High Compressive Strength Research Articles

A Novel Method for Preparing Lightweight and High-Strength Ceramisite Coarse Aggregates from Solid Waste Materials.

A novel method is introduced in this study for producing ceramisite coarse aggregates that are both lightweight and possess high strength. The process involves utilizing fly ash as the primary material, along with coal ash floating beads (CAFBs) that have high softening temperature and a spherical hollow structure serving as the template for forming pores. This study examined the impact of varying particle size and quantity of floating beads on the composition and characteristics of ceramisite aggregates. Results showed that the high softening temperature of floating beads provided stability to the spherical cavity structure throughout the sintering process. Furthermore, the pore structure could be effectively tailored by manipulating the size and quantity of the floating beads in the manufacturing procedure. The obtained ceramisite aggregates feature a compact outer shell and a cellular inner core with uniformly distributed pores that are isolated from each other and mostly spherical in form. They achieve a low density ranging from 723 to 855 kg/m3, a high cylinder compressive strength between 8.7 and 13.5 MPa, and minimal water absorption rates of 3.00 to 4.09%. The performance metrics of these coarse aggregates significantly exceeded the parameters specified in GB/T 17431.1-2010 standards.

Microstructure-dependent deformation mechanisms and fracture modes of gradient porous NiTi alloys

Gradient porous structures based on triply periodic minimal surfaces offer exceptional specific strength and multi-functionality. However, strain heterogeneity complicates their deformation mechanisms and fracture modes. In this study, we fabricated a series of gradient porous NiTi alloys based on gyroid (G), diamond (D), and I-WP (I) unit cells, with porosities ranging from 50% to 70%. Surprisingly, the I structure exhibited an abnormally high compressive strength of nearly 600 MPa at around 50% porosity, more than twice that of the G and D structures. This performance gap was attributed to the activation of mixed deformation mechanisms and distinct fracture modes. While the G structure showed a uniform radial strain distribution, the D and I structures displayed pronounced radial strain gradients with concentrated central strains. The D structure deformed through relative sliding of oblique struts, while the I structure maintained macrostructural stability, with thick edge struts providing continuous strain hardening until monolithic fracture. This unique deformation behavior results from the synergistic effects of its intrinsic macrostructural stability, significant radial strain gradients, and sufficiently thicker edge struts. The integration of metallurgical and architectural design principles represents a novel approach to tailoring the mechanical properties of gradient porous metals for advanced applications.

Comparative investigation on the tribocorrosion resistance of Ti6Al4V and 60NiTi alloys inimulated seawater environment

The Ti6Al4V alloy is extensively utilized in critical marine equipment components due to its low density, high specific strength, and exceptional corrosion resistance in marine environments. However, its low hardness and inadequate wear resistance pose challenges in meeting the urgent demand for prolonged service life of relative motion friction pairs under complex wear and corrosion conditions. As a newly developed lightweight friction pair material, hardened 60NiTi is considered highly desirable owing to its combination of high hardness, high compressive strength, and excellent corrosion resistance. Nevertheless, the tribocorrosion properties of 60NiTi compared to those of Ti6Al4V are not yet fully comprehended. The present study conducted a series of sliding wear tests using a ball-on-plate configuration in artificial seawater environment to compare the response of 60NiTi with Ti6Al4V. In order to gain a comprehensive understanding of the factors contributing to the divergence in tribocorrosion response between both materials, further analysis was performed on the wear track subsurface and transfer film using focused ion beam-scanning electron microscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy respectively. The 60NiTi demonstrates significantly enhanced wear resistance in artificial seawater compared to Ti6Al4V, attributed to its combination of high hardness and excellent corrosion resistance. However, Ti6Al4V exhibits a lower friction coefficient (∼0.30) than 60NiTi (∼0.45) due to the formation of a stable transfer film primarily composed of SiO2, Al(OH)3, and Al2O3.

Effect of sintering temperature on microstructure and properties of Cu/graphite composites hybridized with MoAlB ceramic particles

Using a fast hot press sintering technique, Cu/graphite composites doped with MoAlB ceramic particles were synthesized. The impact of varying sintering temperatures on the composites' mechanical, tribological, and microstructure characteristics were studied. The Al element diffused from the MoAlB particles into the copper matrix and produced the MoB phase when the sintering temperature rose over 850 °C. The formation of MoB phase, which was well bound to the matrix, and the formation of Cu(Al) solid solution could improve the plastic deformation resistance of the composites. This, along with the lubrication supplied by graphite, synergistically improved the mechanical and frictional properties of Cu/graphite composites. The composites exhibited remarkable wear resistance (the wear rate was reduced to 3.36 × 10−5 mm3·N−1·m−1) and high compressive strength (266.25 MPa) when the sintering temperature was set to 900 °C. In order to create high-performance copper-based self-lubricating composites, this effort may offer a new research direction.

Optimization of the FDM Processing Parameters on the Compressive Properties of ABS Objects for the Production of High-Heeled Shoes

The influence of 3D printing parameters on compressive properties is an important factor in the application of additive manufacturing processes for products subjected to compressive loads in use. In this study, the compressive strength and compressive modulus of acrylonitrile/butadiene/styrene (ABS) test specimens fabricated using the fused deposition modeling (FDM) process were investigated with the aim of producing products of high-heeled shoes for women. The experimental part of the study includes a central composite experimental design to optimize the main 3D printing parameters (layer thickness, infill density, and extrusion temperature) and the infill geometry (honeycomb and linear at a 45° angle—L45) to achieve maximum printing properties of the 3D-printed products. The results show that the infill density has the greatest influence on the printing properties, followed by the layer thickness and, finally, the extrusion temperature as the least influential factor. The linear infill at a 45° angle resulted in higher compressive strength and lower compressive modulus values compared to the honeycomb infill. By optimizing the results, the maximum compressive strength (that of L45 is 41 N/mm2 and that of honeycomb 35 N/mm2) and modulus (that of L45 is 918 N/mm2 and that of honeycomb is 868 N/mm2) for both types of infill is obtained at a layer thickness of 0.1 mm and infill density of 40%, while the temperature for L45 can be in the range of 209 °C to 254 °C, but for the honeycomb infill, the processing temperature is 255 °C. Additionally, the study highlights the potential for sustainable manufacturing practices and the integration of advanced 3D printing technologies to enhance the efficiency and eco-friendliness of the production process.

Study of metallisation of titanomagnetite burnt pellets

To efficiently process titanomagnetite deposits in the Urals, new technological solutions must be developed. One such solution is the production of metallized titanomagnetite pellets, followed by electric smelting. Modern electric smelting technologies have strict requirements for the materials used, including a metallization degree above 90%, high metallic iron content (>85%), low FeO content (<1%), and high compression strength. This article explores the potential for producing metallized pellets suitable for further processing into electric arc furnace smelting or for HBI production from enriched concentrates of Gusevogorsky and Pervouralsky deposits under laboratory conditions. The scheme for enriching the poor concentrate of Pervouralskydeposithas been developed. The study analyzed the chemical, phase, and mineralogical compositions of the obtained concentrates. The results showed that the total iron content after beneficiation was more than 65% for both deposits. The study concluded that titanomagnetite iron ore raw materials are suitable for the metallization process. The degree of metallization of burnt pellets, after reduction by gas of CO+N2 composition (90/10%) at exposure (240 min), reached 92% and higher.

Synthesis of high-performance polymethylsilsesquioxane xerogels by improving acid catalytic conditions in aluminum chloride aqueous solution

Organic and inorganic acids are common catalysts to promote the hydrolysis of methyltrialkoxysilanes, but they are challenging to modulate the inherent CH3SiO1.5 backbone of polymethylsilsesquioxane (PMSQ) xerogels. Here, an aluminum chloride aqueous solution is proposed for the first time as an acid catalyst to enhance the hydrolysis of methyltriethoxysilane (MTES). This approach allows the PMSQ xerogels to have a more flexible [-Al-O-]m-[SiO]n backbone structure. The optimal concentration of aluminum chloride and surfactant cetyltrimethylammonium bromide in the MTES sol was 1.069 mmol/L and 0.885 mmol/L, respectively, endowing the as-synthesized PMSQ xerogel with a high compression strength of 0.450 MPa and maximum compression strain of 76.1%. Notably, the tiny incorporation of alumina phase (0.4 mol%) in the Si-O-Si backbone made the PMSQ xerogels hydrophobic up to 400 °C for 1 h in the air. The PMSQ xerogels possessed superior thermal insulation properties (32.0–38.0 mW/(m·K)) and could be processed into desired large-sized shapes.

A novel method for MSWI fly ash resource based on calcium component regulation and CO2 mineralization

While accelerated carbonation has been widely studied for the disposal of municipal solid waste incineration (MSWI) fly ash, there has been limited consideration for high-value applications of carbonization products and environmental risks. High-performance CaCO3 ceramics and cement pastes were produced in a low-carbon and sustainable manner by combining calcium extraction, CaCO3 crystal transformation, and cold sintering to reduce the environmental risks associated with heavy metals in MSWI fly ash. The mechanisms of CaCO3 crystal transformation, dissolution-reprecipitation, stabilization of heavy metals (HMs), and hydration of acid-leached solids were explored. Experiments and density functional theory results show that calcite has a stabilizing impact on divalent HMs (Ba, Cd, Ni, Pb, and Zn) (Ei < 0). According to the principles of thermodynamics and crystallography, temperature, pH, and reaction time affected the gradual transition of Vaterite to calcite. The optimal reaction conditions were 10 % ammonia water and 10 min reaction time. Vaterite in CaCO3 ceramics demonstrated outstanding mechanical properties (compressive strength > 265 MPa) based on pressure solution creep. The potential risk of acid-leached solids in alkaline environments was low (The overall pollution toxicity index is only 15). Calcium sulfate (>50 %) in acid-leached solid reacted with aluminate to form ettringite. Strongly alkaline cement pastes with high compressive strengths (>40 MPa) generated from acid-leached cementitious materials posed a low risk of HMs leaching. Throughout the disposal process, HMs leaching concentration in leachate and reaction solution fulfilled Class III groundwater criteria (GB/T 14848–2017). This approach offers environmental benefits and demonstrates broad applicability across diverse alkaline solid waste types.

Superdurable Full-Life Superhydrophobic Composite Block.

Superhydrophobic materials are attractive for industrial development but plagued by poor mechanical stability. Herein, a superdurable full-life superhydrophobic composite block is designed and fabricated by embedding near-zero contractive superhydrophobic silica aerogel into a rigid iron-nickel foam structured similarly to a regular dodecahedron. The synergistic protection afforded by these materials ensures superrobust mechanical stability for the composite block, which features a high compressive strength of up to ≈7.4MPa, and ultralow Taber abrasion of down to ≈0.567mm after withstanding 50000 cycles, and highly efficient water harvesting capability of up to ≈3114.3mg min-1 cm-2 at a supercooling degree of 40 K. This robust material system provides a novel strategy to design superhydrophobic materials capable of withstanding extreme conditions, including high temperature, humidity, pressure, and abrasion.

Mechanical strength investigation of chemically reinforced sandy soil using organic copolymers for geotechnical engineering applications

The chemical reinforcement of sandy soils is usually carried out to improve their properties and meet specific engineering requirements. Nevertheless, conventional reinforcement agents are often expensive; the process is energy-intensive and causes serious environmental issues. Therefore, developing a cost-effective, room-temperature-based method that uses recyclable chemicals is necessary. In the current study, poly (styrene-co-methyl methacrylate) (PS-PMMA) is used as a stabilizer to reinforce sandy soil. The copolymer-reinforced sand samples were prepared using the one-step bulk polymerization method at room temperature. The mechanical strength of the copolymer-reinforced sand samples depends on the ratio of the PS-PMMA copolymer to sand. The higher the copolymer-to-sand ratio, the higher the sample’s compressive strength. Sand (70 wt.%)-PS-PMMA (30 wt.%) sample exhibited the highest compressive strength of 1900 psi. The copolymer matrix enwraps the sand particles to form a stable structure with high compressive strengths.

Utilization of (Ca, Mg)-Zr phosphates adsorbents saturated by Cs+, Sr2+, Co2+ ions in NZP ceramic matrices

A novel approach to the utilization of (Ca, Mg)-Zr phosphate adsorbents saturated by Cs+, Sr2+, Co2+ ions was developed. The main stages include: (i) Cs+, Sr2+, Co2+ ions adsorption, (ii) the drying and shaping by cold pressing, (iii) the sintering. Metal ions leaching from the powder of the spent adsorbent were 0.2–26.5 % in distillation water (рН 4.0–10.0) and tap water, and increased to 6.4–68.2 % in seawater. Calcination of spent adsorbents at 1000 °C led to a decrease in Cs+, Sr2+, Co2+ ions leaching to less than 1.0 % in tap and seawater. The ceramic matrices with a Cs+, Sr2+, Co2+ content of 8.0–30.2 wt %, mechanical compressive strength of 2.9–260.9 MPa, leaching rate of 1.0×10−4 - 4.3×10−7 g/(cm2×day), density of 1.4–3.4 g/cm3 were obtained by cold pressing with subsequent sintering. The samples obtained at molar ratios Zr/(Ca+Mg) of 0.35 and 0.21 were characterized by the highest compressive strength and Cs+ and Sr2+, Co2+ leaching resistance, respectively. The obtained ceramic matrices fitted to the requirements of GOST R 50926–96 and NRC 1991 for solid high-level waste forms.

Effect of high-strength and stainless steel reinforcement on the flexural behavior of UHPC beams

Ultra-high performance concrete (UHPC) is an advanced cement-based composite which shows remarkable properties including very high compressive strength, increased tensile resistance, impressive toughness and excellent durability. One promising application of UHPC is in heavily-loaded beams and slabs where its use can allow for increased design efficiency and improved durability. Conversely, the high bond capacity of UHPC can lead to early bar fracture failures, especially when using low amounts of ordinary steel reinforcement. This paper examines the influence of reinforcement grade on the flexural ductility of UHPC beams. As part of the study, three beams built with either Grade 400 MPa ordinary steel reinforcement, Grade 690 MPa high-strength reinforcement or Grade 520 MPa stainless steel reinforcement, are tested under flexural loading. The key test parameters include the influence of concrete type (UHPC vs. conventional high-strength concrete) and steel type (high-strength or stainless steel vs. ordinary steel). The results show that the flexural strength and ductility of the UHPC beams is influenced by the steel grade/type. The beam with ordinary steel shows a well-defined yield point but fails by bar rupture. Increased resistance by 47% is observed when using high-strength bars, however bar rupture occurs owing to the low strain-capacity of this steel type. Combining UHPC with higher ductility stainless steel does not increase capacity, but leads to remarkable ductility by 75%. As part of the numerical study the behaviour of the beams is predicted using FE modelling and the effects of tension steel ratio, UHPC tensile strength and high-strength or stainless steel type are investigated.

Characterization of Porous β-Type Tricalcium Phosphate Ceramics Formed via Physical Foaming with Freeze-Drying.

Porous β-tricalcium phosphate (Ca3(PO4)2; β-TCP) was prepared via freeze-drying and the effects of this process on pore shapes and sizes were investigated. Various samples were prepared by freezing β-TCP slurries above a liquid nitrogen surface at -180 °C with subsequent immersion in liquid nitrogen at -196 °C. These materials were then dried under reduced pressure in a freeze-dryer, after which they were sintered with heating. Compared with conventional heat-based drying, the resulting pores were more spherical, which increased both the mechanical strength and porosity of the β-TCP. These materials had a wide range of pore sizes from 50 to 200 µm, with the mean and median values both approximately 100 µm regardless of the freeze-drying conditions. Mercury porosimetry data showed that the samples contained small, interconnected pores with sizes of 1.24 ± 0.25 µm and macroscopic, interconnected pores of 25.8 ± 4.7 µm in size. The effects of nonionic surfactants having different hydrophilic/lipophilic balance (HLB) values on foaming and pore size were also investigated. Materials made with surfactants having lower HLB values exhibited smaller pores and lower porosity, whereas higher HLB surfactants gave higher porosity and slightly larger macropores. Even so, the pore diameter could not be readily controlled solely by adjusting the HLB value. The findings of this work indicated that high porosity (>75%) and good compressive strength (>2 MPa) can both be obtained in the same porous material and that foaming agents with HLB values between 12.0 and 13.5 were optimal.

Embracing entropy in glass-ceramics

Glass-ceramics have extensive industrial applications owing to their superior mechanical, optical and physicochemical properties compared to either glasses or ceramics. Herein, we leverage the concept of high entropy materials to broaden the available chemical compositions for tailoring the properties of glass-ceramics. Among various compositions explored, the high entropy glass 45SiO2-20Al2O3-15MgO-11Li2O-1.5TiO2-1.5ZrO2-2P2O5-2BaO-SnO2-CaO was identified as particularly promising, being easily cast with no pores and cracks. Furthermore, we successfully controlled the crystallization process to produce high entropy glass-ceramics (HEGCs) that range from highly transparent to highly opaque. The concurrent crystallization of γ-spodumene and cordierite led to exceptional mechanical properties such as high Vickers microhardness (10.37 GPa), compressive strength (541 MPa), and flexural strength (305 MPa). These findings not only showcase a novel approach to customizing the chemical composition of glass-ceramics, but also suggest the potential emergence of a new class of glass-ceramics. These materials hold great promise for dental, optoelectronics and energy-related applications.

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&amp;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.

Flexural Behaviour of RC Beam with Pond Flyash and ESP FlyAsh

The use of Supplementary Cementitious Materials (SCM) such as Fly ash, Granulated Slag and Silica fume as a replacement for Portland cement in concrete presents one viable solution with multiple benefits for the sustainable development of the construction industry. Out of various supplementary materials, Fly ash is the most widely used material worldwide. Fly ash has excellent structural and durability characteristics. The pore filling effect and pozzolanic properties of Flyash improves the properties of fresh and hardened concrete. In addition to the cost saving bythe replacement amount of cement; it reduces co2emission during the manufacture of Portland cement. In the present investigation, a controlled beam and six number of ESP flyash and Pond flyash beams of size 200 x 100 x 1700 mm were cast. This paper deals with the investigation on the flexural behaviour of beam with pond flyash and ESP (Electro static precipitated) flyash at various cement replacement levels of 4%, 6%, and 8% and the results are compared with controlled beam. The flexural test was conducted to determine the ultimate load carrying capacity of the beams and their corresponding mid span deflection, load point deflection, crack pattern, Stress vs strain are measured. The flexural strength of ESP flyash is increased 24.76% for 8% replacement level and pond flyash is increased 10.97 % for 6% replacement level than controlled beam respectively. This study revealed that the replacement of cement by flyash concrete provides higher compressive strength &amp; flexural strength compared with controlled concrete.

High-quality recycled concrete aggregates developed through an integrated thermomechanical approach

This study demonstrates an integrated thermomechanical treatment process to produce high quality recycled concrete aggregate (RCA) for structural concrete. RCA is mechanically treated after 90 min of heating at 250 °C in this process. The material properties of RCA produced through 15 combinations of charges and drum revolutions are compared using a statistical method. The highest ranking of an RCA identifies it as a high-quality class. Concrete composed of 100% RCA (recycled aggregate concrete, RAC) has 1.7% higher compressive strength than natural aggregate concrete (NAC). RAC has tensile and flexural strengths of 0.95 and 1.03 in fraction of NAC. RAC meets durability criteria such as UPV greater than 4.4 km/s, rapid chloride ion penetration test (RCPT) less than 1000 C, electrical resistivity greater than 208 Ohm-m, and sorptivity closer to NAC. Water absorption and abrasion resistance are similar to or superior to those of NAC. Coherent and uniform surface morphology of RCA enhances the ITZ microstructure in RAC.

Preparation and properties of carbon dioxide foamed concrete using nanoparticles as foam stabilizer and pre–carbonated cement slurry

The stability of carbon dioxide (CO2) foam is critical for preparation and performance of CO2 foamed concrete (CFC). This study evaluated the effectiveness of nanoparticles for stabilizing CO2 foam and pre–carbonation of cement slurry for mitigating CO2 foam loss during CFC preparation, and conducted a comparative study of CO2 foam, pre-carbonized slurry and CFC, aiming at preparing CFC with excellent performance. The results demonstrated that the incorporation of nano–silica can significantly enhance the stability of CO2 foam, with an improved half–life and diameter distribution. The pre–carbonation process optimized consistency and alkalinity of cement slurry and increased the retention rate of CO2 foam after its introduction into cement slurry, thereby facilitating the production of low–density CFC. CFC exhibits high compressive strength and early internal temperature, and has a low water absorption. The presence of CO2 within pores and their subsequent formation of potential negative pressure via carbonation reaction contributed to a much lower thermal conductivity of CFC compared to air foamed concrete. Moreover, a thin layer of calcium carbonate was formed on the inner wall, which can densify the microstructure and modify the pores. Although the carbonation degree of CFC may be lower compared to that of conventional carbonation–cured foamed concrete, the internal and uniform carbonation within CFC greatly enhanced material strength. The non–destructive nuclear magnetic resonance results show that CFC has a more concentrated pore size distribution with fewer fine pores and a smaller pore throat radius.

High Compression Strength and Thermal Insulation Silica Aerogel Monolith with Scaffold of a Cyclic Olefin Siloxane Co-Oligomer via Ambient Pressure Drying

High Compression Strength and Thermal Insulation Silica Aerogel Monolith with Scaffold of a Cyclic Olefin Siloxane Co-Oligomer via Ambient Pressure Drying

Cartilage-Inspired, High-Strength, and Heat-Tolerant Lubricating Hydrogels by Macrophase Separation.

Hydrogels are considered as a potential cartilage replacement material based on their structure being similar to natural cartilage, which are of great significance in repairing cartilage defects. However, it is difficult for the existing hydrogels to combine the high load bearing and low friction properties (37 °C) of cartilage through sample methods. Herein, we report a facile and new fabrication strategy to construct the PNIPAm/EYL hydrogel by using the macrophase separation of supersaturated N-isopropylacrylamide (NIPAm) monomer solution to promote the formation of liposomes from egg yolk lecithin (EYL) and asymmetric template method. The PNIPAm/EYL hydrogels possess a relatively high compressive strength (more than 12 MPa), fracture energy (9820 J/m2), good fatigue resistance, lubricating properties, and excellent biocompatibility. Compared with the PNIPAm hydrogel, the friction coefficient (COF 0.046) of PNIPAm/EYL hydrogel is reduced by 50%. More importantly, the COF (0.056) of PNIPAm/EYL hydrogel above lower critical solution temperature (LCST) does not increase significantly, exhibiting heat-tolerant lubricity. The finite element analysis further proves that PNIPAm/EYL hydrogel can effectively disperse the applied stress and dissipate energy under load conditions. This work not only provides new insights for the design of high-strength lubricating hydrogels but also lays a foundation for the treatment of cartilage injury as a substitute material.