Calcium Silicate Research Articles (Page 1)

To achieve the national greenhouse gas reduction target for 2030, buildings are being designed with improved thermal insulation performance to reduce heating and cooling energy consumption. In line with this, regulations on thermal insulation performance are being strengthened, and buildings are becoming increasingly airtight. However, indoor air pollution is increasing due to pollutant emissions from building materials and insufficient ventilation. This study examined the characteristics of a cementitious composite with varying replacement ratio of calcium silicate and zeolite. The results showed that as the replacement ratio of calcium silicate and zeolite increased, thermal insulation and adsorption performance tended to improve. When the zeolite replacement ratio was 5%, the flexural strength was measured at 4.2 MPa, satisfying the minimum flexural strength requirement set by KS standards, and was therefore selected as the optimal mix.

ABSTRACT The Dazhuangke section of the Ming Dynasty Great Wall is in urgent need of effective restoration and preservation measures. Central to these efforts is the use of a rehabilitated sticky rice-lime mortar, which serves as a pivotal material. This study explores the enhancement of traditional sticky rice-lime mortar through the integration of cellulose ether, metakaolin, and silica fume, aimed at improving its properties. The entropy value method was employed to assign weights and comprehensively evaluate the macroscopic performance indices of each mortar group. Further, the microstructure of the modified sticky rice-lime mortar was examined using XRD, SEM-EDS, and MIP. The findings reveal that the addition of these additives markedly enhanced the macroscopic properties of the mortar, facilitated the carbonation reaction, and achieved optimal performance in mortar modified with 10% metakaolin content. These additives also refined the pore structure, resulting in reduced porosity. Notably, the modified sticky rice-lime mortars containing kaolin or silica fume formed a hydrated calcium silicate (aluminate) gel closely integrated with CaCO3, which effectively filled the pores. This study offers significant insights for optimizing the restoration of sticky rice-lime mortar in the Dazhuangke section of the Ming Dynasty Great Wall.

The utilisation of magnesium oxide-based binders (M) as an alternative to hydrated calcium silicate materials is a promising avenue for binding methodologies. However, the efficacy of using silica fume (S) as a co-binder with magnesium oxide in sulphate soil stabilisation, along with their ideal blending ratio, has yet to be unveiled. Therefore, an array of artificial sulphate soil specimens was fabricated, each featuring varying combinations of magnesium oxide and silica fume. These specimens were subsequently subjected to comprehensive testing, including unconfined compressive strength (UCS) test, linear expansion test, thermogravimetric analysis, and X-ray diffraction analysis. The outcomes demonstrated that the co-utilisation of silica fume and magnesium oxide significantly improves the compressive strength and linear expansion of sulphate soil, and such an improvement was more efficacious at a stoichiometric amount of 5% magnesium oxide and 5% silica fume (5M5S). This outperforming threshold, characterised by the highest UCS (1834 kN/m2) and minimal expansion (0.2%), occurred through the consumption of surplus brucite and the formation of further magnesium silicate hydrate.

Successful endodontic treatment relies on effective shaping, disinfection and obturation. Calcium silicate sealers such as BioRoot™ RCS show promise due to their bioactivity and sealing properties, but more clinical evidence using standardized protocols is needed. This observational clinical study aimed to assess periapical healing at 6 and 12 months following single-visit root canal treatment using BioRoot™ RCS with hydraulic condensation in teeth with irreversible pulpitis or apical periodontitis. Sixty-six teeth were treated using a standardized protocol: ProTaper Gold instrumentation, sonic-activated irrigation, and hydraulic condensation with gutta-percha cone and BioRoot™ RCS. Periapical healing was evaluated using the periapical index (PAI) at baseline, 6 months, and 12 months. Clinical success was defined as functional, asymptomatic teeth and a PAI ≤ 2. Statistical analysis included repeated measures of ANOVA and McNemar’s test. All 66 teeth remained asymptomatic and functional of 12 months, yielding a 100% survival rate. Clinical success was confirmed in 97% of cases. PAI scores decreased significantly over time (p < 0.001) in apical periodontitis cases. Single-visit endodontic treatment with BioRoot™ RCS and hydraulic condensation demonstrated excellent clinical and radiographic outcomes. This approach promotes resolution of apical periodontitis in non-vital cases and supports the preservation of periapical health in teeth initially diagnosed with irreversible pulpitis.

Abstract This study presents a novel approach to developing eco-friendly cladding materials by recycling Disintegrated Clay Waste (DCW), a by-product of the brick and tile industry. By replacing traditional firing methods with a stabiliser-based formulation, this study explores the transformation of discarded DCW into aesthetic and environmentally friendly claddings. The experimental process is evaluating the influence of variations of cement, water, and Ground Granulated Blast Furnace Slag (GGBS) on the performance of such claddings. The findings highlight that an optimal cement-to-water ratio of 1.4 ± 0.1 ensures stability and strength. An increase in cement content (2%) and density (0.04 gm/cc) of cladding is leading to an increase in flexural strength of around 0.12 MPa. DCW-based claddings are exhibiting a 10% lower density and comparable strength to conventional fired clay cladding. An increase in density by 0.2 gm/cc results in reduced water absorption by 1.5%. The incorporation of GGBS not only reduces cement demand but also significantly improves mechanical strength up to 39%. The slope of strength with binder dosage of GGBS-based cladding is observed as 2 times higher compared to cement-based samples, as the utilization of GGBS promotes enhanced formation of stable calcium silicate hydrate (C-S-H), leading to improved mechanical and durability properties. This research is confirming the potential of DCW as a reliable raw material for modern construction, offering a circular economy solution that is both resource-efficient and low-impact. The study is providing a solution where industrial by-products are reutilised as materials for building and architectural elements for sustainable waste management practice in the construction industry.


This study investigates the fire resistance of columns in container-style steel modular buildings through fire tests. Three individual columns and one combined column were tested to evaluate the fire resistance performance of various protective measures: fire-resistant coatings, calcium silicate boards, and rock wool sandwich panels. The combined column protected by 75mm rock wool sandwich panels achieved a fire resistance limit of 102.1min. The study concludes that rock wool sandwich panels are a feasible, economical fire protection solution for such columns. The required thickness of rock wool for different fire resistance limits was calculated, providing valuable design insights for container-style steel modular buildings.

Background: The development of calcium silicate materials and new techniques have resulted in significant clinical benefits in endodontics and microapical surgery. The objective of this investigation was to analyze the percentage of dentinal tubule penetration of two retrograde obturation techniques in microapical surgery, namely the conventional technique and the lid technique. Methods: 60 single-root human teeth were selected, which were divided into two groups (n = 30). These teeth were subjected to an endodontic procedure using the single-cone technique. They were prepared with apicoectomy and 3 mm apical retrocavity and then obturated using two retrograde obturation techniques with bioceramic materials: TotalFill RRM fast set Putty® (RRM) using the conventional technique and TotalFill BC Sealer HiFlow® (HiFlow) and RRM using the lid technique. The teeth were selected and evaluated using 1 mm portions in the apical third. In each case, the images were obtained using a Leica TCS SP8 Confocal Microscope (CLSM). The extent of penetration into the dentinal tubule regions was measured using AutoCad®. Results: Statistical analyses were performed using the Levene test (p ≤ 0.05) and Student’s t-test (p ≤ 0.05). Analysis of the penetration area of calcium silicate materials into the dentinal tubules revealed that the relative penetration percentages were higher when using the conventional technique with the RRM than the lid technique with RRM + HiFlow in the apical third evaluated. Conclusion: The conventional technique yields significantly better outcomes, showing statistically significant differences in the percentage of penetration into the intratubular area compared to the lid technique.

Cost-effective fabrication of fluorite tailings-based calcium silicate hydrate for excellent adsorption performance of Cr (III) from aqueous solution.

Corrigendum to “Adsorption of malachite green dye over synthesized calcium silicate nanopowders from waste materials” [Mater. Sci. Eng. B 295 (2023) 116605

Efficient selective separation of dyes by TA-MoS2/Calcium silicate hydrate composite filtration system

An investigation of the engineering properties and environmental impact of low-temperature modified electrolytic manganese residue for karst grouting materials.

Microstructural and durability assessment of carbonated calcium silicate cement under sulfate attack

This study investigated the potential of acid-pretreated rice husk ash (RHA) sourced alkaline earth metal silicates for lauric acid (LA) adsorption. The synthesized materials were characterized using BET, FTIR, XRD, EDS, and SEM analyses, demonstrating that metal cation size had a notable effect on surface area, pore structure, crystallinity, and particle aggregation. Magnesium silicate (MS-1.0), with its smaller atomic radius, exhibited the highest surface area and the most porous structure among the samples. Calcium silicate (CS-1.0) displayed a moderate surface area with a mesoporous structure, while strontium silicate (SS-1.0), having the largest atomic radius, exhibited the lowest surface area, a predominantly macroporous structure and the highest degree of particle aggregation. The synthesized alkaline earth metal silicates were tested for LA adsorption performance and compared using the analytical hierarchy process (AHP). CS-1.0 demonstrated the highest LA removal efficiency (59.94% ± 11.24%) and adsorption capacity (8.68 ± 1.60 mmol/g), while MS-1.0 had the lowest removal efficiency (17.64 ± 3.28%) and adsorption capacity (2.60 ± 0.50 mmol/g). Interestingly, the production yield increased from MS-1.0 to CS-1.0 and SS-1.0. Through the AHP method, CS-1.0 was identified as the best-performing adsorbent in this study, considering both adsorption efficiency and production yield with the highest priority value of 0.9603.

This study aimed to compare the physicochemical properties of EndoSequence Root Repair Material (ERRM) Fast and CeraPutty with ProRoot MTA and Biodentine, focusing on setting time, radiopacity, microhardness, and pH. Setting time was measured using a Gilmore-type indenter applied every 5 min until no indentation was observed (n = 15 per group). Radiopacity was assessed via aluminium step wedge, microhardness using Vickers hardness, and pH changes with a digital pH meter. Nonparametric statistical analyses were conducted with a significance level of 95%. Biodentine exhibited the shortest setting time and highest microhardness, while ERRM Fast showed the highest radiopacity. High alkaline pH values were measured for all materials. Within the limitations of this study, the new pre-mixed calcium silicate materials exhibited physicochemical properties comparable to traditionally mixed materials, indicating their potential suitability for endodontic treatments. However, careful selection based on clinical requirements, including handling, setting time, and mechanical properties, is essential.

Aluminium powder coating effluent with potassium hydroxide (KOH) were used in the geopolymerisation of coal fly ash (CFA), ferrochrome slag (FeCr) and gold mine tailings (GMT). In order to come up with a green synthesis route, curing was done at ambient conditions for 56 days. The synthesised geopolymers for CFA, FeCr and GMT were identified as CFA-GP, FeCr-GP and GMT-GP respectively. FeCr-GP, CFA-GP and GMT-GP had an unconfined compressive strength (UCS) of 25.5 MPa, 8.1 MPa and 6.1MPa after 28 days of curing using 6 M KOH. CFS-GP and FeCr-GP were effective in the stabilisation of heavy metals as the leachability of heavy metals was below allowable limits whilst GMT-GP was not effective. This was due to the presence of calcium silicate hydrate and calcium aluminate silicate hydrate in CFA-GP and FeCr-GP. These geopolymerisation products were absent in the microstructure of GMT-GP. The long-term use of CFA-GP and FeCr-GP did not pose any significant heavy metal pollution capability as the static leaching results were below the building material protocols whilst the use GMT-GP presented a significant environmental pollution threat. The use of FeCr-GP produced 270 kg CO2 per tonne of geopolymer resulting in a 19.4% reduction in carbon emissions as compared to the use of cement brick. Furthermore, more FeCr-GP had a 24 h water absorption rate of less than 9%. The geopolymerisation of CFA-GP and FeCr- GP with APCE can therefore be a method to reduce the pollution potential of these materials.

Tin slags generated during cassiterite smelting in Brazil contain significant amounts of technologically important metals such as niobium, tantalum, and zirconium. Improper disposal of these materials represents both an environmental concern and the loss of a valuable secondary source of critical elements. This study aimed to characterize a Brazilian tin slag sample to evaluate its composition, morphology, and potential for metal recovery. The material was homogenized and analyzed by laser diffraction (particle size), ICP-OES (chemical composition), X-ray diffraction (mineral phases), differential scanning calorimetry (metallic tin), and scanning electron microscopy with energy-dispersive spectroscopy (morphology). The slag exhibited a heterogeneous particle size distribution (D90 = 0.75 mm, D50 = 0.30 mm, D10 = 0.09 mm) and a complex multiphase structure composed mainly of silica, calcium silicate, and zirconia. The chemical analysis revealed 4.8 wt% Nb and 0.8 wt% Ta, along with high concentrations of Zr (11.1 wt%), confirming the material’s potential as a secondary resource. Thorium (2.7 wt%) and uranium (0.3 wt%) were also detected, indicating the presence of radioactive constituents. The detailed characterization of the slag provides essential insights into its chemical and mineralogical complexity, which directly influence the selection of suitable recovery routes. Understanding the distribution of Nb- and Ta-bearing phases within the refractory silicate–zirconia matrix is fundamental for defining pretreatment and leaching strategies. Therefore, this study establishes a necessary foundation for the design of efficient hydrometallurgical processes aimed at recovering critical metals from Brazilian tin slags.

The results of experimental studies aimed at improving the strength characteristics of cement stone and fine-grained self-compacting concrete through the use of polyfunctional modifying additives based on nano-silicon dioxide (nano-SiO2) and micro-dispersed mineral components are presented. It was established that the introduction of 0.03% nano-SiO2 by weight of cement increases the compressive strength of cement stone by up to 32%, which is associated with the intensification of clinker mineral hydration processes, the formation of an additional amount of low-base calcium hydrosilicates, and an increase in the number of crystallization centers in the early stages of hardening. The effectiveness of the combined use of nano-SiO2 with microsilica and micro-calcite, which are similar in composition to cement but differ in structure and functional activity, has been experimentally confirmed. The use of two-component systems made it possible to increase the flexural strength of cement stone by up to 29% compared to the reference samples. The greatest effect was achieved by adding a polyfunctional three-component additive, including nano-SiO2, microsilica, and micro-calcite, to the composition of fine-grained self-compacting concrete. The use of this system increased the compressive strength of concrete by 44% (to class B60) and the flexural strength by up to 12.5 MPa (an increase of 53.7% relative to the reference composition). It was additionally established that the complex of additives contributes to the acceleration of self-organization processes in the early stages of hardening by increasing the density of crystallization centers and a more uniform distribution of hydration products in the cement matrix volume.

The development of biomaterials for direct pulp capping has significantly transformed modern vital pulp therapy. For decades, calcium hydroxide was considered the gold standard, but its limitations - such as lack of sealing ability and tendency for resorption- have prompted the search for improved solutions. The introduction of calcium silicate cements and new-generation bioceramics has led to better biological and clinical outcomes. This review aims to discuss the latest advances in biomaterials used for direct pulp capping and to compare their properties, efficacy, and limitations. Literature published between 2018 and 2024, including systematic reviews, meta-analyses, and clinical studies, was analyzed. The results show that bioceramics and contemporary calcium silicate cements exhibit high bioactivity, enable the formation of a dentin bridge, and present a favorable safety profile. Appropriate material selection, meticulous clinical technique, and effective control of infection and moisture are essential for clinical success. The review also highlights certain limitations, such as the higher cost of new materials, technical requirements, and the lack of long-term clinical data. In conclusion, bioceramics currently represent the best choice for direct pulp capping, and further research should focus on optimizing clinical protocols and evaluating long-term outcomes to ensure predictable, minimally invasive dental care.

This study systematically investigates the effects of slag from the argon–oxygen decarburization (AOD) process, fly ash, and recycled aggregate (RA) replacement ratios on the mechanical properties of mortar samples and AOD slag–fly ash recycled concrete. The sustainable reuse of industrial by-products and construction waste is significant for reducing environmental impact and resource consumption during pavement construction. Experimental results demonstrate that when AOD slag and fly ash are used in combination, they undergo synergistic hydration reactions, producing calcium hydroxide (CH), calcium silicate hydrate (C-S-H) gel, and ettringite (AFt), resulting in superior strength compared to the individual use of either material. This research reveals that concrete strength decreases significantly when the recycled aggregate replacement ratio exceeds 50%; therefore, RA = 50% was selected as the optimal replacement ratio for subsequent studies. On this basis, when the combined replacement ratio of AOD slag and fly ash is 10–20%, concrete performance reaches its optimum level: maximum compressive strength is 33.9 MPa, which is 8.57% and 36.2% higher than using fly ash or AOD slag alone, respectively; maximum flexural strength is 4.6 MPa, which is 6.08% and 14.44% higher than using fly ash or AOD slag alone, respectively; and peak axial compressive and splitting tensile strengths are 24.9 MPa and 3.4 MPa, respectively. These findings demonstrate that the synergistic use of AOD slag, fly ash, and recycled aggregates can produce concrete that meets pavement application requirements, while effectively promoting the resource utilization of industrial by-products and construction waste, aligning with circular economy principles.

This study investigates the effects of curing temperatures (20 °C and 60 °C) on the hydration behavior and mechanical performance of bottom ash (BA) incorporated ordinary Portland cement (BAOPC) composites. At 20 °C, the ground BA showed low reactivity, exhibiting minimal participation in hydration reactions and resulting in limited pore refinement and increased large-sized pore formation. These factors contributed to a reduction in compressive strength. Meanwhile, curing at 60 °C significantly accelerated hydration, with BA actively engaging in hydration reactions to form substantial amounts of calcium silicate hydrate and monocarboaluminate phases. This process refined the pore structure, leading to a marked improvement in compressive strength. The findings highlight the critical role of elevated curing temperature in optimizing the pozzolanic reactivity of BA, demonstrating its potential to contribute to sustainable construction by using BAOPC.