Search Results (28)

The increasing demand for sustainable construction materials has intensified research on supplementary cementitious materials capable of reducing Portland cement consumption and associated CO₂ emissions. In this context, porcelain polishing residue (PPR), a fine ceramic waste generated by the tile industry, presents potential for valorization in cement-based composites. This study investigates the use of PPR as a supplementary cementitious material in self-compacting concrete (SCC), focusing on its pozzolanic activity and its influence on fresh, physical, and mechanical properties. Pozzolanic behavior was evaluated using strength-based indices with lime and Portland cement, as well as the modified Chapelle method. SCC mixtures were produced with partial replacement of cement by PPR at different levels and assessed in terms of self-compactability, compressive strength, elastic modulus, water absorption, and void index. The results showed that, although PPR did not meet strength-based pozzolanicity criteria at early ages, it exhibited significant calcium hydroxide consumption, indicating latent pozzolanic potential. Fresh-state properties were preserved in all mixtures, and an optimal replacement level of 20% resulted in improved long-term mechanical performance, reduced void content, and enhanced matrix compactness. These findings demonstrate that PPR can be effectively used as a functional supplementary cementitious material in SCC, contributing to more sustainable and eco-efficient concrete production. Full article

Lightweight artificial aggregates (LWAs) are key materials for sustainable construction, offering reduced structural self-weight, improved thermal performance, and enhanced resource efficiency. However, their production remains geographically concentrated and largely dependent on virgin raw materials, while significant volumes of industrial waste continue to be landfilled. This study addresses these challenges by developing regional LWAs through the incorporation of high levels of porcelain polishing residue (PPR) into red clay matrices, promoting waste valorisation within a circular economy framework. Four mixtures were produced with 20, 40, 60, and 80 wt.% PPR replacing red clay and sintered at 1220 °C and 1240 °C. Raw materials were characterized by laser granulometry, X-ray fluorescence, and X-ray diffraction, while the produced aggregates were evaluated in terms of bloating index, mass loss, bulk density, water absorption, modulus of deformation, crushing strength, and visual morphology. A full factorial experimental design coupled with analysis of variance (ANOVA) was applied to quantify the effects of mixture composition, firing temperature, and aggregate size. All formulations exhibited significant bloating (>35%), with expansion intensifying as PPR content and firing temperature increased, reaching up to 140.6% for mixtures with 80% PPR at 1240 °C. Bulk density values ranged from 0.53 to 1.14 g/cm³, and water absorption remained below 20% for all compositions, confirming their classification as lightweight aggregates. Mechanical performance was strongly dependent on the balance between expansion and matrix densification. The mixture containing 40% red clay and 60% PPR sintered at 1220 °C showed the most favourable performance, achieving crushing strengths of approximately 5.00 MPa while maintaining low density, outperforming commercial reference aggregates. Statistical analysis identified mixture composition and firing temperature as the dominant factors governing expansion and density. The results demonstrate that porcelain polishing residue is a technically viable and sustainable raw material for high-performance LWA production, enabling regional manufacturing routes with reduced environmental impact and strong potential for structural and non-structural construction applications. Full article

Current international standards (EN 12004; SI 4004) are testing ceramic tile adhesives under post-cure thermal aging. However, the standards omit UV radiation exposure during the fresh-adhesive phase. This research investigated three commercial polymer-modified cement adhesives (C2TE, C2TE-S2, C2T) bonding porcelain stoneware tiles under simulated Eastern Mediterranean and desert conditions. Three commercial adhesives were exposed during the initial (uncured) period to elevated temperature (30 °C), humidity variation (40–65% RH), and UV radiation (295–365 nm, 1.5–2.0 mW/cm²) for 20 min, followed by 28 days of curing. Pull-off testing and scanning electron microscopy, combined with quantitative directionality analysis, were used to characterize the mechanical performance and microstructural degradation. UV exposure of adhesives during tiling working time caused a drop of mean bond strength from 1.77 to 0.26 MPa (85% reduction) compared with 1.77 to 0.64 MPa (36% reduction) under hot-arid conditions. Microstructural analysis of the hardened pull-off adhesives revealed that exposure of the fresh adhesive to UV radiation causes thinning and degradation of the interfacial layer (15–40 µm), leading to a drop in macroscopic strength. In contrast, hot-arid exposure induces adhesive bulk cracking while preserving interface integrity. Fracture surface directionality (goodness parameter), crack density, and delamination percentage together distinguish interface failure from adhesive bulk degradation and provide a forecast of long-term durability. This combined SEM-mechanical approach identified critical gaps in testing protocols and enables evidence-based adhesive selection, as current EN 12004 classifications based solely on mechanical properties prove insufficient. Full article

The development of the ceramic industry requires the creation of new innovative products with improved properties. Given the growing demand for high-quality finishing materials and the limited availability of traditional raw materials, the search for more efficient technologies for porcelain stoneware production is a relevant challenge. The aim of this study was to develop porcelain stoneware with enhanced performance characteristics. The research presents the results of a study aimed at improving the production technology of porcelain stoneware in Kazakhstan using local raw materials and microsilica. The raw materials from the Turkestan region were examined for their suitability for porcelain stoneware production. The influence of technological parameters (firing temperature, particle size) on the properties of porcelain stoneware was studied. New ceramic compositions with various microsilica contents, a by-product of silicon production, were investigated. Different compositions with varying raw material mixtures and microsilica content were prepared and fired at temperatures of 1100, 1150, and 1200 °C. The optimization of process parameters for producing porcelain stoneware in different compositions showed the degree of yield dependence on firing temperature and time as well as the effect of microsilica content. The temperature, time, and visually determined parameters at which different yield values were achieved were highlighted in different colors. The results showed that changes in the mixture composition and sintering temperature affect the quality of ceramic tiles. The final experimental conclusions demonstrated that the production of ceramic tiles containing up to 3% microsilica at a firing temperature of 1200 °C. The addition of microsilica increases the flexural strength of porcelain stoneware to 41 MPa (exceeding the standard), reduces water absorption to 0.023%, increases frost resistance to 107 cycles, and also enhances shrinkage. These findings open new prospects for the development of the domestic ceramic industry, the expansion of the product range, and the resolution of environmental issues. Full article

In line with circular economy principles and the reduction of primary material exploitation, waste-to-energy (WtE) by-products such as bottom ash (BA) are increasingly being used as raw materials in cement and ceramics manufacturing. However, it is critical to verify that the final product presents not only adequate technical properties but also that it does not pose negative impacts to the environment and human health during its use. This study investigates the environmental compatibility of the use of ceramic porcelain stoneware tiles manufactured with BA as partial replacement of traditional raw materials, with a particular focus on the leaching behavior of the tiles during their use, and also after crushing to simulate their characteristics at their end of life. To evaluate the latter aspect, compliance leaching tests were performed on crushed samples and compared with Italian End-of-Waste (EoW) thresholds for the use of construction and demolition waste as recycled aggregates. Whereas, to assess the environmental compatibility of the tiles during the utilization phase, a methodology based on the application of monolithic leaching tests to intact tiles, and the evaluation of the results through multi-scenario human health risk assessment and the analysis of the main mechanisms governing leaching at different stages, was employed. The results of the study indicate that the analyzed BA-based tiles showed no significant increase in the release of potential contaminants compared to traditional formulations and fully complied with End-of-Waste criteria. The results of the monolith tests used as input for site-specific risk assessment, simulating worst-case scenarios involving the potential contamination of the groundwater, indicated negligible risks to human health for both types of tiles, even considering very conservative assumptions. As for differences in the release mechanisms, tiles containing BA exhibited a shift toward depletion-controlled leaching and some differences in early element release compared to the ones with a traditional formulation. Full article

Anatase is well known for its photocatalytic properties. However, it can be irreversibly transformed into rutile at temperatures above 600–850 °C. This is a major limitation for ceramic tiles with self-cleaning properties, which are usually single-fired at 1100–1250 °C. To avoid this issue, functionalized tiles are often produced by double firing, where the second firing stays below 850 °C. Supporting TiO₂ on kaolinite helps to stabilize the anatase phase even at temperatures above 850 °C. In this study, a photocatalytic coating was specially developed to be suitable for the single-firing ceramic tile process. TiO₂ and TiO₂ with Nb₂O₅ (from 0 to 12 wt.%) were supported on kaolinite. This material was mixed with a glass frit to create a surface texture typical of ceramic tiles. The coated tiles were single-fired at 1185 °C. The self-cleaning performance was evaluated using contact angle (CA) measurements and methylene blue (MB) degradation under UV-A light, on both unpolished and polished surfaces. The polished sample containing 12 wt.% TiO₂ showed the best photocatalytic activity: it degraded 57% of MB and the contact angle decreased from 64° to 30° after UV-A exposure. XPS, FTIR, and FEG-SEM analyses confirmed the effective presence of TiO₂. The results demonstrate that kaolinite-supported TiO₂ is a promising approach for producing self-cleaning ceramic tiles using a single-firing process. Full article

In order to improve the performance of cement mortar (Portland cement), it was enriched with triclosan, hypochlorous acid, silver nanoparticles and graphene oxide. Cement mortar is used, among other things, to fill the gaps between the tiles of building porcelain stoneware. A number of structural, mechanical and biological tests were carried out. The structural tests included microscopic analysis and contact angle, reflectance and IR spectra, while the mechanical tests involved static bending and compression testing. These tests showed that the additions of graphene oxide and hypochlorous acid were most beneficial. These additions, although not detected by spectral methods, resulted in a significant increase in contact angle and mechanical properties. Studies of the viability of the bacteria Pseudomonas aeruginosa and Staphylococcus aureus showed that all the additives used resulted in a decrease in viability compared to the undoped cement mortar. There was also a beneficial decrease in the viability of fungi of the genus Fusarium on cement mortar mainly doped with silver nanoparticles. Full article

In spite of the amount of construction debris produced every year, recycled aggregates are still not commonly used in the concrete industry. A 100% recycled aggregate concrete—RAC—is not yet allowed by technical codes even though it would greatly help reduce the disposal of debris. This paper considers a construction site that can only be reached by small trucks, where concrete production is performed using manual procedures and the transportation of building materials is difficult and expensive. The aim of this research is to establish a mix design for 100% RAC for structural applications. In this context, recycled aggregates are obtained from the debris crushed by a small portable crusher Crunchy^©. Based on a series of tests on concrete cubes and cylinders of aggregates originating from different types of debris, it is shown that 100% RAC is also a promising material for structural applications. At the cost of more cement in comparison to standard concrete, RAC from high-strength aggregates (concrete and gres-porcelain tiles) may be used in r.c. structures. Some of its features, such as its low pH value and low compressive strength in the case of clay-originated aggregates, still need to be studied for an optimized mix design. In addition, it is shown that RACs have approximately the same carbon footprint as standard concrete. Full article

In this study, we developed formulations of a clay, kaolin, quartz, talc, and feldspar ceramic coating as a standard formulation, with the addition of Hap to improve the mechanical characteristics of the final product. The addition of Hap will help to fill the gaps in the formulation. Furthermore, it could lower the sintering temperature due to the high presence of calcium oxide in its composition. The main mineralogical phases (mullite, quartz, and anorthite) were identified in the sintered samples by X-ray diffraction. After evaluating the physical–mechanical properties (water absorption, linear shrinkage, apparent porosity, and resistance to flexion), the incorporation of Hap (5% in weight, 10% in weight, and 20% in weight) significantly altered the physical and mechanical properties of the final product, where we obtained, in relation to the standard formulation, an increase of more than 15% in mechanical resistance. Full article

This paper begins with an introduction to porcelain tiles. A review of the major scientific and technological features of mullite-based porcelain tiles (MPTs) and anorthite-based porcelain tiles (APTs), focusing primarily on the raw material, processing, phase evolution and mechanical behavior, is then presented. Based on the porcelain tile firing behavior and a series of physical and chemical changes that can occur, a comprehensive comparison is described. In the last part, the prospects for further developments related to MPTs and APTs are discussed. Full article

The construction industry has a significant environmental impact and concrete production is responsible for a large part of CO₂ emissions and energy consumption. This study focused on the reutilisation of a specific type of tiles ceramic waste (TCW), composed only of stoneware and porcelain stoneware tiles, hereafter referred to as ceramic stoneware (CS), as recycled aggregate in concrete. Natural limestone and CS aggregates (sand and gravel) were characterised (particle size distribution, water absorption, resistance to wear, density and X-ray diffraction analyses) and recycled aggregate concrete (RAC) was prepared by replacing 20, 50 and 100 vol.% of sand and gravel, separately. Concrete workability generally improved with CW addition, especially when replacing natural gravel. Although the compressive strengths of the concrete specimens prepared with recycled sand were slightly lower than those of the reference specimens, similar or better results were recorded with the recycled CS gravel. In consonance, the RAC developed with recycled gravel obtained lower water penetration depths than the reference concrete. No significant variation in tensile strength was observed when varying CS content (values within the 2.33–2.65 MPa range). The study contributes to sustainable construction practices and circular economy by promoting the valorisation and reutilisation of industrial waste and reducing the consumption of natural resources. Full article

The aim of this research was to evaluate the possibility of reusing waste foundry sands derived from the production of cast iron as a secondary raw material for the production of building materials obtained both by high-temperature (ceramic tiles and bricks) and room-temperature (binders such as geopolymers) consolidation. This approach can reduce the current demand for quarry sand and/or aluminosilicate precursors from the construction materials industries. Samples for porcelain stoneware and bricks were produced, replacing the standard sand contained in the mixtures with waste foundry sand in percentages of 10%, 50%, and 100% by weight. For geopolymers, the sand was used as a substitution for metakaolin (30, 50, 70 wt%) as an aluminosilicate precursor rather than as an aggregate to obtain geopolymer pastes. Ceramic samples obtained using waste foundry sand were characterized by tests for linear shrinkage, water absorption, and colorimetry. Geopolymers formulations, produced with a Si/Al ratio of 1.8 and Na/Al = 1, were characterized to evaluate their chemical stability through measurements of pH and ionic conductivity, integrity in water, compressive strength, and microstructural analysis. The results show that the addition of foundry sand up to 50% did not significantly affect the chemical-physical properties of the ceramic materials. However, for geopolymers, acceptable levels of chemical stability and mechanical strength were only achieved when using samples made with 30% foundry sand as a replacement for metakaolin. Full article

In this study, 10–50% of porcelain tile polishing residue (PPR) was used as an additive or as partial replacement of cement in concrete. The cement consumption was kept constant by correcting the amount of sand for each mixture. Concrete workability (slump) was reduced by up to 88.72% when PPR replaced the cement by up to 30%, while it was reduced by only 4.10% when PPR was added to the concrete at the same levels. Compressive strength at 28 days increased up to 92.22% with 50% PPR as additive, reducing the equivalent emission of CO₂ per m³ of concrete up to 38.18%. PPR incorporation reduced the water permeability of concrete by up to 30.70% and 17.54% when used in addition and in cement replacement, respectively. Overall, PPR as an additive up to 50% and in cement with substitution levels up to 10–40% presented themselves as viable solutions for developing more resistant and durable concretes than the reference mixture (without incorporation of PPR). Full article

The southern island of the Philippines is abundant in silicate minerals, including the province of Lanao del Norte. However, some of these resources in the region are untapped for use as raw materials in the production of various ceramic products for industrial, pharmaceutical, and nanotechnology applications. These could include tiles, sanitary ware, dinnerware, insulating bricks, porcelain, membranes and coatings. Some of the explored minerals are the red clay in the municipality of Linamon, diatomaceous earth in Kapatagan and black cinder in Salvador. It is the aim of this study that these minerals are evaluated in terms of their physical and chemical properties so that these will be used for optimum application. The properties that were determined were their specific gravities, raw and fired surface colors, Atterberg limits, particle size distribution, thermal properties, morphologies and mineralogical compositions. Pellets were formed for each raw material and fired at two temperature levels 1000 °C and 1200 °C to evaluate their physical properties. Linamon red clay has a 38.88% cumulative passing size of 150 µm, and the black cinder of Salvador and diatomaceous earth of Kapatagan have cumulative passing sizes of 96.53% and 60.12% at 150-micron sieve, respectively. The common mineral contents of the three samples are montmorillonite, quartz and andesine. Black cinder fired at 1200 °C has the darkest shade of red with a greasy quasi-submetallic luster. It attained the highest fusion coverage on the platform among the three materials, which makes it a potential supplement or replacement for feldspar in clay-based triaxial materials for ceramic production. The diatomaceous earth has the potential to be a secondary clay content source and a good source of flux for a certain temperature range. Both the red clay and diatomaceous earth were classified as plastic materials that are suitable for brick production, and the red clay is also feasible for pottery production. These are a few of the features of the clay minerals in the region that present suitable properties for application as raw materials in the production of ceramic tiles and hollow ceramic products. Full article

Porcelain tile manufacturing is an energy-intensive industry that is in dire need of increasing productivity, minimizing costs, and reducing CO₂ emissions, while keeping the product quality intact to remain competitive in today’s environment. In this contribution, alternative processing parameters for the porcelain tile production sequence were proposed based on simulation-based process optimization. Flowsheet simulations in the Dyssol framework were used to study the impact of the milling and firing process parameters on the electrical and thermal energy consumption, final product quality, and productivity of the entire processing sequence. For this purpose, a new model of gas flow consumption in the sintering stage was proposed and implemented. During optimization, the primary condition was to maintain the product quality by keeping the final open porosity of the tile within the specified industrial range. The proposed simulation methodology proved to be effective in predicting the influence of the processing parameters on the intermediate and final products of the manufacturing sequence, as well as in estimating the production costs for the Brazilian and Spanish economic conditions. This approach has shown great potential to promote digitalization and establish digital twins in ceramic tile manufacturing for further in-line process control. Full article