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The infrared (IR) patterns of the glass wools (GW-r, GW-s, and GW-p, shown in blue) and alkali-activated glass wools (A_GW-r, A_GW-s, and A_GW-p, shown in red). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Source publication
This study investigated the effect of organic resin contained in glass wool on synthesis of alkali-activated binders. The study was performed on glass wool containing sugar or phenolic resin, comparing it with glass wool that did not contain resin, as a reference. The results showed that the organic resin could be qualitatively identified using Fou...
Context in source publication
Context 1
... FTIR spectra of the glass wool and prepared alkali-activated materials are presented in Fig. 4. The lower graphs (blue lines) are for the unreacted glass wool, while the upper graphs (red lines) are for the alkali-activated glass wool. The shoulder at around 3400 cm À1 can be ascribed to O-H stretching from the water [31]. This water is mainly adsorbed water in the case of unreacted glass wool, while it is structural and ...
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Citations
... The present work aims to compare AAMs, containing mineral wools and GGBFS as precursors, prepared via onepart and two-part pathways. Mineral wools have been much less studied as AAM precursors compared to GGBFS, but results show that they have promising reactivity as cementitious material [18][19][20][21][22][23][24]. Mineral wool was selected as a coprecursor to supplement the use of blast furnace slag and as a pathway to recycle the waste produced during industrial production, and construction and demolition process in cementitious application. ...
Two synthesis pathways (one-and two-part) in alkali-activated binders were compared using ground granulated blast furnace slag (GGBFS), mineral wool (MW) activated using dry and liquid alkali activators with similar Na 2 O/SiO 2 modulus. The effect of activator type on reaction kinetics, strength development, setting times, and durability shows that one-part synthesis does not only improve early strength, but also provide better durability properties. While the highest compressive strength (56 MPa, 90 days) was achieved for the one-part mix (DM), the reaction products (presence of Mg-Al layered double hydroxide and C-S-H-like phases) observed for both mortar mixes were similar. The DM mortars showed better resistance to sulfate attack than two-part mix (WM) mortars and sets faster. The results highlight the significance of the one-part pathways in the synthesis of alkali-activated materials.
... One challenge with mineral wools in this context is organic resin, such as phenol formaldehyde, added to the mineral wool products during their manufacturing, which may interfere with the alkali-activation reactions 18 . However, the fact that stone wool intended for green houses does not contain organic additives (in order to be water-absorbing) similarly as the mineral wools used in construction, makes it a highly potential precursor 11,19 . ...
Background
Stone wool is commonly used as a plant substrate in soilless cultivation and discarded after one growing season. Stone wool waste is difficult to recycle, and thus it is typically landfilled. Alkali-activation of stone wool (i.e., milling and mixing with an alkaline solution) has been shown to be a feasible way to upcycle this waste fraction into, for example, construction products. In this study, the aim was to develop recycled plant substrate from stone wool waste from greenhouses via alkali activation.
Methods
Waste stone wool from greenhouses was characterized by X-ray fluorescence (XRF) and mixed with sodium silicate solution either directly or after ball milling. The alkali-activation process was combined with the addition of H2O2, pre-made foam, or granulation to obtain suitable porous material for the plant substrate application. Preliminary greenhouse cultivation experiments of pea (Pisum sativum) were conducted with alkali-activated stone wool mixed with peat (a weight ratio of 1:1) and fertility analysis of the mixture were conducted.
Results
The results indicated that the most feasible production method was to use ball-milled stone wool and to combine alkali activation with granulation. The obtained granules could reach 2.7 MPa as compressive strength while the other methods resulted in very fragile material. The preliminary greenhouse cultivation experiments revealed that there were significant levels of nutrients (Ca, P, K, and S) and alkalinity leached from the granules which hindered the growth of pea. The high P and S amounts were also confirmed by the XRF results of stone wool.
Conclusions
It can be concluded that the developed granules did not function well as a plant substrate for pea but could enable the re-utilization of the nutrients contained in the greenhouse stone wool waste. Moreover, their application to acidic sulfate soils could be feasible as it would utilize the alkalinity of granules.
... The presence of microfibres improves the bending strength of AAM [47] whereas the presence of organic resin positively affects the compressive strength [42]. In another study, it was found that organic resins influenced the dissolution, diffusion, and hardening reactions of AAMs; the compressive strengths were lower in the presence of organic binders when cured at room temperature [48]. A solubility test performed by König et al. indicated a higher concentration of dissolved Si at elevated temperatures when using the hydrothermal method for GW [49]. ...
Mineral wool is widely used worldwide as an insulation material, generating a lot of waste material annually, which mainly ends up in landfill. This highly amorphous fibrous material shows good potential for use in alkali activation technology. The following paper demonstrates the possibility of using glass and stone wool as binders in additive manufacturing. In the present work, a mix design was prepared using mainly stone and glass wool, with smaller amounts of calcium aluminate cement, bottom ash and microsilica. The mixture developed was either moulded or 3D-printed, then the mechanical properties were measured before and after exposure to higher temperatures. Upon reaching a temperature of 200 °C the microstructure began to change, due to the presence of an organic binder (on the surface of the mineral wool) which decomposed at higher temperatures, as demonstrated by TG/DT analysis. In the moulded samples exposed to higher temperatures, decomposition of the organic binder had an impact on both the structural changes and the extent of the decrease in mechanical properties. Decomposition of the organic binder had less significant effect on the 3D-printed specimens, because the open structure allows the migration of decomposed gases such as CO2 out of the structure. Mineralogical changes occurred at 800 °C, which is above the sintering temperature of the mixture. Detailed studies using mercury intrusion porosimetry and X-ray computed microtomography showed variations in the pore formation at different temperatures of exposure. Pore size and porosity increased up to 400 °C, then slight shrinkage was observed at 500 °C and significant expansion at 800 °C. Less expansion occurred in the 3D-printed samples compared to the moulded ones due to the porous structure of the printed samples, resulting from the printing process itself. This could be an advantage of this type of printed material, containing organic compounds in the structure, if/when exposed to elevated temperatures.
... The heat of hydration curves of various samples are shown in Figure 8 and Table 3. It is notable that the heat of hydration processes of the AAS-alkali sludge and cement paste were similar, with stages for the initial reaction, induction, acceleration, and retardation [29][30][31]. However, the heat of the hydration curve of the pure cement paste exhibited three peaks, while those of the AASalkali sludge samples only had two peaks. ...
The application of alkali sludge (derived from sodium silicate production) as a supplementary material for the cementitious system of alkali-activated slag was investigated through tests of mechanical strength, rheology, heat of hydration, and microscopic analysis. The enhanced alkali sludge dosage and alkali equivalent content increased the yield stress and plastic viscosity of the alkali-activated slag while decreasing the fluidity due to the better water absorption of the alkali sludge, which increased the flocculation of the particles. The compressive strength reached the maximum, with 30% alkali sludge and 7% alkali equivalent content. The addition of the alkali sludge postponed the formation of the hydrated calcium silicate (C-S-H) gel and, therefore, delayed the peak heat of hydration, but ultimately increased the total hydration heat release. The major hydration product of calcium silicate hydrate was found in the alkali-activated slag with a 10–30% blend of alkali sludge. This work provides a reference for the utilization of alkaline solid waste from the chemical industry as an alkali activator in cementitious construction materials.
... As reported by the same authors [14], by applying sodium-based alkali activator, MWW particles can be partially dissolved with the main reaction product as amorphous sodium/calcium aluminosilicate hydrate (N,C-A-S-H). Lemougna et al. [16] and Pavlin et al. [17] further clarified the possibility of improving the alkali activity via effective milling or suitable heat curing. More recently, Ramaswamy et al. [18] investigated the dissolution kinetics of MWW under alkaline conditions and found that high pH can accelerate the dissolution of Si and Al on the MWW surface, where these dissolved species precipitate/recondense into aluminosilicate gel at certain liquid to solid ratios. ...
... In comparison, a total mass loss of 4.48 wt% is noticed in MWW up to 1000 • C. The weight loss at around 100 • C is ascribed to the absorbed water release. The main mass loss peak approaching 250 • C is associated with the burning of the organic binder [16], and the peak between 650 and 700 • C corresponds to the decomposition of carbonates [28]. The slight DTG peak at approximately 900 • C corresponds to the partial crystallization of the glass phase. ...
... In terms of effects on the mechanical properties of alkaline-activated materials, glass wool could facilitate reactivity with alkaline activators due to its high amorphous silica content, thus increasing its bond strength with other binder particles within the materials [25,26]. The resulting materials exhibited better mechanical properties including higher compressive strength [27], increased thermal insulation [28], and increased tensile strength [29]. Even though substantial research has utilized glass wool as primary and secondary precursors for improving the properties of the materials, there is still a knowledge gap on the effects of glass wool on microstructures, acid resistance, and sulfate resistance of alkali-activated materials. ...
... C-A-S-H) or sodium aluminium silicate hydrate (N-A-S-H) depending on the type of precursor [2]. Meanwhile, AAMs has shown better resistance when subjected to physical and chemically induced deterioration such as acid attacks [11,12], freeze and thaw [13], wetting and drying [14,15], chloride penetration [16], carbonation [17] and corrosion [18]. While significant amount of research has been carried out on the durability of AAMs based on FA, BFS and ferronickel slags [19][20][21], the durability of AAMs based on fayalite slags (FS) exposed to different environmental conditions is not fully understood and therefore needs to be investigated. ...
Fe-rich alkali activated materials (AAMs) require detailed understanding of their durability prior to their real-life application in the construction industry. Three mixes were formulated with fayalite slag (FS) as the main precursor. The effect of incorporation of ladle slag (LS) or blast furnace slag (BFS) on the shrinkage and exposure to physical and chemical attacks representing environmental conditions in cold and tropical regions (acidic solution at room temperature and in freeze-thaw, combined sodium sulfate and sodium chloride solution at room temperature and in freeze-thaw, freeze-thaw in water and dry-wet cycles) was investigated via visual observation, mass loss, compressive strength, X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), and scanning electron microscope coupled with energy dispersive X-ray spectroscopy (SEM-EDS). Experimental results show the considerable role of incorporated LS and BFS in modifying the gels formed and controlling material degradation of blended AAMs after exposure. In contrast, sole FS-based samples were completely degraded particularly those exposed to freeze-thaw in water, acid, and combined sodium sulfate and sodium chloride solution, indicating their vulnerability to frost and chemical attacks.
... The results of this study emphasize the reuse potential of FS with other waste streams in producing eco-friendly AAMs, which can have a wide range of construction applications. [2,3]. AAMs have gained increasing attention in recent years as a possible eco-friendly alternative binder that could at least partly replace PC [4]. ...
The valorization of Fe-rich fayalite slag (FS) as a precursor for alkali-activated materials (AAMs) is hampered by its low reactivity at ambient temperature. Here, FS was blended with waste-based reactive co-binders such as ladle slag (LS) and blast furnace slag (BFS) to improve the fresh and hardened state properties of the AAMs for potential construction applications. The results showed that the incorporation of LS and BFS as an additional source of Ca and Al accelerated the reaction kinetics and influenced the binder gel type and formation mechanism. In all the mixes, Fe, Si and Na are present in the evolving binder gel. In addition to these elements, the binder gel of the blended formulations is also rich in higher quantities of Ca and Al and showed possible formation of C-A-S-H and C-(N)-A-S-H together with the development of andradite, a calcium ferrosilicate hydrate phase formed from chemical interaction between FS and co-binders; it indicates that both FS and co-binder participated in the binder gel formation. Furthermore, the nucleating and filling effects of co-binders improved the workability, ultrasonic pulse velocity and mechanical properties; this also densified the structure and lowered the water absorption and permeable porosity of the blended mortars. The compressive strength of blended mortars was above 20 MPa, thus satisfying the strength requirements of building materials according to ASTM C62. The results of this study emphasize the reuse potential of FS with other waste streams in producing eco-friendly AAMs, which can have a wide range of construction applications.
... In the search for alternative cementitious materials and binder, alkali-activated materials (AAMs) has received wide attention [6]. AAMs including those classified as geopolymers and inorganic polymers (IP) can be derived from a reaction between alkali activator (wastebased and non-waste based) and aluminosilicate precursors (such as fly ashes [7], metallurgical slags [6], mineral wools [8][9][10] and calcined clay minerals [11] or sometimes iron silicate precursors [12,13]. The development of AAMs using such materials can provide numerous benefits such as reduced CO 2 emissions and can also exhibit superior or similar properties in comparison to PC based binders [14][15][16]. ...
Vast amounts of rice husk ash (RHA) are generated annually, with most of them unutilized or disposed to landfills, resulting in serious environmental degradation. To avoid this, the use of RHA as precursors or co-binder in the development of alkali activated materials (AAMs) is viewed as a viable alternative to avert this significant problem. In this paper, the generation, properties, and utilization of RHA in AAMs are systematically and comprehensively reviewed. Furthermore, the physical, chemical, and mineralogical composition of several RHA were critically examined, and their impact on fresh and hardened state properties of AAMs and blended formulations are presented. Generally, the properties of RHA are influenced by the source material and the production process (pre-treatment, burning time, burning temperature, cooling rate, coolingduration and milling) which in turn affect their pozzolanic reactivity. Due to its high pozzolanic nature, low energy requirement and greenhouse gas emission during production, RHA is an environmentally friendly and cost-effective alternative cementitious material to produce AAMs. Various studies have reported the beneficial role of RHA on the mechanical , microstructural and durability properties of AAMs, especially when used at an optimal level. Overall, this review will provide valuable insight, direction, and recommendations for researchers and industrial sectors on the generation, recycling, characteristics, and utilization of RHA in the development of AAMs for potential construction applications.
... The study was performed on glass wool containing sugar or phenolic resin, comparing it with glass wool that did not contain resin, as a reference. The results showed that the organic resin could be qualitatively identified, with gradual decomposition occurring between 200 • C and 550 • C [155]. Using evolved gas analysis and combining the temperature-dependent melt viscosity with x-ray data, Luksic et al. described the evolution of foam structure during the foam growth and subsequent collapse [156]. ...
Advances in on-line thermally induced evolved gas analysis (OLTI-EGA) have been systematically reported by our group to update their applications in several different fields and to provide useful starting references. The importance of an accurate interpretation of the thermally-induced reaction mechanism which involves the formation of gaseous species is necessary to obtain the characterization of the evolved products. In this review, applications of Evolved Gas Analysis (EGA) performed by on-line coupling heating devices to mass spectrometry (EGA-MS), are reported. Reported references clearly demonstrate that the characterization of the nature of volatile products released by a substance subjected to a controlled temperature program allows us to prove a supposed reaction or composition, either under isothermal or under heating conditions. Selected 2019, 2020, and 2021 references are collected and briefly described in this review.
