Residual Properties Research Articles

Strength attributes and microstructural characterization of basalt fibre incorporated self-compacting concrete

The transformation to produce environment-friendly materials around the world demands the construction industry to promote both high-performance and sustainable construction materials. The focus of the study is to develop basalt fibre (BF) incorporated self–compacting concrete (SCC) which provides a plausible solution to meet the demands of the current scenario. BF is known for its excellent strength, durability, and thermal properties. BF is added to the concrete in a volume fraction of 0.1%–0.5%. The characterization of BF and its utilization in SCC is experimentally investigated to determine its compressive, split-tensile, flexural, residual, and impact strength properties. According to the research findings, BF has reduced the diameter of the flow (695 mm–663 mm) and increased the time of flow (3–5.6 s). In contrast, the compressive strength (=52.86 N/mm2) and split-tensile strength (=4.46 N/mm2) has increased at 0.3% volume fraction of BF whereas the flexural strength (=7.06 N/mm2), residual strength (= 2.724 MPa), and impact strength (=4457.44 kNmm) has increased at 0.4% volume fraction of BF. The improved strength properties are due to the bridging effect and prevention of microcrack progression. The predicted regression-based analytical models exhibited a good correlation with analytical models of international codes. BF showed good interfacial bonding with the surrounding concrete matrix and improved the thermal stability of the concrete. Eventually, the characterization and strength assessment of BF validates that SCC is a potential material that can be performed better in all of its strength attributes with the inclusion of BF.

Operando neutron diffraction reveals mechanisms for controlled strain evolution in 3D printing

Residual stresses affect the performance and reliability of most manufactured goods and are prevalent in casting, welding, and additive manufacturing (AM, 3D printing). Residual stresses are associated with plastic strain gradients accrued due to transient thermal stress. Complex thermal conditions in AM produce similarly complex residual stress patterns. However, measuring real-time effects of processing on stress evolution is not possible with conventional techniques. Here we use operando neutron diffraction to characterize transient phase transformations and lattice strain evolution during AM of a low-temperature transformation steel. Combining diffraction, infrared and simulation data reveals that elastic and plastic strain distributions are controlled by motion of the face-centered cubic and body-centered cubic phase boundary. Our results provide a new pathway to design residual stress states and property distributions within additively manufactured components. These findings will enable control of residual stress distributions for advantages such as improved fatigue life or resistance to stress-corrosion cracking.

Experiment and mechanism investigation on the effect of heat treatment on residual stress and mechanical properties of SiCp/Al–Cu–Mg composites

Low-volume fraction particle-reinforced aluminum matrix composites (PRAMCs) are commonly prepared using powder metallurgy (PM) technology, followed by heat treatment processes to improve the performance of PRAMCs. PRAMCs are prone to produce significant uneven residual stresses during the quenching process. It is difficult to eliminate the quenching residual stress of PRAMCs via the heat treatment process of the matrix aluminum alloy. Therefore, this study systematically investigates the effects of solid solution and artificial aging treatment processes on residual stress, mechanical properties, and microstructure of SiCp/Al–Cu–Mg composites through orthogonal and single-factor experimental methods. After optimizing the heat treatment process, minor residual stress with a 71.6% von Mises residual stress relief rate and good comprehensive mechanical properties are achieved. Based on the experimental results, macro and micro mechanisms of residual stress evolution and strengthening of SiCp/Al–Cu–Mg composites during heat treatment are revealed, providing valuable insights into the process of heat treatment of PRAMCs.

Influence of ferrochrome slag as coarse and fine aggregates on thermal and strength properties of concrete at high temperatures

Ferrochrome slag (FCS) as aggregates in concrete provides a sustainable alternative for the construction industry due to its admirable mechanical, durability, and refractory properties. These characteristics of FCS may aid in increasing the strength and durability aspects of the concrete. However, when subjected to high temperatures, the characteristics of concrete incorporating FCS aggregates are not well understood. Therefore, the study examined the effects of replacing natural coarse and fine aggregates with FCS aggregates on the thermal and strength properties of concrete, as well as the resistance of FCS concrete to high temperatures. Along with the reference conventional concrete mixture, four other concrete mixtures were produced using FCS fine and coarse aggregates at replacement percentages of 25%, 50%, 75% and 100% of natural stone aggregates. The residual mechanical properties, mass loss, ultrasonic pulse velocity, and change in different physical properties of the concrete mixtures were tested before and after experience to high temperatures between 200 °C and 1000 °C. The experimental data is also used to derive the relationship between temperature and strength reduction factors for FCS concrete. The inclusion of FCS aggregates was found to maintain relatively higher mechanical properties and less mass loss in the concrete after heat treatment. The thermal characteristics of FCS play an important role in enhancing the high-temperature performance of concrete with FCS aggregates.

In Silico Physicochemical Characterization of Fusion Proteins from Emerging Amazonian Arboviruses.

Mayaro (MAYV), Saint Louis encephalitis (SLEV), and Oropouche (OROV) viruses are neglected members of the three main families of arboviruses with medical relevance that circulate in the Amazon region as etiological agents of outbreaks of febrile illnesses in humans. As enveloped viruses, MAYV, SLEV, and OROV largely depend on their class II fusion proteins (E1, E, and Gc, respectively) for entry into the host cell. Since many aspects of the structural biology of such proteins remain unclear, the present study aimed at physicochemically characterizing them by an in silico approach. The complete amino acid sequences of MAYV E1, SLEV E, and OROV Gc proteins derived by conceptual translation from annotated coding regions in the reference sequence genome of the respective viruses were obtained from the NCBI Protein database in the FASTA format and then submitted to the ClustalO, Protcalc, Pepstats, Predator, Proscan, PCprof, Phyre2, and 3Drefine web servers for the determination of sequence identities, the estimation of residual properties, the prediction of secondary structures, the identification of potential post-translational modifications, the recognition of antigenic propensities, and the modeling/refinement of three-dimensional structures. Sequence identities were 20.44%, 18.82%, and 13.70% between MAYV/SLEV, SLEV/OROV, and MAYV/OROV fusion proteins, respectively. As for the residual properties, MAYV E1 and SLEV E proteins showed a predominance of the non-polar profile (56% and 55% of the residues, respectively), whereas the OROV Gc protein showed a predominance of the polar profile (52% of the residues). Regarding predicted secondary structures, MAYV E1 and SLEV E proteins showed fewer alpha-helices (16.51% and 15.17%, respectively) than beta-sheets (21.79% and 25.15%, respectively), while the opposite was observed in the OROV Gc protein (20.39% alpha-helices and 12.14% beta-sheets). Regarding post-translational modifications, MAYV E1, SLEV E, and OROV Gc proteins showed greater relative potential for protein kinase C phosphorylation, N-myristoylation, and casein kinase II phosphorylation, respectively. Finally, antigenic propensities were higher in the N-terminus half than in the C-terminus half of these three proteins, whose three-dimensional structures revealed three distinctive domains. In conclusion, MAYV E1 and SLEV E proteins were found to share more physicochemical characteristics with each other than the OROV Gc protein, although they are all grouped under the same class of viral fusion proteins.

Cell-filling reinforced materials for improving the low-velocity impact performance of composite square honeycomb sandwiches: Polymethacrylimide foam vs. aluminum foam

In this study, PMI foam and aluminum foam are used as reinforcement materials for filling the cells of carbon fiber-reinforced composite square honeycomb sandwiches (CSHSs), forming two new sandwich structures, namely, PMI foam-reinforced CSHS (PRCSHS) and aluminum foam-reinforced CSHS (AFRCSHS). The impact resistance and residual flexural performance of the composites is compared by using low-velocity impact (LVI) and three-point bending (3 PB) experiments. The different impact energy levels of 25 J, 50 J, 65 J, and 100 J are applied. The impact and bending failure process and failure mechanism are analyzed using a combination of industrial computed tomography (ICT) and scanning electron microscopy (SEM). PRCSHS and AFRCSHS are compared for various enhancement effects and their resulting lightweight features. The residual flexural and impact resistance properties of the two sandwiches improved significantly. Compared with CSHS, the maximum impact load of PRCSHS and AFRCSHS increased by 115.6% and 78.9%, respectively. Moreover, the impact energy absorption, residual flexural load, and residual flexural energy absorption increased by 30.9% and 21.3%, 80.7% and 58.5%, and 173.1% and 84.3%, respectively. The PRCSHS was noticeably lightweight, but AFRCSHS was not sufficiently lightweight. The qualitative results of comparison of the two reinforcement materials in this study can be extended to other carbon fiber-reinforced all-composite 2D honeycomb sandwiches.

Effect of metakaolin and boron-carbide on the properties of magnetite, basalt and quartz concrete at different elevated temperatures

Nuclear buildings are important radiation-shielding structures. They must be shielded against radiation, fire, or heat during service life. Therefore, thermal properties and behaviour under elevated temperatures are essential in designing the nuclear structure. Furthermore, heavyweight concrete is essential for fire resistance in nuclear buildings. Mineral additives improve the physical, mechanical and fire resistance properties. The paper studied the influence of metakaolin and boron carbide additives on the thermal, mechanical and microstructural properties of magnetite, basalt and quartz concrete. Visual observations, residual mechanical properties and microstructural observations using (SEM) were studied at 20, 150, 300, 500 and 800 ℃. Results showed the enhancement of the compressive strength up to 300 ℃ upon using metakaolin and boron carbide additives. As well as metakaolin and boron carbide caused the spalling of magnetite concrete, where the compressive strength had shown a steep decline above 500 ℃. Furthermore, metakaolin and boron carbide positively influenced the strength properties of basalt and quartz concrete by reducing the permeability level and hindering the decomposition level of CSH. The Scanning Electron Microscopy (SEM) images associated the role of metakaolin and boron carbide in improving cement gel structure and reducing the decomposition level of the concrete.

Durability properties of basalt fiber-reinforced mortars with different mineral admixtures exposed to high temperatures

This study investigated the durability properties of mortars containing basalt fiber and various mineral admixtures against high temperatures. Different types of mortar samples were produced with basalt fiber, metakaolin, silica fume and fly ash. The samples were exposed to temperatures of 400 °C, 600 °C and 800 °C. Residual compressive strength, flexural strength, ultrasonic pulse velocity, mass loss, water absorption, capillary water absorption and microscope analysis tests were carried out. Test results revealed that basalt fiber improved the residual durability properties of the mortars exposed to high temperatures. Basalt fibers exhibited bridging behavior and prevented high temperature-induced cracks. Basalt fibers showed excellent consistency with all three mineral admixtures, and the mineral admixtures increased the contribution of basalt fiber to durability properties. Because of this harmony, basalt fiber-reinforced and mineral admixture-added samples had 86.42% greater residual compressive strength and 144.42% greater flexural strength than the control samples. The void-free internal structure provided by mineral admixtures increased the effect of BF and significantly reduced water absorption, capillary water absorption and mass loss values. UPV tests and microscopic analysis revealed that basalt fiber and mineral admixtures reduced high temperature-induced cracks.

Mechanical properties of Q345 structural steel after pre-fatigue loading

This study investigates the residual mechanical properties of Q345 structural steel previously damaged by pre-fatigue loading. Fatigue damage is induced by subjecting Q345 structural specimens to various loading cycles without causing fracture under three pre-fatigue loading stress levels, which is referred to herein as pre-fatigue damage. Subsequently, tensile tests are performed on these specimens to obtain the stress–strain curves and associated parameters, including yield strength, ultimate strength, elastic modulus, and ductility. Based on the test results, the effect of pre-fatigue loading on the mechanical properties of Q345 structural steel is comprehensively discussed and analyzed. Significant differences are observed in the fracture positions and morphological features of the Q345 steel structure after pre-fatigue loading. Additionally, pre-fatigue loading significantly affects the residual strength and ductility of Q345 structural steel. In particular, the residual ductility of Q345 structural steel reduced significantly after being subjected to different cyclic loadings. However, the effect of pre-fatigue loading on the elastic modulus of Q345 structural steel is almost negligible.

Effects of heat and vibration treatments for welding on residual stresses and mechanical properties

Effects of heat and vibration treatments for welding on residual stresses and mechanical properties

Behavioural studies on binary blended high strength self compacting geopolymer concrete exposed to standard fire temperature

The production of Ordinary Portland Cement Concrete (OPCC) results in high carbon emissions and energy demand, necessitating the search for eco-friendly alternatives. Geopolymers, which utilize waste materials, are identified as a suitable alternative. Industrial by-products such as Fly Ash (FA), Ground Granulated Blast Furnace Slag (GGBS), and Metakaolin (MK) are used as precursor materials for binary blended High Self-Compacting Geopolymer Concrete (HSGC) production. Two HSGC mixes and one normal strength self-compacting mix are developed for comparison. This study aims to look at the residual strength characteristics of NSGC and HSGC specimens. Binary blended NSGC, HSGC, and temperature exposure are the key factor examined in the present study. The current study aimed to evaluate the residual strength of NSGC and HSGC exposed to temperature exposure using the ISO 834 guidelines. HSGC specimens are divided into four groups based on curing and cooling type: ambient curing, oven curing, air cooling, and water cooling. Mechanical properties such as Compression Strength, Tensile Strength, and Flexural Strength before and after exposure to elevated temperature are evaluated. Microstructural investigations are conducted to examine the internal structure of the binary blended HSGC mixes. The experimental results are validated using Indian code (IS 456), American code (ACI 318), European code (EC2), and Australian code (AS 3600). Compressive strength of the HSGC specimens was severely reduced when subjected to 1029 ℃, resulting in the formation of wider cracks attributed to the degradation of the gel structure. The oven-cured specimens possess 72 to 80% loss in strength, whereas ambient-cured specimens possess 77 to 86% loss in strength. The findings reveal that the binary blended mix FA/MK = 1 exhibits higher strength loss (%) compared to FA/GGBS and FA. Ambient-cured HSGC specimens exhibit higher mass loss than oven-cured HSGC mixes, and water-cooled samples show higher strength loss and wider cracks compared to air-cooled specimens. The scientific value of this study lies in the the fire performance and residual mechanical properties of binary blended HSGC mixes developed under various curing and cooling methods. Also, the experimental results are validated with multiple international codes (American, Australian and Indian Standards). These findings contribute to the understanding on the behaviour of HSGC under elevated temperature conditions by providing valuable insights for the development of eco-friendly concrete alternatives with improved fire performance.

Residual Properties of Fibre Grids Embedded in Cementitious Matrices after Exposure to Elevated Temperatures

The use of fabrics in the form of grids embedded in cementitious matrices—usually termed as textile-reinforced mortar, fiber-reinforced cementitious matrix, or textile-reinforced concrete—demonstrate a more stable performance in elevated temperature conditions compared with fiber-reinforced polymers. This study investigated the residual tensile properties of bare yarns and fabrics in the form of grids embedded in a cementitious mortar after exposure to 100 °C, 200 °C, and 300 °C. Three different coated fabric textiles were used as reinforcement: carbon, basalt, and glass. Additionally, scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermos-gravimetric analysis (TGA) were conducted to evaluate potential changes in the internal structure of the fibers and the mortar. The cracking stress, the tensile strength, and the ultimate strain of the composite specimens were increased after exposure to 100 °C, while only carbon and glass fiber grids retained their effectiveness up to 200 °C. At 300 °C, the coupons reinforced with carbon and basalt fibers deteriorated rapidly. Only the glass counterparts showed an improved overall performance due to fiber contraction and the differences in the coating material. The results highlight the differences in the performance of the three fiber types and the important role of the coating material in the overall composite behavior.

Effects of wet torrefaction on physicochemical properties of dark tea residue and pyrolysis products

Effects of wet torrefaction on physicochemical properties of dark tea residue and pyrolysis products

Effect of electromagnetic coupling treatment on the residual stress relief and mechanical properties of 7050 aluminum alloy

Effect of electromagnetic coupling treatment on the residual stress relief and mechanical properties of 7050 aluminum alloy

Physico-mechanical properties of plastic waste-containing gypsum composites exposed to elevated temperature

This study presents the characterization of residual physico-mechanical performance of gypsums incorporating two types of plastic waste (i.e. polypropylene and nylon), after exposure to high temperature (23 °C–300 °C). The bulk density, ultrasonic pulse velocity, young’s modulus and mechanical strength were analysed. Furthermore, the fire reaction performance was evaluated according to standards. Also, an experimental toxicity assessment of gases released during combustion was conducted. As a results, the residual properties of the composites present a higher dependence on the reactions that take place in the gypsum matrix than on plastic waste content. Moreover, plastic-containing composites could be classified as A2 non-combustible material.

Influence of fibre orientation, moisture absorption and repairing performance on the low-velocity impact response of woven flax/Elium® thermoplastic bio-composites

The importance of natural reinforced bio-composite materials with desirable properties such as high modulus-to-weight ratio, good impact resistance, and the ability to be easily repaired is crucial in the industry. A woven flax/Elium® thermoplastic bio-composite is manufactured to challenge these needs. Elium® is the only resin that permits the manufacture of large parts with thermoset-like processes, as Liquid Resin Infusion presented in that work. The paper highlights the influence of stacking fibre orientation, moisture absorption, and repair aptitude on its impact resistance. An instrumented drop tower was needed to conduct low-velocity impact tests at several energies and high-speed image coupled with microscopic observations was used to assess the damage evolution. The impact resistance was improved for the dry (0/90)6 orientation, but moisture absorption decreased its impact peak force by 20%. A three-point bending test was preferred to compression after impact for studying the residual properties after impact. The bio-composites with (±45)6 orientation showed higher impact residual performance than the (0/90)6 orientation, and corresponded to the reduction of maximum bending force by 20% than that of the reference. In addition, a thermo-compression process was applied to repair the impacted plates and conduct multiple impact/repair cycles which showed a significant recovery of stiffness and maximum impact force at 4J on (0/90)6 plates, highlighting their potential for repair in the automotive and marine industries.

Material properties of structural aluminium alloys after exposure to fire

Fire safety is one of the major concerns for the design of aluminium alloy structures. In the case of a fire, the temperature of aluminium alloy structural components can rise rapidly, leading to a considerable reduction in their load-carrying capacities. Since fires typically occur in specific areas of a building and may be extinguished before spreading, it is important that the extent of damage and residual material properties of exposed structural aluminium alloys can be quantified. To this end, the residual material properties of structural aluminium alloys after exposure to fire were investigated through an experimental investigation in this paper. A testing programme, including heating tests and 24 post-fire material tests, was performed. Upon completion of the testing programme, the experimentally obtained key post-fire material properties, including the material elasticity, strengths and strains, were analysed through a series of quantitative and qualitative comparisons with their room-temperature counterparts. The analyses and comparisons generally indicate that elevated temperatures have different effects on the key post-fire material properties of structural aluminium alloys. Then, a series of retention factor predictive models were proposed based on the test data, which were shown to provide accurate predictions of the post-fire material properties of structural aluminium alloys.

Residual behavior of reinforced concrete corbels after exposure to elevated temperatures

AbstractMany precast concrete structures make use of corbels, which are small cantilevers that transfer eccentric point loads to columns or walls. When such structures experience a fire event, the residual strength of their corbels may need to be evaluated. This paper examines the residual behavior of reinforced concrete corbels exposed to elevated temperatures. Sixteen full‐scale double‐corbel specimens with two shear span‐to‐depth (a/d) ratios and different reinforcement layouts were fabricated and tested in ambient conditions or after exposure to temperatures of 550°C and 780°C. The load–displacement behavior, failure mode, and load‐carrying capacity of the specimens were investigated. Exposure to 550°C and 780°C reduced the strength of the specimens by up to 22% and 51%, respectively and increased the displacement at failure between 100% and 150%. The strut‐and‐tie method in ACI 318‐19 provided conservative estimates of the residual capacities of heat‐affected corbels if calculations are based on residual mechanical properties at the surface or average mechanical properties between surface and core of the specimens. When exposed to heat, corbels with smaller a/d ratios showed better strength retention if horizontal distributed reinforcement is used while corbels with larger a/d ratios better retained their strength if employing bidirectionally distributed reinforcement.

Influence of sawdust and flax shives on the high temperature mechanical behavior of earthen materials

Earthen materials have recently made headlines due to their high potential reuse in the construction industry. The growing request of earth-based materials is hampered by the lack of information on the fire behaviour of these materials, in particular for issues of instability. Vegetal additions are frequently used in earth construction because they stabilize the clay fraction’s shrinkage property and improve their insulating capacity. The current study focuses on the role the vegetal additions could play in their implementation inside earthen materials, specifically in terms of the latter's high temperature behavior. At various percentages, sawdust and flax shives were added to a raw earth mix. The percentages of those vegetal additions in the earthen matrix ranged between 0 and 7.5 percent of the dry weight of soil. The used additions were characterized before being mixed with soil that was itself characterized also. The manufactured specimens were therefore made up of a mix of raw earth soil mixed with water and vegetal additions, with the characteristics of each addition considered. The specimens were then heated to high temperatures in a furnace programmed to achieve target temperatures of 150 °C, 300 °C, 500 °C, 600 °C and 800 °C at a heating rate of 1 °C/min. The specimen’s residual mechanical properties were then examined. In the absence of vegetal additions, the compressive strength of the specimens increased with temperature. But, the addition of vegetal additions led to a decrease in strength between 150° and 300 °C, which is greater as the percentage of vegetal additions increased. For a lower mass percentage of vegetal additions (2.5%), the compressive strength increased again between 300 °C and 500 °C; and then between 600 °C and 800 °C for all the tested dosages. The comparison between the two types of vegetal additions illustrated the unfavourable influence of a larger size of additions on the residual properties of specimens. In terms of their contribution to the previously determined properties, the sawdust addition outperformed flax shives.

Influence of sawdust and soil type on the high temperature behavior of raw earth bricks

The current study looks into the high temperature behavior raw earth bricks made with varying amounts of sawdust additives. In addition to the various sawdust amounts, two different soil types were used: “Limon des Plateaux” soil from Beauvais city and clay from Barremian. Before being tested at high temperatures, those bricks were referred to an initial characterization to assess their physical and mechanical properties. At room temperature, the compressive strength decreased with increasing the sawdust mass fraction. The “Limon des Plateaux” soil presented a better resistance than the Barremian clay. After that, the blocks were exposed to high temperatures at a slow heating rate of 1 °C/min inside a furnace programmed to attain target temperatures of 150 °C, 300 °C, 450 °C and 600 °C. The residual physical and mechanical properties of the specimens were then determined. High temperature measurements were also assessed during the heating inside the samples by means of thermocouples that were embedded in their center. The obtained results showed that the compressive strength of the earthen bricks without sawdust increased as the temperature was raised. However, the compressive strength of the bricks with sawdust decreased between 150 °C and 300 °C due to the pyrolysis of the sawdust and then increased again between 300 °C and 450 °C as a result of clay dehydroxylation. The “Limon des Plateaux” soil and Barremian clay with sawdust demonstrated a similar evolution with respect to temperature. The temperature measurements in the center of the samples revealed the influence of the sawdust additives on the temperature distribution inside the sample. The amount of sawdust has an influence on the evolution of the residual properties with temperature. The higher the volume fraction of sawdust, the lower the compressive strength increased with temperature between 20 and 600 °C.