Modified Chapelle Test Research Articles

Using ceramic demolition wastes for CO2-reduced cement production

This study focuses on assessing the pozzolanic potential of two types of ceramic demolition waste, namely terracotta roof tiles and sanitary porcelain, as substitutes for traditional calcined clays in blended and limestone calcined clay (LC3) cement production. Experimental methods employed include the modified Chapelle test and XRD for pozzolanic activity evaluation, flexural and compressive strength tests, capillary absorption measurements, and SEM for microstructure analysis. Mortars containing 10%, 20%, and 30% ceramic powders and 5%, 10%, or 15% limestone filler were tested. The findings showed that porcelain powders exhibited lower pozzolanic activity due to their lower surface area and higher firing temperature of the material. Up to 20% substitution of OPC with terracotta had minimal strength impact, with a 103% strength activity index (SAI) at 90 days. Ultrafine terracotta powder showed promise in LC3 production with up to 30% OPC substitution, achieving a 97% SAI after 90 days. The poor mechanical properties of porcelain-containing mortars were explained by surfactants present in sanitary porcelain. This research informs the cement and processing industries on the potential use of specific ceramic demolition waste materials in eco-cement production, offering insights into blended pozzolanic cements and LC3 formulations, with the goal of reducing the carbon footprint of cement manufacturing.

Dosagem de argamassas de alta resistência ecoeficientes otimizadas pelo modelo de empacotamento compressível

Abstract The production of eco-efficient cement-based materials is essential to reduce CO2 emissions from the construction industry. A substantial reduction in global CO2 emissions can be achieved by using clinker in mortar and concrete more efficiently and using low-CO2 minerals as partial replacements for Portland cement. However, the proportioning of eco-efficient composites is complex and the reduction in clinker content may affect its properties. This paper aims to optimize the mix design of high-strength mortars containing supplementary cementitious materials (limestone filler, fly ash, metakaolin, silica fume). The compressible packing model associated with a simplex mixture design were used together with chemical parameters, to limit the amount of active SCMs for the model iterations. The results show a significant decrease in the environmental impact of the mortars, which presented compressive strengths between 76 and 118 MPa at 91 days and binder indexes between 10 and 15 kg/m3/MPa. The reactivity of the SCMs (based on the modified Chapelle test) were successfully used to establish the Portland cement substitution (up to 13%), preventing the presence of unreacted SCMs and optimizing the use of limestone filler and sand, which have a lower environmental impact. The high-performance blends reached 8.73 kg CO2e/MPa, up to a 30% reduction in CO2e emissions compared to the mortar with only Portland cement.

Pozzolanic activity of stockpile ash: Comparison of test methods

The paper deals with the determination of the pozzolanic activity of coal-fired power plant fly and bottom ash deposited in stockpiles in the Czech Republic. The pozzolanic activity of the ash was determined using the Frattini test, modified Chapelle test, electrical conductivity test, and strength activity index. The ash collected from a stockpile was not found to display any pozzolanic activity by the methods utilised. However, milling the fly and bottom ash was shown to be the means of activating its pozzolanic properties. The study demonstrated the pozzolanic activity of the deposited ash notably increasing together with a growing time of milling and the associated increase in the specific surface area. Also, the research study presented here carried out the comparison of the individual methods regarding their effect on the pozzolanic activity and has revealed their good mutual correlation.

Thermo-chemico-mechanical activation of bagasse ash to develop geopolymer based cold-pressed block

• Sugarcane bagasse ash (BA) is used as precursor to develop geopolymer brick. • Reactivity of BA was assessed, and its semi-dry paste was thermo-chemcio-mechanically activated. • Dune sand and river sand was used to further enhance the strength. • Good physico-mechanical relationships have been obtained and results are aligned with ASTM specifications. • FTIR analysis reconfirm the results and strengthen the discussion at molecular level. Sugarcane bagasse ash (SCBA) is an agricultural waste, and it is well recognized as pozzolanic material after calcination. However, it’s potential to be used as precursor in geopolymerization; in raw form, after calcination or chemical treatment, along with the cold pressing is not being investigated in depth. Therefore, this experimental work was designed in which initially, the reactivity of SCBA was assessed by a modified Chapelle test, TGA, and XRD analysis. And later a paste was formed by mixing FA with different dosage of SCBA (10–30 wt%) in an alkaline environment and then further activated mechanically. Afterwards dune sand, another industrially discarded material, was also mixed to formulate mortar and to get benefits of its natural fineness. For mechanical activation, 20 MPa molding pressure was applied and a reduction in strength was observed by increasing SCBA contents. Whereas an increase in strength was observed when calcined SCBA was used (thermo-mechanical activation). The 20 % SCBA has almost the same results under both activation modes and therefore this percentage was selected for mortar formulation and a further increase in strength (up to 73 %) was observed. The strength gain mechanism was discussed at the molecular level by conducting FTIR analysis. Among all techniques, the mechanical activation and incorporation of dune sand was found to be the best choice. Furthermore, the physico-mechanical relationship was established, and the developed block was compared with the fired clay brick. It was observed that developed block has a lower density (1600 kg/m 3 ), lower water absorption (less than 15 %), and more strength than the limit specified (10.7 MPa) by ASTM standards. Moreover, by incorporating sand the strength criterion (21.3 MPa) for severe weathering condition was also achieved.

Novel approach to synthesize clay-based geopolymer brick: Optimizing molding pressure and precursors’ proportioning

A novel approach has been proposed to synthesize clay-based geopolymer brick; series of experiments have been performed and three mandatory steps have been evolved. In Step-1, the reactivity of fly ash (FA) and clay was assessed through the modified Chapelle test. In Step-2, a semi-dry mixture of geopolymer paste was prepared and cylindrical specimens were formulated at molding pressures from 0 to 60 MPa at intervals of 10 MPa. And in Step-3, FA and clay contents were varied from 25 to 75% to form geopolymer paste, and specimens were prepared at two molding pressures (20 and 40 MPa), which is based on the results of Step-2. Physico-mechanical performance of specimens, cast in Step-2 and Step-3, was evaluated, and compared, and the rate of geopolymerization and microstructure was assessed through FTIR and SEM analysis, respectively. From the results, it was revealed that both precursors, clay and FA, were reactive, and molding pressure increases the wettability of both materials and resulted in an increase in compressive strength and density, and a decrease in porosity and water absorption. The amount of clay is attribute to the strength gain at high molding pressure due to its crystallinity load-bearing capacity and chemical surface compatibility with cementing properties of reactive mass. The strength gain mechanism was discussed at the micro-level as well as the molecular level. Finally, the proposed approach was validated by synthesizing the brick at the pilot scale. The physico-mechanical properties of brick were compared with the codes and cylindrical specimens, a close correspondence was observed between them, and also fulfil the criteria mentioned in standards.

Characterization of the Omni-Processor Sewage Sludge Ash for Reuse as Construction Material

Omni Processors (OP) are machines which use sludge as a fuel to generate electricity and clean water, but create ash at the same time. In the present study, fly ash and bottom ash are investigated as materials for potential reuse in the construction field. First, the granular size, density and Blaine finesse are determined. Then, the chemical composition and microstructure are obtained by means of X-ray fluorescence and Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), respectively. Finally, ashes reactivity is determined by two chemical methods (modified Chapelle test, bound water content R3) and a mechanical method (pozzolanic activity index). The characterization results indicate two material types: fly ash similar to cement and bottom ash similar to fine sand. That’s why the mortars mechanical strength with fly ash 0%-30% is better than that with bottom ash at the same rate. Fly ash slightly decreases the mechanical strength of mortars while bottom ash induces a much more significant decrease.

Comminution: A Supplementation for Pozzolanic Adaptation of Sugarcane Bagasse Ash

Sugarcane bagasse ash (SCBA) has commendable potential as pozzolanic material on account of silica as an attractive oxide composition; however, the coarser size of SCBA fractions hinders the fullest potential. In this regard, the choice of the comminution process is inevitable. In the present investigation, three sugarcane bagasse ash samples with a variable loss on ignition (less than 20%), but in compliance with the oxide composition requirement of ASTM C618, were selected to assess the effect of grinding on the particle size of SCBA and, in turn, the pozzolanic reactivity of ground SCBA. Four different methods of pozzolanic reactivity were adopted to evaluate the suitable characteristics of SCBA, enhancing the pozzolanicity. The results of the pozzolanic reactivity of ground SCBA showed that a particle size (D50) lower than 35 μm and particles below 45 μm higher than 60% was a desirable level of grinding in attaining the minimum strength activity index (SAI) (75%). The provided amorphous silica was more than 25%, and oxide composition conformed to ASTM C618. Assessment of the pozzolanic reactivity of SCBA through simple and feasible techniques like the Frattini test and the modified Chapelle test with SAI appears reassuring. The attainment of the suggested level of particle sizes for SCBA through comminution indicates it is a viable method for developing pozzolanic reactivity.

Use of clay from a local source for calcination and subsequent preparation of the mixed cement

This paper deals with the use of calcinated clay and micronized limestone as supplementary cementitious materials (SMCs) for preparation of blended Portland cement CEM II/B-M (Q-LL). Clay used in this study was calcinated at 700°C and pozzolanic activity after calcination was assessed using accelerated R3 pozzolanic test and modified Chapelle test. The influence of calcinated clay and limestone addition on mechanical properties and hydration process was investigated and an optimal ratio for 35% clinker replacement was found. Initial decrease of mechanical strength at early ages, caused by SCM addition, was almost compensated during maturation of the binder.

Investigation of particle characteristics and enhancing the pozzolanic activity of diatomite by grinding

This study aimed to assess the influence of grinding on improving the pozzolanic activity of a low porosity diatomite. To that end, three diatomites were produced, with 50% passing particle sizes (D50) between 7 and 40 μm, and characterized based on oxide composition, loss on ignition, X-ray diffraction (XRD), particle size distribution, and gas adsorption (specific surface area and porosity). Pozzolanic activity was assessed by electrical conductivity, modified Chapelle test, mechanical testing of lime-based mortar at 7 days, and performance index with Portland cement at 28 days. Additionally, portlandite (CH) consumption by diatomite was monitored up to 91 days of hydration by XRD-Rietveld refinement measurements in CH-diatomite pastes combined with controlled calcination at 900 °C. The grinding procedure ensured effective particle size reduction and produced an ultrafine diatomite (D50 below 10 μm) with low energy consumption. The decline in particle size caused an increase in the specific surface area (SSA) of diatomite without significantly changing pore volume and size. The larger SSA raised the silica solubility and pozzolanic activity of diatomite, altering its classification in terms of pozzolanicity. As evidenced by hydration analysis, the increased reactivity and change in pozzolanicity was due to the rise in CH consumption as the SSA of the diatomite increased.

Production and characterization of high-reactivity metakaolins calcined in flash reactor

In this study, we used a flash reactor heated with electrical resistance to produce metakaolins (MKs) from high-purity kaolin. The study aimed to determine the effect of calcination temperature and kaolin influx on the properties of MKs, used as supplementary cementitious material (SCM). We characterized the kaolin starting material through X-ray diffraction (XRD), X-ray fluorescence, particle size distribution, and thermal analysis. The temperature range for complete MK formation was determined through a kinetic study using thermal analysis at different heating rates. Subsequently, the six MK specimens synthesized as above were characterized using the same techniques as for kaolin, whereas the amorphous phase was quantified by the Rietveld method. The pozzolanic characteristics were investigated by (i) testing the pozzolanic activity index using lime and Portland cement at seven days, and (ii) conducting the modified Chapelle test based on Brazilian standards. The results showed that four of the six MK samples obtained were at least 90% amorphous, indicating that the calcination method was efficient. Moreover, their pozzolanic activity was almost twice that required by the Brazilian standard. Finally, a correlation between the mass loss and the degree of amorphism of flash MK samples was established in this study.

Utilization of a novel artificial intelligence technique (ANFIS) to predict the compressive strength of fly ash-based geopolymer

Fly ash (FA) is widely used to synthesize geopolymers, but it is heterogeneous as it consists of reactive, partially reactive, and inert parts, which may influence the behavior of the resultant geopolymer. Therefore, in this experimental and analytical work, at first, the reactivity of the FA was assessed by modified Chapelle test, which was further investigated by conducting a dissolution test to study the influence of temperature (20, 60, and 100 °C) and time (6 – 24 h). Afterward, geopolymer paste was synthesized by varying: (i) alkaline to precursor ratio (0.3 – 0.5), (ii) sodium silicate to sodium hydroxide ratio (2 – 3), and (iii) curing temperature and age. Based on the additional parameter of the molarity of NaOH including the above-mentioned parameters, an adaptive neuro-fuzzy inference system (ANFIS) to predict the compressive strength was optimized. A prominent increase in reactivity was observed at 60 °C as compared to 20 °C. The compressive strength improved significantly at A/P ratio of 0.4 and 0.5 resulted in improved compressive strength in particular for the 2.5 SS/SH ratio which was verified by FTIR. Analytical results by ANFIS were compared with the multivariate adaptive regression spline (MARS) model in terms of R2, RMSE, and MAE it was concluded that the ANFIS model showed better correlation and significantly fewer errors as compared to the MARS model. Finally, the developed model was checked and validated by employing the real experiment test results based on parametric values obtained from the ANFIS model. The developed model of this study can provide a novel approach for the design of geopolymers based on artificial intelligence technique.

Evaluation of the use of silica-alumina refractory waste as a supplementary cementitious material

The use of supplementary cementitious materials (SMCs) is one of the three essential factors for the sustainability of the cement industry. To reduce CO2 emissions, several studies have introduced new methods for the utilization of industrial wastes such as the addition into cementitious materials. The objectives of this study were to chemically and physically characterize refractory ceramic industry waste and determine its viability as an SMC. The pozzolanic characteristics or SMC characteristics of the refractory waste were investigated using standard tests. The results revealed that the refractory waste was mainly composed of Al2O3 and SiO2. The mineralogical analysis revealed that the mullite was the major phase of the waste, followed by small amounts of cristobalite and quartz phases. The results of the modified Chapelle test and pozzolanic activity index with lime after 7 days indicated that the waste did not meet the minimum pozzolanicity required by the standard. However, the waste improved the mechanical resistance of the cement specimens containing the waste after 28 days compared with the reference sample, indicating the promising potential of the material for this application. This result indicated that the refractory waste shows a filler type effect, and thus, can be employed as an SCM.

Development of a framework for the selection of best sugarcane bagasse ash from different sources for use in the cement-based system: A rapid and reliable path

A systematic study on characteristics and pozzolanic reactivity was conducted on as-received/raw (untreated) sugarcane bagasse ash (SCBA) samples collected from 30 different sugar industries spreading over an area of 78,226 km2. The pozzolanic reactivity of these SCBA samples was assessed through six different methods viz. strength activity index (SAI), modified Chapelle test (MCT), Frattini test, saturated lime test, electrical conductivity test and thermo-gravimetric analysis. It is evident from the results that SCBA has the ability to be pozzolanic on account of amorphous silica in a raw state. However, the coarser particles, loss of ignition (LOI), and porous nature of SCBA are the bottlenecks towards the strength development of SCBA blended cement mortars. The pozzolanic reactivity dominating parameters like AFS (Al2O3 (A) + Fe2O3 (F) + SiO2 (S)) content (greater than 70%), LOI (<20%), and amorphous silica (>25%) need to be predominantly observed during the selection of desirable SCBA sample for the cement-based system. The use of the modified Chapelle test with the strength activity index for assessment of the pozzolanic reactivity and selection of desirable SCBA samples seems to be decisive, based on the comparison of pozzolanic reactivity test methods. Finally, a simple protocol for the selection of the best sample of SCBA from different sources for its use in the cement-based products through rapid and reliable way is suggested.

Production of sustainable green mortar by ultrahigh utilization of fly ash: Technical, economic and environmental assessment

Fly ash (FA) utilization in mortar/concrete as partial replacement of cement is commonly around 30 wt% and globally most of the FA is disposed of in landfills which possess environmental burden. The aim of this experimental work is to present a cost effective and practical solution for potential ultra-high-volume utilization of FA for synthesis of three types of mortar as specified in ASTM C1329. At first, the pozzolanic activity of FA was evaluated through modified Chapelle test, thermogravimetric analysis and strength activity index. Then mortar was prepared by replacing cement with FA up to 100% and the targeted compressive strengths were obtained through cementing and by alkali activation (geopolymerization). Different parameters such as; molarity of alkaline activators, liquid to solid ratio and sodium silicate to sodium hydroxide ratio, that influence the properties of geopolymer mortar were also studied. Tensile strength test and interfacial split tensile strength test was also conducted to evaluate its compatibility with conventional concrete. Characterization of all types of mortar was carried out by the Fourier-transform infrared spectroscopy analysis and verified the geopolymerization as well as their mechanical performance. Finally, comparative analysis was carried out in terms of sustainability, evaluation of technical-economic-environmental indicators. It was concluded that formulation of green geopolymer mortar is the sustainable solution, having better mechanical strength, least CO2 footprints and economical. Results revealed that 60% FA replacement is possible through cementing while for higher replacement levels, alkaline activation was needed to reach the targeted strength.

Pozzolanic activity quantification of hollow glass microspheres

Hollow glass microspheres (HGMS) have been widely used in the hydrocarbon industry for cementing wells with low-density slurries. These consist of amorphous siliceous hollow spheres filled with gas, providing a low-density material with high compressive strength. The present study aims to characterize the interaction between HGMS and the cement paste, focusing mainly on the development of the pozzolanic activity, given the nature of amorphous silica. Thus, two HGMS of different crush strength were studied. HGMS were used as a replacement of total cementitious binder at 10% by weight of cement. The pozzolanic activity was measured with the modified Chapelle test, the portlandite quantification with thermogravimetric analysis, and the strength activity index comparing the compressive strength of hardened cement paste samples. Additionally, isothermal calorimetry analysis, X-ray diffraction patterns and scanning electron microscopy images were obtained. Results demonstrated that HGMS interact with the cement paste initially as nucleation agents and later with a pozzolanic reaction, presenting an activity comparable to that of metakaolin or fly ash.

Development of newer composite cement through mechano-chemical activation of steel slag

The aim of present paper is to develop a composite cementitious binder by improving reactivity of Linz Donawitz (LD) slag through mechano-chemical activation. The pozzolanic reactivity of LD slag has been significantly improved as corroborated through modified Chapelle test and slag activity index. The mechanical grinding is carried out with ball milling of LD slag for 20 min followed by chemical activation with four different types of chemical activators namely sodium silicate, sodium sulphate, sodium hydroxide and sodium carbonate. The physico-chemical and strength properties were studied to quantify the efficacy of different alkali activators with 70% of ordinary Portland cement and 30% of ball milled LD slag blend. The sodium silicate and sodium sulphate alkali activators were found effective to enhance the reactivity, which led to increased compressive strength of developed cementitious binder paste cubes as compared to control paste cubes. XRD and Rietveld method results also exhibited the development of more calcium silicate hydrates (CSH) in activated binders, which corroborates increased compressive strength. The normalized heat flow and normalized heat were also found better for both these hydrated blend pastes in comparison to the other blends. The SEM analysis observed more hydration products morphology in blend pastes activated with sodium silicate and sodium sulphate. Based on outcome of different analytical techniques, it was observed that ball milling for 20 min and chemical activation with sodium silicate or sodium sulphate can be applied to enhance the reactivity of LD slag to develop a sustainable composite cement.

The use of iron ore tailings obtained from the Germano dam in the production of a sustainable concrete

The present work aims to identify the influence of the incorporation of iron ore tailings (IOT) obtained from the Germano dam in Brazil in substitution of sand fractions in concrete. The IOT was characterized through particle size distribution, specific weight, and mineralogical composition using x-ray diffraction (XRD). Moreover, a possible reactivity of IOT with Portland cement was investigated using thermogravimetrical analysis, the modified Chapelle test, XRD and by uniaxial compressive tests. It was observed that the used IOT has no pozzolanic activity for the studied particle size distribution. Sustainable concretes were developed using IOT fractions as natural sand replacement in 10, 20 and 30% by weight and characterized by compressive tests and a comprehensive pore size distribution analysis through micro computed tomography. The IOT inclusion resulted in a decrease of the pore sizes leading to an increase in the compressive strength of all studied concretes. Nevertheless, for high amounts of IOT incorporation the concrete workability is reduced due to its high surface area.

Investigation of cementitious properties of different constituents in municipal solid waste incineration bottom ash as supplementary cementitious materials

To investigate the municipal solid waste (MSW) incineration bottom ash (IBA) as a value-added building material, this study focuses on evaluating different IBA constituents (such as glass, ceramic, mineral, slag-I with low-ferrous sintered phase and slag-II with high ferrous sintered phase) to be used as supplementary cementitious materials (SCMs) and then comparing to commercial SCMs (ground-granulated blast-furnace slag-GGBS and fly ash-FA). The investigated IBA constituents were milled into powder and then used as SCMs to partially replace cement in mortars. Their influences on cement hydration were evaluated by an isothermal calorimeter and the pozzolanic activities were assessed through the modified Chapelle test. The strength development of the mortars was studied to quantify their contributions as SCMs when compared to that of GGBS and FA. The microstructure of the hydrated mortar with IBA constituents was further evaluated. The experimental results showed that, at an early age of the IBA blended cement hydration, the powdered IBA constituents contributed to an increase in heat release, which was higher than that of FA and lower than that of GGBS; and the formation of monosulphate was accelerated. After 90 days’ curing, the powdered glass and ceramic fractions derived from IBA contributed significantly to the mortar strength compared to other constituents, indicating their relatively high reactivity that was confirmed by their high consumption of portlandite in the modified Chapelle test. The samples prepared with glass and ceramic powders derived from IBA had a relatively higher efficiency strength index (ESIt,FA/GGBS) than other IBA constituents, indicating their higher potential to be used as SCM alternatives. Therefore, it is suggested that the ground ceramic and glass fractions separated from IBA can be used as SCM alternatives, which can achieve over 80% and over 93% ESI of that of FA and GGBS, respectively. Furthermore, the other fractions of IBA, namely the coarse IBA and IBA-minerals can only be used as fillers.

Sustainable cement with Al-anodizing waste: Evaluating reactivity and feasibility as a shrinkage-compensating admixture

The Al-anodizing waste (AAW) is generated in large amounts from the aluminum anodizing process and is often discarded in landfills. This work proposes a novel and economic recycling route for Al-anodizing waste (AAW) as a shrinkage-compensating admixture (SCA) for Portland cement matrices. The usage of SCA has been shown as an effective way to combat the excessive shrinkage of concrete, which can result in cracking. Most of the commercial admixtures are based on the formation of additional ettringite, inducing expansion in concretes and compensating the later shrinkage. Since commercially available admixtures are relatively expensive, we aim to produce a low-cost and eco-friendly SCA by using AAW. Interactions between waste and cement were extensively investigated in aqueous suspensions by electrical conductivity, mass spectroscopy and modified Chapelle test and in cement pastes by thermogravimetry, isothermal conduction calorimetry, X-ray diffraction, and scanning electron microscopy. Results revealed a strong reactivity between waste and hydrated cement evidencing the consumption of calcium and sulfate and the formation of numerous nuclei of nanocrystals of ettringite. Preliminary shrinkage/expansion tests confirmed the feasibility of using the AAW for such application.

Determination of the physical and mechanical properties of wood-cement boards produced with Pinus spp and pozzolans waste

The objective of this research was to evaluate the physical-mechanical properties of wood-cement boards produced with waste particles of Pinus spp. and sufficient levels of pozzolans to assimilate all Ca(OH)2 pro-duced during the hydration reactions of Portland cement. The pozzolans used were: silica fume, metakaolin, rice husk ash, and calcined ceramic waste. The values of the pozzolans were determined based on the theo-retical determination of the Ca(OH)2 content produced by the hydration reactions of Portland cement. The pozzolanic activity index was determined by the modified Chapelle test. The boards were produced through cold compression, and the test specimens were produced and tested for physical and mechanical properties at 28/91 days of curing. The minimum values employed in the Bison® commercial process were used as a reference for the physical-mechanical characterization. The boards produced presented good physical-me-chanical properties even with high levels of replacement of cement by pozzolans. These properties were sim-ilar to the ones presented by the reference boards, despite the significant reduction in the specific mass of the prototype boards, which demonstrates the technological possibility of the use of these materials in the produc-tion of wood-cement boards