Binding Material Research Articles

Compressive strength of waste-derived cementitious composites using machine learning

Abstract Marble cement (MC) is a new binding material for concrete, and the strength assessment of the resulting materials is the subject of this investigation. MC was tested in combination with rice husk ash (RHA) and fly ash (FA) to uncover its full potential. Machine learning (ML) algorithms can help with the formulation of better MC-based concrete. ML models that could predict the compressive strength (CS) of MC-based concrete that contained FA and RHA were built. Gene expression programming (GEP) and multi-expression programming (MEP) were used to build these models. Additionally, models were evaluated by calculating R 2 values, carrying out statistical tests, creating Taylor’s diagram, and comparing theoretical and experimental readings. When comparing the MEP and GEP models, MEP yielded a slightly better-fitted model and better prediction performance (R 2 = 0.96, mean absolute error = 0.646, root mean square error = 0.900, and Nash–Sutcliffe efficiency = 0.960). According to the sensitivity analysis, the prediction of CS was most affected by curing age and MC content, then by FA and RHA contents. Incorporating waste materials such as marble powder, RHA, and FA into building materials can help reduce environmental impacts and encourage sustainable development.

The Influence of the Addition of Basalt Powder on the Properties of Foamed Geopolymers.

Geopolymers are binder materials that are produced by a chemical reaction between silica or aluminum compounds with an alkaline activating solution. Foamed geopolymer materials are increasingly being cited as a viable alternative to popular organic insulation materials. Since the foaming process of geopolymers is difficult to control, and any achievements in improving the performance of such materials are extremely beneficial, this paper presents the effect of the addition of basalt powder on the properties of foamed geopolymers. This paper presents the results of physicochemical studies of fly ash and basalt, as well as mechanical properties, thermal properties, and structure analysis of the finished foams. The scope of the tests included density tests, compressive strength tests, tests of the thermal conductivity coefficient using a plating apparatus, as well as microstructure tests through observations using light and scanning microscopy. Ground basalt was introduced in amounts ranging from 0 to 20% by mass. It was observed that the addition of basalt powder contributes to a reduction in and spheroidization of pores, which directly affect the density and pore morphology of the materials tested. The highest density of 357.3 kg/m3 was characterized by samples with a 5 wt.% basalt powder addition. Their density was 14% higher than the reference sample without basalt powder addition. Samples with 20 wt.% basalt addition had the lowest density, and the density averaged 307.4 kg/m3. Additionally, for the sample containing 5 wt.% basalt powder, the compressive strength exceeded 1.4 MPa, and the thermal conductivity coefficient was 0.1108 W/m × K. The effect of basalt powder in geopolymer foams can vary depending on many factors, such as its chemical composition, grain size, content, and physical properties. The addition of basalt above 10% causes a decrease in the significant properties of the geopolymer.

Binder-free all-carbon composite supercapacitors

Carbon-based electrode materials have widely been used in supercapacitors. Unfortunately, the fabrication of the supercapacitors includes a polymeric binding material that leads to an undesirable addition of weight along with an increased charge transfer resistance. Herein, binder-free and lightweight electrodes were fabricated using powder processing of carbon nanofibers (CNFs) and graphene nanoplatelets (GNPs) resulting in a hybrid all-carbon composite material. The structural, morphological, and electrochemical properties of the composite electrodes were studied at different concentrations of GNPs. The specific capacitance (Cs) of the CNFs/GNPs composite was improved by increasing the concentration of GNPs. A maximum Cs of around 120 F g−1 was achieved at 90 wt% GNPs which is around 5-fold higher in value than the pristine CNFs in 1 M potassium hydroxides (KOH), which then further increased to 189 F g−1 in 6 M KOH electrolyte. The energy density of around 20 Wh kg−1 with the corresponding power density of 340 W kg−1 was achieved in the supercapacitor containing 90 wt% GNPs. The enhanced electrochemical performance of the composite is related to the presence of a synergistic effect and the CNFs establishing conductive/percolating networks. Such binder-free all-carbon electrodes can be a potential candidate for next-generation energy applications.

From cement to geopolymers: Performances and sustainability advantages of ambient curing

The production of Portland cement results in substantial carbon emissions. Geopolymers are regarded as highly promising alternative binder materials to cement due to their low energy consumption and excellent mechanical properties. However, it should be noted that the thermal curing process of geopolymers diminishes their low-carbon advantage. In this study, ground granulated blast furnace slag (GGBS) was used to replace metakaolin (MK) by the ratio of 10 %, 20 %, 30 %, 40 %, and 50 % to produce geopolymers. The aim was to examine the impact of GGBS content on the thermal curing performance of MK-based geopolymers. The microstructure of the specimens was analyzed using SEM and XRD analysis techniques. Lastly, a comprehensive assessment of their sustainability potential was carried out. As a result, slag may increase flow spread, decrease the setting time, and effectively improve the mechanical properties which curing on ambient temperature. The group with 50 % slag content had the highest compressive and flexural strengths, reaching 55.9 MPa and 8.45 MPa at 28 d, respectively. The drying shrinkage of geopolymers increases as the GGBS content goes up. Notably, owing to the evolution of chemical transformation and gel structure, MK exhibits a significant mitigation on shrinkage. Ultimately, with a 50 % slag content, the carbon dioxide emissions of geopolymer can be reduced to 265.36 kg CO2-eq, which is a 43.6 % decrease compared to that of OPC. With a comprehensive consideration of the performance and sustainability potential of geopolymers, it is recommended to introduce GGBS content in the range of 30 %–40 %.

Properties of road subbase materials manufactured with geopolymer solidified waste drilling mud

In this study, geopolymer was adopted as an eco-friendly binding material to solidify waste drilling mud to fabricate geopolymer solidified waste drilling mud (GSWDM) as a pavement material in the subbase. Using precursor dosage, Na2SiO3 solution dosage, and slag powder (SP) dosage as parameters of mix proportion, the optimal mix proportions of GSWDM were determined through compressive strength tests. Based on a series of tests of unconfined compressive strength, splitting tensile strength, elastic modulus, and compressive resilient modulus, the effects of the SP percentage in the precursor and curing age on the mechanical properties of GSWDM were analyzed. The results indicated that all the mechanical properties of GSWDM were improved with the increasing SP percentage in the precursor. The 28-day unconfined compressive strength, splitting tensile strength, elastic modulus, and compressive resilient modulus of GSWDM were improved by 80.8%, 56.3%, 65.3%, and 76.72%, respectively, when the SP percentage in the precursor increased from 60% to 100%. A nonlinear increase in the mechanical properties of GSWDM was observed as the curing age increased, with a significant increase in the curing age from 7 days to 14 days and a slight increase in the curing age from 14 days to 28 days. Moreover, the microstructure of GSWDM was denser as the curing age and the SP percentage in the precursor grew. The results of this study verified that GSWDM can be used as construction material for road subbase.

Acoustics characterization of reinforced composite for noise reduction

These days, noise pollution is becoming worse due to the faster globalisation of nations, and its effects on human health go beyond hearing impairment. As a result, effective noise pollution control methods are needed. Use a composite reinforced with natural fibres for acoustical purposes. Natural fiber-reinforced composites have several benefits, such as being inexpensive, simple to produce, and eco-friendly. Additionally, natural fibre improves composite sound absorption, structural stability, and mechanical durability. The methods for assessing the acoustical properties of composites improved by natural fibres are described in the paper. Acoustical measures, such as sound transmission losses and absorption efficiency, are also evaluated. This work also examines a factor that influences the mechanical and acoustical properties of composites reinforced with natural fibres. The variables that determine the outcome include the fiber’s characteristics, density, sample thickness, porosity, adhesive material, and filler substance. Increases in the percentage of fibre weight, binder material, and filler material improve the durability and sound absorption of natural fiber-reinforced composites.

A path to carbon neutrality in construction: An overview of recent progress in recycled cement usage

The cement industries as binder materials, produces 1.6 billion metric tons’ carbon dioxide (CO2) in 2022 and cause depletion in ozone layer. The cement is being used in modern construction and cause the environmental impact. Therefore, there is a quest for a sustainable alternative binder to reduce the CO2 emission from the conventional cement production and their effective disposal methods in construction and demolished (C&D) waste is paramount. This article delves into the production of recycled cement by leveraging various methods such as mechanical activation, chemical activation, and heat treatment of C&D waste, ultimately contributing to the carbon neutrality. A comparison with traditional cement production sheds light on energy consumption, CO2 emissions, and resource utilization. The recycled cement displays increased water demand, accelerated early setting, extended final setting time, and reduced compressive strength. However, when used solely as a cementitious matrix, recycled cement can readily achieve up to 30 MPa in 28 days. Utilising recycled cement in concrete applications demonstrates its efficacy in the construction industry. The insights provided herein offer a holistic understanding of the production processes, properties, and applications of recycled cement, reinforcing its potential as a viable and environmentally friendly alternative in the realm of construction materials.

Physicochemical quality of rice bran pellets using different binder materials

Physicochemical quality of rice bran pellets using different binder materials

Layer by Layer: Improved Tortuosity in High Loading Aqueous NMC811 Electrodes

Thick electrode production is a key enabler for realizing high energy density Lithium-ion batteries. Therefore, the investigation of tortuosity as a crucial limiting parameter was conducted in this work. A thickness threshold (>150 μm) for a drastic increase in tortuosity for aqueous processed LiNi0.8Mn0.1Co0.1O2 (NMC811) electrodes was determined. Symmetrical cells, under blocking conditions, were analyzed via electrochemical impedance spectroscopy. To counteract this phenomenon, multi-layer coated electrodes with varying binder concentrations were investigated. This novel coating method, combined with the reduction of binder material, leads to a tortuosity decrease of more than 80%, when compared to high-loading electrodes (>8.5 mAhcm−2) coated with the conventional doctor-blade technique. Additionally, a simplified transmission line model is opposed to a linear fitting method for analyzing the impedance data.

Role of carbide grit size and in-flight particle parameters on the microstructure, phases, and nanoscale properties of HVOF sprayed WC-12Co coatings

Effects of particle temperature and velocity on crystallinity and phase composition of WC-Co coating are successfully decoupled. The effect of grit size on the dissolution and decarburization process is established analytically. The nanostructured coatings were found to be less crystalline than their conventional counterpart for similar in-flight parameters. The cooling rate and the degree of carbide dissolution in the binder phase govern the crystallinity of the as-sprayed coatings. An increase in either of these factors results in a higher degree of amorphization of as-sprayed coatings. The phases present in the coating were quantified, and correlated with particle temperature and velocity independently. The degree of decarburization increased with an increase in particle temperature. The calculated change in Gibbs free energy justified these observations. The effect of particle velocity on crystallinity or phase composition was not significant. The nano hardness of the carbide grits was increased with particle temperature owing to the formation of a hard W2C phase. Similarly, the dissolution of carbides in the binder and the formation of the Co3W9C4 phase increased the binder hardness. The energy analysis revealed brittleness of the binder matrix increased significantly with deposition temperature owing to the formation of the Co3W9C4 phase.

Fresh and mechanical properties of ground granulated blast furnace slag-based concrete: A review

The surge in global urbanization and developmental activities has led to a significant increase in the worldwide demand for concrete. Cement composites, such as concrete and mortar, are among the world's most extensively used construction materials. Cement manufacturing accounts for about 90% of overall carbon footprints in concrete that leads to demand for alternate binding materials derived from industrial by-products. Steel manufacturing is one of the fastest expanding sectors in construction, resulting in massive slag creation. Slag, a solid waste generated during the extraction of iron from its ore, exhibits varying qualities determined solely by the cooling process employed. One of its forms, Ground Granulated Blast Furnace Slag (GGBFS), has characteristics comparable to cement and hence it is a possible alternative. This study gives a comprehensive report on GGBFS as a cement substitute based on previously published research on the effect of GGBFS on various concrete qualities as well as its manufacture. The impact of GGBFS on concrete characteristics such as workability, setting time, flexural strength, compressive strength, and split tensile strength is explored in this study. It has been determined that integrating GGBFS up to a particular level successfully matches the characteristics of standard concrete. The current state-of-the-art evaluation aims to provide a consolidated, complete source that incorporates the general trends, discoveries, areas of study that require additional investigation, and prospective future applications of concrete based on GGBFS.

Evaluation of the operational curve for heat storage technology using n-octacosane/low-density as a binding material

Heat storage technology has a critical role for a number of applications involving renewable thermal energy (such as solar water heater). The application of wax (n-octacosane/OCT) as a medium for storing heat brings many positive influences for the system. However, the operational curve is undesirable for the OCT-based energy storage, which makes it necessary to use a binding material. The present work employed LD-class polymer (LDPE) and linear-LDPE as binding materials for OCT. The mixture is prepared through mechanical hot stirring, which comes into two categories: SOCT1 (OCT/LD) and SOCT2 (OCT/LLD). The assessment through the calorimetry method shows an increment in transition temperature for SOCT with a value of 2.1 °C and 5.5 °C. This contributes to the variation of fusion energy for solid-liquid change for both materials, which amounted to 132.05 J/g (SOCT1) and 113.4 J/g (SOCT2). Another assessment related to its chemical and structural phase demonstrates that SOCT has an identical structure to OCT, indicating that SOCT is mixed physically. At the operational level, SOCT is more optimal than OCT according to the indicator related to charge and discharge duration for energy exchange. SOCT1 demonstrates a short plateau line as the indication of a steady transition between 65.4–67.9 °C, while SOCT2 indicates the average heating rate, which is higher than for single OCT. The heat releasing curve for SOCT1 varies at a lower value between 1.92 °C/min and 0.77 °C/min, while SOCT2 has the lowest variation, which is only 0.17 °C/min. Moreover, the self-insulation for SOCT2 has the lowest rate, which is only 0.3 °C/min. The evaluation and analysis from this work show that SOCT is reliable to increase the operational curve of OCT and can be implemented for thermal systems

Study on the rheology, mechanical properties and microstructure of polypropylene fibers in different binder systems

To explore the effects of polypropylene fiber (PPF) on the properties of different binder materials, the effects of PPF on the rheology, shrinkage, mechanical properties and microstructure of alkali-activated mortar (AAM) and ordinary Portland cement mortar (PCM) were studied. The results showed that the addition of PPF reduced the fluidity of the mortar, and the lower the initial yield stress and plastic viscosity of the paste were, the more obvious the increase. PPF reduced the drying shrinkage of both the AAMs and PCMs by 7.63–12.85 %. The inclusion of PPF to the mortar had a limited effect on enhancing the mortar compressive and flexural strength, but it notably improved the mortar toughness. At a fiber content of 0.5 %, the samples from the cement and slag-steel slag systems exhibited a more compact of the interfacial transition zone (ITZ) between the fiber and paste. Conversely, the slag-steel slag-fly ash and slag-fly ash systems showed poorer compact of the ITZ, which was attributed to increased unreacted precursors and shrinkage cracks. This phenomenon primarily accounted for the superior residual stresses observed in the cement and slag-steel slag systems. This study provides an avenue for analysis the effect of the same fiber on different binder systems.

Experimental Investigation on Mechanical and Durability Properties of Geopolymer Concrete

Abstract: Geopolymer concrete (GPC) is a new type of concrete that is made with alkaline activators and aluminosilicate materials, such as fly ash and ground granulated blast furnace slag (GGBS). GPC has several advantages over traditional Portland cement concrete (OPC), including higher early strength, better durability, and lower environmental impact. This paper presents an experimental analysis of the mechanical and durability properties of GPC. The mechanical properties investigated include compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity. The results show that GPC has comparable or better mechanical properties than OPC at all ages. GPC also has superior durability properties to OPC, with lower water absorption, higher acid resistance, and lower chloride permeability. The overall findings of this study indicate that GPC is a promising alternative to OPC for a wide range of applications. Since Geopolymer concrete doesn’t use any cement, the production of cement shall be reduced and hence the pollution of atmosphere by the emission of carbon dioxide shall also be minimized. Cement, being a key material of concrete, experiencing a rise in global demand. It has a massive carbon footprint having a contribution of about 8% to the global Carbon dioxide emissions. Geopolymer concrete has a huge potential to replace ordinary Portland concrete. For sustainable construction, GPC reduces the use of cement and finds the alternative of cement for the material's binding property. So, the geopolymer concrete is an alternative to Portland cement concrete and it is a potential material having large commercial value and for sustainable development in Indian construction industries.

Microstructural Evolution, Hardness and Wear Resistance of WC-Co-Ni Composite Coatings Fabricated by Laser Cladding.

This study investigated how process parameters of laser cladding affect the microstructure and mechanical properties of WC-12Co composite coating for use as a protective layer of continuous caster rolls. WC-Co powders, WC-Ni powders, and Ni-Cr alloy powder with various wear resistance characteristics were evaluated in order to determine their applicability for use as cladding materials for continuous caster roll coating. The cladding process was conducted with various parameters, including laser powers, cladding speeds, and powder feeding rates, then the phases, microstructure, and micro-hardness of the cladding layer were analyzed in each specimen. Results indicate that, to increase the hardness of the cladding layer in WC-Co composite coating, the dilution of the cladding layer by dissolution of Fe from the substrate should be minimized, and the formation of the Fe-Co alloy phase should be prevented. The mechanical properties and wear resistance of each powder with the same process parameters were compared and analyzed. The microstructure and mechanical properties of the laser cladding layer depend not only on the process parameters, but also on the powder characteristics, such as WC particle size and the type of binder material. Additionally, depending on the degree of thermal decomposition of WC particles and evolution of W distribution within the cladding layer, the hardness of each powder can differ significantly, and the wear mechanism can change.

Investigate the mechanical behavior of alkali-activated slag mortar using sustainable waste sodium silicate-bonded sand as an alkali activator and carbon free aggregate

Various products generate different types of industrial by-products based on their production characteristics and procedures. Therefore, an accurate classification of these characteristics would contribute significantly to achieving the goals of resource recycling and environmental protection. This study focused on Waste Alkali-Activated Slag Mortar (W-AASM). In the past, inorganic aggregation technology was successfully adopted to replace conventional concrete binding materials and reduce cement usage. Besides utilizing inorganic aggregation technology, the study has introduced a novel industrial by-product known as Waste Sodium Silicate-Bonded Sand (WSSS). WSSS not only serves as a substitute for sodium silicate in alkali-activated agents but also acts as a complete replacement for fine aggregates in mortar. The experimental findings showed that, in addition to fulfilling the original strength requirements of concrete, it results in a significant reduction in cement consumption, minimizing the extraction of natural resources, and decreasing the overall cost of Alkali-activated concrete production. The study highlighted the advantage of WSSS and showed a new dimension of waste foundry sand application in the concrete industry. This method leads to the recycling of waste materials and their optimal use, and as a result, leads to a sustainable ecosystem. The results of this study can be applied to secondary structures in civil engineering and construction projects in the future, such as precast concrete products, concrete pavements, or roads.

A Review on the Carbonation of Steel Slag: Properties, Mechanism, and Application.

Steel slag is a by-product of the steel industry and usually contains a high amount of f-CaO and f-MgO, which will result in serious soundness problems once used as a binding material and/or aggregates. To relieve this negative effect, carbonation treatment was believed to be one of the available and reliable methods. By carbonation treatment of steel slag, the phases of f-CaO and f-MgO can be effectively transformed into CaCO3 and MgCO3, respectively. This will not only reduce the expansive risk of steel slag to improve the utilization of steel slag further but also capture and store CO2 due to the mineralization process to reduce carbon emissions. In this study, based on the physical and chemical properties of steel slag, the carbonation mechanism, factors affecting the carbonation process, and the application of carbonated steel slag were reviewed. Eventually, the research challenge was also discussed.

Effect of seashell powder as binder material on the performance and microstructure of low-carbon sustainable alkali-activated concrete

This paper proposes using waste seashells as raw materials to partially replace fly ash in alkali-activated concrete (AAC). Fifteen groups of alkali-activated mortar and concrete were designed, with seashell powder (SP) substitution and sodium hydroxide molar concentration as variables. The material's workability, compressive strength, hydration products and micropore structures were examined. The results showed that the 3 days compressive strength of AAC with SP enhanced significantly, exhibiting an increase of nearly 30 % compared to the fly ash control. The 28 days compressive strength showed that the optimal proportion of SP replacing fly ash was 45 %. SEM images showed that micro/nanoparticles of SP filled the pores in the concrete and provided nucleation sites. Nano CT and MIP analyses indicated that the addition of SP could refine the pore structure of concrete, reducing the total porosity by nearly 30 %. Finally, the carbon emission data for 1 m³ of concrete were analyzed using a life cycle assessment approach. The carbon emissions from AAC with 45 % SP were 173.4 kg CO2/m³, compared to the reference ordinary concrete reduction of approximately 60–70 %.

Mechanical and acoustic performance of mortar with partial replacement by biochar from civil construction wood waste at advanced ages

Civil construction generates large amounts of solid waste, most of which are non-toxic, but extremely voluminous, resulting in a contemporary sanitary health problem. Furthermore, cement fabrication, a widely used binding material, is responsible for the emission of 8% of the world’s CO2 into the atmosphere, making it an industry with a great environmental impact. The consumption figures of cement show an significant increasing over the years. Therefore, much research has focused on the search for energy efficiency in the production processes of cement and materials with potential use as additions, allowing the reduction of clinker consumption, the main component of the cement. In this sense, this research made use of wood waste from civil construction, and through the pyrolysis process, partially replaced cement with biochar at high levels compared to existing research, seeking to find an efficient replacement limit and analyzing its sound absorption and mechanical properties at advanced ages. Mortars were produced with levels of 5%, 10%, and 15% (m/m), replacing cement with biochar. The results demonstrated better mechanical performance at advanced ages, up to 30% for compression and 15% for tensile strength with 10% biochar, and lower water absorption by capillarity. Its acoustic performance showed that the samples with biochar did not exhibit properties of a sound-absorbing material.

Exploring the geotechnical and microstructural properties of composite mixtures for landfill liner materials: an experimental investigation.

The present study directs the need for the development of an economical composite mix comprised locally available soil and industrial waste which satisfy the design parameters of the municipal solid waste (MSW) landfill. The local soil, bentonite, and fly ash mixtures are mixed in different proportions to evaluate the geotechnical and microstructural characteristics for suggesting an optimum composite mix that fulfills the design parameters of landfill liners. The curing periods of different mixes are also considered while evaluating the unconfined compressive strength (UCS) characteristics. The microstructure of the mixtures is examined using advanced imaging techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDAX) to gain insights into the changes at the microscale level due to the inclusion of fly ash. It is observed that soil-bentonite-fly ash composite mix in a ratio of 65:15:20 aligns with the optimal design characteristics required for a landfill liner. Notably, for this composite mix, both liquid limit (LL) and plastic limit (PL) show a significant increase of 48.57% and 32.33% respectively, while the optimum moisture content (OMC) rises by 11.25%. Conversely, maximum dry density (MDD) experiences an 8.79% decrease. Moreover, the free swell index (FSI) escalates by 113%, whereas hydraulic conductivity (HC) records a substantial reduction of 96.04%. Moreover, the UCS exhibited a notable increase of 209% after a 28-day curing period. The highest strength is achieved initially by soil mixed with 20% fly ash, followed by a blend containing 15% bentonite. Therefore, proper fly ash content in filler and other binder materials is an effective and sustainable approach that not only solves the disposal issue but also enhances the material's engineering characteristics, justifying its suitability to be used as a landfill liner.