Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is a rare autoimmune disorder involving 1 or multiple organs, most commonly the pancreas, lacrimal glands, and salivary glands. However, IgG4-related sclerosing mesenteritis (SM) involving the small-bowel mesentery is rare. Given that IgG4-related SM usually mimics the imaging characteristics of mesenteric malignancies, its preoperative diagnosis remains challenging. In addition, no specific consensus has been reached regarding the treatment of IgG4-related SM. Therefore, a better understanding of the characteristics, treatment, and prognosis of IgG-related SM is urgently needed. Herein, we report a rare case of IgG-related SM.A 67-year-old man was admitted to our hospital after incidental detection of an abdominal mass on ultrasound imaging, although he reported being generally well. The findings on triple-phase abdominal computed tomography were highly consistent with a malignant mesenteric tumor.The hallmark histopathological features along with elevated levels of IgG4 (145 mg/dL) and imaging findings were indicative of IgG-related SM.The patient was treated surgically. Postoperative histopathological examinations exhibited tissue infiltration with lymphocytes and IgG4-positive plasma cells, as well as fibrosis.Ten days after surgery, the patient was discharged from the hospital, and did not show any clinical sign of IgG-related SM within 1-year follow-up.This case highlights the mesentery as an uncommon site of involvement as well as how early IgG-related SM can be completely asymptomatic. Thus, this study has advanced our knowledge of IgG-related SM and may improve treatments for similar conditions. The pancreas, lacrimal glands, and salivary glands are the most common sites of involvement, whereas the mesentery is rarely affected.–6 To date, only 13 cases of IgG4-related sclerosing mesenteritis (SM) have been confirmed by characteristic histological findings to be manifestations of IgG4-RD.–18 Because it has imaging features similar to malignant tumors and there is a lack of specific markers, it is extremely challenging for physicians to make an accurate diagnosis of IgG4-related SM without histological examination of biopsy or resected specimens. Thus, misdiagnosis is unfortunately quite common. Notably, the current treatment options are based on the recommendations for the management of IgG4-RD as developed by a panel of experts, and no guideline specific to IgG4-related SM has been realized. In addition, the long-term clinical outcomes of IgG-related SM remain unclear. As such, a better understanding of the characteristics, treatment, and prognosis of IgG-related SM is required.IgG4-related disease (IgG4-RD) is a rare autoimmune disease characterized chiefly by tissue infiltration by lymphocytes, IgG4-positive plasma cells, fibrosis as a response to persistent chronic inflammation, and a tendency toward mass formation.In this case study, we present an uncommon case of IgG-related SM in a 67-year-old man. We also performed a literature review and summarized the reported cases of IgG-related SM.2A 67-year-old male patient was admitted to our hospital 10 days after ultrasound imaging revealed a mass inside the abdominal cavity during a routine physical examination. He had no medical history of abdominal surgery.Laboratory examinations showed that his white blood cell and eosinophil counts were in the normal ranges. Triple-phase abdominal computed tomography (CT) identified an uneven, slightly enhanced mass approximately 4 cm in diameter at the root of the small-bowel mesentery in the lower right abdomen, which was surrounded by multiple nodular satellite foci Fig. A. In addThe patient was discharged from hospital 10 days after surgery. At the 1-year follow-up visit, the patient did not show any clinical sign of recurrent IgG-related SM. However, it must be noted that postoperative ultrasound imaging revealed 2 masses on the left side of the parotid glands, suggesting involvement of the parotid glands. Methylprednisolone tablets (24 mg/d) were prescribed, but the patient declined the hormone therapy. There was no apparent change in the parotid masses at the 1-year follow-up.3 The pancreas, lacrimal glands, and salivary glands have been described as the most commonly affected organs. In this case study, we described an uncommon case of IgG4-related SM with the small-bowel mesentery as the involved site.IgG4-RD is a recently recognized autoimmune disease, and the precise etiology and pathological mechanisms remain unknown.The diagnosis of IgG4-SD is not straight-forward; indeed, it is extremely challenging to make an accurate diagnosis without pathologically assessment of biopsy or resected specimens from an involved organ. Although there is no internationally accepted consensus on diagnostic criteria for IgG4-SD, the following Japanese criteria that were established in 2011 by a Japanese consensus group are widely used:(1)Clinical examination showing characteristic diffuse/localized swelling or masses in single or multiple organs;(2)Hematological examination shows elevated serum IgG4 concentrations (135 mg/dl);(3)Histopathologic examination showsa)Marked lymphocyte and plasmacyte infiltration and fibrosis,b)Infiltration of IgG4+ plasma cells: ratio of IgG4+/IgG+ cells > 40% and >10 IgG4+ plasma cells/ high-power field. In fact, no specific serum marker has been determined to be useful for the diagnosis of IgG4-RD.–6 In clinical practice, IgG4-RD is usually diagnosed after tissue biopsy or resected specimens have been pathologically evaluated. In accordance with the Japanese criteria, the diagnosis of IgG4-Rd is confirmed if the 3 criteria are satisfied. In the present case, the histopathology of resected tissue specimens showed the hallmark features of IgG4-RD, together with an elevated level of IgG4 (145 mg/dL), and imaging findings of mass lesions, which together suggested IgG-related SM. Moreover, we also ruled out malignant tumors in the postoperative pathological examination of resected tissue specimens. The diagnosis of IgG-related SM was finally made and confirmed in our patient.Notably, the serum IgG4 level is elevated in a majority of IgG-RD patients, but not in all such patients.–18 The reported IgG4-related SM patients included 8 males and 5 females with an age range of 7 to 82 years . Chronic abdominal pain was commonly described in those cases, while other clinical manifestations include acute local peritonitis and intestinal obstruction caused by invasion of the intestinal wall. The IgG4-related SM in these cases involved a variety of sites, including the mesentery of the terminal ileum, the mesentery at the root of the small intestine, and the entire small-bowel mesentery. Seven patients had a medical history of abdominal surgery, and 1 patient had a history of tuberculosis, implicating a speculative association between previous abdominal surgery and abdominal tuberculosis and IgG4-related SM. It was noticed that 6 patients had serum levels of IgG4 ≥135 mg/dL, and this is consistent with the fact that IgG4 is not always elevated in IgG4-RD. Thus, the cutoff value of ≥135 mg/dL is not reliable for the diagnosis of IgG4-RD. IgG4-RD is a highly heterogeneous disease, and this characteristic has posed considerable challenges in the diagnosis and differential diagnosis of the disease. CT imaging is commonly used for the detection and localization of abdominal masses. All the IgG4-related SM patients had undergone abdominal CT, and analysis of the CT findings revealed the following specific CT features of IgG4-related SM:To better understand the characteristics, course, treatment, and prognosis of IgG-related SM, we conducted a literature search of PubMed using the keywords “IgG4” and “mesenteritis” and retrieved a limited number of reports on IgG4-related SM cases. Of these studies, 12 cases fulfilled the Japanese criteria for the diagnosis of IgG4-related SM. The major of findings from these cases as well as ours are summarized in Table (1)round or oval mesenteric solid tumors with ill-defined margins located mainly at the root of the small-bowel mesentery or the distal ileum mesentery;(2)slightly enhanced on CT;(3)likely surrounded by enlarged lymph nodes;(4)invasion of adjacent intestinal wall or other organs; and(5)mesenteric vessels running through the mass. However, we did not observe these 2 changes on CT in the present patient. Among the 13 IgG4-related SM patients listed in Table 18F-FDG PET-CT and 4 patients showed an increase in radioactive tracer uptake at the lesion sites. However, 18F-FDG PET-CT in combination is also limited for the diagnosis and differential diagnosis of IgG4-RD. The diagnosis of IgG-SM must rely on the histopathological findings of biopsy or resected specimens of the involved organs, during which precaution must be taken to avoid misdiagnosis by excluding malignancies. Typically, a resected biopsy is required for the diagnosis, as needle biopsy may cause intra-abdominal bleeding. For example, only 2 IgG4-related SM cases underwent a needle biopsy for pathological diagnosis, and a majority of the patients were diagnosed with IgG4-related SM based on analysis of resected specimens of involved organs  and pseudocapsule sign were described as specific CT characteristics of IgG4-related SM. However, there is no definitive treatment for IgG4-RD, in particular, IgG4-related SM. Glucocorticoid therapy is associated with the following limitations: high overall relapse rate as high as 30%, relatively long course of treatment, and adverse effects. Also notable is that IgG4-RD is associated with a high risk of progression into malignant tumors. Greenbaum and colleagues recently suggested that, for autoimmune disease-related mass lesions, especially those suspected of malignant transformation, surgical excision should be considered. Given that it is a considerable challenge to distinguish between IgG4-related SM and malignant tumors. For the above reasons, we are more inclined to manage such cases with a surgical procedure. In this case, we adopted a surgical approach for the treatment of IgG4-related SM and prescribed glucocorticoids as the treatment plan for an involvement of parotid glands. The patient did not have any clinical sign of recurrent IgG-related SM at 1 year after surgery. However, it remains uncertain whether IgG4-related SM patients who have not undergone complete resection of SM will need glucocorticoids to prevent recurrence of IgG4-related SM, as conflicting results have been reported.,20 Additional investigations of the long-term clinical outcomes will be needed to understand optimal post-operative treatment for IgG-SM. Moreover, there are currently no individual risk factors associated with recurrent IgG4-related SM that could be used for prediction of recurrence.At present, glucocorticoid therapy is recommended as the first-line treatment for IgG4-RD. The goal of treatment is to prevent tissue fibrosis and the related dysfunction of affected organs. The international guideline on the management of IgG4-RD has been established.In summary, IgG4-related SM is rare, and its preoperative diagnosis is extremely challenging. This case study demonstrates that although an uncommon site, the mesentery can be a site of involvement, and in the early stages, IgG-related SM can be completely asymptomatic. This case study and literature review have advanced our knowledge of IgG-related SM and can be applied in its diagnosis, treatment, and prognosis.Conceptualization: Daguang Wang.Funding acquisition: Daguang Wang.Investigation: Liang He.Resources: Zhicheng Liu.Supervision: Helei Wang.Writing – original draft: Zhicheng Liu.Writing – review & editing: Yan Jiao.


Hydrophobic films are widely used in aerospace, military weapons, high-rise building exterior glass, and non-destructive pipeline transportation due to their antifouling and self-cleaning properties. This paper details the successful preparation of hydrophobic epoxy caged sesquioxane (EP-POSS) via two steps of simple organic synthesis, along with studies on the effects of viscosity and reaction time on the reaction. Interestingly, the EP-POSS presented a large contact angle of 125°, indicating its excellent hydrophobicity. The surface micromorphology was observed via FE-SEM (field emission scanning electron microscopy), transmission electron microscopy (TEM), and atomic force microscopy (AFM), and the structural composition and elemental contents were analyzed via X-ray photoelectron spectroscopy (XPS) and energy-dispersive spectrometry (EDS). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) tests showed that EP-POSS had excellent thermal properties, and the first degradation reaction occurred at 354 °C. The mechanical performance and abrasion resistance results demonstrated that EP-POSS could be used in solar panels. Polyhedral oligomeric silsesquioxane (POSS), suitable for preparing nano-level hybrid materials ,2,3,4, ig) value decreased with POSS introduction because there were a certain number of flexible chain segments in the polymer matrix [g value until it is increased to a certain amount; molecular simulations results demonstrated this conclusion [Recently, application prospects for POSS have been found in liquid crystal materials, ionic liquids, electronic materials, and other fields ,9,10. EPr matrix . The addnclusion . In summPOSS is a cage structure composed of siloxane groups; the Si–O bond energy is 425 kJ/mol, which is higher than that of the C–C bond (345 kJ/mol). The former structure reduces POSS’s surface energy, resulting in a blocking effect on its main chain, which can be used to design hydrophobic material structures . We specKH 560 was purchased from Chengdu Kelong chemical agent company. Tetramethyl ammonium hydroxide aqueous solution (98%) was purchased from Beijing Couple technology co. Ltd. . E51 epoxy resin was purchased from Sinopec Group. Other agents were purchased from Sigma-Aldrich . All of them were used as received.Quantities of 100 mL of isopropanol, 14 g of 4% tetramethylammonium hydroxide aqueous solution, 100 mL of xylene, and 60 g of KH560 were added into a 250 mL three-port flask equipped with a thermometer, a stirrer, and a drip funnel. Then, the KH560 xylene solution was added into the reactor with stirring, completing the addition within 30 min. The solution was then kept under continuous stirring at room temperature for 24 h. The refluxing reaction was carried out in an 80 °C water bath for 2 h, the pH value was adjusted to neutral, and the mixture was stirred at room temperature for 1 h. Then, distillation was carried out to remove the solvent. After washing with acetone and steaming with an alcohol lamp on an evaporation dish twice, a light-yellow viscous liquid was obtained, which was the EP-POSS product. After further drying with the alcohol lamp on an asbestos net, yellow EP-POSS powder was obtained by crushing.Distilled water, concentrated hydrochloric acid, anhydrous methanol, anhydrous ethanol, and silane coupling agent (KH560) were added into a 500 mL three-port flask in certain proportions, and the reaction temperature was adjusted to 30 °C for 8 h. After that, rotary evaporation was carried out to further remove the solvent to obtain low-viscosity POSS under a reaction temperature of 35 °C. The above steps were repeated to obtain high-viscosity POSS.Certain quantities of epoxy resin and low-viscosity or high-viscosity POSS were mixed and stirred, then mixed evenly with diaminodiphenylsulfone curing agent at room temperature, before pre-polymerizing for 5 h. Then, the mixture was injected into a heated mold, with bubbles pumped in a vacuum oven for about 1 h. Finally, the molded material was cured and shaped according to a curing process of 75 °C for 1 h and 110 °C for a further 1 h. After cooling to room temperature, a further curing process was carried out at 240 °C for 3 h. Finally, standard mechanical test specimens were prepared from the samples.2 nano-composites were prepared by mixing POSS with different viscosity levels and a certain proportion of nano-SiO2 in acetone for 10 h, volatilizing the acetone completely at room temperature.The EP-POSS-SiOContact angle testing (CA): Contact angle testing (CA) was conducted with 4 μL droplets of water using a Krüss DSA 30  device at ambient temperature. WCAs (water contact angles) were measured at least three times for each sample at different spots.Scanning electron microscopy (SEM)/energy-dispersive spectrometry (EDS): SEM/EDS study was carried out using a Hitachi model S3000H field emission device ,  for carbon steel surfaces corroded for 12 h in 1 M HCl solution.Fourier infrared spectroscopy (FTIR): the structure of the EP-POSS was characterized via attenuated total reflection Fourier transform infrared spectroscopy .X-ray photoelectron spectroscopy (XPS): The elemental composition of the EP-POSS surface was determined via X-ray photoelectron spectroscopy (XPS), conducted in an ultrahigh-vacuum chamber equipped with an X-ray photoelectron spectrometer   and a non-monochromatized Al Kα X-ray source (SPECS XR 50).Transmission electron microscopy (TEM): TEM was conducted using a Tecnai G2 Spirit Twin12 microscope . The samples were cut at room temperature using an Leica Ultracut UCT ultramicrotome . The 50 nm ultrathin sections were collected on a microscopic grid, covered with a 4 nm carbon layer in order to limit sample damage in the electron beam, and observed in the TEM microscope at 120 kV using bright field imaging.Thermogravimetric analysis (TGA): Mass loss/temperature curves were obtained using a Perkin-Elmer TGA7 device ). The samples were measured at a heating rate of 10 °C/min. Nitrogen was used as a purge gas.Si-nuclear magnetic resonance spectroscopy (Si-NMR): Si-NMR was carried out using a Bruke AVANCE 400 MHz  superconducting nuclear magnetic resonance spectrometer, with DMSO as the solvent and TMS as the internal standard. Testing was carried out at 25 °C.−1 from 40 to 350 °C under a nitrogen atmosphere.Differential scanning calorimetry (DSC): DSC was performed on a TA Instruments  Q20 model using 3–6 mg of sample at a heating rate of 10 °C minAtomic force microscopy (AFM): AFM was conducted using a Digital Instruments NanoScope III , Santa Barbara, CA, USA) equipped with a J scanner; the scanning range was 150 μm, the force constant was 10 N/m, and the tip radius was 10 nm (NT-MDT).3 and the test rate was 1 mm/min.Flexural performance: the flexural test method followed ASTM D790; the specimen size was 3 × 12.7 × 60 mm3.Impact performance: The impact test method followed ASTM D6110; the specimen size was 4 × 12.7 × 125 mm−1, 1020 cm−1, and 850 cm−1 are the C–H stretching vibration, the characteristic peak of the C–O ether structure, and the Si–C stretching vibration, respectively. The sharp peak at 1092 cm−1 is attributed to the cage-like Si–O–Si opposition stretching vibration. In addition, the characteristic peaks of alcoholic hydroxyl groups at 3200–3500 cm−1 disappeared, indicating that the KH 560 was completely consumed. In the Si NMR spectrum of EP-POSS, there is a sharp peak at −83.0 ppm, suggesting that most of the Si elements are in the same chemical environment, and the main target product is a symmetrical cage structure.The chemical composition of the EP-POSS coating was investigated via FTIR, Si NMR, and XPS measurements. The FTIR and Si NMR spectra are shown in The XPS full spectrum and silicon spectrum are shown in The microscopic morphology of the EP-POSS coating was investigated via FE-SEM (field emission scanning electron microscopy), transmission electron microscopy (TEM), and atomic force microscopy (AFM) measurements. As shown in In order to verify the hydrophobic performance, contact angle (CA) measurements were carried out. As shown in Protective coatings for solar panels have higher requirements for light transmittance. If the hydrophobicity is increased, but the light transmittance is reduced, the material does not have application value. The transmittance was tested by examining the UV–vis spectrum. As shown in The introduction of POSS can usually improve the thermal performance of a material. Considering the higher temperature of the actual use environment, DSC and TGA tests were performed on EP-POSS. The test results are shown in The prepared EP-POSS nanocomposite has excellent hydrophobicity and light transmittance, but can its mechanical properties meet the requirements of a protective coating? For the seven nanocomposites prepared, the mechanical properties were characterized by bending and impact performance testing. The bending strength and modulus are shown in 2 nanoparticles with a size of 30 nm, the bending strength was further improved, and the resulting material could be used as a hydrophobic protective coating. Besides this, the high-viscosity EP-POSS-H had higher bending strength, which is attributed to its higher structural regularity, increasing the crosslinking density to obtain good properties.It can be seen from In order to test the surface hydrophobicity changes of solar panels in the actual environment, simulation testing was conducted using samples of size 26 mm × 76 mm and a 500 g weight. The test method is shown in EP-POSS nanocomposite with POSS groups in the main chain structure was prepared by a simple synthesis method under acidic conditions, and the yield reached 94%. The contact angle of the EP-POSS was 125°, showing excellent hydrophobicity due to the micro–nano structure of the surface. The surface Si element exists as Si–C bonds, which have a main chain shielding effect and are beneficial to improving the material’s hydrophobicity. At the same time, EP-POSS showed excellent heat resistance: its initial decomposition temperature was 354 °C. The flexural strength increased from 118.9 MPa to 126.9 MPa, but the impact performance decreased from 38.0 MPa to 32.6 MPa. This is because the POSS group in the skeleton structure improves its rigidity and thermal stability. In addition, the POSS group enhances the hardness of EP-POSS, and the flexibility of the epoxy segment improves the abrasion resistance. The contact angle of EP-POSS was 115° after 200 rubbing operations, indicating that it can be used as a protective coating for solar panels.


The utilization and effectiveness of a custom-made, portable and low-cost structural health monitoring (SHM) system that implements the PZT-based electro-mechanical admittance (EMA) methodology for the detection and evaluation of the damage of flexural reinforced concrete (RC) beams is presented. Tests of large-scale beams under monotonic and cyclic reversal-imposed deformations have been carried out using an integrated wireless impedance/admittance monitoring system (WiAMS) that employs the voltage measurements of PZT transducers. Small-sized PZT patches that have been epoxy-bonded on the steel bars surface and on the external concrete face of the beams are utilized to diagnose damages caused by steel yielding and concrete cracking. Excitations and simultaneous measurements of the voltage signal responses of the PZT transducers have been carried out at different levels of the applied load during the tests using the developed SHM devices, which are remotely controlled by a terminal emulator. Each PZT output voltage versus frequency response is transferred wireless and in real-time. Statistical index values are calculated based on the signals of the PZT transducers to represent the differences between their baseline response at the healthy state of the beam and their response at each loading/damage level. Finite Element Modeling (FEM) simulation of the tested beams has also been performed to acquire numerical results concerning the internal cracks, the steel strains and the energy dissipation and instability parameters. FEM analyses are used to verify the experimental results and to support the visual observations for a more precise damage evaluation. Findings of this study indicate that the proposed SHM system with the implementation of two different PZT transducer settings can be effectively utilized for the assessment of structural damage caused by concrete cracking and steel yielding in flexural beams under monotonic and cyclic loading. An extreme event such as an earthquake can inflict extensive cracking and severe damage on reinforced concrete (RC) infrastructures. Besides, the structural resilience of RC members is also reduced over time due to gradual deterioration processes, such as ageing, reinforcement corrosion, fatigue and damage accumulation. In particular seismically-induced cracks adversely impact the capacity of RC structural members to withstand future earthquakes. The occurrence of wide cracking also leads to a decrease in the stiffness and durability of the member. Prompt and real-time diagnosis of cracking and evaluation of damage degree in existing RC structures would issue early warnings in order to prevent further deterioration decreasing the risk to catastrophic failures ,2,3,4.Within the field of structural health monitoring (SHM) of RC structures, several studies have been devoted to the topic of damage assessment and localization. Early non-destructive inspection techniques were based on the static displacement or strain response of structures or on the response of low-frequency vibrations of the structure by employing algorithms that include damage index methods or the change in stiffness and in flexibility ,6,7,8. MRecent and advanced SHM techniques using smart materials and systems seem to be capable of providing continuous surveillance for the purposes of damage detection in concrete ,19,20. PMany scholars have conducted extensive research on the development and application of EMA-based SHM techniques combined with the implementation of PZT transducers for strength development in concrete ,32,33,34Recent developments in SHM techniques have increased the efficiency of structural integrity assessment procedures. Most of the developed EMA-based SHM methods are rather complex, costly, non-portable, non-easy-to-apply in existing large-scale civil engineering structures and, therefore, not widely used in practical engineering. However, there are some, rather a few, available portable and wireless impedance-based monitoring systems in the literature. Min et al.  developeInteresting research has also been carried out concerning the implementation of portable PZT-based active sensing boards in prestressed concrete. Nguyen and Kim  introducIn the aspect of PZT-based SHM techniques for crack-induced damage detection of large-scale structural members, the early study of Soh et al.  demonstrRecent studies have highlighted that the installation of a network of multiple PZT transducers in areas nearby the potential damage of the examined structural member increases the effectiveness and the accuracy of the SHM method to identify damage providing a reliable diagnosis of its severity ,96,97. AIn the context of this research and in order to clarify the aforementioned issues and further examine the abilities/limitations of the developed innovative custom-made, portable, remote-controlled and low-cost EMA-based SHM system, the present study combines experimental and numerical investigations. The experimental part includes two large-scale RC flexural beams; one tested under monotonically increased loading and the other subjected to full cyclic reversal deformations. Two installations of internally and externally mounted PZT transducers are implemented to diagnose damages caused by steel yielding and concrete cracking. Finite element modeling (FEM) simulation of the tested beams is also included herein to acquire useful information concerning the internal cracks, the steel strains and the energy dissipation and instability parameters. Numerical results provide verification of the experimental results and support visual observations concerning the damage evaluation procedure with the examined SHM system.This study also contributes to further establishing the implementation of EMA-based SHM systems in real-life existing large-scale RC structures for continuous inspection, early damage diagnosis and prompt warnings before fatal failures. The combination of FEM analysis and experiments addressing in this work provides to the research community an alternative SHM methodology. This approach includes an initial numerical investigation of the inspected, undamaged existing RC structure in order to acquire numerical damage indices in terms of internal energy and energy instability values. These numerical results determine preset values of damage parameters that would be used to alert the developed remote-controlled EMA-based SHM system in case of an extreme loading as seismic excitation that would cause severe cracking and structural damages in the monitoring RC structure.(1)vibrate the PZT transducer, that acts as an actuator, by an amplified harmonic excitation voltage,(2)simultaneously monitor the signal of the PZT transducer, that receives the reflected waves acting as a sensor, in terms of electrical impedance,(3)process the measured impedance values in terms of voltage frequency response, and(4)transmit wireless and in real-time the final output response to the user using a Wi-Fi internet connection.In this study, a real-time EMA sensing PZT-based SHM system is implemented for damage detection and evaluation. Called the wireless impedance/admittance monitoring system (WiAMS), it has been developed by Providakis et al. ,41 and aThis integrated SHM system also enables full remote control via wireless fidelity (Wi-Fi) network connections, providing high processing power, email notifications, wireless data upload to structured query language (SQL) database, terminal emulator and iterative scheduled impedance measurements along with magnitude estimations. The device’s central control unit is a single board computer (SBC) Raspberry PI microcontroller that uses Linux as an operating system performing all necessary computing and interfacing tasks via serial peripheral interface (SPI). The developed WiAMS device comprises of two custom-made boards with the AD7357 analog-to-digital converter (ADC) and the AD9837 frequency generator, a custom-made power supply interface board that also connects the individual modules between them and with the central control unit and a piezo driver module. Further details and the numerical aspects that have been considered in the developed SHM system can be found in ,100.totL = 2000 mm, a net length nL = 1700 mm (support to support), while the ″FLC″ beam had totL = 2700 mm and nL = 2250 mm, respectively. The cross-section of both beams was rectangular with width to height ratio b/h = 200 mm/250 mm, and the effective depth was d = 200 mm. The mean cylinder compressive strength of the concrete obtained from compression tests was cmf = 30.85 MPa and 28.20 MPa for the FLM and FLC beams, respectively.The experimental program included two flexural large-scale RC beams. The flexure—monotonic (FLM) beam was subjected to monotonic loading, and the flexure—cyclic (FLC) beam was subjected to cyclic loading, as displayed in fy = 595 MPa and 550 MPa, for the Ø14 and the Ø12 longitudinal reinforcing bars of the FLM and FLC beams, respectively. The top longitudinal reinforcement of the FLM beam consisted of two (2) steel bars with a diameter of 10 mm (2Ø10) that extended only in the shear spans of the beam. The bottom longitudinal reinforcement of the FLM beam consisted of two steel bars with a diameter of 10 mm (2Ø10) extending only into the shear spans of the beam and one (1) bar with a diameter of 14 mm (Ø14) extending along its entire length. The beam also had transverse reinforcement in the form of closed stirrups, with a diameter of 6 mm placed only in the shear spans at 125 mm spacing (Ø6/125). The top and bottom longitudinal reinforcement of the FLC beam consisted of two (2) steel bars with a diameter of 12 mm (2Ø12 top and 2Ø12 bottom). The beam also had transverse reinforcement in the form of closed stirrups, with a diameter of 6 mm at equal 200 mm spacing (Ø6/200). The steel yield strength was measured as 2) and 2 mm thick PZT patches with material mark designation PIC 255  are used in every RC beam as follows:(i)-The FLM beam includes two (2) internal PZTs denoted as “1S” and “2S” at locations shown in -The FLC beam includes four (4) internal PZTs denoted as “1S”, “2S”, “3S” and “4S” at locations shown in Six (6) PZT patches have been epoxy-bonded on the steel surface of the tension reinforcing bars before concrete casting and located inside the tested RC beams:(ii)-The FLM beam includes four (4) external PZTs denoted as “3X”, “4X”, “5X” and “6X” at locations shown in -The FLC beam includes two (2) external PZTs denoted as “5X” and “6X” at locations shown in Six (6) PZT patches have been epoxy-bonded on the concrete surface of the beams and located outside the tested RC beams:Damage diagnosis of the tested RC beams during the loading procedure is achieved using the PZT voltage frequency responses measured by the developed portable SHM devices. Internally and externally installed PZT transducers are used. Especially, six (6) small-sized  with a rated capacity of 50 mm and 100 mm, and 0.01 mm accuracy . Specifically, for the FLM beam, one LVDT with rated capacity 100 mm was placed in the middle of the bending span, two LVDTs with rated capacity 100 mm at distances of 500 mm from each support and one LVDT with rated capacity 50 mm at each support see also . For theyδ and ±125%yδ, where yδ is the deformation at yield. The installed PZT transducers have been excited by an amplified harmonic voltage of 10 V in the time domain range at every central frequency and their voltage signal responses were measured using the developed portable EMA-based SHM devices at different loading steps and at corresponding damage levels εt=εtf,G is the energy needed for the formation of the cracks included in the fracture process zone as well as for the complete opening of a single crack for a unit area crack plane, and can be expressed as:The characteristics of the fracture and the tension softening response of concrete determine the fracture component parameters of the smeared crack model. The fracture energy, tσ–tw curve of A by-linear descending branch shown in fG, can also be simply expressed using the following relationship as proposed by the author in [tf is the maximum tensile strength, and uw is the ultimate crack width. Also, afr is a coefficient that depends on the shape of the stress versus crack width diagram as well the nature and the size of the concrete aggregates, and it ranges from 2 to 8 [afr = 3.3. Further, Lfr is the length of the fracture process zone of concrete that is taken as equal to 3gd [The fracture energy of concrete, uthor in :(8)Gf=0.m 2 to 8 . In the l to 3dg .To further describe the nonlinearity of concrete, the evolution of damage was also considered. The concrete was modeled in the context of the known concrete damaged plasticity (CDP) model presented in ABAQUS. The non-linear behavior of concrete is related to the mechanisms of damage and plasticity. In the CDP model, the concrete’s constitutive behavior is defined by the introduction of scalar damage variables. Multiple mechanisms such as strain softening, gradual deterioration, volumetric expansion etc., can characterize the plasticity behavior. These contribute to a decrease in the strength and stiffness of the concrete. Damage is typically associated with the loss of stiffness.oE is the initial elastic modulus; d is the plastic damage factor which varies from 0 ≤ d ≤ 1, with zero indicating the undamaged material, to one indicating a complete loss of strength.After the completion of the elastic stage the entering in the stage of damage is described with stiffness degradation. Thus, the modulus of elasticity is reduced to:c is cohesion in the yield criteria, which is proportional to stress; and maxc is proportional to the strength of the concrete.Lubliner et al.  states ttd and cd, that correspond to tensile and compressive damage, define the degradation of elastic stiffness in the softening state.cd is the compressive damage variable and cuσ = cmf (mean concrete compressive strength).td is the tensile damage variable and toσ = ctmf (mean concrete tensile strength).Damage is described in the concrete damage plasticity model for both uniaxial tension and compression during the softening procedure. Two damage variables, In the presented FEM, tensile and compressive damage introduced in the CDP model is considered to be in accordance with the previous equations and the diagrams in yf, yε) as well as the stress and strain at ultimate point .Elastic- perfectly plastic behavior was used to model the reinforcing steel material . Before the yielding point the behavior was assumed elastic and was modeled using Young’s modulus according to test data values and Poisson’s ratio equivalent to 0.3. Plastic behavior after the excitation of yield point, was modeled using yield stress and corresponding plastic strain , the analysis time is longer. FEM analysis requires an investigation before selecting the final mesh size starting from a coarser grid and therefore larger finite elements and gradually decreasing the element size and moving to a finer grid. The solution’s convergence with the experimental results is studied until an appropriate size of finite elements is achieved. In the present study, concrete is the most sensitive material to the size of the finite elements due to its high nonlinearity and its overall response with the appearance of cracking and reduced stiffness. The beams were subjected to loading on their top face, which was simulated according to the experiment’s actual loading setup. The FLM beam was tested under monotonic bending loading, as shown in x, Uy, Uz directions), while the right support acted as a roller support (restricted only in Uy direction). This allows the beams to rotate freely at the supports.The boundary conditions were simulated equivalently to the supports of the experimental beam to ensure convergence. The left support was pinned , 3: Second visible crack at load 26.0 kN, 4: Third visible crack at load 36.5 kN, 5: Steel yielding at load 45.7 kN (end of the pre-yield stage II), 6: Post-yield (stage III) at load 47.1 kN and mid-span deformation 8.83 mm and 7: Post-yield (stage III) at load 49.3 kN and mid-span deformation 16.37 mm. Each loading step corresponds to a different damage level that has been diagnosed using the proposed PZT-based SHM technique.The flexural behavior of the FLM beam, shown in t > 0 (blue color).The experimental hysteretic response of the FLC beam subjected to cyclic loading is demonstrated in 0: Healthy state of the unloaded beam, Damage 1: Maximum positive load and deformation of the first loading cycle, Damage 2: Unloading state of the positive first loading cycle, Damage 3: Maximum negative load and deformation of the first loading cycle, Damage 4: Unloading state of the negative first loading cycle, Damage 5: Positive load and deformation at 75% of yield deformation during the second loading cycle, Damage 6: Maximum positive load and deformation of the second loading cycle, Damage 7: Unloading state of the positive second loading cycle, Damage 8: Maximum negative load and deformation of the second loading cycle, Damage 9: Unloading state of the negative second loading cycle, Damage 10: Positive load and deformation at 75% of yield deformation during the final loading, Damage 11: Maximum positive load during the final loading till failure.During the cyclic loading of the FLC beam the following twelve damage assessment procedures have been performed using the proposed SHM method ||V0 is the absolute value of the voltage signal measurements of the PZT at the healthy “baseline” state, p(f)||VD is the corresponding value at the examined damage level and N is the number of the measurements.The following known statistically damage index of the root mean square deviation (RMSD) is adopted to quantify damage assessment using the voltage signal measurements of the mounted PZT transducers:In In In The previous remarks provide sound indications that the proposed SHM technique with the implementation of two different PZT transducer settings can be effectively utilized to access of structural damage caused by concrete cracking and steel yielding in flexural beams under monotonic and cyclic loading.The effectiveness of a custom-made, portable and low-cost EMA-based SHM system that utilizes PZT transducers in various settings to diagnose flexural damages caused by concrete cracking and steel yielding is demonstrated in this study. The experimental project includes two large-scale RC flexural beams subjected to monotonically increased loading until failure and to cyclic reversal deformations. Small-sized PZT patches are have been epoxy-bonded: (a) on the steel surface of the tension reinforcing bars as pre-installed internal transducers before concrete casting and (b) on the external concrete face of the beams. Excitations and simultaneous measurements of the voltage signal responses of the installed PZT transducers have been carried out at different levels of the applied load during the tests using the developed SHM devices, which are remotely controlled by a terminal emulator. Each PZT output voltage versus frequency response is transferred wireless and in real-time to the user of the monitoring system. Values of the known statistical index RMSD are calculated based on the signals of the PZT transducers to represent the differences between their baseline response at the healthy state of the beam and their response at each loading/damage level. Further, FEM simulations of the tested beams have been performed to acquire useful information concerning the internal cracks, the steel strains and the energy dissipation and instability parameters. Numerical results are used herein to verify the experimental ones and support visual observations concerning a more precise evaluation of damage with the examined SHM system.In the case of the monotonically loaded beam, the variation of RMSD damage index acquired from the internal PZT patches bonded on the tension steel bars versus the loading level presents a sudden and gradual increase after the steel yielding point which is a clear indication of damage. Concerning the RMSD index values of the external PZT patches bonded on the concrete face of the beam, an increased tendency of these values according to the gradual opening of the flexural cracks during loading has been observed. However, propagation and magnitude of visible cracks seem not to justify the high RMSD index values obtained from some of the external transducers. In these cases, the numerical results derived from the FEM analysis provide variation of the dissipated energy and cracking patterns using stress distribution data that verify the RMSD index values, indicating that the damage has probably reached more severely the internal area. Thus, the combined experimental and numerical results lead to more safe conclusions about the effectiveness of the proposed SHM method.In the case of the RC beam under cyclic loading deformations, the RMSD index variation of the internal PZT patches versus the loading steps seems to follow the variation of the tension steel bar strain up to the point of steel yielding. After this point, the frequency response of most PZT transducers exhibits high discrepancies with the baseline signal at a healthy state. Although extensive cracking in larger imposed deformation caused the detachment of the external PZT patch from the concrete surface, the crack opening and closing phenomenon during the cyclic reversal tests is captured effectively by the signal responses of these transducers. The RMSD index values derived from the external PZT patched present increases during crack opening due to loading and decreases during crack closing due to unloading of the beam.The combined results derived from the performed tests and FEM simulations indicate the ability of the proposed SHM method to qualitatively identify damage caused by concrete cracking and steel yielding in flexural beams under monotonic and cyclic loading. Quantitative damage assessment is also attempted using statistically scalar damage index variations. For future works, specific values of this index should be determined for severe structural damage initiation to serve as warnings for imminent failures.


The application of waste tire rubber as aggregates in concrete can help to reduce carbon emissions and achieve green gross domestic product (GDP). However, civil engineers still have concerns about using rubberized concrete in structural members. For the safety of structures, the bearing strength of concrete is a very important parameter to be considered in the design. This paper presented the first experimental and numerical study on the bearing strength of crumb rubber concrete. Prisms of both normal concrete and crumb rubber concrete were tested with loading plates of varying sizes. The test results show that the failure modes and deformation behavior of crumb rubber concrete specimens with different rubber contents were similar to those of normal concrete, and the bearing strength of crumb rubber concrete can be well predicted by current standards for normal concrete. Finite element analysis was performed to further determine the effect of rubber content on the bearing strength of concrete. Proper parameter values for modeling crumb rubber concrete by the concrete damaged plasticity model were investigated. Through the numerical analysis, the reason the rubber content does not have an important effect on the bearing strength of crumb rubber concrete with similar compressive strength was found to be that the influence of rubber content on the tri-axial compression behavior of concrete and the ratio of concrete tensile strength to compressive strength is small. The experimental and numerical results presented in this study provide the insights needed to guide the design of structures utilizing crumb rubber concrete. The waste tires are solid wastes that contain up to 90% of vulcanized rubber , which cemission ,4,5. Nowemission ,7,8.Rubber is a hyper-elastic incompressible material and can withstand large deformation. Rubber does not participate in the hydration reaction in concrete, and thus does not change the chemical properties of concrete. The elastic modulus of rubber is much smaller than the other types of mineral aggregate. Therefore, the rubber particles in concrete act as elastic holes and improve its internal physical structure ,10. The The bearing strength of rubberized concrete is one of the most important issues to be studied. The bearing strength is the strength of a concrete block when the load applied within a small area on top surface of the block, that is, being partially loaded, as shown in The bearing strength of concrete is closely related to its tri-axial mechanical properties . UnfortuIn view of the literatures above, it is necessary to carry out experimental research to investigate the bearing strength of rubberized concrete. In addition to the experimental research, numerical simulations can be an effective research method. However, there are limited studies on the simulation of rubberized concrete. Yan et al.  and Han For rubberized concrete, three types of waste tire rubber categorized by particle size were normally used, which are coarse tire chips, fine crumb rubber, and rubber powder, respectively. This paper presents the first experimental and numerical study on the bearing strength of crumb rubber concrete (CRC), in which the crumb rubber was used to replace sand. Prism specimens of NC and CRCs with rubber replacement ratios of 5.0% and 10.1% were loaded as the bearing plates with various sizes. The results of bearing strength were then compared with the existing equations. Finally, in order to examine the bearing strength of CRC with a wide range of rubber replacement ratios and compressive strengths, simulations and parametric assessments were conducted by establishing three-dimensional nonlinear finite element models in conjunction with the concrete damage plasticity model for simulating CRC.σb (F/Ab), which is concentrated under the loading plate, gradually spreads down to a uniformly distributed stress σl (F/Al), as shown in σb can reach several times the uni-axial concrete compressive strength owing to the confinement provided by the surrounding concrete. According to the tri-axial failure criterion of concrete, the state of confining stresses determines the failure stress of the compressive region. The greater the confining stresses, the higher the failure stress. The tensile region fails when the tensile stress reaches the tri-axial tensile strength of concrete, which attributes to that the tensile region is under tri-axial tension. It is worth noting that the tensile strength of concrete should be less than its uniaxial tensile strength.On the basis of elastic stress analysis of the partially-loaded concrete block , it is kσ) on the surface of the wedge satisfies the following Equation (1).τ and σ are the shear stress and normal stress on the wedge surface, respectively; and C and φ are the cohesion and angle of internal friction of concrete, respectively. On the basis of this failure criterion, a bearing strength equation for concentrically loaded specimens was proposed as follows.fcb is bearing strength of concrete; fc is the compressive strength of concrete; fct is the tensile strength of concrete; Al is the block gross area; Ab is the loaded area; and θ is the half of the apex angle of the pyramid, which is (45° − φ/2), as shown in φ, as well as load concentration ratio (Ab/Al). In most current standards , the deρvr) refers to the rubber replacement by equal volume of mineral aggregates. As known, the compressive strength of concrete decreases with the increase in rubber content, hence the relatively higher cement quantity was used in CRC to compromise the loss in compressive strength upon the addition of rubber, thus reaching a similar compressive strength as that of NC. Although the usage of cement in CRC cases is relatively higher than that in the NC case, the total CO2 emission of CRC cases is still expected to be lower owing to the reuse of waste rubber, which will be discussed later in In this study, prisms specimens with dimensions of 150 mm × 150 mm × 300 mm were used. There are four groups as shown in 3 kg/m3. The photos of aggregates are presented in Portland cement CEM-42.5 and naphthalene-based water reducer were used. Coarse aggregates were the crushed limestone with particle size between 5 mm and 30 mm. Fine aggregates were medium sand with fineness modulus of 2.5. The crumb rubber has a size range of 2~4 mm and a density of 1.42 × 10Before casting, the rubber particles were surface-treated with NaOH aqueous solution with 1% mass fraction of NaOH for 30 min, at room temperature, with stirring. Then, the rubber particles were washed with water and dried at ambient temperature. All mineral aggregates, cement, and half of the water were mixed in a mixing machine for 1 min. The rubber particles and the remaining water were then added to the mixer and mixed for another 3 min. Afterwards, the concrete was placed in formworks, and subsequently compacted using a handheld concrete vibrator. The specimens were tested via a servo hydraulic testing machine with a capacity of 5000 kN. The time and load were recorded by machine readings. In each group, specimens were tested by three square loading plates of 150 mm, 75 mm, and 50 mm sides, respectively. As shown in The results of compressive strength of prism specimens are listed in The compressive stress–strain curves of fully-loaded specimens are shown in 2 emission of all raw ingredients in concrete, which comes from the whole process of production, delivery, and disposal, was calculated.In this paper, the impact of addition of rubber into concrete on the environment was also evaluated via the life cycle assessment (LCA) method, which has usually been used as a comparable tool in recent years. 2 emissions of concrete, the inventory data of ingredients come from the Chinese life cycle database (CLSD) [2 emission; however, as a waste material, reuse of crumb rubber can avoid the CO2 emission during its disposal process, hence it should subtract the CO2 emission during disposing waste rubber when conducting the calculation.During the computations of COe (CLSD) , and are2 emission of concrete. It could be found from 2 emission decreases as the rubber contents increase. Compared with NC, the reuse of waste rubber in CRC5 and CRC10 significantly reduced CO2 emission by 60% and 70%, respectively. This is because that the amount of CO2 emission during the process of disposing waste rubber occupies quite a high percentage of concrete, as shown in After reaching ultimate bearing capacities, the loading was continuously applied to six specimens for the punching out of the concrete wedges, which are shown in σl, as shown in The relationship between the measured displacement and compressive strain is shown in βc is the ratio of bearing strength to compressive strength; βL is the square root function of the ratio of supporting area (Al) to area of the bearing plate (Ab); and a and b are the side lengths of the loading plate and concrete block, respectively. Then, Equation (3) can be written asIn this study, only prism specimens concentrically loaded through a rectangle steel plate were used, hence the following equations are provided for simplicity:Fu is the ultimate load. The ratio βc was calculated. βc increased almost linearly with βL, and Equation (6) can give a good prediction. Moreover, there was not much difference between NC and CRC specimens tested at the same curing age in term of βc. Thus, the current standards for NC could be applied on CRC. Regarding the effect of the curing age, βc for CRC with a rubber replacement ratio of 5% at 14 curing days was slightly higher than that at 28 days. Equation (6) gives the conservative estimation for βc.The bearing strength of the specimen was calculated according to Equation (7), and the results are shown in βc. The reason was not clear yet, and further study was carried out by the subsequent finite element analysis.Although plenty of studies have shown that rubber content affects the mechanical properties of concrete, the test results of partially-loaded prisms in this paper show that CRC specimens exhibited similar failure mode and deformation behavior to those of NC specimens, and the rubber content had a negligible influence on The range of parameters studied in the experiment above was small. In view of this limitation of experimental research, finite element models for specimens were established, and the nonlinear constitutive model of rubberized concrete was introduced. The influence of the rubber content on bearing strength of CRC was revealed through a parametric study.The finite element commercial package ABAQUS  was adopThe rigid plastic model was used to model steel material. The Young’s modulus was taken as 210 GPa, while the yield strength was taken as 350 MPa.The concrete damaged plasticity (CDP) model in ABAQUS has been commonly used to model the mechanical behavior of CRC, with its applicability being verified ,25,26. TJ2 is the second invariant of the stress deviator; I1 is the first invariant of stress; σmax is the algebraically maximum principle stress; and α, β, and γ are dimensionless constants as follows:fb0 and fc0 are the initial equibiaxial and uniaxial compressive yield stresses, respectively; ft0 is the initial uniaxial tensile yield stress; and Kc is a constant that determines the shape of yield surface on concrete in the deviatoric plane. The failure wedge of concrete was under tri-axial compression. The compressive meridian when is concrete under tri-axial compression should be paid attention to, which can be derived from Equation (8) as follows:fb0 and Kc should be obtained from equibiaxial and multiaxial compression tests on concrete. Experimental values of (fb0/fc0) for NC are in the range of 1.10 and 1.16. A value of Kc = 0.667 is typical for NC [fl to fc and the ordinate is the ratio of tri-axial compressive strength fcc to fc. The conclusion was drawn that the axial strength and strain of rubberized concrete increase with confining pressure, following a similar trend to that in NC. This indicates that it is reasonable to use the same parameters as NC for CRC in the yield function.The yield function will affect the ultimate capacity of the model. According the yield function adopted by the CDP model , the fail for NC . Howeverl for NC  conducteKc = 0.667 was suggested by many researchers when modeling CRC [Kc were taken as 1.0 and 0.667. Under small hydrostatic pressures, the value of 0.667 predicted the test data well, while under high hydrostatic pressures, a larger Kc value was appropriate. Therefore, it is necessary to choose an appropriate Kc value for accurately predicting bearing strength.A value of ling CRC ,23,25. Hling CRC . Figure G is the flow potential; e is a parameter, referred to as the eccentricity; σt0 is the uniaxial tensile stress at failure; and φ is the dilation angle. The eccentricity parameter was taken as 0.1 for all of the models in this study. The dilation angle varies with the type of concrete and concrete stress states. φ was taken as 45° by Han et al. [φ affected the load capacity and stiffness of the member, and good simulation results were obtained when the value of φ = 30° was chosen. Duarte et al. [φ value for CRC was lower than that for NC, because of the ability of rubber particles to prevent crack propagation and their incompressible behavior. In their finite element models for short steel tubes filled with rubberized concrete, a lower φ value was used for CRC with a higher content of rubber. In view of the existing inconsistency in the φ value for CRC, the effect of φ on the bearing strength was discussed later.A non-associated plastic potential flow rule is used in the CDP model:n et al.  when modn et al.  showed te et al.  believedfcr is the compressive strength of rubberized concrete; ρvr is the rubber replacement ratio; fc0 is the compressive strength of concrete without rubber content; and λ is the function of the replaced mineral aggregate size:dg is the replaced aggregate size and dg,max is the maximum mineral aggregate size.fctr and Ecr are the tensile strength and elastic modulus of rubberized concrete, respectively.εcr1,1 and εcr0,1 are the crushing strain of rubberized concrete and normal concrete, respectively.wmax,r and wmax,0 are the maximum crack width of rubberized concrete and normal concrete, respectively. The calculated compressive strain–strain curve for each group is shown in A number of experimental studies on the mechanical properties of rubberized concrete showed that the addition of rubber particles significantly reduced the strength , elastic modulus of concrete, and ductility . Existinv) than NC. Its effect on bearing strength needs to be discussed. Duarte et al. [v of the rubberized concrete based on the ‘‘rule of mixtures”:vRuC and vNC are the Poisson’s ratio of rubberized concrete and normal concrete, respectively; vrubber is the Poisson’s ratio of rubber particles; and Vconcrete and Vrubber are the volumetric fraction of concrete matrix and rubber particles in rubberized concrete mixes, respectively. For CRC5 and CRC10 groups in this study, the values of Vrubber were 7% and 14%, respectively. By assuming that vNC equals 0.16, the values of vRuC for CRC5 and CRC10 groups were calculated to be 0.18 and 0.21, respectively.The Poisson’s ratio of the rubber particles is close to 0.5. As a result, the rubberized concrete has a higher Poisson’s ratio , v, the ratio (fb0/fc0), Kc, and φ. The initial values of these parameters were taken as their commonly used values, which were 0.3, 0.16, 1.16, 0.667, and 30°, respectively. When one of the parameters was calibrated, the initial values were taken for the other parameters. As shown in u is greater than 0.1, its influence on the calculation results can be ignored, so the value of 0.3 was used for NC models. As shown in fb0/fc0) were also small, so the initial values were taken. The calculation results in βc decreases with the increase of the value of Kc. The trend is more obvious when βL is larger, because the confining stresses in the compressive region increase with βL, and Kc has a greater impact on the concrete failure strength when concrete is under a larger confining pressure, as shown in βL in this study was 3.0, the commonly used 0.667 was adopted for simplicity. βc increases with the increase of φ, which agrees with the trend predicted by Hawkin’s formula [φ for the failure wedges in NC specimens, φ was taken as 50°.These parameters included the coefficient of friction , and Kc were not changed in finite element models for CRC specimens. Moreover, vRuC was taken as the same value as vNC, because the parametric analysis had shown that it had little effect on bearing strength. In addition, because the measured values of φ for CRC specimens were close to that of NC specimens, the value of φ was also not modified. It can be seen from φ was within 10%. The values of βc fluctuated with ρvr when βL was 5.0, the influence of rubber concrete on βc was very limited. This indicates that, when the compressive strength of CRC is determined, its bearing strength is not affected by the rubber contents. Thus, the reason the results of the three groups of specimens in the experiment differed slightly is that their difference in compressive strength was small.βc increased notably.Further discussions were made by calculating bearing strength of CRC with different compressive strength. fct/fc) is one of the key factors determining the bearing strength. A new equation including the ratio (fct/fc) as a parameter was proposed for the prediction of the bearing strength based on a Mohr failure criterion [α and β depend on the dimensions of the loading plate and concrete block. The fact that lightweight concrete specimens exhibited significantly lower bearing strengths than normal-weight concrete specimens was found to be because lightweight concrete has a lower value of ratio (fct/fc) [fct/fc) increased in RPC with steel fibers and βc was larger than that of RPC without steel fibers.The above numerical results indicated that the compressive strength of CRC is the main factor affecting its bearing strength. In fact, Roberts-Wollmann et al.  pointed riterion :(21)Fu=f(fct/fc) . The sig(fct/fc) , who comβc increases as the ratio (fct/fc) increases. However, for CRC of the same compressive strength with NC, the influence of rubber contents on the ratio (fct/fc) is small [fct) of both CRC and NC was calculated according to Equation (16). As a result, the rubber content does not have an important effect on the bearing strength of CRC, which has been confirmed by experimental results. However, when the compressive strength of CRC is smaller than that of NC, the ratio (fct/fc) is larger, as indicated by Equation (22), which was obtained by dividing both sides of Equation (16) by fcr. Then, the bearing strength of CRC would be larger than that of NC.is small , and theIn this paper, the bearing strength of CRC under partial area loading was investigated via experimental and numerical analysis. The main conclusions can be drawn as follows.From experimental observation, the CRC and NC specimens show similar failure modes and deformation properties, which implies that rubber particles have not changed the force transfer and failure mechanism of concrete under partial area loading. At the same time, the measurement results of failure wedge indicate that the difference in the dilation angle of the two types of concrete is not as large as expected.Although rubber particles have an effect on some mechanical properties of concrete such as elastic modulus, Poisson’s ratio, and dilation angle, it can be seen through finite element parameter analysis that these parameters have little influence on the bearing strength of concrete. On the other hand, CRC and NC have a small difference in the key mechanical properties that affect bearing strength, such as properties under multi-axial compression, the ratio of tensile strength to compressive strength, and so on. This ultimately leads to the similar bear strength of CRC and NC when their compressive strength is the same.The existing formula for calculating the bearing strength of NC can be used to predict that of CRC, including its value at early concrete age, which is very beneficial to the design of CRC structural members.The results in this study would alleviate the concerns of civil engineers on calculating the bearing strength of CRC. The important factors that affect the bearing strength of concrete were revealed. It is suggested to study the bearing strength of steel-fiber reinforced CRC to further evaluate the effect of the ratio of tensile strength to compressive strength on the bearing strength.


The use of construction and demolition wastes (C&DW) is a trending future option for the sustainability of construction. In this context, a number of works deal with the use of recycled concrete aggregates to produce concrete for structural and non-structural purposes. Nowadays, an important number of C&DW management plants in the European Union (EU) and other countries have developed robust protocols to obtain high-quality coarse recycled aggregates that comply with different European standards in order to be used to produce new concrete. The development of self-compacting concrete (SCC) is another way to boost the sustainability of construction, due to the important reduction of energy employed. Using recycled aggregates is a relatively recent scientific area, however, studies on this material in the manufacture of self-compacting concrete have proven the feasibility thereof for conventional structural elements as well as high-performance and complex structural elements, densely reinforced structures, difficult-to-access formwork and difficult-to-vibrate elements. This paper presents an original study on the use of coarse recycled concrete aggregate (CRA) to obtain self-compacting concrete. Concrete with substitution ratios of 20%, 50% and 100% are compared with a control concrete. The purpose of this comparison is to check the influence of CRA on fresh SCC as well as its physical and mechanical properties. The parameters studied are material characterization, self-compactability, compressive strength, and tensile and flexural strength of the resulting concrete. The results conclude that it is feasible to use CRA for SCC production with minimal losses in the characteristics. The construction sector has seen an exponential growth in recent decades throughout the European Union (EU). This growth has led to an increase in the production of construction and demolition waste (C&DW). The developed countries are a major consumer and generator of waste. According to the European Statistics Office, Eurostat, every EU citizen produces an average of 2000 kg of waste per year  .More than a third of all waste generated in the EU comes from the construction sector considering that, after water, aggregates are the raw material most heavily-consumed by man and it is mainly used in concrete, which means the valorisation of this type of waste needs to be promoted. This would reduce the extraction of natural aggregates and eliminate difficult-to-manage waste ,3.Government agencies, the scientific community and the population, in general, are becoming increasingly aware of the depletion of natural resources and advocating sustainable development, which leads to the need of recycling waste so that resources can be part of a circular economy and can be sustained from generation to generation. Everyone is aware of the need for combining economic development with sustainability and environmental protection.It is in this context that new applications and developments for C&DW have been studied. The production of concrete with recycled aggregates has been one of the most often studied applications. It is true that some reliable studies currently support the use of C&DW in conventional concrete ,7,8,9,10In these studies, on the one hand, a reference (or control SCC) concrete mix with natural aggregates is designed and, on the other hand, different mixes of SCC with various incorporation ratios of coarse recycled concrete aggregate (CRA) are tested to compare with the control SCC. Most of the studies only replace the coarse fraction of the aggregate and only some of them replace the sand fine fraction. We have selected the studies in which the recycled aggregates come from old concrete structures as in our case, discarding other normally using ceramic materials.3. The water absorption of the recycled aggregate was 5.08%, and the SP ratio was kept constant (0.7% relative to the weight of cement) and the water content was adjusted, increasing with the substitution ratio.Grdic et al.  designed3 of 342 kg/m3. The W/C ratio and the content of SP are constant in all the mixes, 0.60 W/C and 1.50% respectively. The water absorption of the recycled aggregate used was 1.32%.Safiuddin et al.  designed3. Three W/C ratios are used, 0.43, 0.48 and 0.53. The SP content was adjusted in relation to the percentage of replacement from 0.95% to 1.97% of the cement weight. The water absorption of the recycled aggregate was 4.80%.Tuyan et al.  design f3. The W/C ratio was 0.53. The SP was adjusted in relation to the replacement ratio from 1.3% to 1.58% of the cement weight. The water absorption of the recycled aggregate used was 5.64%.Modani et al.  studied 3. The W/C ratio was 0.56 and 0.57. The SP was adjusted in relation to the replacement ratio from 1.19% to 2.10% of the cement weight. The water absorption of the two used recycled aggregates was 4.10% and 4.05%.Pereira de Oliveira et al.  designedAs a general rule, a number of studies specify that the addition of recycled aggregates in small proportions (≤20%) in substitution of natural aggregates in concrete does not lower the performance of the resulting concrete. These studies have made it possible for these types of recycled materials to be included in standards and/or recommendations throughout the world. At a national level, Annex 15 “Recommendations for using recycled concrete” of the Spanish Structural Concrete Instruction EHE-08  sets forSCC is a high-performance concrete, the main characteristic of which is its fluid and viscous consistency allowing it to flow through densely reinforced structural elements without the addition of outside energy for compaction. Its composition is characterized by a high cement and fine particle content, a lower proportion of coarse aggregate and the use of next-generation additives .The materials used to produce SCC are the same as for conventional concrete yet with some type of admixture, such as superplasticizer (SP) or viscosity modifiers, which are essential to avoid segregation and exudation of the mix. Special attention must be paid to the choice of materials in order to guarantee uniformity and consistency. This is complicated when using recycled aggregates for substitution purposes considering their great heterogeneity .Some authors and studies recommend the use of Portland cement Type II (with a clinker content between 65% and 94%) for use in concrete with recycled aggregates to prevent the generation of alkali-aggregate reactions . Other a3, the cement content 250–500 kg/m3, and the paste volume above 350 litres/m3.Annex 17 “Recommendations for the use of SCC” of the Spanish Structural Concrete Instruction EHE-08  providesThe use of recycled sand is not allowed by the Spanish Instruction for Structural Concrete  even thoThe aim of this research study is to characterize recycled aggregates and design the optimal and feasible content to produce SCC by substituting coarse aggregate fractions with recycled aggregates at 20%, 50% and 100%. The purpose of this comparison is to examine the influence of CRA on SCC concerning the fresh and physical and mechanical properties. Four types of concrete mixes were produced for this study . The characterization of the materials in the mix was studied, compactability tests were performed on the fresh state as well as tests in the hardened state: compressive, tensile and flexural strength.The use of recycled aggregates in the production of self-compacting concrete has been gradually increasing due to the economic and environmental advantages derived from the fusion of the two techniques. On the one hand, there are the advantages of SCC: optimal compaction without vibration, fluidity, complex or specially reinforced works, increase in the quality of the finish in exposed concrete, and greater adherence. On the other, there are the advantages of recycled aggregates: less demand for extraction of natural aggregates from quarries, reduction of the pollution produced by C&DW, savings in transport costs, low energy consumption, less investment as a good quality material is produced at a low cost, and resources are optimised. However, information on the quality of SCC with RCA is still scarce. This study (as well as other similar ones) provides very useful information for the practical use in concrete production. One of the main novelties of our study is the use of real coarse recycled aggregates, obtained from a C&DW management plant, with standard treatment, unlike some other studies that use a specific recycled aggregate obtained from only one specific demolition, construction or maintaining work.This research focused on the study of the mechanical and rheological properties of SCC produced with coarse recycled aggregates from crushed concrete elements designed as per the Okamura recommendations  as well The characteristics of the materials used in its production were carefully studied in the design of SCC as this has an immense impact on the behaviour of the mix. The paste for the concrete mixes was made with Portland CEM Type III/A 42.5 N/SR cement, which complies with the physical, chemical and mechanical requirements established in European standard EN 197-1:2013 . The cemNatural lime filler from a commercial plant was used as an addition. The chemical composition is shown in Three aggregates were used to produce concrete: 0–4 mm fine siliceous aggregate, 4–12.5 mm natural siliceous river gravel and 4–12.5 mm recycled aggregate from concrete elements. The characteristics of the aggregates used are specified below. The recycled aggregates were supplied by C&DW recycling plant. The physical and chemical characteristics established by EHE-08 were used to check the degree of compliance of the results with the acceptable limits . Figure The absorption of aggregate is slightly lower than the EHE-08 limit. This type of aggregate often shows high absorption values, but this specific aggregate is not affected by a higher absorption capacity due to the small quantity of ceramic material and attached mortar. Therefore, in principle, it does not need to be offset with a larger quantity of mixing water. The natural siliceous river coarse aggregate was supplied by a local company. It has a grain size of 4-12.5 mm. The quantitative analysis of the chemical composition of the natural coarse aggregates was carried out by means of X-ray fluorescence (XRF). The fine natural aggregates also have a siliceous nature with a grain size of 0-4 mm. The grain size curve is described in A third generation commercially available superplasticizer (SP), an aqueous-based modified polycarboxylate was used.Finally, the mixing water used came from the city of León drinking water supply. It meets the standards established in EHE-08.3 and a W/C ratio of 0.47 were used as indicated by the standard.SCC was designed considering the instructions found in EHE-08  and follConcrete was mixed in a vertical axis planetary concrete mixer. Once mixing ended, the mix was poured into different moulds, according to the proposed test and then submerged in a curing chamber for 28 days.A reference concrete or control mix was designed as well as mixes substituting 20%, 50% and 100% of coarse natural aggregates with coarse recycled aggregates .The amounts of materials used in the mix are shown in The base mix was modified by increasing the superplasticizer volume  to achieve the self-compactability parameters, finally determining an optimal quantity of admixture of 0.8% with respect to the weight of cement for the control concrete. The W/C ratio was maintained in the mixes, for comparability purposes.Different batches have been done to test the rheological and mechanical characteristics of the mixes. Four different batches per mix  were produced (1) for J-ring test, (2) for compressive strength, (3) for flexural strength, and (4) for tensile strength tests. The number of samples per batch was at least three, to ensure enough representativeness of the results.The concrete mixing procedure used for all samples was based on standard EN 12390-2:2009 , followiFirstly, the mixer was moistened with water to prevent accumulation. The coarse natural and/or recycled aggregates were added from largest to smallest and later sand was added and then mixed for 10 s. The cement and filler were added and mixed for three minutes, slowly pouring in the mixing water with half of the superplasticizer, with time beginning upon completely pouring in the mixing water. The mix was left to stand for three minutes and was then mixed for another two minutes. The rest of the superplasticizer was poured homogeneously during no more than the first 10 s. The mixing was completed and testing began with fresh concrete.To determine the self-compacting parameters prescribed, a flow test was done as per EN 12350-8:2011 , as wellCompressive strength was determined in the hardened state as per EN 12390-3:2009  at 7, 14Tensile and flexural strength were determined in the hardened state as per EN 12390-6:2010  and EN 1It is a concrete-sourced material that comes from C&DW of concrete elements with little rock, ceramic and gypsum impurities. As can be observed, the grain size of the recycled aggregates as well as of the natural aggregates is 4.5–12 mm, which exceeds the minimum size requirements for aggregates established by the Spanish code EHE-08. Although the minimum size of 4 mm is limiting, the grain size is believed to favour the self-compactability and workability of concrete adequate for these applications. Other studies often use grain sizes closer to 8–16 mm .3 to 440 kg/m3 and compensating this range of values with more or less fine particles [The amount of cement and W/C ratio limit values established by EHE-08 were complied with. According to the conclusions of other experimental studies ,19, the articles ,19,26. OIn the mixes proposed herein, the W/C ratio was maintained at 0.47 and no extra mixing water was added even though other authors correct this ratio as the proportion of recycled aggregates is increased, with up to 10% extra mixing water . Other aThe mixes were repeated twice, and the slump flow was measured with the J-Ring test . The Jap500 results of the concrete designed with different CRA contents are shown in 500 slump flow time varies between 4 and 5 s , which greatly influences the self-compactability of the mix. Readjusting the content of SP in some of the mixes could be considered: e.g., adjusting Mix 20 to 1.05–1.10% of SP and mix 100 to 1.325% of SP would be appropriate.-Based on the flow class: Class AC-E1,-Based on the viscosity class: AC-V1,-Based on the blocking resistance class: AC-RB2.The classification obtained for concrete as per the criteria found in EHE-08, Annex 17  and stanIn general, class AC-E1 is the most adequate for most structural elements normally built, although it would be better to use a more fluid concrete such as type AC-E3 with 750 mm ≤ SF ≤ 850 mm for densely reinforced structures and formwork that is difficult to access or demands a long horizontal pouring displacement .The compressive strength test was determined as per standard EN-12390-3 . The resGrdic et al.  concludeTuyan et al.  found thThe study of Modani et al.  concludePereira de Oliveira et al.  establisThe comparison with previous studies showed that, for a 20% substitution ratio, our results share the same trend and range of Tuyan et al. (a)  and Pereck of 40 MPa, coherent with the W/C ratio and the amount of cement used.With these compressive strength values, it is perfectly possible to reach fIn terms of splitting tensile strength, the results of all mixes are shown in Tensile strength decreases with the replacement of CNA with CRA, as expected. For an increase in RCA content, the tensile strength decreased by 12.71%, 31.25% and 30.60% in the mixes with CRA ratios of 20%, 50% and 100% respectively.Tuyan et al.  concludeModani et al.  concludeConcerning this parameter, our work matches previous results of other authors for substitution ratios between 20% and 50%, keeping the same trend. There is hardly a difference of ±1 MPa between them. Equally, for a 100% substitution, our results are in line with results obtained by Modani et al. . Figure Other authors had similar test results and concluded that tensile strength decreases as the CRA incorporation ratio increases, which can be justified by the lower strength and greater porosity of CRA compared with CNA ,27,29,30The results obtained for flexural strength for all mixes are shown graphically in In terms of flexural strength, the recycled aggregates studied herein did not lead to a notable difference relative to CC. The values are almost constant, and hardly suffer a variation of 4%.Grdic et al.  concludeGenerally, authors found that flexural strength decreases as the replacement ratio increases, which is explained by the old mortar adhered to CRA  Figure . In thisIt is feasible to achieve an SCC with recycled aggregates. SCC was produced with this C&DW as aggregate in the proportions recommended by EHE-08 of 20% substitution and above 50% and 100% with minimal loss in the properties. The SP content needs to be increased as RCA content increases, so CC concrete contains 0.8% of the weight cement, Mix 20 contains 1%, Mix 50 contains 1.2%, and Mix 100 contains 1.35%,The aggregates studied showed characteristics within the limits established by EHE-08 for recycled aggregates, a large quantity of concrete (71%) and natural stone (27%) in composition and a low proportion of ceramic, which means absorption is not penalized and it is within the limits allowed by the standard,The consistency of recycled aggregate mixes is not significantly affected by adding coarse recycled aggregates and it shows adequate workability. The slump flow increases with the CRA incorporation ratio due to the gradual increase in SP content,The compressive strength is excellent and coherent with the composition used when producing concrete and is completely feasible for use in structural elements. The compressive strength increases with the CRA incorporation ratio. Mix 20 has 20% more strength than CC and Mix 50 about 18%. Only the total replacement mix, Mix 100, suffered a small drop in compressive strength, 5% less than the CC,Tensile strength decreases with the replacement of CNA with CRA by 12.71%, 31.25% and 30.60% in the mixes with CRA ratios 20%, 50% and 100% respectively. Regarding flexural strength, recycled aggregates concrete mixes did not show a notable difference with respect to CC. The values are almost constant, and hardly suffer a variation of 4%,The good self-compactability, mechanical resistance and durability results obtained should be an incentive to reconsider the use of this type of waste as recycled aggregates in concrete, which would also help make the construction process more sustainable.The following conclusions have been drawn from the development and results of this research study:Readjusting the percentage of SP in some of the mixes, especially in Mix 20,Partial or total replacement of FRA (fine recycled aggregates) in the mixes,Microscopy and durability studies of the resulting concrete.The following could be considered as future lines of research for this study:The results of this research show that coarse recycled aggregates may be considered feasible and workable for use in SCC as appropriate mechanical properties can be achieved with contents that are completely satisfactory for structural purposes. Their use would be a significant contribution to the sustainability of the construction sector.


Neoperlamindoroensissp. nov. (Perlidae), from Mindoro island is described. The new species is assigned to the N.recta species complex of the N.montivaga group on account of its obvious T7 and T8 with pointed processes and the presence of basolateral lobes in the everted aedeagal sac. The male adult is distinguishable by its aedeagus with a slightly raised mediodorsal lobe, fully covered with fine spinules, while the female adult has comparably small eggs (240 × 220 μm) with a punctate, chorionic surface with punctae arranged in polygonal FCIs. The life stages and sexes were assigned using COI mtDNA barcodes (2.2% maximum intraspecific genetic distance), which were compared with available barcodes of congeners, which had interspecific genetic distances varying by at least 23.5%. Biogeographic aspects, ecological habitat requirements, and suitability as potential bioindicator of the species are also briefly discussed.The new stonefly species,  Plecoptera (stoneflies) is a basal, aquatic order of Neopteran insects known for their intolerance to organic pollution ; Biodiversity Laboratory, Ateneo de Manila University, Quezon City, Philippines (AdMU); Collection Arthien Pelingen, Philippines (CAP), currently deposited in AdMU; Museum für Naturkunde Berlin, Germany (ZMB).All type material is stored in alcohol and has been deposited at the COI) region was then amplified using the primers LCO1490_mod (5'-TTTCAACAAACCATAAGGATATTGG-3') and HCO2198_mod (5'-TAAACTTCAGGATGRCCAAAAAATCA-3') (PCR) mix, it includes 17.8 µl ddH2O, 2.5 µl 10× buffer, 1 µl Mg (25 mM), 0.5 µl dNTP mix (10 mM), 0.5 µl of each primer (10 mM), 0.2 µl Taq Polymerase (NEB), and 2 µl template DNA of unknown concentration. The PCR program was set as follows: 180 s at 94 °C; 30 s at 94 °C, 30 s at 47 °C, 60 s at 72 °C (× 35 cycles); 300 s at 72 °C. The amplification success was then checked in a 1.5% agarose gel using gel electrophoresis. The successfully amplified PCR products were sent to MACROGEN for cleaning and sequencing. The forward and reverse sequences were then manually traced and aligned (CLUSTALW) using BIOEDIT v. 7.2.5  and Neoperlaobliqua Banks, 1913 retrieved from GenBank as seen in Table DNA was extracted from the legs using Qiagen DNeasy kit  following the protocol for animal tissues . The 5'-ATCA-3') . In a 25v. 7.2.5  along wiThe pairwise genetic distance analysis was performed in MEGA 7  using KiTaxon classificationAnimaliaPlecopteraPerlidae868D7173-E96F-5084-BB0E-B2C9005B7963http://zoobank.org/22178DC3-B257-48B3-BDED-3193FFDF7F4F12°36'30"N, 121°22'38"E, ca 200 m asl.Philippines • Oriental Mindoro, Municipality of Roxas, Barangay San Vicente: Quirao Buhay Creek tributary Tagugoy Creek; secondary forest, ca Holotype: 1 ♂ adult (NMP), labelled “PHIL: Or[iental]. Mindoro, Roxas, Brgy. San Vicente, Quirao \ Buhay tributary, Tagugoy Creek; secondary forest; \ 12°36'30"N, 121°22'38"E 200 m a.s.l.; leg. AL Pelingen, \ C Pangantihon, H Freitag 05 Feb. 2018 (HBT)L”, preserved in a cryovial with 95% ethanol, right hindleg and all left legs missing as used for DNA extraction (PL50), both cerci partially broken, tips of wings partially broken, dissected aedeagus stored inside the same vial. Paratypes: Philippines • 1 ♂ adult; HBT E; 12 Aug.–21 Sept. 2018; leg. Freitag & Pangantihon; NMP; left midleg and hindleg missing, both cerci partially broken, dissected aedeagus stored inside the same vial • 1 ♂ adult; HR3 E; 15 Jan.–17 Feb. 2019; leg. Pangantihon; ZMB; both cerci partially broken, dissected aedeagus stored inside the same vial • 1 ♀ adult; TDR1 L; 08 May 2018; leg. Freitag and Pangantihon; NMP; right legs used for DNA extraction (PL22), both cerci partially broken, eggs used for SEM • 1 ♂ nymph; TDR1f; 22 Sept. 2019; submerged wood in run; leg. Freitag and Pangantihon; AdMU; dissected mouth parts stored in the same vial • 1 ♀ nymph; TDR3f; 08 Feb. 2018; submerged wood in run; leg. Freitag; NMP; left midleg and hindleg used for DNA extraction (PL21); left foreleg broken but stored in the same vial, both cerci partially broken • 1 ♂ adult; TDR3/TBC L; 08 May 2018; leg. Freitag & Pangantihon; CAP-AdMU; right and left midlegs broken but stored inside the same vial, both cerci partially broken, dissected aedeagus stored inside the same vial • 1 ♀ adult; TDR3/TBC L; 08 May 2018; leg. Freitag & Pangantihon; AdMU; left hindleg missing, both cerci partially broken, right forewing broken but stored in the same vial • 1 ♀ adult; THC E; 19 Nov.–02 Dec. 2018; leg. Freitag; ZMB; both cerci broken • 1 ♂ adult; TIR E; 24 Jan.–16 Feb. 2018; leg. Pangantihon; ZMB; right cercus partially broken, dissected aedeagus stored inside the same vial • 1 ♂ adult; TIR E; 24 Jan.–16 Feb. 2018; leg. Freitag; AdMU; left hindleg missing, both cerci partially broken, tips of wings partially broken, dissected aedeagus stored inside the same vial • 1 ♀ adult; TR2 L; 11 Aug. 2019; leg. Freitag; ZMB; both cerci partially broken • 1 ♀ adult; TR2 L; 11 Aug. 2019; leg. Freitag & Pangantihon; NMP; left midleg missing, both cerci partially broken • 1 ♂ adult; TR2 E; 22 Dec. 2018–15 Jan. 2019; leg. Freitag & Pangantihon; AdMU; right midleg broken but stored in the same vial, both cerci partially broken, wings damaged, dissected aedeagus stored inside the same vial. Other Material: Philippines • 1 ♂ larva; HOCg; 16 Jan. 2019; rock surface in riffle, leg. Freitag; AdMU; right hindleg missing, both cerci partially broken • 1 ♀ larva; TIRd; 22 Sept. 2019; leaf pack in riffle; leg. Freitag and Pangantihon; AdMU; both cerci partially broken • 1 ♂ larva; TIRd; 22 Sept. 2019; leaf pack in riffle; leg. Freitag and Pangantihon; CAP-AdMU; segments IX and X including cerci missing • 4 ♀ adults; TR2 E; 19 Nov.–02 Dec. 2018 leg. Freitag; AdMU; some legs missing and all cerci partially broken • 3 ♀ adults; TR2 E; 22 Dec. 2018–15 Jan. 2019; leg. Freitag & Pangantihon; AdMU; some legs missing and all cerci partially broken.Imago: Medium-sized species  and has less pronounced FCIs than that of the supposedly conspecific female of N.nishidai (340 × 300 μm)  and an entirely different morphology from N.mindoroensis sp. nov. In addition, Neoperla PA-9 egg has a thin and obscure opercular line, but bearing a series of small, raised spine-like processes, while N.mindoroensis sp. nov. does not have any spine-like structure. The aedeagus of N.palawan Sivec & Stark, 2011 also resembles that of N.mindoroensis sp. nov., but its basolateral lobes are distinctly smaller, rounded, and not elongate, with a low, rounded medioventral lobe. In addition, it does not have a prominent T8 process on the dorsal abdomen. From all other male adult Philippine Neoperla, the new species can easily be distinguished externally by the distinct, complex pattern in its pronotum, structure of its hemitergites, and its genitalia, as described above. The female adult bears the same pronotum pattern. 300 μm) . NeoperlThe toponym refers to the Philippine island of Mindoro, where the type locality is situated.This species is known so far only from the Baroc River Catchment, Roxas, Oriental Mindoro, Philippines.5) 0.1–1.18 mg/L. The maximum values for dissolved nutrients were 0.5 mg/L phosphate and 1.0 mg/L nitrate.In the Baroc River Catchment, the specimens were found in altitudes of 140–530 m a.s.l. from Hinundungan River and Tauga River tributaries Fig. . These cN.agtouganon Sivec & Stark, 2011 (Mindanao)N.agusani Sivec, 1984 (Mindanao)N.andreas Sivec & Stark, 2011 N.atripennis Banks, 1924 N.connectens Zwick, 1986 N.dentata Sivec, 1984 N.flinti Sivec, 1984 N.hermosa Banks, 1924 (Mindanao)N.jewetti Sivec, 1984 (Luzon)N.mindoroensis sp. nov. (Mindoro)N.nigra Sivec, 1984 (Luzon)N.nishidai Sivec, 1984 N.obliqua Banks, 1913 N.oculata Banks, 1924 N.palawan Sivec & Stark, 2011 N.pallescens Banks, 1924 (Mindanao)N.pallicornis Banks, 1937 N.philippina Sivec, 1984 (Busuanga)N.pseudorecta Sivec, 1984 N.recta Banks, 1913 N.sabang Sivec & Stark, 2011 N.salakot Sivec & Stark, 2011 N.wagneri Sivec, 1984 (Mindanao)N.zwicki Sivec, 1984 Neoperla is the best documented genus in the country, with currently 24 species as listed above. For the first time, an integrative taxonomic approach was applied to describe a new Philippine Neoperla species using a newly designed primer. The same primer has proved to be efficient in generating DNA barcodes of Ephemeroptera species , which suggests it has value as bioindicator for such habitats. However, to further assess its suitability and potential, an intensive ecological assessment is recommended.