High Powder Content Research Articles

Optimisation of hybrid alkaline binder with a high glass powder content

There is a growing interest in utilising waste glass in cement and concrete production to reduce the environmental impact. This paper studies the feasibility of incorporating a very high volume of glass powder (≥65 %) in a hybrid alkaline binder (HAB) activated by sodium carbonate and sodium citrate. The HAB was optimised in two stages to achieve optimal performance in terms of flowability, strength, cost-effectiveness, and carbon footprint: the first stage focused on the optimisation of the ternary binder consisting of 5–20 % slag, 10–25 % ordinary Portland cement (OPC), and 65–80 % glass powder; and the second stage optimised the contents of activators (sodium carbonate and sodium citrate) and superplasticisers. The prepared pastes were tested for flowability and compressive strength. Meanwhile, microstructural analyses were conducted to characterise the morphology and structure of the paste samples. The optimal HAB comprising 65 % glass powder, 25 % OPC, and 10 % slag was suggested based on a multi-criteria decision-making approach. This mix achieved very good flowability (210 mm flow diameter) when activated by 4.75 % sodium carbonate and 1 % sodium citrate. Meanwhile, a very high compressive strength of up to 63.0 MPa was achieved at 28 days. The optimised HAB also exhibited very good hydrolytic stability and high early strength. Compared with the OPC counterpart, the optimised HAB is approximately 33 % more cost-effective and emits 53 % less greenhouse gases.

Phase Transformation of AlV55 Alloy at High Temperature

Vanadium–aluminum alloy is an important intermediate alloy for preparing aviation grade titanium alloys, and its product quality directly affects the finished product quality of titanium alloys. In this study, focusing on the problems of high powder content (19.8%) and low product yield in AlV55 alloy products, we conduct research on alloy quality control technology and implement a vanadium–aluminum alloy cooling crystallization control process. The research results indicate that there are three phases in AlV55 alloy, namely Al8V5, AlV, and Al2V3 phases. As the temperature decreases, the AlV phase gradually decomposes into Al8V5 phase and Al2V3 phase, and the proportion of Al8V5 phase is positively correlated with the fineness. Rapid cooling can reduce the formation of Al8V5 phase. The experimental results show that high-temperature water quenching can increase the proportion of vanadium–aluminum solid solution phase in the alloy from 19.03% to 31.76%, and reduce the fine powder rate to 13.2%, providing important product quality control means and technical support for the production of vanadium–aluminum alloys.

A Comprehensive Overview of Recycled Glass as Mineral Admixture for Circular UHPC Solutions

This review article analyzes the influence of recycled glass (as sand and powder) beyond the durability, rheology and compressive strength of plain UHPC, even exploring flexural and direct tensile performance in fiber-reinforced UHPC. Interactions with other mineral admixtures like limestone powder, rice husk ash, fly ash, FC3R, metakaolin and slags, among others, are analyzed. Synergy with limestone powder improves rheology, reducing superplasticizer usage. Research highlights waste glass–UHPC mixtures with reduced silica fume and cement content by over 50% and nearly 30%, respectively, with compressive strengths exceeding 150 MPa, cutting costs and carbon footprints. Furthermore, with the proper fiber dosage, waste glass–UHPC reported values for strain and energy absorption capacity, albeit lower than those of traditional UHPC formulations with high cement, silica fume and quartz powder content, surpassing requirements for demanding applications such as seismic reinforcement of structures. Moreover, durability remains comparable to that of traditional UHPC. In addition, the reported life cycle analysis found that the utilization of glass powder in UHPC allows a greater reduction of embedded CO2 than other mineral additions in UHPC without jeopardizing its properties. In general, the review study presented herein underscores recycled glass’s potential in UHPC, offering economic and performance advantages in sustainable construction.

Maximising the utilisation of WGP in seawater-mixed UHPC

Using high-volume reactive binders and superplasticisers in ultra-high-performance concrete (UHPC) would be costly, resulting in poor workability and high autogenous shrinkage. Using seawater for UHPC production could magnify these issues. This study incorporated a high waste glass powder (WGP) content in seawater UHPC to reduce the reactive binder and superplasticiser dosages. Through the combined effects of seawater and WGP, a self-compacting seawater UHPC was developed with a compressive strength of 140 MPa and a reduced autogenous shrinkage of approximately one-third of the reference. The self-compactibility and reduction of the stickiness of the UHPC were achieved because of reduced plastic viscosity, which was contributed by a high zeta potential of WGP and lower yield stress due to the hydrophobic surface of WGP. In addition, the mechanical performance of the seawater UHPC incorporating high-volume WGP could be maintained at least 120 MPa because of minimising trapped air and porosity by reducing the plastic viscosity, enhancing reactivity of WGP and SF and achieving a higher polymerisation degree (PD) and longer mean chain length (MCL) of C-S-H. The reduced autogenous shrinkage was attributed to replacing binders with a higher reactivity by WGP, which resulted in fewer fine pores and reduced shrinkage in the microstructure.

Application of green material on durability behaviour of green concrete

Since several decades, concrete is most preferred and cheaper material used in infrastructure industry throughout the world. In today’s era of sustainability and high-rise construction, green concrete with self-compacting property is the only solution for reducing the negative impact on environment. Green concrete can be made by employing quality material like fly ash and calcite which minimizes consumption of cement and encourages the sustainability. For developing Self Compacting Concrete (SCC), higher powder content is most important requirement which can be achieved by using fly ash and calcite in a definite proportion. Herein, experimental investigation on green SCC is reported wherein, four different SCC mixes i.e. M25, M30, M40 and M50 are studied by varying the proportion of fly ash and calcite. The developed mixes are evaluated for strength and durability to understand their applicability in construction.

Optical Recrystallization of Nanocrystalline Silicon Ribbons

The Silicon on Dust Substrate (SDS) is a gas-to-wafer process that produces multicrystalline silicon ribbons directly from gaseous feedstock (silane), avoiding the standard industry steps of polysilicon deposition, crystal growth, and wafering. The SDS technique consists of three main steps: (i) micrometric-sized silicon powder production by grinding silicon chunks; (ii) chemical vapor deposition (CVD) of silicon over this silicon powder substrate; and (iii) zone-melting recrystallization (ZMR) of the nanocrystalline pre-ribbon obtained in the CVD step. Several samples were produced by this technique. During CVD, mechanically self-sustained nanocrystalline pre-ribbons were grown over silicon powder substrates, with growth rates in the order of 50 µm/min. The ZMR process performance is substantially impacted by the pre-ribbon physical characteristics. The best and largest recrystallizations were achieved on pre-ribbons grown over powder substrates with smaller particle sizes, which also have lower substrate powder incorporation ratios. Multicrystalline silicon ribbons with crystalline areas as large as 2 × 4 cm2 were successfully produced. These areas have visible columnar crystal growth with crystal lengths up to 1 cm. The SDS ribbons’ measured resistivity confirmed the high powder content of the resulting material. The ability to produce solar cells on SDS multicrystalline silicon ribbons was demonstrated.

Study on the mechanism of improving the lap-shear properties of EVA hot melt adhesives by optical preform waste powders

A large amount of waste is produced during the preparation of optical fiber preforms, and thus the resource utilization of the optical preform waste powders is of great significance. The addition of the calcined optical preform waste powders to pure EVA hot melt adhesives can increase the lap-shear strength. To investigate the reasons for improving the mechanical properties of the pure EVA hot melt adhesives by the optical preform waste powders, XPS, ATR-IR, and Gaussian calculations were utilized to explore the mechanisms of the reactions between the optical preform waste powders and the pure EVA hot melt adhesives. It was found that the hydroxyl groups on the surface of the silicon particles reacted with the ester groups in the EVA resin through the nucleophilic addition and decomposition reactions, which resulted in the formation of long-chain alkyl alcohols and the formation of acylate on the surface of silicon particles, which reduced the agglomeration of the particles. DSC was used to characterize the crystallization behavior of the EVA composite hot melt adhesives with different contents of the optical preform waste powders. With the increase in powder content, the crystallinity of the composite hot melt adhesives decreased obviously, and the decrease in crystallinity increased the lap-shear strength of the composites. Nevertheless, when the crystallinity was too low, a high powder content tended to increase the agglomeration of the particles, which reduced the dispersion compatibility of nanoparticles and organic polymer chains, resulting in a decrease in lap-shear strength.

SOME PROPERTIES OF ICE CREAM PRODUCED WITH DIFFERENT RATIOS OF BUTTERMILK POWDER

Bu çalışmada bir süt yan ürünü olan yayıkaltı tozu, dondurma üretiminde farklı oranlarda kullanılmıştır. Yayıkaltı tozu miktarı, miks bileşiminde kullanılan yağsız süttozu miktarının %5, %10, %20, %30 ve % 40’ı kadar olacak şekilde hesaplanmıştır. Olgunlaştırılmış mikslerde gerçekleştirilen analiz sonuçlarına göre, yayıkaltı tozu ilavesi örneklerin titrasyon asitliği, pH değeri ve kurumadde içeriğini etkilememiş (P > 0.05), kıvam indeksi ile yağ ve kül içeriklerini ise artırmıştır (P < 0.05). Ayrıca, yayıkaltı tozu miktarının artması ile faz ayrılmasının azaldığı belirlenmiştir (P < 0.05). Kullanılan yayıkaltı tozu miktarı arttıkça, dondurma örneklerinin hacim artışı ve b* değerleri artmış, sertlik değerleri azalmış ve ilk damlama süreleri uzamıştır (P < 0.05). Duyusal analiz sonuçlarına göre, yayıkaltı tozu miktarının artışı dondurma örneklerinin görünüş ve yapı özelliklerini etkilememiş (P > 0.05) ancak lezzet yönünden toz miktarı yüksek olan örnekler panelistlerden daha düşük puan almışlardır (P < 0.05).

The anisotropy of bonded ferrite magnets obtained by centrifugal casting in magnetic field

• The orientation of bonded magnets in an external magnetic field depends on the powder particle size. • For powders composed of multidomain particles, the orientation occurs in the circumferential direction. • The orientation of the powder occurs in a way that leads to a minimization of the energy. Bonded magnets were produced by centrifugal casting of a powder mixture comprising a magnetically hard material (strontium ferrite) and a chemically hard polymer (epoxy resin) in an external, constant magnetic field perpendicular to the axis of rotation. The tests were carried out for commercial strontium ferrite powder, with micrometre-sized particles. At 5% and 10% powder content by volume, the magnets exhibited a gradient structure, i.e. the proportion of magnetic powder was highest at the surface and decreased towards the sample’s axis. At higher powder content, the viscosity of the slip was high enough to prevent particles to move over significant distances, and no marked change in the proportion of ferrite in the sample volume was observed. Measurements of the magnetic properties in the characteristic directions of the cylindrical sample (radial, axial and circumferential) showed that the powder particles tend to align their easy axis with the axis of the cylinder, i.e. perpendicular to the direction of the magnetic field. These results indicate that the magnetization anisotropy obtained is different from that described in earlier work, where strontium ferrite powder with a particle size above 100 μm was oriented circumferentially (the easy axis was perpendicular to the radius and axis of the cylinder). These differences are due to the different proportion of single and multidomain particles in the two powders and to the different mechanisms of their remagnetization. The results are explained on the basis of the presented model assuming that the single domain particles rotate in such a way that their remagnetization during mould centrifugation is achieved by rotating the magnetization vector in a plane perpendicular to the easy axis, which minimises the energy loss in this process.

ECO2 framework assessment of limestone powder concrete slabs and columns

Producing limestone powder requires comparably far less energy than the production of ordinary Portland cement (OPC), making it a promising sustainable solution for partial replacement of OPC in concrete. Lower production energy could be translated into lower environmental impact and lower cost, which are two pillars of the sustainability of the resulting concrete. However, the question remains if replacing OPC with larger percentages of limestone powder would compromise the performance of the resulting concrete to a level that surpasses the environmental and economic gains. In order to assess the collective impact of these concretes, a performance-based multi-criteria decision analysis framework, ECO2, is used. For that purpose, 26 experimentally verified, concrete mixtures with and without limestone powder were evaluated through potential application in two types of reinforced concrete (RC) structural elements (slabs and columns) under identical environmental condition. The main results of the research showed a clear environmental advantage of concrete with a reduced OPC content, but the relatively higher superplasticizer amount in some cases could affect the final sustainability performance of the resulting mix. In the case of RC slabs, the best ECO2 score was obtained for concrete containing limestone powder. Mixtures with 200–250 kg of cement per unit volume of concrete had the highest ECO2 score for all the considered criteria. In the second case, due to the nature of the structural performance requirements in columns, the crucial influence of the concrete compressive strength is clear. The obtained results have shown approximately equal sustainability potential of OPC and limestone concretes in vertical elements such as columns. However, it seems that a certain improvement in the design of concrete mixtures with a high limestone powder content could make these competitive in all fields.

Influence of nano waste materials on the mechanical properties, microstructure, and corrosion resistance of self-compacted concrete

Recycling nano wastes materials (NWM) including nano waste glass (NWG) and nano waste ceramic (NWC) as an eco-friendly alternative binder helps the reclamation of construction waste and reduces the demand for cement. Considering that self-compacted concrete (SCC) which needs high powder content has been largely used in building engineering due to its high flowability, which allows it to self-compact and maintain homogeneity without separation, and thus, substituting NWM for partial cement in preparing SCC is more sustainable. This paper explores the effect of replacing cement in SCC with nanomaterials that were made in two ways. The first way is the milling technique, where glass and ceramic wastes are converted to NWM to overcome the problem of some wastes and the emission of CO2 during ordinary Portland cement manufacturing. The second way Also, to compare the behavior, a chemically prepared NS by precipitation technique was used. Several SCC mixes were made using nanomaterials as cement replacement materials with replacing percent up to 5% and analyzed. Fresh properties, mechanical characteristics, microstructure, and corrosion rate of SCC mixes were studied. The testing results revealed that SCC's flowability, passing ability, and viscosity declined as the NS, NWG, and NWC increased while being within the EFNARC-2005 recommended limit. Waste-milled nanomaterials are comparable to nano-silica, which is chemically prepared to improve SCC mechanical properties and purify the microstructure; replacing cement with 3% NWG increased compressive strength by 32.4%, while NWC and NS increased compressive strength by 17.3% and 26.4%, respectively. Replacing cement with nanomaterials decreases the anodic and cathodic overpotentials and shifts the corrosion potential (Ecorr) of high-strength steel (HSS) embedded in SCC specimens cured in 3.5% NaCl solution to preferable values, in addition to reducing the current densities of corrosion (Icorr).

Effect of Combined Supplementary Cementitious Materials on the Fresh and Mechanical Properties of Eco-Efficient Self-Compacting Concrete

Global concrete demand is causing depletion of natural resources at an alarming rate. Self-compacting concrete (SCC) is an innovative solution as it uses less aggregates; however, the drawback of SCC is that high cement content is required compared to conventional concrete. Considering that cement production emits 7% of carbon dioxide (CO2) gas emissions, the use of high content of cement in SCC production is concerning. Though the high powder content of SCC may be of a concern, however, it allows the opportunity to substitute the cement content with supplementary cementitious materials. This experimental work was therefore conducted to reduce the cement content by substituting it with waste materials, such as eggshell powder (ESP) and palm oil fuel ash (POFA), and develop an eco-efficient SCC. The cement content was partially substituted by 0 to 5% ESP and 0 to 15% POFA by weight of total binder. A total of 90 cubes of 100 mm and 60 cylinders of 100 × 200 mm dimension were prepared to evaluate the compressive and splitting tensile strengths, modulus of elasticity, and Poisson’s ratio. Furthermore, the environmental impact assessment was conducted to assess the embodied CO2 and eco-strength efficiency of the developed eco-efficient SCC. It was found that the combination of POFA and ESP increased pozzolanic reactivity, developing additional calcium silicate hydrate gels, thus increasing strength. The combination of 2.5% ESP and 5% POFA (a total of 7.5% cement substitution) was deemed to be the optimal combination as it provided better strength in SCC after 28 days of curing, which leads to 9.66% higher compressive strength than the control SCC. Furthermore, the developed SCC was observed to be eco-friendly as it reduced embodied carbon ranging from 3.86 to 15.33% and eco-efficiency ranging from 2.38 to 15.48% on 28 days compared to the control SCC.

Effect of magnetic powder content on circumferential anisotropy of centrifugally cast bonded magnets

The current paper focuses on determining the degree of powder orientation in a magnet centrifugally cast in a magnetic field and on determining the influence that the amount of ferromagnetic powder has on this parameter. Strontium ferrite powder and epoxy resin were used as starting materials. The manufactured magnets were cylindrically shaped and had a circumferential orientation. It was shown that the magnetic powder particles were oriented along the easy axis of magnetization in the direction tangential to the cylinder’s surface. On the basis of magnetic measurements, it was found that the powder particles’ degree of orientation decreases with increasing powder content in the magnet. For small contents of up to 20 vol% magnetic powder, a significant degree of orientation of the powder particles was observed. It was found that at 60 vol% magnetic powder content, the obtained magnets are isotropic. It was observed that at higher powder content, particle chains aligned with the magnetic field lines begin to interact with each other, which as a consequence causes the deterioration of particle orientation.

Effect of limestone powder on self-compacting concrete

Self-compacting concrete (SCC) is an innovative construction material in the construction industry. It is a highly fluid and stable concrete that flows under its own weight and fills completely the formwork. The SCC requires high powder content (mainly of cement) up to 600kg/ to achieve its properties. This will be problematic because increasing the cement content is not feasible, and may cause high cost and some other technical problems such as higher heat of hydration and higher drying shrinkage. This paper investigates the effect of limestone powder (LSP) on fresh and hardened properties of SCC due to the use of LSP as a partial cement replacement. For comparison, a control sample of concrete was prepared without LSP to compare it with the various samples containing different percentages of LSP as a partial replacement of cement. Four mixes with a constant amount of (superplasticizer, sand, coarse aggregate, and water) at various replacement levels of 0%, 10%, 20% and 30% from the cement weight were prepared. The experimental results show that the LSP can be effectively used as a partial cement replacement on SCC to reduced cost and enhanced the performance of SCC in fresh and hardened stages.

Correlations between the Hardened Properties of Combination Type SCC Containing UFGGBFS

Abstract This study aims to develop models to correlate the different hardened properties of ultra-fine ground granulated blast-furnace slag (UFGGBFS) admixed SCC mixtures. Seven self-compacting concrete mixtures (SCC-A to SCC-G) were produced with a high powder content of 587 ± 2 kg/m3. The 450 kg/m3 (76 %) of powder was derived from the binders, and the remaining 137 ± 2 kg/m3 (24 %) was obtained from the powder particles (<125 µm) existing in the crushed stone sand. UFGGBFS was utilized as a supplementary binder. Properties of these SCC mixtures were evaluated in fresh as well as in the hardened state. The homogeneity, surface hardness, chloride permeability, electrical resistivity, and absorption of hardened SCC were detected with ultrasonic pulse velocity (UPV), rebound hammer, rapid chloride permeability, Wenner’s four-probe electrical resistivity, and water absorption test methods, respectively. All the seven SCC mixtures demonstrated a nonsegregating flowability and excellent passability without stacking and blocking. At 28, the mix SCC-B recorded a maximum strength of 54 MPa and 4.41 MPa under cube compression and splitting tensile tests, respectively. Moreover, the mix SCC-G demonstrated a 30-MPa compressive strength with a significant cement range of 150 kg/m3. Correlations between the various properties of SCC was also arrived using the experimental results, and it was compared with the existing models.

Insights on the molecular structure evolution for tricalcium silicate and slag composite: From 29Si and 27Al NMR to molecular dynamics

Slag, an important supplementary cementitious material, is widely utilized for producing sustainable cement-based materials. In this paper, to study the effect of hydration stage and composition on the microstructure of cement-slag powder composites, the hydrated tricalcium silicate (C3S) curing at 20 °C at 28-day and 90-day with slag dosage from 0% to 45% were investigated by 29Si and 27Al NMR spectrum and molecular dynamics. Silicate connectivity from 29Si NMR test showed that with increasing slag substitution content, the mean chain length (MCL) of the C3S-slag hydrated paste at 28-day increased from 2.99 to 4.02 and the AlO4/SiO4 ratio rose from 0 to 0.043. Aluminate coordinates of 27Al NMR analysis revealed that the incorporation of slag could contribute to transformation from ettringite to Aft and formation of Al [4] in the C-A-S-H gel. Furthermore, reactive force field molecular dynamics was utilized to study the structural, reactivity and mechanical properties of C-A-S-H gel in hydrated composite. The AlO4 species in the C-A-S-H gel played an essential role in healing the defective silicate chains and transforming dimmer-rich silicate chains at low slag powder content to a long aluminate-silicate skeleton with high slag powder content. The structural evolution was attributed to the polymerization reaction between aluminate species and non-bridging silicate tetrahedron, with neighboring water molecule dissociations. In respect of dynamical properties, the aluminate-silicate structure exhibited good stability due to high Al–O–Si connection characterized by time correlated function. Uniaxial tensile modeling revealed that C-A-S-H gel with long aluminate-silicate chains exhibits good loading resistance and the cohesive strength of C-A-S-H gel is improved to a great extent due to the incorporation of slag powder. Hopefully, this study may provide molecular insights for design of sustainable and durable cement-slag powder composites.

Proportioning Self Compacting Concrete in Hot Weather Utilizing Limestone Powder

Self-compacting concrete (SCC) is a special type of concrete able to flow and compact under its self-weight. The SCC requires high powder content (mainly of cement) up to 600kg/m3 to achieve its properties. This will be problematic if all cement content in the powder exceeded 400 kg/m3used in hot weather of Sudan. This paper investigates addition of Sudanese limestone powder (LSP) to reduce cement content. The LSP dosages between 20% and 28 % (by cement weight) are used in six mixes having maximum cement content 380kg/m3. Results show that five trial mixes achieved the self-compactibility tested by slump flow, sieve segregation, V-funnel and U-box tests. Compressive strength of these mixes show that the LSP increases strength with dosage. Therefore, further investigations of hardened concrete properties are recommended for the successful mixes to be applied in real projects in the Sudan. Also, it has been found that dry batching and forced-action pan mixers are the most suitable for producing SCC with high homogeneity compared to commercial tilted-drum mixers.

The role of powder content of the recycled aggregates of CDW in the behaviour of rendering mortars

Abstract In recent years, the number of studies on the incorporation of recycled aggregate (RA) into mortars has grown considerably. However, mixed recycled aggregate (MRA) is investigated on a much smaller scale due mainly to its high-water absorption capacity and higher powder content (

From the Chief Executive and IFST News

From the Chief Executive and IFST News

Effect of Sulphate and Acid on Self-Compacting Concrete Containing Corn Cob Ash

Self-compacting concrete requires high powder content which implies increased cost and increased CO2 emission into the environment; hence, the need for the inculcation of a supplementary cementitious material (SCM) to the concrete mix such as corn cob ash (CCA) which is obtained by drying, grinding and burning the corn cobs. The chemical composition of the corn cob ash showed that it was pozzolanic as it conformed to the requirements stated in ASTM C618. Replacement of cement with CCA was carried out at levels of 0% (control), 5%, 10%, 15% and 20% and workability test was conducted at each replacement levels. The curing of the cubes was conducted for 7, 14 and 28 days in 3 mediums; water, hydrochloric acid (HCl) and magnesium sulphate (MgSo4). The cubes were weighed and crushed from which it was observed that 5% replacement showed better compressive strength, proving to be the optimum result. Results from 15% and above were unable to attain close enough values to the required strength but showed better resistance when submerged in the sulphate and acid solution. It was also observed that increasing CCA content, reduced the strength deterioration factor (SDF) of the concrete, indicating improved durability and the possible use of CCA for partial replacement of cement in SCC. However, replacement levels from 15% and above require longer curing period to attain better strengths as increase in CCA levels decreases the compressive strength of the concrete.