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Research on the Concrete-Filled Double Skin steel Tubular (CFDST) columns subjected to axial force after fire

This article investigates the structural performance of Concrete-Filled Double Skin Steel Tubular (CFDST) columns after fire under the axial compress. 13 experiments were conducted on the residual bearing capacity of CFDST columns under axial compression after different fire duration time. The variation parameters included the hollow ratio, fire duration time and strength of concrete. The effect of different parameters on the axial load and displacement changes after fire was revealed. The experimental and finite element simulation results were compared and analyzed, and they were in good agreement. The results indicate that CFDST columns have good fire resistance, and the strength of concrete has little effect on the residual bearing capacity of CFDST columns after the fire. With the increase of hollow ratio from 0 to 0.72, the axial residual bearing capacity of CFDST columns increases first and then decreases after the same fire duration time. Compared with the column without initial load, the residual bearing capacity of CFDST columns will increase with an initial load before fire, but different initial loads have no significant impact on the ultimate bearing capacity after fire.

Mode I fracture behaviors of plain and PVA reinforced ice at Arctic low temperatures

Since the Mode I fracture of ice materials determines the safety and integrity of ice constructions, this study investigated Mode I fracture behaviorus of strengthened ice materials at Arctic low temperatures. Forty-five three-point bending (TPB) beams, including 12 plain saline water ice (PI) and 33 PVA reinforced saline water ice (PRI), were tested to investigate the mode I fracture behaviors of plain and reinforced ice at low temperatures. The investigated parameters included the low temperature (ranging from −10 °C to −80 °C), ice type (PI and PRI), and mass fraction of fibre (ωf = 0, 1, 2, and 3%), respectively. The failure modes, general P-δ and P-CMOD curves, initial cracking load, double-K fracture toughness, and fracture energy of PI and PRI at low temperatures were revealed. Meanwhile, the effects of temperature and PVA fibre content on fracture behaviors of PI and PRI were also discussed in details. Test results showed that as the temperature decreased from −10 °C to −30 °C, the increments in unstable fracture toughness of PI, PRIA, and PRIB were 414%, 757%, and 250%, respectively. Moreover, the fracture energy of PRI with 3% ωf was 113 times of PRI with 0%. Based on the results and mechanism explanation, three empirical formulae considering the influences of temperature on the unstable fracture toughness of PI, PRIA, and PRIB materials were proposed.

Initial and unstable fracture toughness of quartz-diorite rock under mixed mode I/II loading: Experimental and numerical investigation

The initiation and propagation of crack in rock bodies is a complex process because the rock is a typical quasi-brittle material. In this study, the fracture process of the specimens under four angles of crack inclination (α = 0°, 15°, 30°, and 46°) was examined using the digital image correlation technique, and, based on the double-K fracture model and linear superposition principle, the initial fracture toughness and unstable fracture toughness of the specimens under different fracture modes were obtained. The crack is in the elastic state when the load is less than the crack initiation load; when the load exceeds the crack initiation load, the crack propagates stably; and when the load reaches the peak load, the crack propagation becomes unstable and uncontrollable, which coincides the principle of the double-K fracture model. The initial fracture toughness (KI,IIini) and crack propagation angle (θ0) of the specimens are consistent with the predictions of the MTS criterion. Furthermore, the fracture of the specimens will transform into pure mode I with the extension of crack though they are initially loaded in the mixed mode I/II or pure mode II conditions. Accordingly, the rock fracture toughness at the peak load, i.e., the unstable fracture toughness (KI,IIun), is controlled by the mode I component (KIun) and shows less dependence on the fracture mode. Finally, it was shown that the MTS criterion coupled with the initial fracture toughness is applicable for simulating the fracture of rock specimens under mixed mode I/II loading.

Nitrocellulose-containing sediment as renewable resource for hydrogen and high-pure carbon production

Nitrocellulose accumulated in sludge accumulators does not undergo any changes and remains explosive for decades but it can be used as initial recourse for H2 and nanocarbon production through biogas. Anaerobic biotransformation of waste with a nitrocellulose content of about 75% with native microflora, consortia of mesophilic or thermophilic microorganisms from industrial bioreactors under various volume loading of microorganisms and temperature conditions has been studied. Stimulation by an additional source of biogenic elements and the development of native microflora made it possible to reduce the concentration of nitrocellulose by 44% at 35 °C in 100 days. With a biocatalyst volume loading of 30% at 35 °C with mesophilic biocatalyst 39% of nitrocellulose (with 50% initial volume loading) was conversed to biogas, at 55 °C with thermophilic biocatalyst-99%. The rate constant of decomposition of nitrocellulose using a thermophilic biocatalyst was 0.0248 day−1, while the half–life of nitrocellulose was 28 days.

Maternal, fetal, and perinatal outcomes among pregnant women admitted to an Ebola treatment center in the Democratic Republic of Congo, 2018-2020.

This study aims to investigate maternal, fetal, and perinatal outcomes during the 2018-2020 Ebola outbreak in Democratic Republic of Congo (DRC). Mortality between pregnant and non-pregnant women of reproductive age admitted to DRC's Mangina Ebola treatment center (ETC) were compared using propensity score matching. Propensity scores were calculated using age, initial Ebola viral load, Ebola vaccination status, and investigational therapeutic. Additionally, fetal and perinatal outcomes of pregnancies were also described. Twenty-seven pregnant women were admitted to the Mangina ETC during December 2018-January 2020 among 162 women of childbearing age. We found no evidence of increase mortality among pregnant women compared to non-pregnant women (relative risk:1.0, 95%CI: 0.58-1.72). Among surviving mothers, pregnancy outcomes were poor with at least 58% (11/19) experiencing loss of pregnancy while 16% (3/19) were discharged with viable pregnancy. Two mothers with viable pregnancies were vaccinated, and all received investigational therapeutics. Two live births occurred, with one infant surviving after the infant and mother received an investigational post-exposure prophylaxis and Ebola therapeutic respectively. Pregnancy was not associated with increased mortality among women with EVD in the Mangina ETC. Fetal and perinatal outcomes remained poor in pregnancies complicated by EVD, though novel therapeutics may have potential for improving these outcomes.

Potato peel waste fermentation by Rhizopus oryzae to produce lactic acid and ethanol.

Potato peel waste (PPW), a zero-value by-product generated from potato processing, is a promising fermentation substrate due to its large quantity of starch, nonstarch polysaccharides, lignin, protein, and lipid. Rhizopus oryzae is a filamentous fungus that is mainly known as a lactic acid producer and can ferment various agro-wastes. This study aimed to use R. oryzae for the fermentation of PPW. A series of batch fermentations were conducted to investigate the effects of different PPW loading rates (2%-8%) and particle sizes (0-4 mm). Under an initial PPW loading rate of 8% and particle size of 1-2 mm, the maximum ethanol (18.83 g/L) and lactic acid (3.14 g/L) concentrations, the highest ethanol (9.41 g/L·day) and lactic acid (1.89 g/L·day) average production rates were obtained. Under these conditions, the yield of ethanol and lactic acid was 0.235 g/gPPW and 0.039 g/gPPW, respectively. R. oryzae was shown to utilize PPW as a substrate to produce value-added bioproducts such as ethanol (major product) and lactic acid.

Moment-Rotation Calculation Method and Parameter Analysis for Loose Continuous-Tenon Joint in Column-And-Tie Timber Structure

ABSTRACT To quantitatively calculate the moment-rotation relationship of loose continuous-tenon joints in traditional column-and-tie timber frame, the rotational deformation of loose joints is divided into two stages: free sliding and contact compression. Using constitutive, geometric, and equilibrium equations, a theoretical formula for moment-rotation is derived. The calculated values are then compared with experimental results to validate the accuracy of the theoretical calculation method. A sensitivity analysis is conducted on typical parameters, such as beam height, column diameter, joint clearance, and perpendicular compression modulus of wood, to explore their effects on the moment-rotation relationship of tenon joints. The results show that increasing the perpendicular compression modulus of wood leads to greater bending stiffness and load carrying capacity of tenon joints, with the latter increasing more significantly. In the elastic stage, the rotational stiffness of the joint increases with beam height or column diameter, while after entering the elastoplastic stage, the joint stiffness is less influenced by these factors. The initial rotational stiffness and load carrying capacity of the joint both decrease with joint clearance, and the effect of joint clearance on load carrying capacity decreases as the clearance increases when the joint enters the yielding stage.

Surface Modifications of Superparamagnetic Iron Oxide Nanoparticles with Polyvinyl Alcohol and Graphite as Methylene Blue Adsorbents

Methylene blue (MB) is one of the toxic synthetic dyes that are being discharged heavily into water supplies. Hence, MB removal is one of the most important tasks for a cleaner water supply. By using inexpensive, abundant, and easy-to-synthesize materials, superparamagnetic iron oxide nanoparticles, which were synthesized using the co-precipitation method with polyvinyl alcohol and graphite (SPION/PVA/GR), can be used to adsorb MB. The adsorbent was characterized using FE-SEM, FTIR, XRD, VSM, and BJH. The entrapment efficiency of MB on SPION/PVA/GR after 12 days was 33.96 ± 0.37–42.55 ± 0.39%, at 333.15, 310.15, and 298.15 K, and the initial concentration of MB was 0.017–0.020 mg/mL. The adsorption process can be considered spontaneous, endothermic, chemisorption, heterogeneous, or multilayer adsorption. When releasing MB at 298.15 K and a pH of 3.85 after 7 days, the release percentage ranged from 11.56 ± 0.33 to 22.93 ± 5.06 depending on the initial loading conditions and mainly the releasing temperature following the Higuchi kinetic model. Since this is a novel SPION-based MB adsorbent, optimization, and different forms of adsorbent (i.e., thin film composite) should be further researched.

Low Prevalence of Pre-Treatment and Acquired Drug Resistance to Dolutegravir among Treatment Naïve Individuals Initiating on Tenofovir, Lamivudine and Dolutegravir in Zimbabwe.

Dolutegravir (DTG) use in combination with tenofovir and lamivudine (TLD) is scaling up in Africa. However, HIV drug resistance (HIVDR) data to DTG remain scarce in Zimbabwe. We assessed the prevalence and genetic mechanisms of DTG resistance in people living with HIV initiating on TLD. A prospective cohort study was conducted between October 2021 and April 2023 among antiretroviral therapy (ART) naïve adults (≥18 years) attending care at an HIV clinic in Zimbabwe. Pre-treatment drug resistance (PDR) was assessed prior to TLD initiation and viral load (VL) outcome and acquired drug resistance (ADR) to TLD were described after 24 weeks follow-up. In total, 172 participants were enrolled in the study. The median (IQR) age and log10 VL were 39 (29-48) years and 5.41 (4.80-5.74) copies/mL, respectively. At baseline, no PDR to DTG was found. However, as previously reported, PDR to non-nucleotide reverse transcriptase inhibitor (NNRTI) was high (15%) whilst PDR to NRTI was low (4%). After a median duration of 27 (25-30) weeks on TLD, virological suppression (VL < 1000 copies/mL) was 98% and among the 2 participants with VL ≥ 1000 copies/mL, no ADR was found. HIVDR to DTG is rare among ART naïve individuals. DTG is more likely to address the problems of HIVDR in Africa.

Acidogenic fermentation of potato peel waste for volatile fatty acids production: Effect of initial organic load.

As a renewable carbon source produced from organic wastes by acidogenic fermentation, volatile fatty acids (VFAs) are important intermediates in chemical and biological fields and beneficial to resource recovery and carbon neutrality. Maximizing VFA production by some strategies without additional chemicals is critical to increasing economic and environmental benefits. In this study, the effects of initial organic load (OL) on the performance of VFA production, variations of intermediate metabolites, and the thermogravimetric properties of potato peel waste (PPW) during batch acidogenic fermentation were studied. The results showed that the concentration of VFAs increased with the increase of initial OL, while the VFA yield decreased with the increase of initial OL. When the initial OL was in the range of 28.4g VS/L-91.3g VS/L, the fermentation type of PPW was butyric acid fermentation. The highest butyric acid proportion of 61.3% was achieved with the initial OL of 71.5g VS/L. With the increase of initial OL, the proportion of acetic acid and the utilization rate of protein in the PPW decreased. VFAs were produced from proteins and carbohydrates in the early stage and mainly produced from carbohydrates in the later stage. The production efficiency of VFA was relatively high with the initial OL of 71.5g VS/L, because more easily-biodegradable compounds were solubilized. The results showed that suitably increased initial OL could accelerate acidogenesis, reduce hydrolysis time, and increase the proportion of butyric acid. The findings in this work suggest that PPW is a promising feedstock for butyric acid biosynthesis and appropriate initial OL is beneficial to VFA production.

Evaluation of residual flexural behavior of corroded fiber-reinforced super workable concrete beams

This study investigates the effect of macro synthetic fiber (MSF) volume and crack widths on corrosion of the reinforcing bars and residual flexural behavior of fiber-reinforced super-workable concrete (FR-SWC) beams exposed to accelerated corrosion. FR-SWC beams prepared with 0, 0.33%, and 0.66% MSF were pre-cracked at 0.2-, 0.4-, and 0.75-mm widths before corrosion testing. The controlled crack width was initiated in one set of beams that were then unloaded. The crack width was maintained for another set of beams during corrosion testing by inserting a shim. Test results showed that the use of 0.33% and 0.66% MSF reduced crack development and crack propagation, delayed corrosion initiation time, and significantly increased the residual flexural strength of beams subjected to accelerated corrosion. The beams reinforced with 0.66% MSF enhanced residual ultimate load, residual yield load, and residual flexural toughness by 10%–45%, 38%–113%, and 42%–150% compared to the corresponding non-fibrous beams. The improved flexural performance of beams made with MSF after accelerated corrosion can be attributed to the ability of MSF to reduce crack width due to corrosion damage. Crack width lower than 0.2 mm showed no significant effect on the residual flexural behavior of beams after corrosion testing. However, the pre-crack width over 0.2 mm showed a significant influence on the crack initiation and residual flexural behavior after accelerating corrosion. The pre-cracked beams with a 0.75 mm crack width retained the ultimate load of 65%–76%, yield load of 47%–80%, and toughness of 38%–83%, respectively, compared to their corresponding uncracked beams subjecting to accelerated corrosion. The un-shimmed beams allowed partial closure of cracks due to the presence of MSF after initial loading and increased the residual ultimate load, yield load, and flexural toughness by 7%–45%, 27%–82%, and 3%–56%, respectively, compared to their corresponding shimmed beams. A correlation between the residual flexural behavior and the rate of cross-sectional area loss of reinforcing bars due to corrosion was developed. Furthermore, a mechanism was proposed to explain the effect of MSF in improving the residual flexural performance in the cracked FR-SWC beams.

Organophilic clays for efficient removal of eosin Y dye properties

organophilic local clay materials from Boyolali- Central of Java were prepared via exchange reaction with hexadecyltrimethylammonium bromide (C16TMABr) solution. These materials were used as potential agent for the removal of an acidic eosin Y dye from artificially polluted solution. Different techniques were used to characterise these materials. The uptake amount of surfactants depended on the initial surfactant loadings, different increase of interlayer spacing of clay layers were obtained due to different orientations of the intercalated surfactants. TGA and DSC data indicated that the intercalated surfactants behave differently than the pure surfactant salt, and it was supported by FTIR studies The eosin removal was operated under various conditions such as dye initial concentrations, different amounts of surfactants, solid dose, temperature, and pH. The pH of removal could be attained by modifying the eosin Y solution or the treatment of the organophilic solid by different acid or basic solutions prior adding to natural eosin Y solution. Good removal efficiencies were obtained at acidic pH below 4.The studied materials exhibited a maximum removal capacity of 78.05 mmol/kg, depending of up take amount of C16TMA cations. The removal trials were found to be endothermic and spontaneous. The reactivity of the different dye forms at different pHs values towards the organophilic clay was compared based on the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy values. The regeneration process of spent organophylic clays by a friendly method to the environment was reported and tested over seven successive cycles. Single stage adsorber design was proposed using Langmuir and balance equations, for various volumes of dye solutions at fixed initial concentration and different reduction percentages.

Investigation of the damage of L-HPC under stress corrosion

This paper presents a study on the performance damage of lightweight aggregate high performance concrete (L-HPC) under stress corrosion. While L-HPC was undergoing accelerated corrosion in 15% NaCl solution, it was continuously loaded for 90 d, 180 d and 270 d at stress levels with initial L-HPC peak loads of 0%, 50%, 70%. The chloride ion content change, mechanical property deterioration and microstructural damage of L-HPC were studied in detail. The results show that: The dense structure of L-HPC makes it free from obvious cracks at high stress levels (70% peak load), and the quality does not change significantly. The internal curing effect of the lightweight aggregates makes the interfacial transition zone more dense, which hinders the intrusion of chloride ions. The deterioration of L-HPC was slowed down at the initial stage of stress corrosion, but aggravated at the later stage of stress corrosion due to the corrosion of steel fibers.

Competition Status of Salmonella sp., Shigella sp., and Escherichia coli in Tris Egg Yolk Semen Preservation Medium at Different Experimental Conditions

Competition is a very important fact of microorganisms’ life, with the major goal to gain an advantage in terms of scarce nutrients and limited space. In this study, bacterial competition of Salmonella sp., Shigella sp., and Escherichia coli were assessed in Tris- egg-yolk (TEY) semen preservation medium at two temperature degrees and three periods of incubation (3 h at 37°C, 1 and 7 days at 4°C). The three pathogen species were incubated with an initial bacterial load of 103 CFU/mL. After three hours of incubation at 37°C, there were significant differences (P &lt; 0.05) between the three species; however, Salmonella sp. had the highest CFU/ml compared to the two other pathogen species in bilateral and triple competition. Also after one day of storage at 4°C, a clear dominance of Salmonella sp. was noted, while in contrast, no significant difference (P &gt; 0.05) between E.coli and Shigella sp., was observed in the bilateral and triple competition cases. However, the maximum dominance of Salmonella sp. was observed after 7 days at 4°C, where the bacterial load percentages between all species for the triple competition were 74±5.6/12±5.9/14±6.9 for Salmonella sp., E. coli, and Shigella sp., respectively. In conclusion, regardless of the temperature degrees and the time point of incubation, Salmonella was always able to dominate and compete very effectively compared with the two other bacterial pathogens in the TEY medium. Moreover, 4°C gave clear preference to the survival of salmonella with its clear vitality percentage in this media compared to both E. coli and Shigella sp.

Research on Daily Load Curve Classification Based on Improved Fuzzy C-means Clustering Algorithm

For the problem of severe unpredictability and three-phase unbalance of user demand in low-voltage distribution networks, a daily load curve clustering technique integrating the sparrow search algorithm (SSA) and the fuzzy C-mean clustering algorithm (FCM) is presented. The initial load data set is pre-processed to lessen the interference of classification results. The load characteristic index of the daily load curve is removed to produce a reduced dimensional data set. The clustering validity index is introduced to solve the optimal number of clusters, and the early warning mechanism of the sparrow search algorithm is adopted to improve the global search capability. These improvements are made to improve the sensitivity of the initial clustering center of the FCM algorithm and the problem of local optimum in the process of finding the optimum. The simulation used to validate the revised clustering algorithm’s accuracy and efficacy for daily load categorization is a reference for resolving the three-phase load unbalance issue.

Refined simulation of bond-slip behavior between ribbed steel and concrete: Effects of initial stress and temperature

The bond performance between steel and concrete exposed to fire is influenced by many factors, including the presence of an initial load before the temperature increase. To investigate such effect, a 3-D refined simulation model is presented accounting for the heterogeneity of concrete at the mesoscopic level and the external geometry of ribbed steel bars. The rationality and validity of the refined simulation model and of the multi-step analysis were verified by comparison with existing experimental data. Subsequently, the effects of aggregate gradation and distribution, initial loading level and temperature on the bond behavior were analyzed. The load transfer mechanism at the steel–concrete interface as a function of temperature under different loading levels is captured and discussed. It is found that the influence of aggregate grading and distribution on the bond-slip curve can be ignored under the aggregate volume fraction set in this work. Additionally, results show that the damage initially concentrates at the rib tip of the deformed steel bars, with an increase across the concrete section as the slip increases, as it could be expected. However, the bond stress and both stress and strain of steel at the same position decrease as the temperature increases. Finally and most importantly, it is found that the heating and loading sequence induce a different damage evolution inside the specimen, with a significant effect on the bond stiffness, the plateau portion of the bond stress-slip curve and the bond strength associated to a given critical temperature.

Assessing opportunities and weaknesses of green hydrogen transport via LOHC through a detailed techno-economic analysis

In the transition towards a more sustainable energy system, hydrogen is seen as the key low-emission energy source. However, the limited H2 volumetric density hinders its transportation. To overcome this issue, liquid organic hydrogen carriers (LOHCs), molecules that can be hydrogenated and, upon arrival, dehydrogenated for H2 release, have been proposed as hydrogen transport media. Considering toluene and dibenzyltoluene as representative carriers, this work offers a systematic methodology for the analysis and the comparison of LOHCs, in view of identifying cost-drivers of the overall value-chain. A detailed Aspen Plus process simulation is provided for hydrogenation and dehydrogenation sections. Simulation results are used as input data for the economic assessment. The process economics reveals that dehydrogenation is the most impactful cost-item, together with the carrier initial loading, the latter related to the LOHC transport distance. The choice of the most suitable molecule as H2 carrier, ultimately, is a trade-off between its hydrogenation enthalpy and cost.

Stress-Strain and Resistance-Strain Hysteresis in Single-Wall Carbon Nanotube Films for Stretchable Battery Electrodes

The need to protect the vulnerable and limited resources that are naturally available while meeting the growing energy demand of the world makes the sustainable development of renewable energy of paramount importance. To address these needs, a new type of battery electrode has been developed at Honda Research Institute (HRI), based on free-standing single-wall carbon nanotube (SWNT) films containing active battery materials as dispersed nanoparticles. The SWNT films provide both mechanical support and electrical conductivity, removing the need for metal electrodes (increasing the energy density of the battery) and binder materials (making the process environmentally friendly).Under cyclic strain, the SWNT-based electrodes show hysteretic behaviors in both stress-strain and electrical resistance-strain relations. The electrical resistance-strain behavior shows a different trend from the previously observed behavior on 2D SWNT films (on elastic substrate). We hypothesize that this change can be attributed to the differences in the SWNT network structures in the 2D and 3D films. To understand the microscopic origin of the hysteresis, we performed coarse-grained molecular statics (CGMS) simulations of the SWNT film. The simulations show that the intrinsic Van der Waals interaction between SWNTs is responsible for the observed robust mechanical properties of the electrodes. In addition, our study also reveals that the sparsity of the 3D morphology results in the current being carried across the simulation box only by a few paths. As a consequence, the resistance hysteresis is governed entirely by the change in the power-carrying capacity of the network due to the breaking and formation of contacts between the SWNTs during loading-unloading. The qualitative nature of the resistance-strain hysteresis can thus be attributed to the rapid formation of inter-nanotube contacts, as the nanotube bundles (elongated by initial loading) buckle during unloading.

An [formula omitted]-adaptive discontinuous Galerkin method for phase field fracture

The phase field method is becoming the de facto choice for the numerical analysis of complex problems that involve multiple initiating, propagating, interacting, branching and merging fractures. However, within the context of finite element modelling, the method requires a fine mesh in regions where fractures will propagate, in order to capture sharp variations in the phase field representing the fractured/damaged regions. This means that the method can become computationally expensive when the fracture propagation paths are not known a priori. This paper presents a 2D hp-adaptive discontinuous Galerkin finite element method for phase field fracture that includes a posteriori error estimators for both the elasticity and phase field equations, which drive mesh adaptivity for static and propagating fractures. This combination means that it is possible to be reliably and efficiently solve phase field fracture problems with arbitrary initial meshes, irrespective of the initial geometry or loading conditions. This ability is demonstrated on several example problems, which are solved using a light-BFGS (Broyden–Fletcher–Goldfarb–Shanno) quasi-Newton algorithm. The examples highlight the importance of driving mesh adaptivity using both the elasticity and phase field errors for physically meaningful, yet computationally tractable, results. They also reveal the importance of including p-refinement, which is typically not included in existing phase field literature. The above features provide a powerful and general tool for modelling fracture propagation with controlled errors and degree-of-freedom optimised meshes.

Study on the dynamic fracturing characteristics of aggregate-mortar interface under various loading rates using DIC

The dynamics of fracture characteristics at the aggregate-mortar interface under varying loading rates present a significant area of investigation, pivotal for comprehending the response of concrete to dynamic load conditions. In concrete, the interface between the aggregate and the mortar forms a significant region, fundamentally dictating concrete structures' comprehensive strength and durability. This study aims to investigate the interface crack propagation process, including the crack propagation velocity and the propagation direction using Digital Image Correlation (DIC). Three-point bending beams with a single-size aggregate were fabricated. Beams with different initial crack tip-to-aggregate distances, d0 (aggregate position) of 20 mm, 40 mm, and 60 mm, were tested at five different displacement-loading rates (0.012 mm/min, 0.12 mm/min, 1.2 mm/min, 12 mm/min, and 120 mm/min) using an electro-hydraulic servo testing machine. The crack propagation process was documented utilizing a high-speed video camera. The study reveals a direct correlation between loading rates and concrete's mechanical attributes. The results indicate that as loading rates rise, the compressive strength, tensile strength, and modulus of elasticity of concrete notably increase, while the Poisson's ratio decreases. The initial fracture toughness (KIcini) also escalates with increasing the rates, its sensitivity notably influenced by d0. Concurrently, fracture energy increases with the increase of loading rate and the decrease of d0, a trend more evident at high loading rates. The crack initiation load (Pini) for all single-size aggregate concrete beams was higher than that of plain concrete, and Pini decreased as d0 increased. Observations were made on the trajectory of crack formation, further scrutinizing the effects of d0 and the variable loading rate. Notably, the presence of the interface was found to slow the crack propagation velocity, and this ability to inhibit crack propagation decreased as d0 increased. As the loading rate increased, the crack propagation velocity at the mortar matrix and interface also increased. This study also reports additional material properties, such as critical crack length, and interfacial fracture mode.