Polishing Residue Research Articles

Optimization of hydrothermal autoclaving parameters for the synthesis of porous ceramics from porcelain tile polishing residue

Porous ceramics were synthesized using porcelain tile polishing residue (PTPR) and slaked lime (Ca(OH)2) as a reinforcing agent through a hydrothermal autoclaving method. The process parameters, including the quantity of slaked lime added, the hydrothermal autoclaving temperature, and the reaction duration, were optimized meticulously. The composition, structure, thermal and physical properties of the samples were thoroughly analyzed via Brunauer–Emmett–Teller (BET) measurements, powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). The results indicated that the incorporation of slaked lime and hydrothermal autoclaving led to the formation of calcium silicate hydrate, which corresponded with an enhancement in the strength of the sample. Notably, when the quantity of slaked lime added was optimized at 30 wt%, the formation of tobermorite (5CaO·6SiO2·5H2O) was detected. At a hydrothermal autoclaving temperature of 150 °C, the formation of only sheet-like calcium silicate hydrate was observed. In contrast, at an elevated temperature of 180 °C and 210 °C, needle-like tobermorite was successfully synthesized. The porous ceramic with the most favorable structure was obtained through autoclaving at 180 °C for 10 h with 30 wt% slaked lime, exhibiting a total pore volume of 0.11 mL/g, a specific surface area of 26.35 m2/g, and a mesoporous volume fraction of 90.40%.

Utilizing porcelain tile polishing residue in eco-efficient high-strength geopolymers with steel microfibers

Geopolymers are an alternative that produces low environmental impact binders with satisfactory mechanical properties. This research evaluated the influence of adding steel microfibers to a binary geopolymer matrix composed of metakaolin and ceramic tile polishing residue. Three mortar compositions (1:2, 1:3 and 1:4 cement:sand mass ratios) were produced with three microfiber concentrations (vf = 0.45, vf = 0.90 and vf = 1.35 % of total volume). The mechanical properties were evaluated by testing compressive strength, dynamic modulus of elasticity, flexural strength, and toughness. For 1:3 mortar, autogenous shrinkage measurements were performed for the 3 microfiber concentrations. Equivalent carbon dioxide emissions and binder intensity were also quantified. The mechanical properties classify the geopolymer concrete as high strength, achieving up to 95 MPa (composition 1:3) of compressive strength at 28 days and low binder consumption (9.82 kg.m−3. MPa−1). An improvement in flexural tensile strength was observed as the concentration of steel microfibers increased, reaching 20 MPa with vf= 1.35 %. For the concentration vf= 0.90 %, there was a reduction of ∼38 % of the autogenous shrinkage measurements about the reference (vf=0.0 %) at 28 days. In addition, regarding the CO2 intensity index, the lowest values were obtained for the 1:3 compositions, being minimum for vf= 0.90 % (9.01 [kg. ECO2-eq /m³ of mortar]/MPa), producing geopolymeric composites with low CO2 emissions, allowing the production of construction materials with low environmental impact.

Porcelain Tile Polishing Residue in Concrete as an Additive or Replacement for Portland Cement

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).

Thermo Physical and Mechanical Characterization of Lightweight Porous Ceramics Produced from Porcelain Polishing Residues

Traditional porcelain tile companies worldwide produce large amounts of residues during the polishing process. The recycling of these porcelain polishing residue becomes more critical. This study evaluates the incorporation of porcelain polishing residues as a raw material to produce lightweight porous ceramics as a new insulation material. Also, cellulose was used as the pore-making additive. The effect of sintering temperature and cellulose additive on the sintering behavior of porous ceramics, such as bulk density, linear shrinkage, water absorption were investigated. Flexural strength of the fired specimens was measured by three-point bending method. Thermal conductivities of the porous ceramics were predicted using laser flash method. Microstructural and phase observations were performed by scanning electron microscopy and X-ray diffractometry. Relatively low thermal conductivity of the samples sintered at 1100°C was obtained at 0.097 W.m–1.K–1 when 2.5 wt% cellulose additive was added, with low bulk density (<1 g.cm–3), water absorption (0.7%) and flexural strength (3.09 Mpa). These results indicate that the porcelain polishing residues could be used for lightweight porous ceramics production, thus giving rise to a new possibility for an environmental management of this abundant waste.

Valorization of porcelain tile polishing residue in the production of cellular ceramics

Porcelain tiles polishing residues are the leftovers of the tiles after the polishing step, formed by a mixture of a glassy phase, from the porcelain tiles, water, organic substances, and abrasive particles, mainly SiC, resulting in a sludge. When the sludge is dried and fired at high temperature, the SiC particles of the abrasive are oxidized and form SiO 2 and CO 2 , producing gases that can expand the glassy phase of the sludge forming cellular ceramics. In this context, this work aimed to study the feasibility of producing cellular ceramics from porcelain tiles polishing residues and to evaluate their physical, mechanical, and microstructural characteristics. A 2³ factorial design was used, where the study variables were the compaction pressure (20 and 40 MPa), the firing temperature (1170 and 1200 °C) and the firing time (30 and 60 min). The mechanical strength, apparent density and linear expansion after firing were determined for the cellular ceramics, being the response variables of the DoE. SEM analysis was performed to evaluate the porous microstructure of the ceramics. By image analysis, the average pore size was determined. Based on the experimental results and statistical analysis, cellular ceramics can be produced using the porcelain tile polishing residue. The ceramics subjected to the highest firing temperature (1200 °C) and firing time (60 min) have resulted in the highest linear expansion, lowest apparent density, largest pores, and lowest tensile strength due to the increase in porosity caused by the presence of SiC, since at these temperatures the pore formation kinetics is higher. • Polishing residue from ceramic tiles were used as raw material for cellular ceramics. • The tensile strength decreased with increasing time of sintering (p < 0.05). • The apparent density decreased with increasing firing temperature and time (p < 0.02). • SiC particles inside the polishing residue were the porogenic material during firing. • Pore sizes up to 250–260 μm can be achieved using only polishing residue.

Utilization of Porcelain Tile Polishing Residue

The research focuses on the properties of by-products formed in the production of porcelain stoneware: polishing residue and residue of the mixture-preparation shop. The polishing residue consists of glassy phase (80%), quartz (14%), mullite (5%). Residue of the mixture-preparation shop consists of quartz (~ 18%), muscovite (~ 6.9%), kaolinite (~ 20.5%), calcium-sodium feldspar (~ 51.4%), diopside (~ 2.98%). Polishing residue occurs when polishing porcelain stoneware to create a glossy surface and when polishing the side faces of porcelain stoneware to obtain accurate tile geometry. The particle size of the polishing residue is less than 0.2 mm, and the residue of the mixture-preparation shop is less than 40 microns. Residue of the mixture-preparation shop is formed when cleaning equipment: mills, mixers, slipways, etc. The ways of utilization of by-product are follows: as a filler for the silicate production; for polymer-cement, water-dispersion and oil paints; as a filler for the production of roofing materials, bituminous roofing mastics based on organic binders; raw materials for the production of foam glass materials and products.

Evaluation of the mechanical and durability properties of eco-efficient concretes produced with porcelain polishing and scheelite wastes

The construction industry uses large-scale natural resources to production of concrete among which cement and aggregates are fundamental components. This process causes environmental impacts that are not aligned with sustainable propositions and perspectives. Likewise ceramic and mining industries generate various wastes disposed of inappropriately which can be harmful to environmental systems. Given these facts the present study aims to understand better the physical mechanical and durability of eco-efficient concrete produced with partial and hybrid substitutions of cement and sand by porcelain polishing residue (PPW) and scheelite residue (SW) respectively. For this an experimental campaign was developed divided into two stages. The first phase consisted of performing tests (consistency water absorption and porosity by immersion and compressive strength) in concretes with fixed fine aggregate contents (mixture of 81% and 19% of SW and sand respectively) and with partial replacement of Portland cement by 0 5 10 15 20 25 and 30% of PPW aiming to select the mixture with better physical and mechanical performance. Finally the second experimental phase consisted of evaluating the evolution of compressive strength and durability (capillary water absorption and chloride penetration) properties of the selected eco-efficient concrete. A microstructural analysis using XRD was also conducted to identify the main phases present in the concretes with wastes. The results showed that 15% is the optimum content to replace cement with PPW. A decrease in the consistency compressive strength water absorption and porosity of the concretes with this waste compared to the reference mixture was also observed 28 days. However at 90 days the mechanical behavior of the concretes was improved due to the filling effect and the pozzolanic activity of PPW. The durability properties indicated less pore connectivity and resistance to chloride migration equivalent or slightly higher than the reference concrete.

Rheological and hydration behaviour of cement pastes containing porcelain polishing residue and different water-reducing admixtures

The pozzolanic activity and great availability of ceramic wastes (such as porcelain polishing residue – PPR) have increased their usage as supplementary cementitious material. However, studies investigating the effect of water-reducing admixtures on the early-age performance of cement-based materials containing such wastes are still lacking. This work investigated the effect of a lignosulfonate-based plasticizer (PL) and two polycarboxylate-based superplasticizers (SP1 and SP2) on the rheology and hydration kinetics of cement pastes containing PPR and quartz filler. Rheological results show that the volumetric replacement of 20% cement by PPR increased the yield stress, viscosity and thixotropy. PL and SP2 show inferior affinity with PPR, exhibiting increased yield stress, viscosity and thixotropy compared with the reference mix. By contrast, SP1 resulted in rheological properties similar to those of the reference mix and improved performance compared with the quartz filler-containing mix. Calorimetry results indicate that both SPs extended the induction period and increased the main heat flow peak compared with PL. The use of a proper water-reducing admixture can overcome workability losses caused by PPR incorporation, reinforcing the feasibility of using this residue as supplementary cementitious material.

Effect of porcelain tile polishing residue on eco-efficient geopolymer: Rheological performance of pastes and mortars

Brazil produces 900 mi m2 of ceramic tiles annually, which generates about 60,000 tons of porcelain tile polishing residue (PPR). In previous work, the authors confirmed the feasibility of using PPR in the production of geopolymer pastes regarding mechanical and microstructural properties. This work investigated the rheological and ecological performance of geopolymer pastes and mortars produced with metakaolin replacement by PPR in 0–100%, activated with Na2SiO3/NaOH solution. Rotational rheometry and mini slump test were conducted in pastes, in addition to flow table test for mortars. Furthermore, the CO2 emission related to 1 m³ of mortar was estimated for each composition. Results showed that geopolymer pastes behaved as a Bingham fluid (R2 of 0.999–1.000). The increase in PPR level linearly decreased the yield stress of the pastes from 10.5 to 0.2 Pa, and the viscosity from 4.2 to 1.5 Pa.s. Furthermore, PPR incorporation progressively increased the spread of the pastes (mini slump) and mortars (flow table) by up to 20% and 17%, respectively. The yield stress and mini slump spread of the pastes showed a linear correlation with R2 of 0.992, indicating that this test is efficient to assess the yield stress of geopolymer pastes, as widespread for Portland cement pastes. Finally, PPR incorporation progressively reduced the CO2 emission per m³ of mortar from 636 (0% PPR) to 532 kg CO2-eq/m³ (100% PPR). Replacing 15% metakaolin with PPR reduced the CO2 intensity of the material (i.e. kg CO2-eq/m³.MPa) by 11% and 7% respectively at 7 and 28 days. Overall, PPR incorporation improved the fresh and hardened performance of metakaolin-based geopolymer composites while reducing its CO2 emission, reinforcing the good technical and environmental performance of the residue as binding material.

Cementing efficiency factors of ceramic polishing residue in compressive strength and chloride resistance of mortar

During the polishing process of ceramic tiles, plenty of ceramic polishing residue (CPR) is generated. In order to evaluate the reutilization of CPR as a supplementary cementitious material (SCM) in mortar/concrete, and investigate its effects on the strength and durability, a series of mortar mixes containing different CPR contents were made for conducting compressive strength test and rapid chloride permeability test. It was found that adding CPR as a SCM up to 20% could still markedly improve the compressive strength and chloride resistance, while at the same time reduce the waste disposal, cement consumption and carbon footprint for sustainable development. Moreover, the cementing efficiency factor of the CPR in 28-day compressive strength was generally higher than 1.5 whereas that in chloride resistance was generally higher than 4.0, indicating that the CPR is a highly effective SCM for replacing part of the carbon-intensive cement and improving the strength and durability performance.

Properties of porcelain influenced concrete

The ceramic sector is responsible for a huge quantity of waste in terms of calcined-clay wastes annually. Most often, a large quantity of this is utilized as landfills but efforts can be made in the utilization of these wastes in concrete production. Hence, this research study makes use of porcelain waste, porcelain polishing residue (PPR), as partial replacement of cement in the production of concrete. Porcelain was used at a certain percentage of 5%, 15%, and 30% replacement of the total quantity of cement in the mix proportion. All specimens were cured in water till the age of test which is 7, 14, 21, and 28 days ages and designated as control, C, 5PPR, 15PPR, and 30PPR according to the percentage of replacement. All concrete specimens were tested in accordance with fresh concrete and engineering properties. The results show that the optimum compressive strength (CS)and flexural strength (FS) among all the PPR were observed with the replacement level of cement at 15% from PPR which gives 19.11 and 18.635 MPa at 28 days, whereas the control specimens give the highest CS with the value of 24.0 MPa and 21.795 KN at 28 days, respectively. The engineering properties of concrete specimens somewhat were enhanced with the replacement level of cement by 15% PPR.

Use of porcelain polishing residue as a supplementary cimentitious material in self-compacting concrete

The reduction of Portland cement content in concretes and the use of waste materials in the construction industry are two major challenges for eco-efficient construction. Brazil generates about 60,000 tons of porcelain polishing residue (PPR) per year. In a previous study, the authors verified that Portland cement replacement by up to 20% PPR improved the rheological properties of self-compacting concrete (SCC). In this work, the use of PPR as a pozzolanic supplementary cementitious material in self-compacting concrete was investigated. The hydration kinetics of the cement was evaluated by isothermal calorimetry and the pozzolanic activity of the residues was evaluated by thermogravimetric analysis (TG). The compressive strength of the concretes was determined at 28, 91 and 365 days. Finally, the emission of CO2-eq/m3 of concrete was estimated for each mixture, for a given strength. The isothermal calorimetry showed that the presence of PPRs enhanced the hydration of the cement and TG confirmed the pozzolanic activity of the residues. The compressive strength of the concretes containing PPR reached up to 95 and 98% of the reference at 91 and 365 days respectively, and the residue reduced the cement content per m3 of concrete to reach 1 MPa (kg.m−3.MPa−1) by up to 25% at the latter age. In addition, for a compressive strength of 70 MPa, the incorporation of PPR would reduce the emission of CO2-eq/m3 of concrete by up to 17%, while incorporating 127 kg of the residue per m3 of concrete.

Rheological behavior of Portland cement pastes and self-compacting concretes containing porcelain polishing residue

Brazil is the second largest producer of ceramic tiles in the world, generating 60,000 tons of porcelain polishing residue (PPR) annually. This material presents high pozzolanic activity, with great potential for use as a supplementary cementitious material. In this work, cement pastes and self-compacting concretes (SCCs) with different replacement levels of Portland cement by two PPRs and a limestone powder were prepared. The flow behavior of the mixtures was evaluated by paste and concrete rheometry and concrete workability tests. The results showed that the replacement by either PPR increased the plastic viscosity and yield stress of pastes. In the SCCs, replacement of the cement by up to 20% of PPR resulted in mixtures with similar rheological properties and better passing abilities compared with the reference paste (no replacement). Higher contents led to considerable increases in the viscosity and significant reductions in the passing ability of the SCCs. The replacement of cement by limestone powder led to reduction in viscosity and yield stress, both in pastes and concretes. The slump flow and T500 did not show good correlations with the rheological parameters of the SCCs, while V-Funnel time and J-Ring/slump flow ratio adequately evaluated the viscosity and passing ability of the mixtures, respectively.

Effect of porcelain tile polishing residue on geopolymer cement

Abstract The polishing of ceramic tiles surface produces high amounts of residual sludge, which requires deposition in controlled landfills. However, porcelain tile polishing residue (PPR) can be used as a partial source of aluminosilicate to produce geopolymer cement. Therefore, in this work, a geopolymeric cement based on PPR and metakaolin was developed using sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) as activator solution. A 23+1 factorial design was used with three factors: PPR content (15, 30 and 45 mass % in relation to metakaolin); NaOH (5, 6 and 7 mass %) and Na2SiO3 (48, 50 and 52 mass %). After synthesis, the samples were characterized by mechanical (compressive strength, hardness and dynamic modulus) and structural analyses (XRD and FTIR). The highest compressive strength was 72 MPa, obtained at 28 days (cured at 23 °C) in the composition containing 15% of PPR and 85% metakaolin, corresponding to a chemical composition with 53% SiO2, 25% Al2O3 and 11% Na2O, relation SiO2/Al2O3 = 3.44, and a structure characterized as poly (sialate-disiloxo). The results showed that PPR can be used as an alternative source of raw material to produce geopolymer cement, while contributing to the reuse of an industrial waste.

Study on planarization machining of sapphire wafer with soft-hard mixed abrasive through mechanical chemical polishing

This study investigated the material removal mechanism of sapphire wafer with soft-hard mixed abrasives through mechanical chemical polishing (MCP). The polishing film, which contains diamond as hard abrasives and high reactivity silica as soft abrasives, is prepared through sol-gel technology. Silica abrasives with regular spherical shape and high reactivity are prepared through hydrolysis-precipitation. Diamond grits with three different particle sizes are used as abrasives. Results show that the rate of material removal of mixed abrasives during MCP is more than 52.6% of that of single hard abrasives and the decrease in surface roughness is more than 21.6% of that of single hard abrasives. These results demonstrate that the ideal planarization of sapphire wafer with high removal rate and good surface quality can be achieved when the effect of mechanical removal of hard abrasives and the chemical corrosion effect of soft abrasives are in dynamic equilibrium. A model that describes the material removal mechanism of sapphire with mixed abrasives during MCP is proposed. The results of thermodynamic calculation and polishing residue analysis are used to demonstrate the rationality of the model.

Analysis of Etched CdZnTe Substrates

State-of-the-art as-received (112)B CdZnTe substrates have been examined for surface impurity contamination and polishing residue. Two 4 cm × 4 cm and one 6 cm × 6 cm (112)B state-of-the-art as-received CdZnTe wafers were analyzed. A maximum surface impurity concentration of Al = 1.7 × 1015 atoms cm−2, Si = 3.7 × 1013 atoms cm−2, Cl = 3.12 × 1015 atoms cm−2, S = 1.7 × 1014 atoms cm−2, P = 1.1 × 1014 atoms cm−2, Fe = 1.0 × 1013 atoms cm−2, Br = 1.2 × 1014 atoms cm−2, and Cu = 4 × 1012 atoms cm−2 was observed on the as-received CdZnTe wafers. CdZnTe particulates and residual SiO2 polishing grit were observed on the surface of the as-received (112)B CdZnTe substrates. The polishing grit/CdZnTe particulate density on CdZnTe wafers was observed to vary across a 6 cm × 6 cm wafer from ∼4 × 107 cm−2 to 2.5 × 108 cm−2. The surface impurity and damage layer of the (112)B CdZnTe wafers dictate that a molecular beam epitaxy (MBE) preparation etch is required. The contamination for one 4 cm × 4 cm and one 6 cm × 6 cm CdZnTe wafer after a standard MBE Br:methanol preparation etch procedure was also analyzed. A maximum surface impurity concentration of Al = 2.4 × 1015 atoms cm−2, Si = 4.0 × 1013 atoms cm−2, Cl = 7.5 × 1013 atoms cm−2, S = 4.4 × 1013 atoms cm−2, P = 9.8 × 1013 atoms cm−2, Fe = 1.0 × 1013 atoms cm−2, Br = 2.9 × 1014 atoms cm−2, and Cu = 5.2 × 1012 atoms cm−2 was observed on the MBE preparation-etched CdZnTe wafers. The MBE preparation-etched surface contamination consists of Cd(Zn)Te particles/flakes. No residual SiO2 polishing grit was observed on the (112)B surface.

Phase Transformation of Monocrystalline Silicon Induced by Polishing With Diamond Abrasives

A newly developed semi-fixed flexible polishing tool called sol-gel (SG) polishing pads can satisfy the polishing demand of silicon wafers with scratch-free and nano-roughness surface. However, an obvious damage layer emerges on the surface of monocrystalline silicon wafer after polished by SG polishing pads with diamond abrasives. In this paper, combined characterizations consist of grazing incidence X-ray diffraction, Raman spectroscopy (RS), focused ion beam-scanning electron microscopy (FIB-SEM), transmission electron microscopy (TEM), and SEM were used to observe the damage layer together with the polishing residue. The results indicated that the surface monocrystalline silicon transformed to α-Si and nano-Si. Analysis on the polishing processes under the same experimental parameters with different tools and abrasives revealed that the material removing scale about 100-300 nm may account for the generation of damage layer.

Pozzolanic effect of porcelain polishing residue in Portland cement

Ceramic tiling is used on a large scale by the construction industry. The production process of tiles produces porcelain polishing residues (PPR), one of the main residues in the sludge, with loss rates above 1%. Since it is a residue that is impure for reuse in the process, it ends up being discarded in landfills. However, considering its characteristics, its fineness and chemical composition, its potential as a pozzolanic material was evaluated for use in the manufacture of cement-based construction materials in order to improve their yield. Tests were conducted on mortar and cement pastes using substitutions of 5%, 10% and 20% cement by PPR. The results of compressive strength (at 84 days) determined for the mortars showed an increase of 18%, with reduced cement consumption per MPa/m3 for mortar of 11.5 kg MPa−1 m−3 at 0% and 7.5 kg MPa−1 m−3 at 20% residue content. Thermogravimetric analysis revealed that the portlandite formed by cement was consumed by the silica present in the residue, forming calcium silicate hydrate (C–S–H), which characterizes a pozzolanic reaction. This effect contributed to the study and to the applications of supplementary cementitious materials, while optimizing the use of Portland cement and reducing the environmental impact of carbon dioxide emissions originating from its production.

Production of surfactin from rice mill polishing residue by submerged fermentation using Bacillus subtilis MTCC 2423

Rice mill polishing residue (RMPR), an abundant and cheap agro residue, was used as substrate for microbial growth of Bacillus subtilis MTCC 2423 by submerged fermentation process to produce surfactin. Nutrients present in the residue were sufficient to sustain the growth of the microorganism. Multi stage foam fractionation followed by acid precipitation was used to concentrate and recover the product. Recoverable yield of surfactin was 4.17g/kg residue. Product recovered in the foamate accounted for 69% of the total yield. The residual broth containing ∼30% surfactin exhibited biological oxygen demand and chemical oxygen demand values of 23 and 69mg/L respectively. The microbial growth data was correlated using three parameter sigmoid models. Surfactin synthesized had a predominance of molecular weight 1076Da. Foam separation of copper using surfactin resulted in a maximum removal of 72.5%.

Ceramic waste as aggregate and supplementary cementing material: A combined action to contrast alkali silica reaction (ASR)

Abstract Recently, many efforts have been made to recycle waste of different nature as constituents of sustainable concrete. This practice produces large environmental benefits that can be further extended if deleterious chemical side-reactions, deriving from the use of some types of waste and/or raw materials, could be prevented and suppressed. This paper presents the combined action of different ceramic wastes partially replacing natural sand and cement, respectively. Alkali silica reaction (ASR) promoted by boron–silicate and lead–silicate glass used as fine aggregates (⩽4 mm) is limited and controlled by using a new type of blended cement based on a siliceous residue coming from sludge produced by the polishing of porcelain stoneware tiles. The results of expansion tests carried out in accelerated conditions together with mechanical and microstructure characterisations of mortar samples highlight the combined action of the investigated wastes. Indeed, the blended cement containing porcelain stoneware polishing residue can be effectively exploited as valid alternative to pozzolan cement.