Pozzolanic Activity Research Articles

STUDY OF THE PROPERTIES OF MODIFIED BINDER OBTAINED ON THE BASIS OF BENEFICIATION WASTE OF THE MINING AND PROCESSING PLANT

The introduction of active mineral additives into cement makes it possible to obtain concrete with high physical, mechanical and operational characteristics, namely, they increase the density, water resistance, frost, sulfate, alkali resistance and salt resistance of concretes and mortars, while reducing the consumption of clinker cement. The scale of construction of facilities using cement concrete is growing every year, which raises the question of reducing the consumption of clinker cement, due to the high energy intensity of production using active mineral additives. The use of active mineral additives in the form of waste from enrichment has high economic and environmental significance. The article examines the ways of using waste tailings of polymetallic ore enrichment in cement as a complex modified binder with an active mineral additive. To select the optimal ratio of silica and Balkhash GOK enrichment waste, their pozzolan activity was determined, which is 3.8-4 times higher for silica than for BGOK waste. The pozzolan activity of Balkhash GOK enrichment waste 16 hours after mixing with lime solution is 24 mg/g, and microsilicon is 114 mg/g. The pozzolan activity of a complex mineral additive for cements consisting of 60% of Balkhash GOK enrichment waste and 40% of microsilicon is 48 mg/g. The introduction of 40% silica into the Balkhash GOK enrichment waste increases the pozzolan activity of the complex additive by 2 times. This made it possible to obtain a modified binder using a complex mineral additive of up to 20%.

Evaluating the durability performance of concrete containing clastic sand and GGBS

The manufacturing process of materials utilized in concrete production has environmental implications. The production of cement releases significant amounts of greenhouse gases, while the extraction of aggregates and sand poses challenges to the natural environment. To minimize the aforementioned challenges researchers are suggested to utilize industrial by-products as a partial alternative for these materials Fly ash, stone dust, GGBS, silica fume, and metakaolin are widely utilized alternatives to construction materials. The specific use of clastic sand as a partial substitute for fine aggregate has recently gained popularity . However, studies on the characteristics of concrete prepared using cementitious materials and clastic sand are very few. In this work, the effect of clastic sand with ground granulated blast furnace slag concrete is being investigated. The GGBS is added in place of cement from 0% to 45%. Further, clastic sand is added in different proportions in GGBS concrete. The electrical resistivity, water absorption, acid attack, and micro-structural studies are carried out on all mixes to know the durability properties. The results confirm that the addition of GGBS as a cementitious material enhances durability. The inclusion of 35% of GGBS as a substitute for cement is optimum for enhancing durability. Further, the inclusion of 35% GGBS as a cement substitute and 20% clastic sand shows a dense matrix and optimum results in enhancing durability. This is due to the pozzolanic activity of GGBS and clastic sand works as filler materials. This investigation suggests utilizing clastic sand along with GGBS as a cementitious material.

Combining thermodynamic modeling and experiments to characterize the effect of ceramic polishing powder in cement-based materials

Ceramic polishing powder (CPP), a by-product of ceramic tile production, has the potential to prepare building materials. While the hydration and thermodynamic properties of CPP remain largely unexplored, thereby limiting its widespread application. This study utilized R3 tests to demonstrate that CPP exhibits pozzolanic activity comparable to that of fly ash. Then it analyzed the effects of substituting 10–20 % of cement with CPP on the hydration products, microstructure, and mechanical properties of composite materials, utilizing a synergistic approach that combines thermodynamic simulations with experimental investigations. The findings showed that adding CPP does not generate new crystalline products but enhances the formation of C-S-H through the pozzolanic reaction, which consumes calcium hydroxide. However, adding over 25 % CPP significantly lowered the pH of the pore solution, altering hydration products and causing volume contraction. In addition, CPP improved the microstructure at later ages, particularly by increasing micropores, leading to enhanced mechanical properties at 28 and 90 days. For instance, at a w/b ratio of 0.5, the 90 days compressive strengths of composite mortars CPP10, CPP15, and CPP20 were recorded at 67.0 MPa, 63.3 MPa, and 65.1 MPa, respectively. These values represented increases of 17.3 %, 10.9 %, and 14.0 % over the control group (57.1 MPa). Conversely, this also resulted in increased autogenous shrinkage due to higher capillary pressure. Notably, the 6 days shrinkage of CPP15 and CPP20 was about 50 % higher compared to that of the pure cement mortar. These findings highlight the necessity of balancing CPP content for optimal performance.

Influence of processing methods on the strength activity index for sludge as a supplementary cementitious material

Utilizing activated sludge as a partial substitute for cement can both curb cement consumption and address sludge reuse in an economically and environmentally-friendly manner. This study delves into the pozzolanic activity of mechanically-thermal (MT) activated sludge and alkali-mechanical-thermal (AMT) activated sludge, employing the strength activity index (SAI) method. Microscopic insights provided by X-ray diffraction (XRD), scanning electron microscopy (SEM), and laser particle size analysis aid in the interpretation of observed phenomena. The findings underscore the superiority of MT activation over AMT activation, with an SAI of 97 %. Optimal pozzolanic activity is achieved through a 2-hours holding time, slow heating at 10 °C/min, and rapid cooling. A calcination temperature of 800 °C effectively promotes the decomposition of active minerals and enhances the sludge's pozzolanic activity. Additionally, a ball milling time of 2 minutes proves sufficient to meet practical demands, as prolonged ball milling has a limited impact on sludge pozzolanic activity.

Environmental and technical assessment on the application of slate waste in Portland-composite cement CEM II

Large volumes of waste are generated from the manufacture of slabs, roofing, and tiles using slate stone. The use of waste in the construction industry is prevalent due to the environmental advantages associated with the implementation of circular economy standards. This paper examines the production of Portland cement CEM II using heat-treated slate waste. The fineness index results were 10.95 % for the 75-μm sieve and 23.53 % for the 45-μm sieve. Assessment of reactivity using mechanical methods showed that mortars produced with 20 % slate waste (SW) achieved a strength of 42.35 MPa and a mechanical index of 84.93 %. Direct measurement (FTIR), along with chemical methods (Frattini Test and Saturated lime test), confirm the pozzolanic activity of the slate waste. The environmental impact assessment demonstrated a reduction in the carbon dioxide emission rate by 21.49 % (6.54E+02 kgCO2-eq/t) with the use of Portland cement CEM II/CSW. The valorization of slate waste can contribute to the availability of an alternative source of raw material and the reduction of natural resource consumption. However, further studies on mechanical performance and durability are necessary for this waste to be applied in structural cementitious matrices.

Analysis of wood fly ash as a sustainable alternative to cement replacement in concrete

Supplementary cementitious materials (SCMs) can contribute to reducing the carbon dioxide footprint of concrete. One of these SCMs is biomass fly ash (BFA), which is waste from wood production. Although different researchers have used BFA as SCM, it is fundamental to know the behaviour of concrete with local materials (including available BFAs) to reduce the environmental impact of transportation. In particular, the Biobío region produces 57% of Chilean wood, concentrated in Eucalyptus globulus and Pinus radiata production. This paper describes the behaviour of concrete mixtures with replacements of eucalyptus BFA (BFAE) or pine BFA (BFAP) at 0, 10 and 20% by weight of cement. Workability, compressive and flexural tests were performed, and the specimens were examined using scanning electron microscopy as well. The results showed that BFAE reduced the slump of fresh concrete and BFAP increased it in all cases due to their morphology. An increase in resistance at later ages was evident due to an increase in pozzolanic activity and an improvement in BFA morphology. The results indicate that BFAE and BFAP are suitable for replacing at least 10% of cement, because those mixes present similar, and even higher, compressive and flexural strengths than the control mix.

Utilization of municipal solid waste incinerator fly ash under high temperature sintering and alkali excitation for use in cementitious material

It is crucial to have a secure and dependable approach to treat and reuse municipal solid waste incinerator (MSWI) fly ash to prevent potential hazards. High temperature sintering is regarded as an efficient method for solidifying heavy metals, and alkali excitation provides a practicable solution for utilizing MSWI fly ash. In this work, the activation mechanism of MSWI fly ash was figured out under high temperature sintering. Besides, the preparation and optimization of sintered MSWI fly ash with metakaolin for use in alkali–activated cementitious material were explored based on Box–Benhnken design (BBD), considering different modulus and alkali equivalent of alkaline activator, as well as different contents of sintered MSWI fly ash and metakaolin. The mechanical performance and alkali excitation mechanism of the cementitious material were investigated. The results showed that the pozzolanic activity of MSWI fly ash treated by high temperature sintering was increased by 81.7 %, which further was improved by alkali excitation. The optimal mix proportion of alkali–activated sintered MSWI fly ash–metakaolin cement mortar consisted of a modulus of 1.332, an alkali equivalent of 1 %, a sintered MSWI fly ash content of 20 %, and a metakaolin content of 10.5 %, whose flexural and compressive strength were 8.5 and 57.3 MPa, respectively. Moreover, SiO32− and OH− in alkaline activator and Al(OH)4–, SiO2(OH)22−, and SiO(OH)32− in metakaolin promoted Ca2+ in sintered MSWI fly ash to generate C–S–H and C–A–S–H. Finally, the alkali–activated mortar made from sintered MSWI fly ash demonstrated high safety and eco–friendliness, with a synthesis toxicity index (STI) of 25.59.

Study on preparing sustainable limestone calcined clay cement (LC3) through CO2-active treatment of municipal solid waste incineration fly ash (IFA)

Municipal solid waste incineration fly ash (IFA) is theoretically more suitable for forming a composite cementitious system with cement and calcined clay compared to inert limestone due to its pozzolanic activity. In addition, IFA contains high levels of alkaline calcium compounds that have the potential for carbonation. The study examined the improvement of CaCO3 content within IFA facilitated by CO2-active (CIFA), replacing limestone in limestone calcined clay cement (LC3), and creating sustainable cementitious materials. The hydration behavior, heavy metal morphologies and mechanical properties of (C)FC3 were studied. The research indicates that introducing IFA adversely affects the initial hydration process of the system, but this inhibition is alleviated by using CIFA. This is facilitated by the reduction in sulfate dissolution rate attributed to the formation of carbonate shells. The incorporation of IFA into the system leads to the effective utilization of Ca(OH)2, thereby enhancing the pozzolanic reaction of the calcined clay. Consequently, (C)FC3 show higher compressive strength than LC3 at 56 d, with L15, F15 and CF15 achieving 29.9 MPa, 39.6 MPa and 46.8 MPa, respectively. While there is an increase in the exchangeable and acid-soluble states in CFC3, the elevation of oxidizable and residual states contributes to a reduced potential for total leaching in harsh environments. The excellent mechanical properties and environmental stability confirm the feasibility of using (C)IFA for LC3.

Preparation and properties of porous rice husk ash for internal curing of high performance cement pastes

To address the challenges posed by significant autogenous shrinkage in high-performance concrete and mitigate the adverse effects of conventional internal curing materials on its mechanical properties, this study explored the potential use of rice husk ash (RHA) as internal curing materials. The research investigated the impact of combustion regime (combustion temperature and dwelling time) and the milling process on the microstructure and physical-chemical properties of RHA. Moreover, the effect of RHA on autogenous shrinkage, compressive strength, and microstructure in cement pastes were also reported. Experimental results demonstrated that the combustion regime and milling time could significantly affect the pore structure, particle size and pozzolanic activity of RHA. RHA had good potential for internal curing when it was burned at 600°C for 1 h and milled for 15–30 min. RHA released the entrained water after 12 h to slow down the depletion of free water, and thus inhibited the development of self-drying and autogenous shrinkage. The 168 h shrinkage was reduced by 56.8 %, 62 %, and 51.8 %, respectively when the milling time increased to 30 min. Moreover, the addition of RHA with a smaller particle size could refine the microstructure of matrix and enhance the compressive strength due to its higher pozzolanic activity. These findings suggest promising applications for RHA as an effective internal curing material in high-performance cementitious materials.

Pozzolanic activity of secondary aluminum ash sintered and ground fine powder in Portland cement

To better facilitate the resource utilization of secondary aluminum ash and reduce the consumption of Portland cement, this study investigates the pozzolanic activity grinding fine powder of secondary aluminum ash sintered and ground fine powder (MP) in a Portland cement matrix with different fineness and content. The mechanism of volcanic ash activity was explored using microscopic testing techniques such as XRD, FTIR, TG, SEM, and MIP. The outcomes revealed that as the MP content increased, the fluidity of the cement-based matrix exhibited a declining trend. The addition of MP has a diluting effect on Portland cement, resulting in a decreasing trend of strength activity index with the increase of MP content. Furthermore, under identical content conditions, much finer MP showed a reduction in its pozzolanic activity within the Portland cement-based matrix. Hydration processes and microscopic tests indicated that the addition of the coarser MP particle resulted in higher pozzolanic activity, which is attributed to the faster hydration rate, lower porosity, and higher microstructural compactness. Simultaneously, with an increase in MP content, the porosity and detrimental pore content of the cement-based matrix notably increased, and the content of hydration products reduced.

Physical-chemical characterization of construction and demolition waste powder with thermomechanical activation for use as supplementary cementitious material

Cement production is responsible for large anthropogenic CO2 emissions into the atmosphere, partly through the decarbonization of limestone rock. Reducing the clinker/cement ratio is a viable alternative to reducing the environmental impact of construction. To achieve this, the continued exploration of additional cementitious materials is necessary. With adequate particle size and chemical composition, construction and demolition waste powder (CDWP) can be used as supplementary cementitious material (SCM). In this sense, the present work aims to evaluate the CDWP physical-chemical characteristics when subjected to thermomechanical treatment (calcination and milling), aiming for application as SCM. The powders (fraction smaller than 150 µm) were subjected to different calcination temperatures (600, 700, 800, and 900°C) without milling and milled for 5 hours. The physicochemical characterization was carried out using laser granulometry, X-ray diffraction (XRD), thermogravimetry (TG), X-ray fluorescence (XRF), BET, scanning electron microscopy (SEM), specific mass, pozzolanic activity index (PAI) and Portlandite consumption. The results indicate that thermomechanical activation made it possible to obtain a powder with physical-chemical characteristics of interest for application as SCM. The amount of Si2O, Fe2O3, and Al2O3 is greater than 70 %, making them suitable. Calcination from 700°C presents a loss of ignition of less than 6 %, meeting regulatory requirements for pozzolanic materials. Milled for 5 hours leads to a 75 % reduction in particle mean diameter. With the combination of thermal and mechanical treatments, a PAI of 97 % was obtained, and a decrease in the quantity of Portlandite of 12 %. Analysis of variance (ANOVA) indicated a significant influence of thermal and mechanical treatment on the compressive strength of mortars. Based on the data found, it can be stated that CDWP has the potential to be used as an SCM, decreasing CO2 emissions from the cement industry and contributing to the circular economy of the construction sector.

The phase changes of the mortars containing waste glass powder during carbonation

The utilization of glass powder (GP) with high pozzolanic activity to replace cement is a promising option for reusing waste glass. In such systems, Carbonation is a key factor that affects the durability. However, carbonation mechanisms remain poorly understood. In this study, the phase evolution of the GP - cement composites exposed to CO2 was determined by accelerated carbonation tests of samples with different cement-to-GP substitution rates (0, 15, 30, and 50 wt%). The carbonation depth was determined using phenolphthalein spray tests. Furthermore, the chemical information regarding the carbonation profiles was obtained by the X-ray diffraction (XRD), thermogravimetric analysis (TG), and Fourier transform infrared spectroscopy (FT-IR). It was found that an increase in the GP content increased the carbonation depth of the samples because of the low calcium hydroxide (CH) content. The increase rate was more similar to those of fly ash (FA) and silica fume (SF) rather than that of Ca-rich granulated blast-furnace slag (GBS). Moreover, XRD and TG tests revealed that compared to the plain cement, GP addition influenced crystalline forms of CaCO3, as well as the quantity of produced CaCO3. Combined with the FT-IR test results, when the replacement level of the GP up to ≥30 wt%, the produced CaCO3 and the depolymerised C-S-H by the carbonation significantly differed from the pure Portland cement. This study offers insights into the carbonation mechanisms of GP – cement mortars to promote glass recycling.

Study on Sugarcane Bagasse Biochar in Concrete for Carbon Sequestration

Abstract: Embodied carbon from manufacturing of cement is increasing day by day as constructions are happening everywhere so the consumption of cement is increasing by default. In next decade there are much more constructions are going to takes place that will lead to Increase in GHG’s emissions from cement manufacturing. It is supposed to be a threat to climate . To reduce this increase in embodied carbon there is need to reduce cement consumption by partially replacing cement with other suitable options. biochar which is a by-product of pyrolysis of biomass and is effective in carbon sequestration activity and results in high water and carbon dioxide holding capacity. In this study Sugarcane bagasse biochar is used in concrete and mortar as partial replacement of cement for carbon sequestration. Strength characteristics of materials are supposed to be interlinked with pozzolanic activity hence pretreatment is done with 0.1 N HCl to enhance pozzolanic property activity of biochar. This pozzolanic activity is calculated by considering Ca(OH)2 fixation during the titration in chapelle test. From the study results its is observed that pretreatment with 0.1 N HCl at room temperature is sufficient to increase the pozzolanic activity of biochar also this Sugarcane bagasse biochar is observed to be sequestering carbon dioxide and it is increasing with increase in biochar. But compressive strength of concrete is decreasing with increase in sugarcane bagasse biochar. Hence it is not suitable to be used in construction work but can be used in plaster mortar where no much compressive strength is required . Sugarcane bagasse biochar can act as carbon sequestering media in concrete but it can’t be recommended in concrete or mortar for construction work.

Biochar Enriched Concrete for Carbon Sequestration

Abstract: In upcoming years , a lot of construction is going to happen leading to more cement consumption and more GHG’s emissions by default as an embodied carbon. Reduction of cement consumption is possible by partially repacing it with biochar which is a by-product of pyrolysis of biomass or adding it as an additive in cement mortar and concrete for carbon sequestration. Biochar is effective in carbon sequestration activity and results in high water and carbon dioxide holding capacity. Increase in biochar lead to increase in carbon sequestration . As pozzolanic activity lead to strength gaining characteristics and durability of concrete, this study focusses on investigating pozzolanic activity of biochar. Biomass considered in this study were walnut shells and pretreatment was done with 0.1 N HCl and and pozzolanic activity is checked by chapelle test by observing Ca(OH)2 fixation during the titration. It was observed that increase in temperature or Normality of HCl in pretreatment does not enhance pozzolanic activity of biochar . Hence pretreatment with 0.1 N HCl at room temperature for an hour is sufficient to enhance the pozzolanic activity of biochar with much high carbon dioxide sorption as compared to usual concrete without compromising with the strength of concrete. This study reclaims the potential use of biochar in concrete is reliable for carbon sequestration.

Analyzing the long-term effects of e-glass mortar on sustainability and radiation shielding using ANOVA.

Significant investigations were performed on the use and impact on physical properties along with mechanical strength of the recycled and reused e-glass waste powder. However, it has been modeled how recycled display e-waste glass may affect the characteristics and qualities of dune sand mortar. This study investigates the long-term feasibility of using recycled display e-glass waste as a partial substitute for dune sand at varying percentages (5%, 10%, 15%, and 20%). The main focus is on evaluating its effectiveness in radiation shielding, strength properties, and durability for long-term development under the heating environmental process. Statistical analyses, including analysis of variance, are used to assess the significance of factors and their interactions on these characteristics. Additionally, a regression equation derived from the model offers insights into the quantitative relationship between the factors and properties. The results of the experiments led to the conclusion that the most effective proportion of e-glass waste to include in mortar is 20%, with the weight of dune sand. Including e-glass waste, they significantly increased the five characteristics of the mortar, making it suitable for high-strength mortar applications continue up to 68MPa. The ANOVA model used in this study was trained using the same experimental research design and was critical in predicting the properties of the mortar. The model produced an accurate result with an R2 value greater than 0.99. E-glass replacements exhibit remarkable radiation shielding, characterized by pozzolanic activity and superior internal bonding due to its compact texture, contributing to enhanced long-term strength.

Pozzolanic activity of FCC catalyst waste slag (CWS) for cement and geopolymer production

Catalyst waste slag (CWS) is generated in large amounts when fabricating the catalyst required in the fluid cracking catalyst (FCC) process used for oil refining. Currently, CWS is landfilled. This paper characterizes the CWS and measures its pozzolanic activity. It determines whether the CWS can be used as partial Portland cement (PC) replacement for the first time in the literature. CWS is primarily composed of Al2O3 and CaO. It contains a negligible quantity of heavy metals that can be immobilised in a matrix. The raw CWS is totally amorphous and extremely reactive which results in flash set. Calcination is an effective method to control the reactivity of CWS. Reactivity increased when CWS was calcined between 300 and 600 °C and it peaked at 500 °C, but this caused flash set. Calcination at 800 °C lowers reactivity (as the highly disordered aluminium phases achieve a greater order) which allows for proper handling. Temperatures over 800 °C caused partial crystallization significantly lowering reactivity.The 800°C-calcined CWS reached high mechanical index (6.25), comparable to other pozzolans such as fly ash and red mud, and greater than alum sludge. CWS combines lime profusely and develops more abundant cementing hydrates than similar pozzolans such as calcined alum sludge. The pozzolanic reaction of the 800°C-calcined CWS provides abundant cementing minerals including AFt and AFm phases, calcium aluminium carbonate hydrates and calcium aluminium hydrates.The high reactivity of CWS and its prolific production of cementing phases in pozzolanic reactions indicate that it can be used as a supplementary cementitious material in PC and lime systems; and that it can be used as a precursor to produce low-carbon and geopolymer cements. CWS constitutes a reactive aluminium source which, in a PC system, participates in hydration reactions and can enhance the properties of the resultant materials.

ПЕРСПЕКТИВЫ ИСПОЛЬЗОВАНИЯ ОТХОДОВ СТРОИТЕЛЬНОЙ КЕРАМИКИ ПРИ ПРОИЗВОДСТВЕ СТРОИТЕЛЬНЫХ МАТЕРИАЛОВ

The main technological aspects of the production of building ceramics are given. Based on the analysis of literary sources, a comprehensive assessment of the feasibility of using construction ceramic waste as a secondary raw material for the production of new building materials was carried out. Based on the research of modern scientists, it has been established that the waste from the scrap of building ceramics is suitable for use as an aggregate, partial replacement of cement and a reactive additive in concretes and mortars. When using scrap of con-struction ceramics as an aggregate, it is recommended to limit the substitution of natural aggregate at the level of 20-30%, together using various additives: plasticizing and improving rheotechnological and physico-mechanical properties of concrete. Finely ground waste from brick scrap has pozzolan activity and, when used as a reactive additive or partial replacement of cement in concretes and mortars, up to 20-25% can improve the structure of cement stone, increase strength, reduce macroporosity and penetration of chloride ions, and increase sul-fate resistance. This kind of binder is prone to a later set of strength compared to Portland cement. In addition, the waste of building ceramics can be used in the production of alkali-activated cements and slag-alkali binders, as well as s raw materials for the production of new bricks or the construction of road surface bases. It has been revealed that the production of building materials and products based on con-struction ceramics waste is a promising direction for the development of construction production. It is possible not only to obtain materials of equal quality to products based on natural raw materials, but also with improved characteristics.

Microstructural Assessment of Pozzolanic Activity of Ilmenite Mud Waste Compared to Fly Ash in Cement Composites.

This paper presents the influence of adding rinsed ilmenite mud waste (R-MUD) on the microstructure of Portland cement composites, compared to similar composites containing fly ash (FA). The aim of the study is the assessment of the pozzolanic activity of ilmenite mud waste by its impact on the microstructure of the cement matrix in comparison to the undoubted pozzolanic activity of fly ash. The presented test results include pore size distribution, phase composition, pozzolanic activity using thermal analysis, R3 bound water test, and microstructural analysis using scanning electron microscopy (SEM). Tests were performed on mortars cured for up to 360 days. The results presented in this paper have shown that R-MUD has a pozzolanic activity level similar to FA or better, which influences pore size distribution in the composite and its microstructure. During the curing process, the microstructure of composites containing R-MUD became more compact and sealed than those with FA, which might also increase their durability. The results of the R3 tests have proven the pozzolanic activity of R-MUD but its level was lower than FA. R-MUD might be a useful substitute for fly ash, especially given the lack of good-quality fly ash on the market.

Compressive Strength, Permeability, and Abrasion Resistance of Pervious Concrete Incorporating Recycled Aggregate

Extensive use of cement in the construction industry increases CO2 emissions and has a negative impact on the environment. In this work, recycled coarse aggregate (RCA) from construction and demolition wastes (C&DW) was used to fabricate sustainable pervious concrete (PC). In order to mitigate the environmental hazards of excess cement waste and to improve the engineering properties of PC, silica fume (SF) and ground granulated blast-furnace slag (GGBS) were added. The effects of SF and GGBS on the compressive strength, permeability coefficient, porosity, and abrasion resistance of recycled aggregate pervious concrete (RAPC) were investigated. The results show that the incorporation of GGBS and SF effectively improves the compressive strength of RAPC but reduces the permeability coefficient and porosity. Moreover, due to the filling effect and pozzolanic activity, the incorporation of GGBS and SF significantly enhances the abrasion resistance of RAPC. Furthermore, the relationships between the compressive strength, permeability coefficient, porosity, and abrasion resistance of RAPC are clarified. The optimum replacement is achieved when the SF content is 7%, and the GGBS content is 20%, respectively, which results in the highest compressive strength (28.9 MPa) and the lowest permeability coefficient (1.2 mm/s) at 28 days, and the lowest mass loss rate (12.1%) after the Cantabro abrasion test.

Determination of Fe3O4 Content and Total Nonhydraulic Minerals in Steel Slag

The nonhydraulic minerals (Fe3O4, RO phase, Fe) in slag are important indicators for evaluating the pozzolanic activity and detecting the quality of the slag activation processing technology. Fe3O4 is an important characteristic mineral among the nonhydraulic minerals. In order to accurately assess the pozzolanic activity of steel slag powder and to monitor the quality of the activation process of steel slag powder for separate nonhydraulic minerals, it is imperative to precisely determine the nonhydraulic mineral content within the steel slag. Further refinement and enhancement are required for both the HNO3 dissolution method used in determining Fe3O4 content in steel slag, as well as for the EDTA-DEA-TEA (ethylenediamine tetraacetate sodium-diethylamine-triethanolamine) dissolution method employed in determining total nonhydraulic minerals, due to potential deviations caused by challenging impurity separations. The results show that the content of Fe3O4 is determined by 10%HNO3-20%NaOH-chemical analysis method, which solves the problem that the impurities of refractory materials (quartz, corundum, mullite) and amorphous phase affects the content determination in HNO3 dissolution method. The total amount of nonhydraulic minerals (Fe3O4, RO phase, Fe) was determined by the EDTA-NaOH-TEA dissolution method, which solved the problem that the incomplete dissolution of C2F in the EDTA-DEA-TEA dissolution method affected the content determination. The maximum error between the content determination value and the theoretical calculation value of the two methods is less than 0.50%. The improved Fe3O4 and total nonhydraulic mineral quantification methods are feasible and reliable.