessed. Additionally, the impact of a 5% concentration of H2SO4 and MgSO4 solution for a month on the compressive and splitting tensile strengths and density were studied. The workability of all the LWSCC mixes satisfied standard requirements except of L-Box result; nevertheless, as the WS content increased, the workability of the LWSCC mixtures declined. Following the exposure period for both sulphate attacks, all characteristics of LWSCC mixes were reduced. In contrast to the control mixture, the SEM analysis shows that when WS was added in greater amounts, the concrete became less dense and had more voids. Furthermore, the statistical analysis was performed by using two-way variance (ANOVA) technique which revealed that the effects of all independent variables on the strength and other properties of cement mortar were significant under all experimental conditions.

Alkaleri Metakaolin Powder Performance Evaluation by Response Surface Method.

Alkaleri metakaolin (AMK) based geopolymer binder has been identified as one of the alternatives to the Ordinary Portland Cement (OPC), which qualifies the criteria for green construction material. In this work, 20No of experimental mix proportions (RUNs) were designed by Central Composite Design (CDD) of Response Surface Method (RSM). Mixture of AMK and Alkaline Solution was heated for 45mins at 60oc with stirring interval of 15mins, after which aggregates were added to the hot mix. 60No of 100X100X100mm cubes were cast. Samples were tested at the 28th day of ambient curing. The reported Compressive Strengths are the average of the 60 sample tested with 38.6N/mm2 as the maximum, hence established the experimental optimum mix proportion (EOMP). The ANOVA model developed statistically validated by having F-value of 15.54 and P-value of less than 0.0001 indicating that the model is statistically significant. Also, the adequate precision of 10.7850 which is greater than 4.00 indicates adequate signal and desirable. Furthermore, the difference between predicted R2 and adjusted R2 is less than 0.2 testifying that they are rationally in good agreement. Effects of three principal variables namely: molarity of sodium hydroxide, sodium silicate to sodium hydroxide ratio, and fineness (particle size) on the properties of the fresh and hardened AMK geopolymer concrete (normal consistency, soundness, setting times, slump, dry density, water absorption, compressive strength, flexural strength, split tensile strength, sorptivity and acid attack) were investigated. All the results for the properties investigated were found to have fallen within the ranges of the international standard codes such as ASTM and British Standard, hence AMK is qualify to be used as Metakaolin based geopolymer binder.

Preliminary results of construction and demolition waste (CDW) and fly ash (FA) based geopolymer composite materials

There is need to research and develop green construction materials, to address increasing infrastructural demand and environmental challenges. Preliminary investigation of construction and demolition waste (CDW) and fly ash (FA) based geopolymer composite materials is presented in this paper. The average compressive strength of mechanically activated materials based FA geopolymer composite specimen was 53.8% higher compared to the unground specimen. Investigation on CDW and ground FA based geopolymer composite materials, show that 50% CDW precursor content had the highest strength. Cracks were observed on the ground fly ash composite specimen surface, attributed to surface moisture loss. The optimum compressive strength, 47 ± 9.13 MPa can be considered for structural application. Mitigation measures for adverse cracks should be applied.

Upcycling of molybdenum tailings, coal gangue and slag into sustainable repaired composites by geopolymerization technology: Workability, embodied carbon and mechanical-microstructural development

The major disadvantage of reinforced concrete structure was multi cracks under loading, seriously affecting its normal performance, but using traditional repaired materials to strengthen reinforced concrete structures can bring some side-effects, such as higher carbon oxide and cost. Herein, this study successfully designed an eco-friendly geopolymer repaired composites developed by molybdenum tailings, ground granulated blast-furnace slag and coal gangue. Firstly, the fresh and harden properties of geopolymer repaired composites was systematically studied including water bleeding rate, fluidity, setting time, unconfined compressive strength and bonding strength. The micro performance of geopolymer repaired composites was analyzed via scanning electron microscopy, thermogravimetry-derivative thermogravimetry, X-ray diffraction and fourier transform infrared spectroscopy to give some new viewpoints for revealing the coupled geopolymerization mechanism of molybdenum tailings/coal gangue/ground granulated blast-furnace slag in geopolymer repaired composites. Meanwhile, the gray level of concrete contact surface is calculated. The results show that the properties of geopolymer repaired composites with 5% NaOH designed by 1:3 binder/sand, 0.5 w/c and 1:3 molybdenum tailings/ground granulated blast-furnace slag were optimal properties with 1.73% water bleeding rate, 192 mm fluidity, 58 min and 178 min the initial and final setting time, respectively, 21.443 MPa 28-d unconfined compressive strength and 2.642 MPa bonding strength. Excessive NaOH amount would inhibit the unconfined compressive strength and bonding strength of geopolymer repaired composites, while the increase of ground granulated blast-furnace slag would improve unconfined compressive strength and bonding strength. The primary hydration products of geopolymer repaired composites were C–S–H and C-A-S-H gels. Molybdenum tailings, coal gangue, and ground granulated blast-furnace slag showed an important synergistic effect, improving its geopolymerization reaction and strength. Besides, bonding strength of geopolymer repaired composites was highly correlated with unconfined compressive strength and fractal dimension of surface roughness. The relation coefficients are 0.92005 and 0.94006, respectively. With the higher the unconfined compressive strength of geopolymer repaired composites and the larger fractal dimension of the concrete contact surface, the bonding strength of geopolymer repaired composites is higher and the bond between geopolymer repaired composites and concrete is denser. The increase in the amount of NaOH and the increase in ground granulated blast-furnace slag have an increasing and decreasing trend on the carbon emissions of geopolymer repaired composites, respectively. The most obvious increasing and decreasing trends are that the carbon emissions of GRC increase from 66.41 kg CO2-e/m3 to 96.28 kg CO2-e/m3 and decrease from 79.81 kg CO2-e/m3 to 76.37 kg CO2-e/m3. The increase in the amount of NaOH is the main reason for the increase in the carbon emissions of geopolymer repaired composites, while the increase in ground granulated blast-furnace slag helps to reduce the carbon emissions of geopolymer repaired composites. The carbon emission of geopolymer repaired composites was reduced by 75.08%–83.4% compared with traditional mortar. The 28-day per unit unconfined compressive strength carbon emission of the geopolymer repaired composites with the optimal mix is 46.63% lower than that of the traditional mortar. Overall, this study can provide new viewpoints and novel channels for converting solid waste, including molybdenum tailings and coal gangue, into green recycled construction materials, provide highly promising insight for designing green construction products and new ideas in the development of low-carbon remediation materials for environmental sustainability, contribute an important force to environmental protection, and promote the growth of economic benefits in the process.

Soil Water Characteristics Curves (SWCC) of Residual Soils Stabilized using Emerging and Novel Bioinspired Technique

The development of unsaturated soil mechanics stemmed from the inadequacies of classical soil mechanics in addressing the partial pore spaces found in real-world soil systems. However, assessing soil parameters under partial saturation is resource-intensive. To streamline this, the Soil-Water Characteristic Curve (SWCC) theory was introduced. Widely applied across geotechnical engineering, water resources, and agriculture, SWCC predicts parameters of unsaturated soil systems. In geotechnical engineering, SWCC is vital for designing systems near the Earth's surface, like slopes, clay liners and foundations. Furthermore, most of conventional soil improvement techniques pose a lot of environmental concerns. thus, emergence of green construction materials widely known as bio mediated and bioinspired soil improvement techniques like Enzymatic induced calcite precipitation (EICP). EICP, an emerging eco-friendly as it employs use of simply chemical compound that reduces carbon footprints, bioinspired technique as it mimics natural forming process, was applied to stabilize tropical soil for SWCC determination. SWCC parameters were derived by subjecting EICP-treated soils at varying concentration of cementation solutions (0 – 1.00 M) using pressure plate method. Results revealed that saturated water content θs, retention water content θr, and air entry value Ψa increased with higher cementation solution concentration. The values of θs, θr, and Ψa improved from of 0.663, 0.23405, and 3.4832 at 0 concentration of cementation solution to 0.701, 0.22864, and 7.7086, respectively upon treatment with 1.00 M cementation solution. Finally, it has been demonstrated EICP is capable of improving the SWCC parameters of residual soil, thus the EICP technique can be exploited in stabilization of residual for construction of compacted clay liner.

Mechanical properties and probabilistic models of wood and engineered wood products: A review of green construction materials

Wood and engineered wood products are green construction materials with excellent mechanical properties, widely utilized in various buildings and bridges. This paper reviews their short-term and long-term mechanical properties and probabilistic models. Short-term mechanical properties analysis reveals strong tensile (up to 165 MPa) and bending strengths (up to 264 MPa), contrasted by lower compressive strength (up to 103 MPa) and minimal shear/rolling strength (up to 14 MPa). These properties vary based on species type, lay-up angle, and dimensions, and are mutually influential. It also demonstrated that innovative techniques such as compression and cross-laminated lay-ups enhance the strength and sustainability of wood products, utilizing smaller logs effectively and reducing carbon emissions. For long-term mechanical properties, empirical models typically used for creep strength assessment fail to account for load duration variability, a gap partly addressed by damage accumulation models which require further development. The considerable time for long-term tests underlines the need for developing accelerated load tests to more effectively assess durability. As for probabilistic models, numerical methods and machine learning provide advanced probabilistic models by analyzing extensive data, offering significant improvements over traditional experimental methods.The global contribution of the work is mainly to enhance the understanding of wood and engineered wood products for properly design and extensive application of timber structures in civil engineering and promoting sustainable development.

Compressive Strength Characteristics of Compressed Stabilized Earth Block (CSEB) Units and Walls

This paper is mainly focused on compressive strength behavior of Compressed Stabilized Earth Block (CSEB) units and CSEB walls. Compressed Stabilized Earth Block (CSEB) is a rectangular block used in wall construction. The ingredients of CSEB are soil, cement, fine aggregate, crusher dust, and a small amount of water. These blocks have less energy consumption and carbon emission, and they provide improved thermal insulation. In addition, they use local resources and disseminate appealing aesthetics with elegant profile and uniform size. Due to these advantages CSEB can be used as a green construction material. This research aims to study the strength characteristics of CSEB wall in compression and evaluate the suitability of CSEB walls as load bearing walls in structures. This research studies physical and mechanical characteristics of CSEB units made from red residual soil of Lele (Lalitpur) with 8% cement for stabilization. This paper discusses the compressive strength behavior of walls constructed of size 0.660m x 1.100m x 0.220m using CSEB units in cement sand mortar and stabilized mud mortar separately which were tested after 28 days. The experimental values after laboratory testing of CSEB masonry wall with height to thickness ratio 5:1 for cement sand mortar (1:6) and stabilized mud mortar (stabilized with 8% cement and 16% extra sand) separately are compared with relevant values from different codes. Results obtained from compressive strength tests of masonry walls constructed in the laboratory and those values from different codes concerning the strength of masonry unit and mortar are compared and found to be in agreement. The comparison of laboratory results with codal provisions of design of masonry walls illustrate that CSEB masonry walls can be designed in the similar way as brick masonry walls.

Bio-inspired synthesis of nanocrystalline calcite demonstrating significant improvement in mechanical properties of concrete: a construction-nanobiotechnology approach.

The bioinspired synthesis of construction material, known as biocement, represents a significant advancement in addressing the environmental sustainability issues associated with traditional cement use in the built environment. Biocement is produced through the process of microbially induced bio-mineralization (MIBM), which offers a promising alternative or supplement to conventional cement, potentially reducing its consumption. Despite extensive literature on the application of biocement in construction biotechnology, the fundamental mechanisms underlying its ability to enhance concrete quality remain poorly understood. This study focuses on the kinetics of biomineral synthesis by two Bacillus species; Bacillus megaterium RB05 and Bacillus foraminis DRG5, to identify the most effective strain for biomineralization. Bioconcrete specimens were created by adding inoculum containing Bacillus megaterium RB05 cells with a nutrient solution to the concrete mixture in a layer-by-layer approach. After 28days of water curing, nanoparticles of CaCO3, ranging in size from 27 to 82nm, were produced in the bioconcrete specimens. The resulting concrete, containing nanocrystalline biogenic calcite, demonstrated significant improvements in mechanical properties. Specifically, compressive and tensile strengths of the bioconcrete, tested using a universal testing machine (UTM), increased by 7.69 ± 0.08% and 22 ± 0.1%, respectively, after 72h of curing. Additionally, the biocement was found to exhibit an organic-inorganic hybrid nature, as identified by TEM, EDAX, FESEM, FTIR, and XRD analyses. The enhanced mechanical properties were attributed to the high surface-to-volume ratio and hybrid nature of the calcite nanoparticles. The findings of this investigation are encouraging, suggesting the potential development of future green and self-sustainable construction materials or bioconcrete.

Revolutionizing Waste Management: Solidification of Landfill Leachates Using Alkali-Activated Slag

AbstractLandfill leachate is a highly hazardous effluent characterized by a high concentration of recalcitrant pollutants, presenting a significant environmental challenge. This study investigated the solidification of landfill leachate contaminants using sodium hydroxide-activated Granulated Blast Furnace Slag (GBFS). The stability of the resulting geopolymer was evaluated through unconfined compressive strength and leaching tests. Optimal curing conditions were identified as 7 days at a sodium hydroxide concentration of 12 M, achieving an unconfined compressive strength of 45.738 MPa at a liquid-to-solid ratio of 15%. A linear relationship was observed between the liquid-to-solid ratio and flow workability, with maximum flow workability evidenced by an average diameter of 242 mm at a liquid-to-solid ratio of 0.25. However, a minimum liquid-to-solid ratio of 0.15 was necessary to obtain a workable mortar. The produced geopolymers were characterized using X-ray Fluorescence (XRF) for mineralogical analysis, Scanning Electron Microscopy (SEM) for morphological examination, and the Toxicity Characteristic Leaching Procedure (TCLP) for leaching tests. The findings demonstrated the successful solidification of landfill leachate using GBFS geopolymer. The leachability tests revealed that the geopolymer did not release metals in concentrations exceeding the allowable limits set by the United States Environmental Protection Agency (USEPA), indicating effective encapsulation of the pollutants within the geopolymer matrix. Furthermore, the resultant geopolymer brick is eco-sustainable and can be classified as a green construction material.

Comparative studies on the seismic performances of precast segmental columns with different concrete, reinforcement and tendon materials

In recent years, precast segmental columns cast with ordinary Portland cement (OPC) and reinforced with steel rebars have gained popularity in engineering practices owing to its obvious advantages. However, the use of OPC in the construction associates to significant emission of carbon dioxide. Moreover, the corrosion of steel reinforcements and tendon are unavoidable during the lifetime of the structure, which will significantly lower the structural strength and durability. To overcome these issues, very recently, this study proposes using green and sustainable construction materials, i.e., the geopolymer concrete (GPC), together with basalt fibre reinforced polymer (BFRP) reinforcements and tendons, which possess the characteristics of less CO2 emission and excellent corrosion resistant capability, to construct precast segmental columns (i.e., to construct GPC-BFRP segmental columns) for seismic resistant applications. Experimental studies on the proposed GPC-BFRP and the conventional OPC-steel segmental columns were then performed to examine the performances of the proposed design. However, the comparisons of the experimental results were not strictly fair since the key parameters of the two types of columns, e.g., concrete strength and posttension force, in the experiments could not exactly be the same even though they were designed to be the same. This paper therefore extends the recent experimental study and performs numerical simulations. In particular, the experimentally tested columns were used to validate the three-dimensional (3D) finite element models (FEMs) of the two segmental columns with different materials (i.e., OPC-steel and GPC-BFRP). The validated numerical models are then used to examine the seismic performances of these two types of columns under the same design parameters. Numerical results show that under small earthquakes, two types of columns present almost identical structural responses. Under moderate to severe earthquakes, the two columns also have comparable performances, but GPC-BFRP segmental column presents larger displacement responses and failed earlier because of the smaller BFRP elastic modulus. The results in this study demonstrate the potentials of constructing sustainable and durable GPC-BFRP segmental columns in seismic regions.

Effect of polyvinyl alcohol on the mechanical and sound properties of recycled rubber mortar

Recycled rubber mortar is a novel green construction material which alleviates the environmental impact of waste rubber tires and greatly improves the sound insulation performance. Existing cement mortar with high rubber content exhibits poor mechanical properties, limiting its application in construction field. In this study, polyvinyl acetate (PVA) was introduced to modify recycled rubber mortar and the effect of PVA contents on its fluidity, flexural, compressive, impact strengths, and drying shrinkage was analyzed. To improve the analytical accuracy, analytic hierarchy process (AHP) was used to select the optimal mix proportion. The results indicate that PVA has positive effects on the mechanical properties of recycled rubber mortar. Further, comparing the trend of the normalized impact sound pressure level with an increase in frequency and the weighted normalized impact sound pressure level revealed that mixing 50 % recycled rubber particles and 8 % polyvinyl acetate effectively improved the sound insulation performance of cement mortar. These findings can promote the application of recycled rubber mortar in housing construction projects and having environmental benefits.

Chemical shrinkage, autogenous shrinkage, drying shrinkage, and expansion stability of interfacial transition zone material using alkali-treated banana fiber for concrete

ABSTRACT It might be of interest for authors to learn more that in the early 1900s, fibers were used in cement-based material, as cement-based materials exhibit shrinkage cracking over time, which can be controlled by adding fibers. The main aim of the inserting natural fiber into cement-based material is to decrease the shrinkage of cement-based material, prevent the rising of shrinkage cracks, and develop low-cracking cement-based material. In the research, the same aim aforementioned was kept same way. For carrying out the aim, agricultural waste, known as banana fiber (BF), can be considered a shrinkage reducer, expansion stabilization, a renewable material and has potential to make cement-based material transformed into a green construction material. This research investigated the effect of BF incorporation on cement paste shrinkage. Thus, five mixes were developed with different BF additions based on the total volume of cement paste (0, 0.5, 1, 1.5 and 2%). For each mixture, four tests were carried out to assess the impact of BF addition on the paste’s volume stability: chemical, autogenous, drying shrinkage and expansion. Testing was conducted for up to 90 days. Compared to the control mix, the addition of 2% BF reduced chemical shrinkage, autogenous shrinkage, drying shrinkage, and expansion by 27%, 57%, 47%, and 66%, respectively. Furthermore, a positive correlation was observed between chemical shrinkage and both autogenous and drying shrinkage and the percentage of BF content. Conversely, there was an inverse relationship between chemical shrinkage and expansion. The most significant conclusion to emerge from this study is that the incorporation of banana fiber (BF) into alkali-treated concrete results in a reduction in chemical shrinkage, autogenous shrinkage, drying shrinkage, and expansion. This is attributed to the molecular structure of BF, which is characterized by uninterrupted glycosidic linkages, leading to alkaline breakdown within the alkaline environment. Consequently, the alkali-treated BF can be described as a volume stability admixture in concrete technology.

Compressive Strength of Paver Block Using Rubber Tyre Waste and Bamboo Fibre Under Extreme Conditions

The utilisation of by-products in paver block production has gained significant attention due to its potential in environmental condition. This research investigates the effect of incorporating rubber tyre waste and bamboo fibre into the fabrication of paver block on compressive strength, water absorption, density and ultrasonic pulse velocity tests. This research comprises two batches of paver blocks fabrications following a 1:2:3 ratio(cement: fine aggregate: coarse aggregate). Batch 1 involves the fabrication of paver blocks by incorporating varying percentages of rubber tyre waste (0, 10, 20, 30, 40 and 50%), which replace a portion of the sand (referred to as rubber paver block). In Batch 2, various dosages of bamboo fibre, used as a reinforcement material were added to the paver block containing 40% rubber tyre waste, which are referred to as rubber-bamboo fibre paver blocks. Nevertheless, the compressive strength of the rubber-bamboo fibre paver blocks was further examined under two simulated environmental conditions: (1) air and dry cycle, and (2) wet and dry conditions. These conditions aim to assess the block’s resistance to temperature fluctuations, moisture effects, and theiroverall durability. The strength of the paver blocks decreases with the additional inclusion of rubber tyre waste. While the utilisation of 0.3% bamboo fibre has shown improvement in its strength performance compared to 0.2% and 0.4%. It suitable to used for non-loading structural applications that require strength below 25 kPa. This study was able to promote sustainable and green construction materials for paving applications through the efficient recycling of waste materials. It aligns with Sustainable Development Goals (SDG) 9 (Industry, Innovation, and Infrastructure) and 11 (Sustainable Cities and Communities).

Enhancing flame retardant wood’s versatility and adjustable properties through multi-scale micro-coating strategy

Wood, a naturally renewable material with a porous structure and breathability, rendering it a green construction material that can absorb sound, isolate heat and regulate moisture. Efforts to enhance wood’s resistance to combustion while maintaining its porous nature are hindered by the potential impact of physical and chemical treatments on its porous structure, posing a challenge in achieving flame-retardant wood that retains its breathability. Inspired by the multi-layer coating decoration method used on walls of various rooms in frame structure buildings, the study applies multi-scale micro-coating strategy to the multi-scale microstructure of wood. This strategy applied polyamino polyether methylene phosphonate (PAP), metal ions (Al3+/ Mg2+/ Ca2+), and alkali solutions to create a persistent multifunctional protective coating for the multi-scale wood structure. This coating effectively preserved the wood’s vessel, ray tissue, cell cavity, and pit structure, protecting its permeability. The modified wood demonstrated an increased limited oxygen value from 19.7 % to 38.4 % and a 55.9 % decrease in the total smoke release compared to natural wood, obtaining high fire safety. Furthermore, the modified wood exhibited adjustable antibacterial, photoaging-resistant and corrosion resistance properties depends on the type of metal. This strategy demonstrated proven reliability, versatility, and durability in the treatment of various metal ions, enabling the production of functional wood with tailored properties.

Date palm wood-derived cellulose aerogel dissolved in ionic liquids as a green thermal insulation construction material

Heat insulation materials used in the construction industry are essential for energy conservation. Nonetheless, the majority of current commercial heat insulators are fossil-fuel derived materials; thus, it is vital to provide sustainable, biodegradable, and environmentally friendly alternatives. In this work, an innovative method for producing cellulose II aerogels extracted from date palm waste and from microcrystalline lab-grade cellulose, targeting thermal insulation applications in the construction industry was introduced. A key aspect of the investigated approach is the use of a co-solvent system that combines 1-butyl-3-methylimidazolium chloride (Bmim)Cl and dimethylformamide (DMF), chosen for its efficiency in dissolving cellulose. The cellulose (at 3, 5, 7, and 9 wt%) was dissolved in a co-solvent system of 70 wt% (Bmim)Cl ionic liquid and 30 wt% DMF, saving costs associated with using purely ionic liquid solvents. The prepared aerogels exhibited low thermal conductivity (0.033–0.065 W/m⋅K), low densities (0.08–0.15 g/cm3), high porosity (89.85–94.69 %) and good thermal diffusivity (0.06–0.022 mm2/s). Furthermore, the developed insulators required a compressive strength of 75 kPa to reach 50 % strain and exhibited a sound absorption coefficient of 0.9. Structural characterization of the materials, including X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis, highlights the prospect of cellulose extracted from date palm wood in aerogel preparation and the potential for the (Bmim)Cl/DMF co-solvent system in dissolving cellulose.

Effects of alkaline activators and other factors on the properties of geopolymer concrete using industrial wastes based on GEP-based models

This study aims to develop reliable and practical models for estimating the compressive strength and CO2 emission of geopolymer concrete (GPC) using the Gene-expression programming (GEP) technique. Approximately 274 data points on the strength and CO2 emission of GPC using fly ash (FA) and ground granulated blast furnace slag (GGBFS) were used to generate two prediction models considering the effects of 19 input variables. The research results show that the proposed GEP-based models perform well with high correlation coefficients (R > 0.95) and reasonable errors. The parametric study demonstrates that increasing the GGBFS content, the Na2O (dry) content, and the molarity of NaOH solution, and decreasing the FA content, the FA/GGBFS ratio, and the added water or total water/binder ratio could significantly enhance the strength of GPC. Besides, the proposed GEP-based models were used to optimise the mix proportions of GPC concrete with minimisation of CO2 footprint. The range and reasonable values of the FA and GGBFS contents, the alkaline activators, the aggregates, and other parameters were suggested based on the in-depth analyses. This significant reference data source could promote the use of GPC widely in the construction industry as green construction materials for sustainable development.

Potential for Recycling Metakaolin/Slag-Based Geopolymer Concrete of Various Strength Levels in Freeze-Thaw Conditions.

Geopolymer concrete (GPC) represents an innovative green and low-carbon construction material, offering a viable alternative to ordinary Portland cement concrete (OPC) in building applications. However, existing studies tend to overlook the recyclability aspect of GPC for future use. Various structural applications necessitate the use of concrete with distinct strength characteristics. The recyclability of the parent concrete is influenced by these varying strengths. This study examined the recycling potential of GPC across a spectrum of strength grades (40, 60, 80, and 100 MPa, marked as C40, C60, C80, and C100) when subjected to freeze-thaw conditions. Recycling 5-16 mm recycled geopolymer coarse aggregate (RGAs) from GPC prepared from 5 to 16 mm natural coarse aggregates (NAs). The cementitious material comprised 60% metakaolin and 40% slag, with natural gravel serving as the NAs, and the alkali activator consisting of sodium hydroxide solution and sodium silicate solution. The strength of the GPC was modulated by altering the Na/Al ratio. After 350 freeze-thaw cycles, the GPC specimens underwent crushing, washing, and sieving to produce RGAs. Subsequently, their physical properties (apparent density, water absorption, crushing index, and attached mortar content and microstructure (microhardness, SEM, and XRD) were thoroughly examined. The findings indicated that GPC with strength grades of C100, C80, and C60 were capable of enduring 350 freeze-thaw cycles, in contrast to C40, which did not withstand these conditions. RGAs derived from GPC of strength grades C100 and C80 complied with the criteria for Class II recycled aggregates, whereas RGAs produced from GPC of strength grade C60 aligned with the Class III level. A higher-strength grade in the parent concrete correlated with enhanced performance characteristics in the resulting recycled aggregates.

Perface: Proceedings of the first International Conference on ‘Sustainable Experimentation and Modeling in Civil Engineering (SEMCE-2023)

The current volume comprised the proceedings of the first International Conference on ‘Sustainable Experimentation and Modeling in Civil Engineering (SEMCE-2023)’ which was organized by the School of Civil Engineering, Lovely Professional University, Punjab, India in association with Dr B R Ambedkar National Institute of Technology Jalandhar and Indian Geotechnical Society (IGS), Jalandhar Chapter in a hybrid mode during 10th-11th August 2023.Research articles were invited covering six themes Green and Sustainable Construction Materials, Innovation, Infrastructure and Management, Material Recycling and Reuse, Modelling, Simulation and Analysis, Energy and Climate and Water and Sanitation. The two-day event attracted 188 abstracts of research articles, out of which only 125 were selected for conference presentation after peer review. The event witnessed 145 participants including a few ‘attendees only’ also. The primary goal of SEMCE-2023 was to provide a common platform to bridge the gap between researchers, engineers, scientists and industry professionals to initiate an innovative dialogue on academic and technical exchange related to Civil Engineering. Deep-dive deliberations on diverse topics in physical inventions and engineering were also part of the agenda of SEMCE-2023.The success of SEMCE-2023 is attributed to all those who have contributed to the event. The organizers sincerely express their gratitude to all.List of Committee is available in this Pdf.