Silicon Ions Research Articles

SiONx Coating Regulates Mesenchymal Stem Cell Antioxidant Capacity via Nuclear Erythroid Factor 2 Activity under Toxic Oxidative Stress Conditions.

Healing in compromised and complicated bone defects is often prolonged and delayed due to the lack of bioactivity of the fixation device, secondary infections, and associated oxidative stress. Here, we propose amorphous silicon oxynitride (SiONx) as a coating for the fixation devices to improve both bioactivity and bacteriostatic activity and reduce oxidative stress. We aimed to study the effect of increasing the N/O ratio in the SiONx to fine-tune the cellular activity and the antioxidant effect via the NRF2 pathway under oxidative stress conditions. The in vitro studies involved using human mesenchymal stem cells (MSCs) to examine the effect of SiONx coatings on osteogenesis with and without toxic oxidative stress. Additionally, bacterial growth on SiONx surfaces was studied using methicillin-resistant Staphylococcus aureus (MRSA) colonies. NRF2 siRNA transfection was performed on the hMSCs (NRF2-KD) to study the antioxidant response to silicon ions. The SiONx implant surfaces showed a >4-fold decrease in bacterial growth vs. bare titanium as a control. Increasing the N/O ratio in the SiONx implants increased the alkaline phosphatase activity >1.5 times, and the other osteogenic markers (osteocalcin, RUNX2, and Osterix) were increased >2-fold under normal conditions. Increasing the N/O ratio in SiONx enhanced the protective effects and improved cell viability against toxic oxidative stress conditions. There was a significant increase in osteocalcin activity compared to the uncoated group, along with increased antioxidant activity under oxidative stress conditions. In NRF2-KD cells, there was a stunted effect on the upregulation of antioxidant markers by silicon ions, indicating a role for NRF2. In conclusion, the SiONx coatings studied here displayed bacteriostatic properties. These materials promoted osteogenic markers under toxic oxidative stress conditions while also enhancing antioxidant NRF2 activity. These results indicate the potential of SiONx coatings to induce in vivo bone regeneration in a challenging oxidative stress environment.

Formation of optical planar waveguides on fused quartz by MeV ion implantation

AbstractThe optical losses and the refractive index change of optical planar waveguides formed by MeV ion implantation were correlated with the experimental ion implantation parameters. Direct ion implantation was performed by means of carbon, silicon and copper ion beams impinging on the substrate surface at normal incidence. The ions were accelerated at energies ranging from 3 to 12 MeV with fluences varying from 1 × 1012 to 2 × 1016 ion/cm2, according to the type of implanted ion. The modification of the substrate refractive index due to the ion irradiation‐induced damage was evaluated using the prism coupler method, and the refractive index profiles were determined by means of a reconstruction method using a multilayer structure approximation. The guiding properties of the waveguides were analysed using the fibre‐coupling technique to determine both the optical transmission and transversal modes at 635 nm. The main practical relevance of our research is the obtention of high‐quality waveguides at low current density MeV ion implantation (≤80 nA/cm2) without post‐implantation annealing.

Gallic acid–coated nanolayer on mineral trioxide aggregate for regulating the inflammatory and differentiation cellular response profile of human dental pulp stem cells

Mineral trioxide aggregate (MTA) is a biomaterial used in endodontics due to its high bioactivity, antibacterial behaviors, and good biocompatibility. However, it has several disadvantages related to certain physical properties, including a long setting time and poor mechanical properties. Therefore, we hypothesized that coating MTA with gallic acid (GA) would regulate physical properties and lead to enhanced adhesion, proliferation, and secretion of angiogenic- and odontogenic-related proteins. This study examined whether MTA can be modified with GA to form GAMTA cement and evaluated its physicochemical and biological behaviors and immune suppression, angiogenesis, and odontogenesis capabilities. We soaked MTA in Tris buffer containing different concentrations of GA to coat the MTA powders. X-ray diffraction (XRD) and diametral tensile strength analyses were conducted to assess the physical characteristics of GAMTA. Then, we immersed GAMTA cement in simulated body fluid to evaluate its hydroxyapatite precipitation capabilities and silicon ion release profile. We used human dental pulp stem cells to assess the cell responses and the immunosuppressive, angiogenic, and odontogenic capabilities of GAMTA. The XRD results showed that GA was successfully coated onto MTA without the disruption or loss of MTA’s advantageous original structural properties. GAMTA demonstrated excellent physicochemical and biological properties, improving hydroxyapatite formation and angiogenic, odontogenic, and anti-inflammatory properties compared with MTA alone. Our results indicate that the GAMTA cement is a useful dental material for future tissue engineering and clinical applications.

Ligand-Selective Targeting of Macrophage Hydrogel Elicits Bone Immune-Stem Cell Endogenous Self-Healing Program to Promote Bone Regeneration.

Targeting macrophages can facilitate the site-specific repair of critical bone defects. Herein, a composite hydrogel, gelatin-Bletilla striata polysaccharide-mesoporous bioactive glass hydrogel (GBMgel), is constructed via the self-assembly of mesoporous bioactive glass on polysaccharide structures, through the Schiff base reaction. GBMgel can efficiently capture macrophages and drive the recruitment of seed stem cells and vascular budding required for regeneration in the early stages of bone injury, and the observed sustained release of inorganic silicon ions further enhances bone matrix deposition, mineralization, and vascular maturation. Moreover, the use of macrophage-depleted rat calvarial defect models further confirms that GBMgel, with ligand-selective macrophage targeting, increases the bone regeneration area and the proportion of mature bone. Mechanistic studies reveal that GBMgel upregulates the TLR4/NF-κB and MAPK macrophage pathways in the early stages and the JAK/STAT3 pathway in the later stages; thus initiating macrophage polarization at different time points. In conclusion, this study is based on the endogenous self-healing properties of bone macrophages, which enhances stem cell homing, and provides a research and theoretical basis upon which bone tissue can be reshaped and regenerated using the body's immune power, providing a new strategy for the treatment of critical bone defects.

Investigation of compound state of SiO2-TiO2 aerogel synthesized through controlled sol-gel reaction

In this work, a compound state of silica-titania aerogel was investigated through sol-gel reaction for hybridization of silica and titania with increasing reactivity by using high surface area and charge imbalances. By minimizing the sol-gel reaction rate difference and preparing a homogeneous and stable sol, a compound state of silica-titania aerogel could be obtained, without separation onto single metal oxide aerogel. The benefits of using the sol-gel synthesis method for synthesizing silica-titania compound aerogels are over a limit of substitution solubility and get binary metal oxide compound material. Diffraction and spectroscopic analyses showed that the heterogeneous linkage resulted from interaction among silicon, titanium, and oxygen ions. The coordination environment changes by the formation of an Si-O-Ti linkage following interaction among ions without phase separation on SiO2 and TiO2 aerogels. Thus, the atomically controlled sol-gel reaction can be used to design new metal-oxide-based compound aerogels and immiscible oxide materials.

Features of Hardening of Aluminosilicophosphate Binder in Cellular Concrete

Cellular phosphate concretes are used as an insulating material for some high-temperature aggregates due to their high temperature resistance, fire resistance and residual strength at the level of values after drying. The use of industrial waste in phosphate cellular concrete technology made it possible to improve some properties without reducing the application temperature. The paper shows that dispersed aluminosilicate waste from refractory production has sufficient activity (porization ability) to obtain a phosphate binder. The features of the hardening of an aluminosilicophosphate binder cured with dispersed metallic aluminum have been studied; the change in the phase composition of the cured binder after firing at different temperatures has been studied by differential thermal and X-ray phase analysis. It has been established that the developed aluminosilicophosphate binder makes it possible to obtain fireclay cellular concrete with an application temperature of up to 1400оC. A comparison of the changes in the phase composition for the developed aluminosilicophosphate composition and a pure aluminophosphate binder is performed. A shift in the temperature of the processes is noted in an upward direction for the aluminosilicophosphate binder, which is explained by the fact that silicon ions do not form independent phosphate compounds, but are embedded in the crystal lattice of aluminophosphates, changing their properties and shifting the intervals of phase transitions.

Coordination Structure of Si(II) Ions in Binary Melts (LiF-KF, LiF-NaF, and NaF-KF) and Ternary Melt (LiF-NaF-KF).

The formation of Si(II) by the comproportionation reaction between electrodeposited silicon and Si(IV) ions [Si(IV) + Si0 ⇄ 2Si(II)] in fluoride melts has been discussed in many previous reports on the electrochemical processing of silicon. In this study, the coordination structure of Si(II) ions in LiF-KF, LiF-NaF, NaF-KF, and LiF-NaF-KF melts was investigated by high-temperature Raman spectroscopy and quantum chemical calculation based on density functional theory. The formation of Si(II) ions was induced by mixing metallic silicon powder as the source of Si0, with the melts containing hexafluoro silicate or silicon dioxide as the source of Si(IV) ions. The simulated vibrational modes of the Si(II) species and the experimental Raman bands showed good agreement. It was found that both Si(II) and Si(IV) species were detected in either fluoride melt, demonstrating that the proposed comproportionation reaction between Si0 and Si(IV) occurred. In addition, the interaction between Si(II) and F-, O2-, Li+, Na+, and K+ ions significantly changed depending on the composition of fluoride melts. The coordination structure of the Si(II) ions reported in this study will provide clues for controlling the electrodeposition process of silicon in fluoride melts.

Simulated galactic cosmic ray exposure activates dose-dependent DNA repair response and down regulates glucosinolate pathways in arabidopsis seedlings.

Outside the protection of Earth's magnetic field, organisms are constantly exposed to space radiation consisting of energetic protons and other heavier charged particles. With the goal of crewed Mars exploration, the production of fresh food during long duration space missions is critical for meeting astronauts' nutritional and psychological needs. However, the biological effects of space radiation on plants have not been sufficiently investigated and characterized. To that end, 10-day-old Arabidopsis seedlings were exposed to simulated Galactic Cosmic Rays (GCR) and assessed for transcriptomic changes. The simulated GCR irradiation was carried out in the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Lab (BNL). The exposures were conducted acutely for two dose points at 40 cGy or 80 cGy, with sequential delivery of proton, helium, oxygen, silicon, and iron ions. Control and irradiated seedlings were then harvested and preserved in RNAlater at 3 hrs post irradiation. Total RNA was isolated for transcriptomic analyses using RNAseq. The data revealed that the transcriptomic responses were dose-dependent, with significant upregulation of DNA repair pathways and downregulation of glucosinolate biosynthetic pathways. Glucosinolates are important for plant pathogen defense and for the taste of a plant, which are both relevant to growing plants for spaceflight. These findings fill in knowledge gaps of how plants respond to radiation in beyond-Earth environments.

Scalable Non-Volatile Tuning of Photonic Computational Memories by Automated Silicon Ion Implantation.

Photonic integrated circuits (PICs) are revolutionizing the realm of information technology, promising unprecedented speeds and efficiency in data processing and optical communication. However, the nanoscale precision required to fabricate these circuits at scale presents significant challenges, due to the need to maintain consistency across wavelength-selective components, which necessitates individualized adjustments after fabrication. Harnessing spectral alignment by automated silicon ion implantation, in this work scalable and non-volatile photonic computational memories are demonstrated in high-quality resonant devices. Precise spectral trimming of large-scale photonic ensembles from a few picometers to several nanometres is achieved with long-term stability and marginal loss penalty. Based on this approach, spectrally aligned photonic memory and computing systems for general matrix multiplication are demonstrated, enabling wavelength multiplexed integrated architectures at large scales.

Research on reactivity evaluation and micro-mechanism of various solid waste powders for alkali-activated cementitious materials

Alkali-activated cementitious material (AACM) based on the utilization of solid waste is a new type of environmentally friendly inorganic material, which has the advantages of early strength, fast hardening, high strength, and better durability. The reactivity of solid waste powder is a key factor for its appropriate utilization in alkali-activated cementitious materials, necessitating a rational evaluation of its reactivity. The reactivity evaluation was conducted on various solid waste powders, including fly ash (FA), red mud (RM), recycled micro-powder (RMP), red brick powder (RBP), coal gangue powder (CGP), and cement kiln dust (CKD). The effects of NaOH concentration, weight ratio of water to solid waste powder (W/P) and curing humidity on the compressive strength were investigated，then the compressive strength under optimal conditions was determined based on response surface analysis. The compressive strength under optimal conditions was used to evaluate the reactivity of solid waste powders. Moreover, microscopic tests (e.g., XPS test, ICP test, and NMR test) were carried to evaluate the reactivity of the solid waste. The relative number of bridging oxygen (RBO) measured by the NMR method in conjunction with chemical composition analysis serves as an effective method for evaluating the reactivity of solid waste powders. The leaching rate of Silicon (Si) and Aluminum (Al) ions in the ICP method depended mainly on the NaOH concentration and the elemental content in the raw material. In addition, the binding energies of O1s, Si 2p, and Al 2p tested by the XPS method had no particular correlation with the compressive strength.

Multi-crosslinked hydrogel built with hyaluronic acid-tyramine, thiolated glycol chitosan and copper-doped bioglass nanoparticles for expediting wound healing

The migration of fibroblasts and endothelial cells is a critical determinant of wound-healing outcomes for skin injuries. Here, hyaluronic acid-tyramine (HAT) and thiolated glycol chitosan (TGC) conjugates were combined with copper-doped bioglass (ACuBG) nanoparticles to build a novel type of multi-crosslinked hydrogel for stimulating the migration of cells, and thus, expediting wound healing. The optimally devised HAT/TGC/ACuBG gels had markedly improved strength and stiffness compared to the gels built from either HAT or TGC while showing sufficient elasticity, which contributes to stimulating the migration of fibroblasts. The sustainable release of silicon and copper ions from the gels was found to jointly induce the migration of human umbilical vein endothelial cells. The results based on mouse full-thickness skin defects demonstrated that they were able to fully restore the skin defects with formation of complete appendages within two weeks, suggesting their promising potency for use in expediting wound healing.

Synthesis and analyses of injectable fluoridated-bioactive glass hydrogel for dental root canal sealing.

This study aimed to synthesize fluoride-doped bioactive glass (F-BG) based thermo-sensitive injectable hydrogel for endodontic applications. The structural and phase analyses were done with Fourier Transform Infrared spectroscopy and X-ray Diffraction, respectively. The setting time of prepared injectable was investigated at 21°C (in the presence and absence of an ultrasonic scalar) and at 37°C. Flowability was tested according to ISO-6876:2012 specifications, whereas injectability was checked by extrusion method using 21-, 22-, and 23-gauge needles. The in vitro bio-adhesion and push-out bond strength were studied on days 7 and 90 and compared with the commercially available TotalFill®. The ion release profile was analyzed for up to 30 days with Inductively Coupled Plasma Optical Emission Spectroscopy. The fluoride release analysis was conducted periodically for up to 21 days in deionized water and artificial saliva using an ion-selective electrode. The final setting time at 21°C, 21°C+ultrasonic scalar, and 37°C were 38.66±3.21, 29.12±1.23, and 32±3.46 min, respectively. The flowability was 25±3.94 mm, and the injectability coefficient was ≥70.3 for 22, 21, and 57% in a 23-gauge needle. Fluoride release in deionized water was found to be significantly higher than in artificial saliva and increased with time. A significant difference in bond strength was found between days 7 and 90, where the strength was increased, and a new apatite layer was formed on the tooth surface. A rapid release of calcium, phosphate, and silicon ions was seen initially, whereby the continuous release of these ions was observed for up to 30 days. The prepared F-BG injectable hydrogel has shown promising results and has the potential to be used as an endodontic sealer.

Nuclear-Targeted Nanostrategy Regulates Spatiotemporal Communication for Dual Antitumor Immunity.

Intercellular communication between tumor cells and immune cells regulates tumor progression including positive communication with immune activation and negative communication with immune escape. An increasing number of methods are employed to suppress the dominant negative communication in tumors such as PD-L1/PD-1. However, how to effectively improve positive communication is still a challenge. In this study, a nuclear-targeted photodynamic nanostrategy is developed to establish positive spatiotemporal communication, further activating dual antitumor immunity, namely innate and adaptative immunity. The mSiO2 -Ion@Ce6-NLS nanoparticles (NPs) are designed, whose surface is modified by ionic liquid silicon (Ion) and nuclear localization signal peptide (NLS: PKKKRKV), and their pores are loaded with the photosensitizer hydrogen chloride e6 (Ce6). Ion-modified NPs enhance intratumoral enrichment, and NLS-modified NPs exhibit nuclear-targeted characteristics to achieve nuclear-targeted photodynamic therapy (nPDT). mSiO2 -Ion@Ce6-NLS with nPDT facilitate the release of damaged double-stranded DNA from tumor cells to activate macrophages via stimulator of interferon gene signaling and induce the immunogenic cell death of tumor cells to activate dendritic cells via "eat me" signals, ultimately leading to the recruitment of CD8+ T-cells. This therapy effectively strengthens positive communication to reshape the dual antitumor immune microenvironment, further inducing long-term immune memory, and eventually inhibiting tumor growth and recurrence.

Metformin-loaded PLGA microspheres combined with an in situ-formed injectable SA/BG hydrogel alleviate rotator cuff muscle degeneration

Rotator cuff tears are a prevalent musculoskeletal problem that affect many individuals and may result in substantial social and health-related expenses. Moreover, the muscular fat infiltration and dystrophy associated with rotator cuff tears have been persistent challenges in rotator cuff surgical repair and postoperative rehabilitation. In this study, an in situ-formed injectable sodium alginate (SA) and bioglass (BG) hydrogel consisting of poly (lactic-co-glycolic acid) (PLGA) microspheres containing metformin (SA/BG-PLGA-Met) was developed for the prevention of muscular fat infiltration and dystrophy. Metformin and silicon ions were slowly released by the combined hydrogel, resulting in long-term biological effects. Moreover, the hydrogel displayed excellent degradability and biocompatibility. Extracts of SA/BG-PLGA-Met inhibited the adipogenesis of 3T3-L1 cells and stimulated the myogenic differentiation of C2C12 cells in vitro. In a mouse model of rotator cuff degeneration, the SA/BG-PLGA-Met hydrogel inhibited fat infiltration and dystrophy of the supraspinatus muscle. Overall, the SA/BG-PLGA-Met hydrogel, as a novel biomaterial, has great clinical potential for preventing rotator cuff muscle fat infiltration and atrophy.

Optical and Surface Structure Modification of Gallium Arsenide

The surface morphology modification and optical property modification of semi-insulating gallium arsenide sample implanted with 100 keV silicon ions with the fluences ranging between 5 × 10[Formula: see text] and 4 × 10[Formula: see text] ion cm[Formula: see text] were analyzed using scanning electron microscopy and UV–Vis–NIR spectroscopy study. Scanning electron microscopy study revealed pore-like structure formation on the surface of gallium arsenide samples after silicon ion implantation. The size of these pore-like structures was found to increase with increasing ion fluence. Energy dispersive X-ray analysis showed an increase in silicon concentration in the gallium arsenide sample after silicon ion implantation with increasing ion fluence. The UV–Vis–NIR spectroscopy study revealed a decrease in optical transmission for silicon ion implanted gallium arsenide sample with increasing ion fluence. An additional absorption band was observed for the gallium arsenide sample implanted with the highest fluence (4 × 10[Formula: see text] ion cm[Formula: see text]. Urbach tail energy was found to increase with respect to ion fluence.

Linear-energy-transfer-independent nanoclay radio-fluorogenic gel dosimeter under energetic ion beams of 28Si14+, 40Ar18+, 56Fe26+, 132Xe54+, and 12C6+

Recently, a radio-fluorogenic gel dosimeter that can evaluate the depth–dose distribution of high-energy carbon ion beams within a radio-therapeutic dose range was reported. This study performed a detailed characterization of this gel dosimeter using five types of ion beams (high-energy carbon, silicon, argon, iron, and xenon ion beams). In addition, this paper explains the mechanism of linear-energy-transfer (LET)-independent sensitivity by evaluating the effect of the composition conditions and contribution of water-decomposed molecules and radicals. Thus, it was observed that the dosimeter could be used to evaluate the dose distribution of various high-energy heavy ion beams in bioequivalent materials. The LET range was 25–8000 eV/nm. Additionally, it was suggested that this feature was caused by two mechanisms, i.e., an increase in the reaction by hydrogen peroxide and a decrease in the contribution of OH radicals by degassing.

Highly dense calcium phosphate ceramics prepared by self-hydration with hollow silicon calcium additives

Vertebral compression fractures are common nowadays. The application of calcium phosphate bone cement (CPCs) in the treatment of vertebral compression fractures is the research focus, because of its advantages of good biocompatibility, bone conductivity and injectability. However, it is still limited in the clinical application because of its poor mechanical properties. The main reason for the insufficient strength of CPC is that there are many defects inside the solidified body during the hydration reaction. Therefore, we design a kind of hollow silicon calcium additives to regulate the crystallization behavior of CPC hydration products in the self-curing process to achieve the densification of solidified bodies in the microstructure. Firstly, we plan to increase the nucleation site of hydration products during α-TCP hydration to fill structural defects by introducing hollow bioglass. Secondly, we prepare hollow calcium silicon additive by in situ mineralization which can dissolve calcium and silicon ions efficiently are used to regulate the local hydration microenvironment to reduce the crystal size and increase the number of hydration products to obtain a highly dense solidified body structure. The experimental results show that the initial hydration intensity of CPC increased from 18.36 ± 1.72 MPa to 35.37 ± 1.84 MPa, an increase of about 92.65 %. Also, the toughness of the solidified body has been greatly improved, reaching more than 200 %. After 7 days of hydration, the mechanical strength of CPC was further improved, reaching 89.39 ± 3.65 MPa. With the addition of hollow calcium silica additives, we achieved the conversion from calcium phosphate cement to the calcium phosphate ceramic. Our work provides reference value for the clinical replacement of calcium phosphate ceramic for PMMA in vertebral compression fractures.

The effect of thermal history on the additively manufactured AlSi10Mg alloy response to ion irradiation

Aluminum alloys, mainly from the 5xxx and 6xxx families, are used extensively in research reactors due to their suitable properties. However, alloys common in nuclear applications are not yet suitable for Additive Manufacturing (AM). The alloy AlSi10Mg has good engineering properties and is the most used and investigated AM Al-alloy. In this work, stress relieved (SR) samples of AM AlSi10Mg have been compared to samples that underwent a subsequent heat treatment at 500°C (SHT), producing two distinctly different microstructures. The SHT samples contain larger grains with a cleaner matrix and coarser silicon particles compared to the SR samples. Samples with the two microstructures were irradiated using silicon ions up to damage of ∼20 dpa at a depth of about 1 µm. To compare the response of both conditions to irradiation, properties were measured using nano-indentation and transient grating spectroscopy (TGS). Microstructure was characterized using TEM. Results show that the SHT condition is much more sensitive to irradiation, compared to SR. Irradiation caused thermal diffusivity to decrease by ∼5% in the SR condition and by more than 50% in the SHT condition. Hardness increased by 12 and 24% in the SR and SHT conditions, respectively. Also, the void number density was significantly larger in the SHT condition. No change was observed in young's modulus. The lower sensitivity of the SR condition is attributed to a higher sink density present in the initial microstructure, resulting in overall less irradiation damage retained in the material after irradiation. The explanation offered for the major drop in thermal diffusivity observed only in the SHT condition is the large size of the silicon particles, which increases their instability during irradiation, causing them to partly dissolve and release atomic silicon into the matrix around them. These silicon atoms are effective electron and phonon scatter centers. The findings of this work show that the pre-irradiated microstructure of AM AlSi10Mg has a crucial role in the material's performance in nuclear reactor core conditions. Careful thought and care need to be implemented to the heat treatment applied to an as-built part.

Bentonite alteration and retention of cesium and iodide ions by Ca-bentonite in alkaline and saline solutions

The nuclide retention capacity of bentonite can be affected by changes in the repository environments, such as alkaline and saline conditions. This study investigated the effects of bentonite alteration on the nuclide retention capacity of Ca-bentonite. A series of batch experiments was conducted at room temperature (25°C) for 7 d using Ca-bentonite and alkaline and saline solutions spiked with 10 mM each of cesium (Cs) and iodide (I). Cation exchange and a decrease in the basal spacing (d001) of montmorillonite were observed, as was the formation of zeolite minerals in bentonite samples reacted with an alkaline solution (0.1 M KOH and 0.1 M NaOH). Illitization, partial dissolution, and aluminum ions substitution for silicon ions in the tetrahedral sheets of montmorillonite were also observed in the bentonite samples reacted with an alkaline solution (0.1 M KOH). However, the Cs retention capacity of bentonite was not significantly affected by the mineral and physicochemical changes of montmorillonite in alkaline and saline solutions. Competing ions, including Mg, Ca, K, and Na ions in solutions with high ionic strength, all played a crucial role in Cs retention. Further, the cation exchange capacity of bentonite samples increased due to the formation of zeolite minerals under alkaline conditions.

Application of binders with lower carbon footprint in the AAC production

AbstractAutoclaved aerated concrete (AAC) is a building material that mainly contains calcium silicate hydrate phases, especially 11 Å tobermorite. For forming these mineral phases, calcium ions from the binders and silicon ions from the milled sand are necessary. Currently, hard‐burnt lime and Portland cement are used as binders for AAC production. Both raw materials contribute significantly to the carbon footprint of AAC products. On the way to climate neutrality of AAC production, it is thus necessary to replace hard‐burnt lime and Portland cement with binders with a lower CO2 impact. Therefore, tests with middle‐burnt lime in combination with different Portland limestone cement were carried out to investigate their influence on processing, material properties, and the mineral phase composition. It can be concluded that both these lower CO2 impact raw materials can be used for AAC production, as there are no changes in material properties and mineral phase composition.