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One‐part alkali‐activated materials can be processed into semi‐finished products by mixing a solid activator with the powder. They only require the addition of water, which greatly improves their commercial feasibility. So, we used one‐part alkali‐activated slag mortar to investigate the effects of the dosages of the activator (sodium metasilicate), fly ash (FA), and gypsum on its fluidity, flexural strength, compressive strength, and drying shrinkage. The microscopic mechanisms of the mortar were analyzed using scanning electron microscopy and x‐ray diffraction. The below conclusions were drawn. First, the drying shrinkage and compressive strength of the mortar gradually increased with the increase of the activator dosage. Second, the drying shrinkage of the mortar initially decreased and then increased as increasing FA substitution, while the compressive strength decreased gradually in the early stage and then increased and decreased in the later stage. Lastly, by increasing the gypsum dosage, the drying shrinkage of the mortar was significantly reduced. However, the compressive strength gradually decreased. Besides, when adding 20% of FA and 2.4% of gypsum, it was found that ettringite, which underwent expansion, formed in the system. This not only reduced the drying shrinkage by 25.3% but also increased the compressive strength by 1.3%. Furthermore, our investigation has led to the development of a low‐shrinkage one‐part alkali‐activated slag and FA mortar, which not only facilitates the recycling of solid waste materials but also presents commendable environmental and economic advantages. [ABSTRACT FROM AUTHOR]

The article offers information on the precarious nature of motherhood in India, emphasizing its centrality in defining a woman's identity and success. Topics include the pressure on women to conform to the norm of motherhood; the intersection of cinema and literature in portraying these issues; and the examination of infertility, societal constructs and maternal norms through the characters of Ponna and Lajjo in Perumal Murugan's novel "One Part Woman" and Leena Yadav's film "Parched."

The lack of a code for preparing one-part geopolymer concrete (GPC) is one of the major obstacles to its wide use. This study adopted one of the most common methods for preparing ordinary concrete, the ACI method, taking into account the most important variables affecting this method and then modified it to suit one-part GPC. Three different sizes of aggregates and four water-to-binder ratios (W/B) were used in preparing the concrete mixtures in this study. In addition, three different proportions of sodium metasilicate were used as the activator, which ultimately resulted in a total of 36 mix designs. Specimens were subjected to various tests, including setting time, workability, and compressive strength. In addition, the material's behaviour was studied using X-ray diffraction and scanning electron microscope. The results indicate that the ACI method is generally applicable for designing geopolymer concrete mixtures with minor adjustments. Consequently, the table used for predicting concrete strength based on a specific water/cement ratio has been replaced with relevant figures that depict the relationship between compressive strength and the water-to-binder ratio. In addition, a step-by-step flowchart has been presented that explains how to design one-part geopolymer concrete. Conducted experiments indicated that the properties of geopolymer concrete are greatly affected by the ratio of W/B and the size of aggregate used in preparing the concrete mixture. Furthermore, the quantity of activators has significant effects on concrete's workability and compressive strength. Results of the experiment suggest that one-part GPC can provide greater compressive strength than ordinary concrete. [ABSTRACT FROM AUTHOR]

The design and development of environmentally oriented cements with predominant content of widespread noncalcined precursors contribute to a more promising future for constantly evolving alkali-activated materials (AAMs). In this study, natural and designed blends of calcined clays and abundant raw calcium carbonate minerals were investigated as binary precursors for one-part AAMs using standard techniques, thermal, X-ray diffraction, and scanning electron microscopy/energy dispersive spectroscopy (EDS) analyses. The influencing factors to set optimal parameters were the mineralogical assemblage, precursors fineness, formulation details, means of alkali reactant incorporation, and curing regimes. It was stated that hydraulic one-part AAMs can be derived from calcined marl incorporated with limestone powder containing 5.8%–7.0% of calcined clay minerals and 54.6%–60.5% of calcite or nonhydraulic one-part AAMs from a mixture consisting of 20%–30% metakaolin and 70%–80% limestone powder. It was found that, compared with a metakaolin-limestone-based binary precursor, alkali activation of calcined marl–limestone results in the formation of a higher amount of binder gel with a greater extent of Ca incorporation into the structure of Na aluminosilicate gel and the formation of Ca aluminosilicate and Ca silicate hydrogels. This provides an alkali-activated calcined marl–limestone binder system with better mechanical properties and continuous strength development, including under wet conditions. [ABSTRACT FROM AUTHOR]

This paper characterizes the efficacy of borax on different properties of alkali-activated materials (AAMs). Fly ash (FA) and ground granulated blast slag (GGBS) were used as base substances at different ratios. The effects of borax on workability, compressive strength, efflorescence formation and crack resistance are the main ideas of the study. The results indicated the positive effects of borax on the properties of one-part fly ash/slag-based alkali-activated materials such as increasing workability and decreasing efflorescence. The microscopic images and scanning electron microscope (SEM) showed that the addition of borax reduced the cracks and a higher amount of slag made the samples denser with less unreacted raw materials, respectively. The compressive strength test results showed that borax had a detrimental impact at early ages with a positive effect at later ages. Binders with borax and 20-25% replacement of FA with GGBS were found to have the best performance when workability, compressive strength, efflorescence formation, and cracks on the samples were taken into account. [ABSTRACT FROM AUTHOR]

Solid activators based on waste glass for the manufacture of one-part alkali-activated fly ash/red mud materials were synthesized, characterized, and tested in this work. The synthesis was carried out via alkaline fusion with sodium hydroxide at different reaction temperatures and at different sodium hydroxide/waste glass mass ratios. The results showed that the reaction temperature decisively influences the properties of the obtained solid activators. Thus, the best results regarding the water solubility of solid activators were obtained for the synthesis temperature of 600 °C, regardless of the sodium hydroxide/waste glass mass ratio. Also, the use of these assortments of solid activators led to obtaining the best compressive strength of one-part alkali-activated fly ash/red mud materials. The best results were obtained for the solid activator synthesized at a temperature of 600 °C and a sodium hydroxide/glass waste mass ratio of two. [ABSTRACT FROM AUTHOR]

The article focuses on the challenges faced by mental health nurses, emphasizing the importance of resilience in overcoming workplace stress and distress. Topics discussed include the diverse challenges encountered by mental health nurses, the impact of the COVID-19 pandemic on healthcare systems, and the need for a comprehensive toolkit of skills and strategies to support nurses' well-being.

Background: Urinary tract problems are a common complaint in small animal medicine and urolithiasis is considered to be an important cause of urinary tract disease in dogs. In this study the main aim was to investigate whether the occurrence of cystine urolithiasis increased during a five-year period. A second aim was to evaluate possible risk-factors as breed, age and gender. This study also evaluated how urine specific gravity, pH and level of cystine in urine responded to preventive strategies. Medical records of dogs with urolithiasis presented at nine Norwegian animal clinics and one animal hospital between 2015 and 2020 were retrospectively reviewed. Results: The incidence of cystine uroliths increased significantly during the five study years (R2 = 0.72, P = 0.0199). Dogs with cystine uroliths were significantly younger (5.0 years (n = 84, 95% CI [4.4–5.6])) when they were diagnosed with cystine uroliths compared to dogs with other types of uroliths (8.1 years (n = 255, 95% CI[7.8-8.5]) P < < 0.0001). Cystine levels in urine were increased in 93% of the dogs with cystine urolithiasis. Cystinuria decreased significantly after neutering (P < 0.0001). Breeds most commonly affected with cystine urolithiasis in this study were Staffordshire bull terrier, Danish Swedish farmdog and Chihuahua. Conclusions: The results from this study supports a suggested genetic basis for cystine urolithiasis as described in previous studies. Neutering is considered an important part of preventing reoccurrence since cystine values decreased significantly after neutering. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms controlling the early (fresh) and long‐term (hardened) hydration of one‐part alkali‐activated slags (AAS) is key to extend their use as low CO2 substitutes for ordinary Portland cement (OPC). Their "just add water" use makes them easier and less hazardous to manipulate than the more studied two‐part ones. This is due to the absence of liquid alkaline activators, which are environmentally and energy demanding. In this work, numerous experimental techniques have been linked to obtain a comprehensive physico‐chemical characterization of a one‐part AAS activated with Na2CO3 and Ca(OH)2 powders at several water to solid ratios (w/s). Calorimetry and pH/conductivity measurements describe the functioning of the activators immediately after contact with water. Early reactivity is characterized through in situ X‐ray powder diffraction (XRPD) and small amplitude oscillatory shear (SAOS) rheology, which reveal a rapid precipitation of nanometric hydration products (nano‐C‐A‐S‐H), which results in a continuous increase in the paste cohesivity until setting. Moreover, SAOS shows that rejuvenating the paste by means of shearing (performed externally to the rheometer in this study) is enough to restore the initial cohesion (i.e., workability) for long time spans until setting occurs. The long‐term hydration is characterized by ex situ XRPD on aged AAS pastes, in parallel with mechanical testing on AAS mortar. A correlation can be observed between the amount of nano‐C‐A‐S‐H and the increase in compressive strength. Overall, this formulation shows satisfactory fresh and solid properties, demonstrating suitability for low‐ and normal‐strength applications. [ABSTRACT FROM AUTHOR]

Waste brick powder (WBP) has enough pozzolanic characteristics to be employed as a supplemental cementing material in Portland cement‐based concrete or as a precursor in the manufacture of alkali activated materials. This study was aimed to study the strength, thermal, microstructural and durability properties of ground blast furnace slag (GBFS) and WBP based one‐part alkali‐activated lightweight mortars (AAMs) produced with expanded vermiculite. One‐part AAM mixtures were produced by using GBFS and WBP as binary precursors. Sodium metasilicate powder was used as the alkali activator. Two curing regimes namely heat curing at 75°C for 24 h and air curing at ambient conditions were adopted. GBFS was used as main binder and WBP was added at the rates of 0%, 10%, 25%, and 50% instead of GBFS. Four different mixtures were prepared by replacing GBFS at the rates of 0%, 10%, 25%, and 50% with WBP for each curing regime (totally eight mixtures). Expanded vermiculite powder were used as lightweight aggregates in all mixtures. The effects of WBP on AAM mixtures properties, including flowability, compressive strength, flexural strength, dry bulk density, thermal conductivity, porosity, and water absorption were studied. The effects of WBP and curing regime on drying shrinkage, sorptivity were also investigated. High temperature performance of the produced mixtures were determined. Results showed that air‐cured WBP incorporated AAM mixtures exhibited better compressive strength, flexural strength, shrinkage, and sorptivity performance than the heat‐cured WBP incorporated AAM mixtures. The air‐cured AAM mixtures containing 25% WBP achieved the best results of 5.69 and 1.43 MPa for compressive strength and flexural strength at test age of 28 days. The heat‐cured 50% WBP incorporated AAM mixture showed the best high temperature resistance and the lowest thermal conductivity. [ABSTRACT FROM AUTHOR]

Alkali-activated engineered composites (AAECs) are cement-free composites developed using alkali activation technology, which exhibit strain hardening and multiple micro-cracking like conventional engineered cementitious composites (ECCs). Such AAECs are developed in this study by incorporating 2% v/v polyvinyl alcohol (PVA) fibers into alkali-activated mortars (AAMs) produced using binary/ternary combinations of fly ash class C (FA-C), fly ash class F (FA-F), and ground-granulated blast furnace slag (GGBFS) with powder-form alkaline reagents and silica sand through a one-part mixing method under ambient curing conditions. The mechanical and microstructural characteristics of eight AAECs are investigated to characterize their strain-hardening performance based on existing (stress and energy indices) and newly developed tensile/flexural ductility indices. The binary (FA-C + GGBFS) AAECs obtained higher compressive strengths (between 48 MPa and 52 MPa) and ultrasonic pulse velocities (between 3358 m/s and 3947 m/s) than their ternary (FA-C + FA-F + GGBFS) counterparts. The ternary AAECs obtained a higher fracture energy than their binary counterparts. The AAECs incorporating reagent 2 (Ca(OH)2: Na2SO4 = 2.5:1) obtained a greater fracture energy and compressive strengths than their counterparts with reagent 1 (Ca(OH)2: Na2SiO3.5H2O = 1:2.5), due to additional C-S-H gel formation, which increased their energy absorption for crack propagation through superior multiple-cracking behavior. A lower fracture and crack-tip toughness facilitated the development of enhanced flexural strength characteristics with higher flexural strengths (ranging from 5.3 MPa to 11.3 MPa) and a higher energy ductility of the binary AAMs compared to their ternary counterparts. The tensile stress relaxation process was relatively gradual in the binary AAECs, owing to the formation of a more uniform combination of reaction products (C-S-H/C-A-S-H) rather than a blend of amorphous (N-C-A-S-H/N-A-S-H) and crystalline (C-A-S-H/C-S-H) binding phases in the case of the ternary AAECs. All the AAECs demonstrated tensile strain-hardening characteristics at 28 days, with significant improvements from 28% to 100% in the maximum bridging stresses for mixes incorporating 40% to 45% GGBFS at 365 days. This study confirmed the viability of producing green cement-free strain-hardening alkali-activated composites with powder-form reagents, with satisfactory mechanical characteristics under ambient conditions. [ABSTRACT FROM AUTHOR]

This paper describes an experimental investigation into the properties of ambient cured one-part alkali-activated materials (AAMs). Mixes incorporating waste glass (WG), ground granulated blast-furnace slag (GGBS), fly ash (FA), and sodium metasilicate pentahydrate were assessed in terms of workability, water absorption, physical and mechanical properties, and environmental impact. Microstructure investigations on selected mixes were also carried out. The GGBS-only mixes had low workability and high early strength that declined over time, whereas FA-only mixes had virtually no strength. Equal proportions of WG and GGBS provided similar fresh properties to those of GGBS mixes yet comparatively higher strengths and a positive strength time gradient. Mixes incorporating 50% GGBS, 25% FA, and 25% WG had the best balance between mechanical properties and workability, with compressive strengths above 40 MPa suitable for structural applications. An increase in activator content from 14% to 21% enhanced the strengths by 39.1%–54.6%. The flexural strengths were largely proportional to the compressive strengths, the water absorption properties were like those of cement mortars, and dry densities depended on the proportions of the constituent binders. Finally, the AAM mixes had between 53% and 72% less embodied carbon compared with a corresponding cement mortar. [ABSTRACT FROM AUTHOR]

One-part geopolymer concrete/mortar is a pre-mixed material made from industrial by-products and solid alkaline activators that only requires the addition of water for activation. Apart from being environmentally friendly, it also reduces complexity and improves consistency in the mixing process, leading to more efficient production and consistent material properties. However, developing one-part geopolymer concrete with desirable compressive strength is challenging because of the complexity of the chemical reaction involved, the variability of the raw materials used, and the need for precise control of curing conditions. Therefore, 80 different one-part geopolymer mixtures were compiled from the open literature in this study, and the effects of the constituent materials, the dosage of alkaline activators, curing condition, and water/binder ratio on the 28-day compressive strength of one-part geopolymer paste were examined in detail. An ANN model with the Levenberg–Marquardt algorithm was developed to estimate one-part geopolymer's compressive strength and its sensitivity to binder constituents and alkaline dosage. The ANN model's weights and biases were also used to develop a CPLEX-based optimization method for achieving maximum compressive strength. The results confirm that the compressive strength of one-part geopolymer pastes increased by increasing the Na2O content of the alkaline source and the slag dosage; however, increasing the Na2O content in alkaline sources beyond 6% by fly ash weight led to decreasing the compressive strength; therefore, the optimum alkaline activator dosage by weight of fly ash was to be 12% (i.e., 6% Na2O). The proposed ANN model developed in this study can aid in the production and performance tuning of sustainable one-part geopolymer concrete and mortar for broader full-scale applications. [ABSTRACT FROM AUTHOR]

One-part geopolymer (OPG) grout offers advantages over two-part geopolymer grout in the handling and storage of feedstocks, mainly because of the large quantities of caustic solutions that must be handled for producing two-part geopolymer. However, OPG often suffers from a low degree of reaction, a high number of crystalline by-products and, as a result, low strength. Here, one-part geopolymer was assisted by mechanochemical activation (MC-OPG) to produce grout. The precursor materials (slag and fly ash) and sodium silicate were mechanochemically activated utilising co-grinding to produce a geopolymeric precursor, after which water is the only additive required to initiate the geopolymerisation reaction. The effects of slag/fly ash ratios on grout mixtures were also investigated. A series of tests was examined, including rheological characteristics, setting time, bleeding, unconfined compressive strength (UCS), ultrasonic pulse velocity, scanning electron microscopy and X-ray diffraction. The results showed that the mechanochemical activation technique increased the rheological characteristics and reduced the fresh properties (setting time and bleeding) of geopolymer grout compared to the one-part geopolymer. Considering mechanical properties, the UCS of MC-OPG grout was higher (41–73%) than that of OPG grout. Furthermore, slag content significantly affected the rheological, fresh and mechanical properties of all the geopolymer grouts regardless of the activation method. [ABSTRACT FROM AUTHOR]

To evaluate the feasibility of mixing saline underground water (SUW) in the preparation of cemented fine tailings backfill (CFTB), the compressive strength, pore fluid pH, slag hydration degree, hydration phase composition/structure, and pore morphology of CFTB have been tested. The binder used was a one-part alkali-activated slag composed of ground-granulated blast furnace slag (67.8% by weight) as precursor and desulfurized gypsum (25.9% by weight) and hydrated lime (6.3% by weight) as composite activator. The results showed that using SUW instead of deionized water as mixing medium had both negative and positive effects on the strength development of CFTB, depending on the curing time. At the very early ages (1–3 days), mixing SUW resulted in a decrease of the pore solution pH, which is due to the reaction of positive ions in SUW with OH− ions and the decrease of slag hydration rate, leading to a lower strength of CFTB. The positive effects were observed at the later ages (7–28 days). The higher later-age strength of SUW-mixed CFTB is attributed to two factors: (1) a smaller amount of ettringite (AFt) was generated at the very early ages, which reduced the encapsulation-hindering effect on the slag decomposition; and (2) SUW increased the slag hydration rate, promoting the condensation of calcium silicate hydrates, which results in increased formation of a calcium silicate aluminate hydrate [C-(A)-S-H] phase with rigid three-dimensional structure. These findings can provide important information for the use of SUW in CFTB in coastal and arid regions. [ABSTRACT FROM AUTHOR]

Alkali-activated binder (AAB) is a product with lower carbon footprint and has great potential to be an alternative to Portland cement in civil construction. In this study, one-part AAB has been synthesized by mixing alternative sodium silicate powder, obtained from rice husk ash (RHA) and metakaolin (MK). The main objective was to verify the effect of MK (two types were used with different reactivity characteristics) and water content on the mechanical properties of pastes and mortars produced with the one-part AAB. Some tests were conducted (e.g. setting times, flexural and compressive strengths, elastic modulus) and the results indicated that the MK type and the water content directly affect different properties. As expected, the decrease in water content decreased the workability of the mortars and improved the mechanical strength. A more reactive MK provided an increase in compressive strength higher than 60%. The results confirm the possibility of producing an alternative sodium silicate powder from RHA dissolution, that when mixed with MK, results in AAB with acceptable compressive strength. This paper reveals that with the correct materials and a good mix design, the properties of this eco-friendly AAB can be considerably improved. [ABSTRACT FROM AUTHOR]

This paper aims to assess the durability of one-part geopolymer (OPG) pastes exposed to acidic environments. Two different acids (HCl and H2SO4) with different pH values (pH of 2, 4, and 6) were used to simulate the acidic environment in the current study. Acid resistance of the OPG paste activated by sodium hydroxide [NaOH (NH)] and sodium metasilicate [ Na2SiO3 (NS)], respectively, was assessed in terms of pH variation, mass change, visual appearance, deterioration depth, and compressive strength loss for varied immersion periods (∼120 days). The scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDS) and mercury intrusion porosimetry (MIP) tests were employed to investigate the evolution of porosity, morphological change, and hydrate composition for the varied immersion times. The experimental results revealed that due to the formation of a dense structure, the NS-activated OPG paste had better resistance to the acid attack compared with the NH-activated paste. It was also found that the gypsum crystals formed in the sample immersed in H2SO4 solution could fill the open pores and adhere to the surface of the sample, which reduced the further acid attack to some extent. However, the expansion properties of gypsums would lead to a loss of mechanical performance at the later immersion period. Furthermore, higher porosity of the OPG paste developed as the pH value of the acid solution decreased, thereby inducing the loss of mass and compressive strength and the increase of deterioration depth. Finally, as the immersion age and acid concentration increased, decalcification in the sample tended to occur, which caused a greater loss of compressive strength and a higher porosity. The outcome of this study could provide guidance for the application of the novel material in acid soil layer improvements or acid-resistant geotechnical structures. [ABSTRACT FROM AUTHOR]

This study reports on the possibility of applying one-part pressed geopolymers as a support for microfiltration membranes. The mineralogical, physical, mechanical, microstructural and hydraulic properties of the investigated materials are presented. Metakaolin-based geopolymeric membrane flat supports were synthesized by uniaxial pressing a dry-mixed powder (Si/Al = 1.45, Na/Al = 0.9, Na/Si = 0.62, H 2 O = 12%), with pressure between 2 and 20 MPa and a curing temperature of 70 °C. Mixing and pressing optimization resulted in samples with a total open porosity up to 39%, a modal pore diameter up to 23.5 μm and a flexural strength up to 20.4 MPa. Permeation measurement with demineralized water and ethanol-water solutions were carried out using a dead-end geometry membrane apparatus. A hydraulic permeability up to 31.3 · 103 L h−1 m−2 bar−1 has been obtained. Furthermore, permeation tests using water-ethanol solutions have demonstrated that the material is hydrophilic. These results highlighted the potential of geopolymers as microfiltration support. • Pressed one-part geopolymers are suitable to be used as membrane supports. • Geopolymer membrane supports possess a peculiar threshold pressure. • Geopolymer supports have similar characteristics to ceramic membrane supports. [ABSTRACT FROM AUTHOR]

The evolution of globalization and rapid industrialization, coupled with intensive human activities, leads to a significant release of acidic gases and particles (e.g., NO X and SO 2) is unavoidable. These emissions eventually result in dry and wet acid depositions due to atmospheric circulation. This infiltration of acidic elements alters the chemical properties of water systems, thereby deteriorating ground stability. The economically developed soft clay areas face considerable threats from these acid environmental attacks. This study focused on employing a ''one-part'' geopolymer (OPG) comprising ground granulated blast furnace slag (GGBFS), fly ash (FA), and solid sodium hydroxide (NH) to stabilize the soft clay. Simultaneously, the deterioration behavior of OPG stabilized soft clay under two different acids (HNO 3 and H 2 SO 4) with various pH values (pH of 2, 4, and 6) and varied immersion periods up to 240 days was evaluated including the mass loss, neutralization depth (ND), pH value, and unconfined compressive strength (UCS). Additionally, scanning electron microscopy (SEM) and X-ray energy spectrometry (EDS) characterized the evolution of microstructure and hydrate composition of OPG-stabilized soft clay post varied acid immersion. The results highlighted the superior acid resistance of the stabilized soft clay with an 80:20 GGBFS/FA ratio compared to other ratios. The presence of significant hydration products, such as calcium silicate hydrates (C–S–H), calcium aluminate (aluminosilicate) hydrates (C-A-(S)–H), and sodium aluminosilicate hydrates (N-A-S-H), was observed in the OPG stabilized soft clay. In addition, the contents of Si in the OPG played a significant role in enhancing the acid resistance of the OPG stabilized soft clay. Based on these experimental results, two proposed mechanisms detailed the deterioration and acid resistance of the OPG stabilized soft clay under HNO 3 and H 2 SO 4 attack. The findings of this study contribute to advancing scientific comprehension concerning the acid resistance of the OPG stabilized soft clay in ground improvement practices. • The acid resistance of the OPG geopolymer stabilized soft clay was evaluated by mass loss, UCS, neutralization, and pH tests. • Effects of GGBF/FA, the type of acid solution, the pH value of acid solution, and the immersion time were investigated. • The superior acid resistance of the stabilized soft clay with an 80:20 GGBFS/FA ratio compared to other ratios. • The evolution of microstructure and hydrate composition in OPG stabilized soft clay were analyzed. • The deterioration and acid resistance mechanism of OPG stabilized soft clay under acids attack were proposed and discussed. [ABSTRACT FROM AUTHOR]

Sodium hydroxide (NaOH) as an alkaline activator presents a vital limitation in the mass production of alkali-activated binders due to its severe effect on users' safety. In this study, safe and sustainable one-part alkali-activated slag mixes (OP-AAS) were prepared through an efficient microwave sintering for a mixture of active amorphous ground granulated blast furnace slag (GGBFS) and sodium hydroxide powder (NaOH). Different microwave-sintered powders were prepared using microwave energy of power 900 W for the mixture at different treatment periods (10, 20, and 30 min). Fresh and hardened properties of different OP-AAS mixes were studied. Moreover, the phase composition and microstructure were investigated using X-ray diffraction (XRD) analysis and scanning electron microscope (SEM). Cytotoxicity/viability testing was performed to evaluate the cell death induced by the developed materials to measure their safety for the user. According to compressive strength, cytotoxicity/viability analysis, environmental impact and cost calculation of developed OP-AAS, it is concluded that employing microwave sintering for a short duration is sufficient to produce safe binding materials with adequate mechanical properties suitable for commercial applications in the construction sector. [ABSTRACT FROM AUTHOR]

3D printing of conductive elastomers is a promising route to personalized health monitoring applications due to its flexibility and biocompatibility. Here, a one‐part, highly conductive, flexible, stretchable, 3D printable carbon nanotube (CNT)‐silicone composite is developed and thoroughly characterized. The one‐part nature of the inks: i) enables printing without prior mixing and cures under ambient conditions; ii) allows direct dispensing at ≈100 µm resolution printability on nonpolar and polar substrates; iii) forms both self‐supporting and high‐aspect‐ratio structures, key aspects in additive biomanufacturing that eliminate the need for sacrificial layers; and iv) lends efficient, reproducible, and highly sensitive responses to various tensile and compressive stimuli. The high electrical and thermal conductivity of the CNT‐silicone composite is further extended to facilitate use as a flexible and stretchable heating element, with applications in body temperature regulation, water distillation, and dual temperature sensing and Joule heating. Overall, the facile fabrication of this composite points to excellent synergy with direct ink writing and can be used to prepare patient‐specific wearable electronics for motion detection and cardiac and respiratory monitoring devices and toward advanced personal health tracking and bionic skin applications. [ABSTRACT FROM AUTHOR]

Alkali-activated materials (AAM) are recognized as potential alternatives to ordinary Portland cement (OPC) to limit CO2 emissions and beneficiate several wastes into useful products. Compared with its counterparts involving the concentrated aqueous alkali solutions, the development of "just add water" one-part alkali-activated materials (OP-AAM) has drawn much attention, mainly attributed to their benefits in overcoming the hazardous, irritating, and corrosive nature of activator solutions. This study starts with a comprehensive overview of the OP-AAM; 89 published studies reported on mortar or concrete with OP-AAM were collected and concluded in this paper. Comprehensive comparisons and discussions were conducted on raw materials, preparation, working performance, mechanical properties, and durability, and so on. Moreover, an in-depth comparison of different material pretreatment methods, fiber types, and curing methods was presented, and their potential mechanisms were discussed. It is found that ground granulated blast-furnace slag (GGBS) provides the best mechanical properties, and the reuse of most aluminosilicate materials can improve the utilization efficiency of solid waste. The curing temperature can be improved significantly for precursor materials with low calcium contents. In order to overcome the brittleness of the AAM, fiber reinforcement might be an efficient way, and steel fiber has the best chemical stability. It is not recommended to use synthetic fiber with poor chemical stability. Based on the analysis of current limitations, both the recommendations and perspectives are laid down to be the lighthouse for further research. [ABSTRACT FROM AUTHOR]

This study explores developing and characterizing a one-part geopolymer, an innovative and sustainable construction material. The effects of incorporating polyvinyl alcohol (PVA), polyethylene (PE), and glass fibers (GF) on the toughness of slag and fly ash-based one-part geopolymer mortars were investigated through compressive, three-point flexural, and four-point bending tests. The findings demonstrate that fiber incorporation reduces fluidity and compressive strength due to increased porosity, lower elastic modulus of fibers, and weak interfacial bonding. However, fibers significantly enhance damage resistance and toughness via crack bridging and load transfer mechanisms. Formulations with 2 % PVA fibers and combinations of 1 % PVA with 1 % PE fibers and 1 % PVA mixed with 0.5 % PE and 0.5 % GF demonstrate excellent toughness. Notably, the latter two fiber blends achieve 14 % and 10 % cost reductions, respectively, compared to using only PVA fibers, making them economically viable for large-scale applications. Scanning electron microscopy and X-ray diffraction provided insights into the toughening mechanisms, including crack bridging, fiber pull-out, and enhanced stress distribution within the geopolymer matrix. Digital image correlation techniques further elucidated the fibers' role in improving the post-cracking behavior and structural resilience under load. • Comprehensive investigation of PVA, PE, and glass fiber reinforcement in one-part geopolymer mortars, focusing on toughness optimization and cost-effectiveness. • Fiber incorporation significantly enhances damage resistance and toughness through crack bridging and load transfer mechanisms, despite minor reductions in fluidity and compressive strength. • Economically viable fiber blends (1 % PVA + 1 % PE; 1 % PVA + 0.5 % PE + 0.5 % GF) achieve excellent toughness with 14 % and 10 % cost reductions, respectively, compared to using only PVA fibers, making them suitable for large-scale applications. • SEM and XRD provide insights into the toughening mechanisms, including crack bridging, fiber pull-out, and enhanced stress distribution within the geopolymer matrix. DIC techniques elucidate the fibers' role in improving the post-cracking behavior and structural resilience under load, further validating the effectiveness of fiber reinforcement in one-part geopolymers. [ABSTRACT FROM AUTHOR]

The application of sewage sludge ash (SSA) in alkali activated cementitious material, i.e., geopolymer, was one of the effective measures to dispose of and recycle the sewage sludge. However, the geopolymer efflorescence could be aggravated due to elevated alkali content, especially for one-part geopolymer, where the dissolution reaction of solid alkali activator was less sufficient. This study focused on the efflorescence of GGBS-SSA based one-part geopolymer, as compared to two-part geopolymer, and the effect of silica fume on the efflorescence, strength and micro-properties of the one-part geopolymer. The results showed that the extent of efflorescence crystallization and the concentration of leached Na+ ions in the one-part geopolymer were more severe than the two-part geopolymer, due to the lower degree of geopolymerization reaction and the heterogeneous dense microstructure of the one-part geopolymer. After adding silica fume to the one-part geopolymer, the extent of efflorescence crystallization and the concentration of leached Na+ ions reduced significantly, and the compressive strength increased from 41.6 MPa to 57 MPa when the silica fume content was 10 %, but then decreased slightly. Adding the silica fume reduced the release rate of reaction heat, which helped to increase the solubility of solid alkali activator and improve the geopolymerization reaction, thus significantly reducing the content of mobile alkali ions and enhancing the compressive strength. Moreover, the silica fume with tiny spherical particle had better ball effect and micro-aggregate filling effect, which refined the pore size and reduced the connectivity of pore network, significantly reducing the diffusion rate and leaching of mobile alkali ions. • Efflorescence between one-part and two-part GGBS-SSA based geopolymer was contrastively analyzed. • Influences of silica fume on efflorescence and compressive strength of one-part GGBS-SSA based geopolymer were investigated. • Inhibition mechanisms of silica fume on the efflorescence of one-part GGBS-SSA based geopolymer were revealed. [ABSTRACT FROM AUTHOR]

Geopolymers have the advantages of low carbon, being environmentally friendly and low price, which matches the development direction of building materials. Common geopolymer materials are also known as two-part geopolymers (TPGs). TPGs are usually prepared from two main substances, which are formed by polymerization of a silicoaluminate precursor and an alkaline activator solution. The TPG has many limitations in engineering application because of its preparation on the construction site, and the use of solid alkaline activator in one-part geopolymers (OPGs) overcomes this shortcoming. However, the brittleness of OPGs such as ceramics also hinders its popularization and application. The properties of the new OPG can be improved effectively by toughening and strengthening it with fibers. This review discusses the current studies of fiber-reinforced one-part geopolymers (FOPGs) in terms of raw precursors, activators, fibers, physical properties and curing mechanisms. In this paper, the effects of the commonly used reinforcement fibers, including polyvinyl alcohol (PVA) fiber, polypropylene (PP) fiber, polyethylene (PE) fiber, basalt fiber and other composite fibers, on the fresh-mixing properties and mechanical properties of the OPGs are summarized. The performance and toughening mechanism of FOPGs are summarized, and the workability, macroscopic mechanical properties and durability of FOPGs are investigated. Finally, the development and engineering application prospect of FOPGs are prospected. [ABSTRACT FROM AUTHOR]

Suppose G is a simple graph. If f is a mapping from V(G) ∪ E(G) to {1,2,...,k} such that f(e), f(u), f(v) are distinct for each edge e = uv of G, then f is called an E-total coloring of G using k colors (k-E-total coloring of G, in brief). For an E-total coloring f of a graph G and any vertex x of G, we denote the set {f(x)} ∪ {f(e)|e ∈ E(G) and e is incident with x} by C(x) and refer to it as the color set of x under f. If C(u) ≠ C(v) for any two different vertices u and v of V (G), then we say that f is a vertex-distinguishing E-total coloring of G or a VDET coloring of G for short. Let χvte(G) = {k|G has a VDET coloring using k colors }. Then the positive integer χvte(G) is called the VDET chromatic number of G. The VDET coloring of complete bipartite graph K5,n is discussed in this paper and the VDET chromatic number of K5,n has been obtained. [ABSTRACT FROM AUTHOR]

Lithium slag (LS) exhibits potential as a silica-alumina precursor for geopolymer synthesis, yet its limited reactivity poses challenges for widespread application in one-part geopolymers. This study employs alkali fusion activation to enhance LS reactivity and investigates the underlying mechanisms using XRD, FTIR, and ICP techniques. Results reveal that post-alkali fusion treatment transforms spodumene and quartz within LS into amorphous phases, significantly increasing the amorphous content from 15.9% to 53.1%. However, excessive inclusion of sodium hydroxide (NaOH) during alkali fusion reduces the amorphous phase content. Alkali fusion also enhances LS leaching concentration in an alkaline solution, but an overly abundant incorporation of NaOH adversely affects Si and Al leaching. Within specific parameters, increasing the alkali solution concentration and dissolution temperature enhances Si and Al leaching from LS. Subsequently, alkali-fused LS, along with slag and fly ash, is utilized to fabricate a one-part geopolymer that exhibits outstanding compressive strength. Results indicate that the compressive strength of alkali-fused LS geopolymer consistently surpasses that of the initial LS geopolymer during the curing period, reaching 50.6 MPa after 28 days. Alkali fusion effectively raises the pH of the geopolymer pore solution, promoting the formation of N(C)-A-S-H gel. The overall structure of the geopolymer prepared from alkali-fused LS is dense, with unreacted particles covered by a flocculent gel. However, excessive NaOH incorporation during alkali fusion reduces LS reactivity, diminishing the formation of N(C)-A-S-H gel. Simultaneously, the alkaline environment resulting from excessive NaOH facilitates carbonation reactions in geopolymer samples, thereby reducing compressive strength. • Alkali fusion altered the phase composition and crystalline structure of lithium slag. • Alkali fusion facilitated the leaching of Si4+ and Al3+ from lithium slag. • One-part geopolymer was prepared using alkali-fused lithium slag. [ABSTRACT FROM AUTHOR]

This paper presents an innovative application of a one-part geopolymer for microwave absorption. The influences of frequency, ageing time and mixing formulations on the mechanical, dielectric, and microwave-absorbing performance of the one-part binary geopolymer using fly ash and ladle furnace slag were investigated. The mixing formulations included alkali activators-to-aluminosilicate sources, sodium metasilicate-to-sodium hydroxide, and water-to-binder ratios. The results demonstrated that the dielectric constant decreased while the dielectric loss and loss tangent increased and remained constant with increasing frequency. The geopolymers have the highest dielectric values at an early age and diminish with ageing time. These resulted in the geopolymers having excellent microwave absorption (50 – 80%) at high-frequency levels and later ages. A higher water content resulted in higher porosity, reducing mechanical strength but enhancing microwave absorption. An optimal water content must be attained to achieve dual mechanical strength and microwave absorption performance. • One-part binary geopolymer based on FA and LFS was synthesized. • Geopolymers show excellent microwave absorbing performance at higher frequency. • Microwave absorption of the geopolymers improved at later age. • Porosity creates path to attenuate the microwave energy. [ABSTRACT FROM AUTHOR]

In the construction of traffic engineering, a large amount of waste soils was generated. These soils have poor engineering properties, cannot be used as subgrade fill, so they were solidified treatment, commonly used cement curing agent have adverse effects on the environment. One-part geopolymer (OPG), as a green and new type of soil stabilizer, not only provides a new idea for the solidification of engineering waste, but also offers an effective way for the disposal of industrial solid waste, and reduces the consumption of cement. In order to evaluate the durability of geopolymer solidified soil, in this paper, with fly ash (FA) and ground granulated blast furnace slag (GGBS) as raw materials, solid NaOH and Na 2 SiO 3 as solid alkali-activator to prepare OPG, which was used as a solidifier to solidify the waste dredged silt to produce one-part geopolymer-solidified soil (OPGSS). The variation patterns of mass, unconfined compression strength (UCS) and elasticity modulus of OPGSS with attack time under 0%, 5% and 10% Na 2 SO 4 solutions were investigated. The changes in the phase composition, micro-morphology and pore size distribution of OPGSS were characterized by XRD, SEM-EDS and nuclear magnetic resonance (NMR). The results showed that: Under both 5% and 10% Na 2 SO 4 solutions, the UCS of OPGSS decreased in two stages with attack time, and the number of large pores and total pores of OPGSS increased in two stages. The inflection points appeared on day 8 under 5% Na 2 SO 4 solution; the inflection points appeared on day 5 under 10% Na 2 SO 4 solution. This was mainly due to the expansion of corrosion products formed by OPGSS under Na 2 SO 4 attack, which destroyed the microstructure of OPGSS and led to a reduction in the UCS of the OPGSS. [ABSTRACT FROM AUTHOR]

Fly ash (FA) and exhausted bed sands (sands wastes) that are generated in biomass burners for energy production are two of the wastes generated in the pulp and paper industry. The worldwide production of FA biomass is estimated at 10 million tons/year and is expected to increase. In this context, the present work aims to develop one-part alkali-activated materials with biomass FA (0–100 wt.% of the binder) and sands wastes (100 wt.% of the aggregate). FA from two different boilers, CA and CT, was characterized and the mortar's properties, in the fresh and hardened conditions, were evaluated. Overall, the incorporation of FA decreases the compressive strength of the specimens. However, values higher than 30 MPa are reached with 50 wt.% of FA incorporation. For CA and CT, the compressive strength of mortars with 28 days of curing was 59.2 MPa (0 wt.%), 56.9 and 57.0 MPa (25 wt.%), 34.9 and 46.8 MPa (50 wt.%), 20.5 and 13.5 MPa (75 wt.%), and 9.2 and 0.2 MPa (100 wt.%), respectively. The other evaluated characteristics (density, water absorption, leached components and freeze–thaw resistance) showed no significant differences, except for the specimen with 100 wt.% of CA. Therefore, this work proved that one-part geopolymeric materials with up to 90 wt.% of pulp and paper industrial residues (FA and sand) can be produced, thus reducing the carbon footprint associated with the construction sector. [ABSTRACT FROM AUTHOR]

One-part alkali-activated materials (AAMs) are developed to improve conventional two-part systems. One-part AAMs technology has been used in cement binders to produce concrete, mortar, and paste. Current research mainly focuses on synthesizing raw materials obtained from industrial and agricultural waste as the main aluminosilicate precursors of the cement binder for a concrete application. The one-part AAMs were reported to have higher early compressive strength at 7 days of age, contributed by its fast-setting time, mainly when the binder activates by a higher dosage of alkaline activator and containing OPC-rich. Due to bonding issues, single or combination, FA/GGBFS/MK precursors were reported as unsuitable for use as a concrete repair material. They were the reason for the lack of one-part AAMs application of mortar compared to concrete usage. This study was conducted to determine the potential of one-part AAMs used as concrete patch mortar by investigating its rheology and mechanical properties. The compressive strength of the mortar was tested under lab ambient temperature in the tropical climate country of Malaysia. The setting time of fresh mortar and bonding strength were set under controlled lab temperature. The one-part alkali-activated mortar was composed of hybrid aluminosilicate precursors between fly ash (FA), Ground Granulated Blast Furnace Slag (GGBFS) and ordinary Portland cement (OPC). A low alkaline activator of solid potassium carbonate was used for the geopolymerization process. Three types of solid admixtures were added to complete the composition of the new mix design. The experiment's outcome showed that the mortar composed with the combination of conventional Portland cement and industrial waste products has compressive and pull-off adherence strength that meets with Class R3—EN1504-3 standard for structural concrete repair materials requirement. [ABSTRACT FROM AUTHOR]

One-part geopolymers are a greener alternative to Portland cement and are more suitable in engineering applications compared with two-part geopolymers. The effects of mechanical activation on the properties and the mechanism of the pozzolanic reaction of fly ash (FA)/slag-based geopolymer paste prepared using the one-part method were studied. Simple mixing was used for the control group and the effect of mechanical activation on the macroscopic properties of geopolymers was studied using tests for compressive strength, fluidity and setting times. The effect of mechanical activation on the pozzolanic reaction of geopolymers was assessed using isothermal calorimetry, X-ray diffraction, Fourier transform infrared spectroscopy and thermogravimetric analysis. The results showed that the 28-day compressive strength of the geopolymer formed by mechanical activation was 26% higher than that of the geopolymer prepared using simple mixing. Workability and fluidity were also enhanced. The reactivity of the precursor was improved by mechanical activation, particularly for the FA. The mechanically activated FA experienced a pozzolanic reaction within 7 days, while the undisturbed FA produced pozzolanic activity after 14–28 days. In addition, mechanical activation lessened the carbonisation of the one-part FA/slag-based geopolymer The implications of these results in terms of the influence of mechanical activation on pozzolanic activity are discussed. [ABSTRACT FROM AUTHOR]

• An alkaline solid reagent (SR) based on NaOH and colloidal silica suspension was synthesized. • The processing stages and physico-mechanical properties of one-part MK-geopolymers were evaluated. • Optimal results were achieved with a mixing time of 20 min and a formulation containing 50 wt% of SR. In recent years, there has been a growing interest in one-part geopolymers due to their simplified preparation process, which involves adding water instead of highly alkaline and corrosive solutions. This study aimed to synthesize a solid reagent (SR) based on NaOH and colloidal silica and investigate its impact on the processing stages and resulting physico-mechanical properties of one-part geopolymers based on metakaolin. After curing the samples at 40 °C, various properties, including elastic modulus, cold crushing strength, apparent porosity, and density, were evaluated. Optimal results were achieved with a mixing time of 20 min and a formulation containing 50 % by weight of SR. Under these conditions, the cured samples exhibited an elastic modulus of 8.2 GPa, a crushing strength of 14.04 MPa, an apparent porosity of 16 %, and a density of 1.51 g/cm3 after one day. These findings highlight the potential application of the developed solid reagent in the design of geopolymers for thermal and acoustic insulation in modern construction projects. [ABSTRACT FROM AUTHOR]

Deep mixing method (DMM) has been widely used in geotechnical and highway engineering to stabilize soft soil foundations. The emerging material, one-part geopolymer (OPG), is environmentally friendly, which is promising to be used as an alternative binder to replace ordinary portland cement (OPC) partially or even completely for stabilizing the soft clay. In this paper, the dynamic shear modulus and damping ratio of the OPG-stabilized soft clay are investigated through the dynamic triaxial test. X-ray computed tomography (X-ray CT) is adopted to analyze the evolution of microstructure, especially the porosity distribution in OPG-stabilized soil samples. Factors affecting the dynamic behaviors of the OPG-stabilized soil, including the mass ratio of fly ash (FA) to ground granulated blast furnace slag (GGBFS), curing stress, curing time, confining pressure, cyclic-stress frequency, and cyclic-stress ratio (CSR) are studied. Results show that among all the mixing proportions, the sample with FA/GGBFS mass ratio of 0.1 could get the highest dynamic shear modulus and lowest damping ratio. With the curing stress increasing and curing time elapsing, dynamic shear modulus increases and the damping ratio decreases significantly. Furthermore, the higher the confining pressure is, the higher the dynamic shear modulus achieves. However, the higher confining pressure, such as 300 kPa, might disturb the original structure of the OPG-stabilized soil sample and then induce the breakage of bonding between hydration gels and soil particles, further causing the substantial loss of transmission energy. Finally, the higher cyclic-stress frequency would induce the larger shear strain of the sample under the given CSR, resulting in the lower dynamic shear modulus and higher damping ratio. The outcome of this study could provide guidance for the application of OPG binder in the ground improvement. [ABSTRACT FROM AUTHOR]

Mining is facing a transformation in terms of environmental and social performance with improved mine waste management practices required. The valorisation of iron ore tailings, a fine material rich in silica, should be sought as it can be used in geopolymers. In this study a methodology to produce a one-part geopolymer using iron ore tailings as fillers is presented. All experiments used 50 wt.% of tailings with varying proportions of activators tested. The best result of compressive strength achieved is 48.1MPa after 28 days curing at room temperature. This study demonstrates the potential application for using geopolymers as future construction materials. [ABSTRACT FROM AUTHOR]

Developing a low-cost and eco-friendly alternative to cement is of great significance for reducing CO 2 emissions. Mine tailings (MTs) rich in Si and Al can be served as a promising precursor for geompolymer preparation only when the severe defect in the low reactivity is overcame. Alkali-hydrothermal activation technology was used to enhance the reactivity of MTs, and then activated tailings (ATs) and slag served as the precursors for the one-part geopolymer (OPG) preparation. Activation mechanism of MTs, workability, compressive strength, and hydration reactions of OPG samples were studied. The crystalline mineral phases in the MTs reacted with NaOH to form the amorphous sodium aluminosilicate, thus increasing the amorphization degree. High NaOH content favored the MTs activation, and the ATs with high NaOH content tended to create a higher initial pH and release more active species (Si and Al) for the slag hydration. The increase of NaOH content shortened the setting time, decreased the fluidity, and increased the strength of OPG samples. This was because the duration of the induction period was shortened and the hydration rate in the acceleration period of OPG samples was improved with increasing NaOH content, which generated large amounts of calcium–sodium aluminosilicate hydrate (C(N)-A-S-H) gel and yield the compact microstructure. However, excessive NaOH content resulted in a poor microstructure, and it is likely responsible for the reduction in strength. [ABSTRACT FROM AUTHOR]

Alkali-activated cements utilising fly ash can be a low-carbon alternative to Portland cement. However, fly ash alkali-activated cements require curing at elevated temperature and have cost plus environmental implications owing to the use of strong alkali solutions. Unclassified fly ash, silica fume, calcium hydroxide and sodium carbonate were used to develop novel one-part fly ash alkali-activated cements. When cured at ambient conditions, the cements gained compressive strength up to 11.0 and 44.2 MPa at 3 and 28 days, respectively. Microstructural investigations revealed that cation exchange reaction between the activators was the key element in the development of the microstructure and strength of the cements. The novel fly ash alkali-activated cements have at least 50% lower impact on global warming than highly blended Portland cements. [ABSTRACT FROM AUTHOR]

The one-part geopolymer binder was synthesis from the mixing of aluminosilicate material with solid alkali activators. The properties of one-part geopolymers vary according to the type and amount of solid alkali activators used. This paper presents the effect of various sodium metasilicate-to-sodium aluminate (NaAlO2/Na2SiO3) ratios on fly ash-based one-part geopolymer. The NaAlO2/Na2SiO3 ratios were set at 1.0 to 3.0. Setting time of fresh one-part geopolymer was examined through Vicat needle apparatus. Mechanical and microstructural properties of developed specimens were analysed after 28 days of curing in ambient condition. The study concluded that an increase in NaAlO2 content delayed the setting time of one-part geopolymer paste. The highest compressive strength was achieved at the NaAlO2/Na2SiO3 ratio of 2.5, which was 33.65 MPa. The microstructural analysis revealed a homogeneous structure at the optimum ratio. While the sodium aluminium silicate hydrate (N-A-S-H) and anorthite phases were detected from the XRD analysis. [ABSTRACT FROM AUTHOR]

Geopolymers are amorphous silicate polymers that have been extensively studied due to their applications, scientific and technical relevance, and their potential as cement in substitution to Portland. Much of the focus has been in the use of precursors and aggregates that are rarely pure and homogeneous with the use of tailings being very common. The presence of these impurities complicates the interpretation of some spectral methods, mainly infrared spectrometry. Therefore, this research focuses on the use of a nearly pure kaolin main precursor, having only a trace of iron and titanium, along with other almost pure reagents, to achieve an ideal geopolymer. It was possible to produce metakaolinite, resulting in a material with a good size particle (8.24µm) and surface specific area (6.57m2/g). The XRD result shows that the calcination process resulted in 100% of amorphous material. FTIR data revealed the presence of H2O and NaCO3 in the geopolymer. More important, the Si-Al-O various bands located between 1100 and 500cm-1 validate the polymerization reaction effectiveness. SEM-EDS analyses have demonstrated that the reaction with Na2SiO3 and NaOH were nearly complete, concerning the finer metakaolinite particles that comprised the material's matrix. However, the coarser metakaolinite lamellae, in the 15-35µm range, did not react completely; a thin border layer was enriched with sodium and most of the interior material maintained its Si-Al-O composition. The presence of traces of iron and titanium did not influence in the polymerization reaction. Compressive strength values of the geopolymer have presented good values in the range of 25 to 35 MPa. [ABSTRACT FROM AUTHOR]

In this paper magnesium oxychloride cement (MOC) is prepared from dolomite by calcinations process. The effect of different ratios of additive prepared from magnesite MOC (0.5, 1 and 1.5%) on the mechanical properties of dolomite MOC is recorded at 7, 14 and 28 days. Infrared spectroscopy (IR-spectra) is used to characterize the effect of magnesite MOC additive on the mineralogy of dolomite MOC mixes air cured at 28 days. The results indicated that one-part MOC additive posted the mechanical compressive strength of dolomite MOC mix at addition rate of 0.5 and 1% and was declined at 1.5%. The water resistance of MOC increased with increase of additive in mix. The micro structural investigation revealed that the mechanical performance of MOC was predominantly dependent on abundance and crystals size of phase 5. [ABSTRACT FROM AUTHOR]

• Waste glass is used as a partial activator and as a mineral precursor in one-part AAMs. • Waste glass powder serves as an effective silica supplier in the solid activator. • Waste glass as a mineral precursor retards the early strength of one-part AAMs. • Waste glass-based one-part AAMs are 23% cheaper and 84% greener than OPC binders. The feasibility of the extensive recycling of waste glass in alkali-activated materials (AAMs) was evaluated. The waste glass was utilised in AAMs for two purposes: a partial activator and a mineral precursor. The waste glass was blended with commercial sodium hydroxide and then heated to produce the solid activator powder. The technical performance of waste glass-based activator was investigated to replace commercial sodium silicate, a common alkali-activator used in AAMs. The effect of waste glass using only as the activator (WGA) and using as both activator and precursor (WGAP) in fly ash/slag-based one-part AAMs was studied using strength and microstructure characterisations. A mass-cost and emission analysis of waste glass-based AAMs (WGA and WGAP) was conducted, comparing the results with ordinary Portland cement (OPC). Characterisation tests of waste glass-based activator showed the effective formation of sodium silicate minerals with the adequate dissolution of activator in water by releasing reactive alkali and silica. Both WGA and WGAP showed comparable strengths at 56 days with a denser microstructure under ambient curing. According to mass analysis, waste glass could be utilised up to 17% by mass of total binder. Based on the analysis of cost and CO 2 emissions, WGA and WGAP are around 23% and 15% cheaper and 84% and 82% greener than OPC. The dual role of waste glass in AAMs as an activator and as a precursor broadens the recycling of glass waste in the cement industry by favouring technical and environmental outcomes. [ABSTRACT FROM AUTHOR]

While cast geopolymers are deeply investigated, geopolymers shaped by pressing are still rather unexplored. This work aims at developing one-part pressed geopolymers investigating the influence of parameters such as Na/Al molar ratio, water content and pressure load on the physical, microstructural and durability properties of the hardened geopolymers. Geopolymers were prepared by dry mixing and cured at 70 °C for 24 h and at room temperature for further 6 days. Density, water absorption, porosity features, microstructure and durability have been determined for all the samples. The results show that Na/Al molar ratio, water content and pressure load are key parameters to control the properties of one-part geopolymers. Their optimization can allow to obtain geopolymers suitable for microfiltration flat membrane support. Finally, the best performances in terms of durability are obtained when using the highest pressure load (20 MPa) and water content (15%). [ABSTRACT FROM AUTHOR]

Since alkali activators negatively effect the environmental impact assessment, it is necessary to develop the alternative activators from natural sources with low environmental impact. Therefore, in this study, the usage of boron refined products colemanite, ulexite and boron pentahydrate as activators in slag-based alkali-activated mortar systems was investigated in detail. Flexural and compressive strength tests, isothermal calorimetry measurement, thermogravimetric and differential thermal analysis, inductively coupled plasma mass spectrometry analysis, field emission scanning electron microscopy, and energy dispersive analysis and elemental mapping and X-ray diffraction analysis were carried out on the samples. In addition, sample production was subjected to life cycle analysis (LCA) with a cradle-to-gate approach using two different transportation scenarios. According to the results obtained, it was determined that colemanite, ulexite and boron penta hydrate, when used in optimum proportions, had a positive effect on strength (up to increase 40% compressive strength by 20% ulexite replacement) and could be used as an activator in slag-based alkali-activated systems. The positive results obtained in strength as a result of using boron-refined products are also supported by other test results conducted within the scope of the study. Furthermore, according to the LCA results, it was observed that there was a significant decrease in global warming potential with the substitution of 20% colemanite, ulexite or boron pentahydrate as activators, not only compared to the reference sample but also traditional cementitious systems. • Replacing boron product with alkali activator result with increase in strengths. • Boron products caused lower heat flow peaks and the total heat of hydration. • Boron products provide compact and denser microstructure compare to reference. • Boron products shows better environmental performance than reference mortar. [ABSTRACT FROM AUTHOR]

Recycled concrete aggregate (RCA) is a voluminous solid waste material derived from the construction sector and is typically stockpiled in landfills. In recent years, the ground improvement industry has grappled with challenges stemming from the depletion of natural quarry materials, resulting in a skyrocketing of their prices and increased project costs. This research investigated the feasibility of using RCA stabilized by one-part geopolymers to produce an innovative semi-rigid inclusion column system for ground improvement of soft soils. Na 2 SiO 3 -anhydrous was used as a sole solid activator for the activation of fly ash (FA), slag (S) or a binary precursor (FA+S) in the stabilization of RCA. The unconfined compressive strength (UCS) and microstructure of the stabilized mixtures have been examined with respect to different binder formulations and curing conditions. The permanent deformation characteristics of mixtures under cyclic loading were evaluated through repeated load triaxial (RLT) tests to replicate the moving wheel loads imposed on the semi-rigid inclusion columns. In addition, the cost and environmental impacts of the optimum mixtures suggested in this research were studied. The test results indicated that stabilizing RCA with as low as 5% one-part alkali-activated FA, S or (FA+S) met the minimum strength requirement (1.034 MPa) for ground improvement work. Compared with standalone FA and S geopolymer stabilized RCA mixtures, (FA+S) geopolymer stabilized RCA mixtures were identified as preferred industrial formulations due to their prolonged setting time for ease of mixing and handling when used in stone column applications. It was found that curing temperature and duration played a pivotal role in the strength gain of the mixtures. The RLT test results demonstrated that implementing the optimum RCA + 5%(FA+S) mixture as identified in this study for semi-rigid inclusion columns, led to a reduction in permanent strain values by approximately 90% compared to conventional unbound stone columns. The comparison between the optimum mixture highlighted in this study with other stabilization methods showed that the semi-rigid inclusion columns had great potential to enable large-scale production, cost and emission reduction in future ground improvement projects. • Recycled concrete aggregate was one-part geopolymers stabilized as semi-rigid inclusion columns. • Anhydrous sodium metasilicate was the sole activator. • Application-oriented materials enable large-scale applications. • Optimum mixtures had significantly lower cost and emission compared to traditional materials. • Acceptable properties for ground improvement work. [ABSTRACT FROM AUTHOR]

In this study, environment-friendly one-part alkali-activated slag-based mixes were prepared by using solid sodium carbonate as the alkali activator and incorporating reactive MgO (r-MgO) as the additive. Substitution of r-MgO in reference mixes was carried out at various levels, up to 15%, to enhance the reaction mechanism and strength development. The strength development was measured up to 56 days and analyzed microstructurally using Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric, and scanning electron microscopy analyses. Additionally, the influence of incorporating nano-silica in the binary mixes on strength development and microstructure was investigated. It was observed that the reaction mechanism could be improved by incorporating a low amount of reactive MgO, leading to expedited setting time and significant increases at both early age and final compressive strength values. Nano-silica incorporation was found to be effective in improving compressive strength at all ages, resulting in the formation of a higher matrix phase as demonstrated by microstructure tests. The highest compressive strength was attained in the nano-silica and r-MgO incorporating ternary mixes, reaching 25.9 MPa on the 3rd day and 47.2 MPa on the 28th day after production. Furthermore, the environmental impacts of the produced mixes were assessed. This study highlights the feasibility of one-part sodium carbonate-activated slag-based materials, especially with r-MgO inclusion, and underscores the role of nano-silica incorporation in enhancing strength properties. • One-part sodium carbonate-activated slag-based mixes were produced. • The effects of substituting r-MgO and nano-silica with slag on the microstructure were investigated. • r-MgO and nano-silica improved both the mechanical properties and microstructure. • r-MgO remarkably accelerated the activation process and enhanced mechanical properties. • One-part sodium carbonate-activated r-MgO/slag blends are considered potential binder systems. [ABSTRACT FROM AUTHOR]

One-part geopolymers, an easily prepared and environmentally friendly cement alternative, play a significant role in mitigating CO 2 emissions. Abundant in silicon and aluminum, molybdenum tailings present an ideal precursor for one-part geopolymers, particularly when addressing low reactivity limitations. In this study, molybdenum tailings undergo alkaline hydrothermal activation to serve as a precursor for synthesizing one-part geopolymers in conjunction with slag. With an 80% slag admixture, the compressive strength of the one-part geopolymer using activated molybdenum tailings reaches 44 MPa in 28 d, notably surpassing the strength of untreated tailings. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetry (TG) elucidate that amorphous C-A-S-H and N-A-S-H gels predominantly contribute to the strength. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses reveal that activated molybdenum tailings act as alkali exciters and reaction materials, filling the gel product as microaggregate and forming a dense microstructure. [ABSTRACT FROM AUTHOR]

The development of one-part geopolymer mortars has greater potential than the traditional two-part mortars, especially in repair applications, to convert waste into useful beneficial products while simultaneously eliminating the hazards associated with the alkaline solutions. Nevertheless, the inherent brittleness exhibited by the one-part geopolymers displays drawbacks like OPC when subjected to flexural loading. The fibers selection as well as their strengthening effects from literature is considerably scarce, especially for the repairing geopolymer system. This work aims to investigate the influences of fiber types and volume fractions on the workability, physical behavior, and cracking/fatigue resistance of ambient air-cured one-part geopolymer mortar. Reaction kinetics, mineralogical phases, and elemental components were explored by means of the TAM, quantitative XRD, and EDS mapping analysis. The FESEM and X-CT were employed to compare the microstructures and pore characteristics of the fibers-reinforced products. The results show that the copper-plated steel fiber produced the least change in workability, while the basalt fiber produced the lowest flow values. Setting time was the shortest for the basalt fiber reinforced, followed by polyvinyl-alcohol fiber. The steel fiber and carbon fiber would improve the mechanical properties of mortar significantly, especially in the early stage. The fatigue strength of 1 vol% carbon fiber reinforced mortar under 2 million cycles loading was the highest (3.72 MPa). The fibers addition a substantial decrease in sphericity and compactness of the pores (high anisotropy) as evidenced by X-CT data. Moreover, three hydration heat processes occurred after water was added to the one-part geopolymer mortar, which included dissolution of Na 2 SiO 3 particles, network degradation, and a second pozzolanic reaction. More crystalline formation occurred over curing time to form gel networks with high stability and generated different bonding modes with various fibers. • Geopolymer powder could produce ambient-cured one-part GPMs by mixing with water. • Effects of micro-fiber type and volume fraction on the one-partGPMs were investigated. • Workability, strength properties, cracking/fatigue resistance were measured. • Geopolymerization and fiber bonding of GPMs were analyzed using TAM, FESEM, EDS, QXRD and X-CT. [ABSTRACT FROM AUTHOR]

The elemental composition of precursors is crucial for the performance development of geopolymers. Metakaolin (MK) was used to produce one-part geopolymers (OPG), and the influence of calcium-based components (lime and gypsum) on their properties was investigated. The experimental results show that the use of lime instead of MK increases the fluidity of the mixture, while the addition of gypsum decreases the fluidity. Meanhwlie, the use of lime to replace a small amount of MK increases the concentration of activator by consuming water and the dissolution of calcium ions also participates in the geopolymerization reaction, which enhances the mechanical properties and durability of OPG. When 10 % lime is applied, the 7-d and 28-d compressive strengths of OPG are increased by 210 % and 157.14 % compared with the plain sample, respectively. The addition of gypsum generates AFt in OPG, which reduces the compactness of the microstructure, which is not conducive to the development of the strength and durability of OPG. When 10 % gypsum is applied, the 28-d compressive and flexural strengths of OPG are decreased by 32.14 % and 26.67 % compared with plain samples, respectively. As the lime content increases, further addition of gypsum to OPG has a more negative effect on OPG due to the plundering of calcium ions in the lime. The 28-d dry density of OPG is between 1585 and 1729 kg/m3, which makes it have a lower thermal conductivity (0.87–0.94 W/m·K). • A one-part semi-lightweight geopolymers were prepared and characterized. • The effect of the calcium-based component on the properties of the MK-based geopolymer was discussed. • The mechanical properties and durability of one-part MK-based geopolymers were systematically characterized. [ABSTRACT FROM AUTHOR]

To obtain a green and cost-effective one-part alkali-activated grouting material (OAGM) with good comprehensive performance for subgrade reinforcement and determine its proper mix parameters. In this study, using response surface methodology (RSM), multiple objective particle swarm optimization (MOPSO) algorithm and the technique for order preference by similarity to an ideal solution (TOPSIS) algorithm coupled with entropy weight method, two multi-objective optimization schemes for OAGM were performed, one only considering performance and another considering performance, embodied CO 2 emission (ECO 2 e) and cost. Then, the correlation-based feature selection (CFS) algorithm was used to evaluate the importance of various molar ratios as mix parameters on the performance of OAGM. Finally, the effects of key mix parameters on the microstructure and reaction products of OAGM were studied. RSM results show that W/S (water to solid) ratio, borax (BR) content and UCG content chiefly govern the flowability, initial setting time and mechanical strength of OAGM respectively, and the interactions between some factors also significantly affect these properties. MOPSO and entropy-TOPSIS algorithm can be used to optimize OAGM objectively. Two optimal OAGM pastes both have better comprehensive performance and much lower ECO 2 e than ordinary Portland cement (OPC) paste. And the optimal OAGM considering performance, ECO 2 e and cost even has 7.68% lower cost than OPC paste. But another optimal OAGM has the best comprehensive performance. CFS results show that the molar ratios of Si/Al, Al/Ca, Na 2 O/H 2 O, B 2 O 3 /CaO and B 2 O 3 /Al 2 O 3 are the key mix parameters of OAGM. Al/Ca rather than Si/Al is the most important mix parameter to the 28-day compressive strength. And higher Si/Al and Al/Ca deteriorates the microstructure and hinders the formation of C-A-S-H gel, while higher Na 2 O/H 2 O has the opposite effect. This study provides guidance for objective optimization and the determination of proper mix parameters of OAGM, and promotes the market-oriented application of OAGM. • Multi-objective optimization was conducted for OAGM using MOPSO and entropy-TOPSIS algorithm. • Key mix parameters of OAGM were determined by CFS algorithm. • The optimal OAGM with low carbon footprint, low cost and good comprehensive performance was obtained. • Quadratic regression equations used for performance prediction of OAGM were obtained by RSM. • Effects of key mix parameters on the microstructure and reaction product of OAGM were characterized. [ABSTRACT FROM AUTHOR]