Immunoglobulin G4-related disease (IgG4-RD), is an immune-mediated fibroinflammatory condition, which may involve multiple organs and mostly presents with high serum IgG4 levels and specific histopathological characteristics. As IgG4-RD is a relatively new entity the etiology, prevalence and epidemiologic knowledge is quite limited. Although involvement of almost all anatomical regions has been reported, the most commonly affected regions are pancreas, lacrimal glands, salivary glands, retroperitoneum, orbita, lymph nodes, kidney and lungs. Diagnosis is made with combined evaluation of clinical, radiological and histopathological findings. Typical histopathological features include storiform fibrosis, dense lymphoplasmacytic infiltrates and obliterative phlebitis. Its course is typically marked by remission and relapsing attacks and it may lead to fibrosis, destructive lesions in tissues and organ failure unless promptly treated. In the treatment of IgG4-RD, many approaches including surgical resection of tissues, systemic glucocorticoids, steroid-sparing immunosuppressive drugs, and biological agents are employed. Although association is not clear, malignancies are frequently reported in IgG4-RD patients. Therefore, it is prudent to monitor patients for the symptoms of malignant diseases.In this review, recent advances in clinico-pathological characteristics, diagnosis, and treatment of IgG4–RD are discussed. Diagnosis is made with combined evaluation of clinical, radiological and histopathological findings. Its course is typically marked by remission and relapsing attacks and it may lead to fibrosis, destructive lesions in tissues and organ failure unless promptly treated. It also leads to pressure findings, secondary sclerosis and obstruction owing to tumefactive lesions . In the treatment of IgG4-RD, many approaches including surgical resection of tissues, systemic glucocorticoids, steroid-sparing immunosuppressive drugs, and biological agents are employed. The spectrum of differential diagnoses includes malignancies, infections, autoimmune diseases, ANCA-associated vasculitis and Erdheim-Chester disease. In this review, recent advances in clinico-pathological characteristics, diagnosis, and treatment of IgG4–RD are discussed.Immunoglobulin G4 related disease (IgG4-RD), is an immune-mediated fibroinflammatory condition, which may involve multiple organs and mostly presents with high serum IgG4 levels and specific histopathological characteristics. The concept of IgG4-RD was originally reported by Hamano et al. in 2001 with the rise in serum IgG4 levels in patients with autoimmune pancreatitis (AIP) [1]. Its etiology and triggering factors are still unclear. It occurs most commonly in middle aged and elderly males, but preponderance of male sex may vary according to the involve sites. Although involvement of almost all anatomical regions has been reported, the most commonly affected regions are pancreas, lacrimal glands, salivary glands, retroperitoneum, orbita, lymph nodes, kidney and lungs [2]. IgG4-onset counterpart. In children, IgG4-RD presents with dacryoadenitis and mostly as an orbital mass [7].The precise prevalence of IgG4-RD is not known, due to being relatively a new entity and largely underrecognized in clinical practice. The disease occurs mostly in middle aged and elderly males, peaking between the 5th and the 7th decade. Studies have shown a male/female ratio varying between 1.6:1 to 4:1[4].A single study from Japan, reported a lower male/female ratio, i.e. 1:0.77 [5]. Type-1 AIP (IgG4-related), retroperitoneal fibrosis and IgG4-related tubulointerstitial nephritis occur more commonly in males, whereas head and neck involvement  is more common in females [6]. Certain studies revealed higher IgG4 serum levels and increased risk of recurrence in men [6]. In a study, it was observed that patients of Asian origin had higher IgG4 concentrations than patients of Western origin. The disease can also occur in pediatric age groups and shares characteristics with its adult-control study, retroperitoneal fibrosis was found to be associated with HLA-DRB1*03, a marker of many autoimmune disease [10].The exact etiology of IgG4-RD still remains to be elucidated. However, some susceptibility genes and environmental factors have been described. Kawa et al. reported that HLA-DRB1*0405, HLA-DRB1*0401 haplotypes were associated with type-1 AIP in Japanese population [8]. As to Korean population, HLA-DQB1*0202, HLA-DRB1*0701 haplotypes were found to be associated with type 1 AIP [9]. In a large case[11–13]. Estrogen is found as a risk factor in patients with IgG4-related mastitis. Due to eosinophilia in peripheral blood and involved tissues, an allergic etiology has also been considered [14]. Atopy/allergy occursin 20%–60% of IgG4-RD patients. A recent study form the Netherlands found increased occupational substance exposure among IgG4-RD during their lifetime including solvents and metal dusts [15]. Finally, an Italian case-control study showed asbestos exposure and smoking as risk factors for retroperitoneal fibrosis [16].In a few studies, autoantigens such as galectin-3, laminin 11, and annexin A11 have been reported, the presence of which, probably causes the triggering of condition-dominant infiltration and granuloma formation are absent, and if they are present, this is one of the exclusion criteria according to 2019 classification criteria [19]. If the above findings are present, a different accompanying disease such as vasculitis should be considered. Obliterative phlebitis or storiform fibrosis are rare in IgG4 associated lacrimal gland, salivary gland, lymph node and lung involvement, therefore they are not common features of IgG-RD. Another significant pathological finding is storiform fibrosis (an irregularly cartwheel like fibrotic pattern).Collagen fibrils are interspersed within fibroblasts and myofibroblasts. Dense lymphoplasmacytic infiltration comprises mature, immature plasma cells and small lymphocytes . Lymphocytes are mostly CD4+T lymphocytes and spread throughout the lesion. B cells are found in scattered small lymphoid aggregates and ectopic germinal centers.Similar pathological features are observed across the affected tissues [17]. General pathological findings include dense lymphoplasmacytic infiltrates consisting of IgG4+ plasma cells, storiform fibrosis, obliterative phlebitis and mild to moderate eosinophilia [17]. The most specific findingis obliterative phlebitis, complete or partial obliteration of venous vessels, characterized by infiltration of vessel wall or lumen with dense lymphoplasmacytic infiltrate, composed of lymphocytes and plasma cells. Complete obliteration of the lumen can take place due to cell accumulation and fibrosis. After obliteration, venous channels are not visible with standard hematoxylin and eosin (H&E) stain, hence require specific elastin staining. Luminal fibrosis without inflammatory cells is not specific for IgG4-RD and it should suggest other diagnoses such as organized thrombus. Phlebitis not causing obliteration may also occur, but it is neither sensitive nor specific for IgG4-RD. Arterial vessels may also be affected in addition to venous vessels, but not as severely. Arterial involvement occurs mostly in cases with lung involvement and autoimmune pancreatitis but, it is rare in IgG4-RD and its presence does not rule out the diagnosis [18]. In IgG4-RD, necrosis, neutrophilIn addition, eosinophils are present at mild or moderate degree and rarely macrophages and histiocytes may be present. In conditions when eosinophils are preponderant, eosinophilic angiocentric fibrosis or eosinophilic cholangitis should be primarily considered. The degree of fibrosis compatible with IgG4-RD and IgG4 + plasma cell per high power field (HPF) cut-off number of IgG4 positive cells may vary from tissue to tissue. Although these numbers have not been verified yet, depending on the involved organ, cut-off value may range between 10–200 /HPF. In some organs such as the kidney, 10 IgG4+ / HPF and in salivary and lacrimal glands, >100 /HPF is considered as cut-off value. IgG4 /IgG+ plasma cell ratio provides stronger evidence for the diagnosis of IgG4-RD than IgG4 +plasma cell number. Cut off value for IgG4+/IgG+ plasma cell ratio is >40%. In many neoplasms, increasing number of IgG4+ plasma cells can be found both intratumorally and peritumorally. InIgG4-RD, plasma cells are polytypic. Typical electrophoretic pattern of a patient with IgG4-RD demonstrates polyclonal hypergammaglobulinemia with beta gamma bridging. Monotypic plasma cells are mostly seen inlymphoma and plasma cell malignancies [20]. A thorough physical examination may reveal the optimal sites for tissue sampling . Needle biopsies and fine-needle aspiration are usually inadequate for the diagnosis of IgG4-RD as they may not be able to detect storiform fibrosis and obliterative phlebitis. Yet, they may yield enough tissue to reliably rule out lymphoma and other malignant conditions. Nevertheless, for a firm diagnosis, pathological findings should always be supported by clinical, serological and/or radiological features.IgG4-RD is classified as a fibroinflammatory disorder, with involvement of both adaptive and innate immune mechanisms in its pathophysiology. IgG4 accounts for 1%–4% of IgG subtypes [11] and IgG4 antibodies are specific to mankind. IgG4 antibodies are considered to have antiinflammatory activity given the fact that they can undergo Fab-arm exchange and limit immune-complex formation. Due to the antiinflammatory properties of IgG4, IgG4 releasing plasmablasts represent a regulatory response to inflammatory stimuli. In spite of increased serum IgG4 level and tissue IgG4+plasma cells, which are characteristic of IgG4-RD, abnormal T cell activity is considered as the principal immune defect. Most lymphocytes present in the affected tissues of patients with IgG4-RD are T lymphocytes. Multiple studies have showed the involvement of follicular T helper (Tfh) lymphocytes and CD4+ cytotoxic T lymphocytes (CTL) in the pathogenesis of the disease [21]. It was observed that Tfh cells increase in affected tissues and peripheral blood of patients. In some studies, it was observed that IgG4-RD associated Tfh cells, induce differentiation and proliferation of B cells at a higher degree than normal Tfh cells in tissues [22]. Studies on subtypes of Tfh cells have indicated that,cells without CXCR3 and CCR6 expression, release Th2 type cytokines  [23]. IL-4, a Tfh cytokine, induces germinal center development, B cell differentiation, plasmablast induction and class switch recombination, culminating in IgG4 production [24]. Many studies have demonstrated that progression of fibrosis is maintained via IL-4, IL-5, IL-13 cytokines [25]. IL-5 and IL-13 increase IgE and IgG4 production and lead to eosinophilic infiltration. In AIP, an increase in CD4+CD25+ Treg cells was found [26]. Treg cells contributeto IgG4 class switching and fibrosis respectively by releasing IL-10 and TGF-B [27]. Recent studies have stressed the importance of CD4+ CTL T lymphocytes in the physiopathology of the disease [28]. Matto et al. demonstrated oligoclonal expansion of CD4+ effector /memory CTL cells in both blood and tissues of IgG4-RD patients [29]. These CTL T cells contribute to the development of fibrosis in association with the mediators they release such as granzyme A, perforin, interleukin-1 β (IL-1 β), transforming growth factor -beta (TGF-β) and interferon-gamma (IFN-γ). Besides, cytotoxic T cells express F7 (SLAMF7) molecule on their surface, which contributes to fibrosis and is not present in other T cells. [28]. In patients with active IgG4-RD, rituximab leads to reduction in CD4+CTL cells secondary to B cell depletion [29]. In addition to T cells IgG4+ hypermutated plasmablasts have also been described in the blood of patients with active IgG4-RD [30].-RD is usually a systemic disease, but a recent cluster analysis identified the following main phenotypes: pancreato-hepato-biliary disease, retroperitoneal fibrosis and/or aortitis, head and neck limited disease, classical Mikulicz syndrome with systemic involvement [31]. The main organ manifestations are discussed below.IgG4Although lymphadenopathy usually occurs in conjunction with other clinical and laboratory findings of the disease, sometimes it may be the initial or sole finding. There are 5 histological patterns and nodal inflammatory pseudotumor-like represents the most specific pattern for IgG4-RD (Table 1). Lymph nodes are usually, nontender and have elastic consistency. Symptoms usually emerge due to mass effect by enlarged lymph nodes. Usually, more than one lymph node group is affected. Mediastinal, hilar, intraabdominal and axillary lymph nodes are the most commonly involved. As storiform fibrosis, one of the characteristic features of IgG4-RD, occurs rarely and IgG4 plasma cells stain positive in many diseases, making diagnosis solely with lymph node biopsy is quite challenging. While a true lymphadenitis is characterized by the presence of IgG4+ plasma cells in interfollicular regions, their presence in intrafollicular regions is nonspecific. The differential diagnosis of generalized lymphadenopathy includes sarcoidosis, multicentric Castleman disease, infections , lymphoma and other malignant conditions. IgG4 related lymphadenopathy is distinguished from other lymphadenopathies by its mild lymph node enlargement, typical characteristics in biopsy, absence of constitutional symptoms, and response to glucocorticoids [32].-unrelated AIP is type 2 AIP or idiopathic duct-centric chronic pancreatitis (IDCP) or granulocyte-positive epithelial pancreatitis. Type 2 AIP occurs much more rarely than type 1 AIP and is sometimes associated with inflammatory bowel disease. Types 1 and 2 AIP display different clinical features. Type 1 AIP occurs mostly in elderly males and is less likely to cause jaundice and abdominal pain. Type 2 AIP affects mostly younger people without any sex predilection. In addition, its rate of recurrence is lower and is confined to the pancreas. In the majority of type 1 AIP patients, extrapancreatic IgG4-RD involvement occurs. Development of endocrine and exocrine pancreatic insufficiency manifesting with hyperglycemia and steatorrhea is not uncommon among patients who suffer from wither type of AIPs. In some patients with type 1 AIP, acute recurrent chronic pancreatitis may occur. Type 1 AIP may imitate pancreatic carcinoma as it leads to mass-like lesions of the pancreas. It is also difficult to clinically discriminate AIP patients from those with adenocarcinoma since painless obstructive jaundice and high serum IgG4 concentrations may be seen in both conditions [33]. Many AIP patients had to undergo radical surgery due to concern about pancreatic cancer. In CT images of type 1 AIP patients, enlarged pancreas, sausage-like pancreas, loss of lobulation, irregular pancreatic duct, hypodense rim/halo sign  and minimal peripancreatic fat stranding are observed. Magnetic resonance cholangiopancreatography (MRCP) images of patients with IgG4 autoimmune pancreatitis show nonvisualization of a long segment of the main pancreatic duct. Patients who are left untreated or have long term AIP can develop symptoms of chronic pancreatitis with atrophic pancreas and intraductal calcifications on imaging [34].There are two types of autoimmune pancreatitis (AIP). The IgG4-RD associated AIP is called as type 1 AIP, while the IgG4-RSC usually produces obstructive jaundice, weight loss and/or steatorrhea and elevation in hepatic function tests [35]. IgG4-RSC is different from primary sclerosing cholangitis (PSC) which occurs at younger ages in association with inflammatory bowel disease and histopathologic examination shows circumferential or onion-skin like fibrosis and in advanced stages, ductopenia [36]. Unlike PSC, IgG4-RSC tissue biopsy yields IgG4 + plasma cell infiltrates, severe interstitial fibrosis, transmural thickening and more severe portal and lobular inflammation [36]. Other differences are increased serum IgG4 concentration and characteristic response to corticosteroids. IgG4-RSC is the most common extra pancreatic disease in patients with type 1AIP, with a prevalence of 70%. It seldomly appears in the absence of pancreatitis. Considering the difficulties in making the diagnosis of isolated IgG4-RSC in the biliary system, it is not easy to estimate its actual prevalence and to appreciate its severity [37]. IgG4-RSC can also be confused with cholangiocarcinoma, but the latter has higher serum bilirubin and CA19-9 levels [38]. CT findings of IgG4-RSC include multiple focused strictures, >2.5 mm thickening in bladder wall, and long segment narrowing. These strictures are smooth in morphology, with resultant proximal biliary tree dilatation. Posttreatment imaging may reveal radiologic improvements in strictures and biliary tree wall thickening [39].IgG4The involvement of major salivary (parotid and submandibular) glands is a common feature of IgG4-RD. Lacrimal or parotid gland enlargements, which was previously termed as Mikulicz syndrome, and Küttner tumor  have been incorporated into IgG4-RD context [40]. In IgG4-RD, lacrimal gland, parotid gland and submandibular gland are usually involved together at different combinations. Although it is not always symmetrical, glands are usually involved bilaterally. Renal involvement with low complement levels might be encountered in this condition [4].In the morphology of IgG4-related sialadenitis, fibroinflammatory infiltration occurs in interlobular septa, but lobular architecture is preserved, and commonly hyperplastic irregular lymphoid follicles are detected [41]. In some sialadenitis cases due to stones, IgG4 positive cells may be present. In a study, serum IgG4 levels were found elevated in 7.5% of patients with primary Sjögren syndrome (pSS). Compared to pSS, in IgG4-RD have higher serum IgG4 levels and negative antinuclear, anti-Ro/SSA and anti-La/SSB antibodies [42]. Radiologically, pSS demonstrates the “apple-tree sign” on sialography, indicative of contrast spilling from degenerated glands. Both pSS and IgG4-RD enlarge lacrimal and salivary glands, but dryness in mouth and eyes is milder in IgG4-RD and more severe in pSS due to more extensive epithelial cell apoptosis. Upon immunosuppressive treatment IgG4-RD patients regain their salivary functions whereas, pSS often leads to irreversible destruction of salivary units.IgG4-RD presenting with the involvement of lacrimal glands (IgG4-related dacryoadenitis) [43] and orbital involvement occurs at the rate of 17%–23% [44]. IgG4 related orbital inflammatory disease commonly involves lacrimal glands, while involvement of orbital soft tissue , extraocular muscles, palpebrae, optical nerve, or orbital bone have also been reported. Approximately 70%–80% of patients have extra ophthalmic findings. Some studies have suggested that it is more common in females [45], whereas some other studies reported that it is more common in males [46]. Patients may present with symptoms of exophthalmos, periocular swelling and mass which can lead to proptosis and compression of local nerves. IgG4 related dacryoadenitis may lead to blindness unless treatment is rapidly commenced [47]. Fibrosis occurs mostly in interlobular septa and causes impairment of the architecture of lacrimal gland [48]. The differential diagnosis of IgG4 related orbital disease includes Sjögren’s syndrome, granulomatosis with polyangiitis, sarcoidosis, lymphoma, infection, orbital pseudotumor and idiopathic orbital inflammation [48] (Table 2). IgG4-RD accounts for 25%–50% of orbital pseudotumor. In addition, depending on diagnostic criteria used, it also accounts for 5%–25% of idiopathic orbital inflammations [49]. In a study, 38 patients diagnosed with chronic dacryoadenitis or orbital pseudotumor, 15(39%) met the definite criteria of IgG4-RD, while 5 patients had probable disease [50]. Some other studies have demonstrated that IgG4-RD itself, produces susceptibility to ocular adnexal mucosa associated lymphoid tissue (MALT) lymphoma and other lymphomas [51].Retroperitoneal fibrosis (RPF) is one of the most commonly encountered subtypes of IgG4-RD. RPF may be idiopathic (Ormond disease) or may have a secondary cause (Table 3). Idiopathic forms account for 70% of cases and may be of IgG4-RD or non-IgG4-RD origin. In a study, it was established that IgG4-RD was responsible for many of RPF cases, which were previously considered idiopathic [52]. Asbestosis and tobacco exposure increase RPF risk [16]. Patients usually present with urinary obstruction and kidney failure and frequently complain of lower back, flank and abdominal pain due to urinary obstruction [53]. In two large retrospective studies, pain was evident in more than 90% of patients on presentation . Pain is dull and not well localized and does not change with activity or body position. Sometimes, the pain may be acute/sharp resembling that of a renal colic. In a study performed in North America, many cases of retroperitoneal fibrosis were identified during radiologic examinations performed for the suspicion of nephrolithiasis [56]. Due to inflammatory nature of lesion, pain responds better to NSAIDS than opioids. In a study conducted on 40 patients, testicular pain was reported in more than 50% of male patients [57]. Kidney atrophy may be seen as a result of unilateral chronic obstructive uropathy or renal artery stenosis caused by RPF. Patients may exhibit edema, thrombophlebitis or deep vein thrombosis in lower limbs due to obstruction of inferior vena cava. In a study conducted in Netherlands, hydrocele was detected in 29% of patients [55]. Serum creatinine and urea levels may rise secondary to urinary obstruction. High acute phase reactants are usually associated with a more symptomatic disease however they respond poorly to treatment and usually do not increase during flares. The initial imaging modality employed for investigating urinary pathologies is ultrasonography [58]. For visualization of pancreas and retroperitoneal organs CT or MRI is preferred. Histological confirmation of RPF may be required if the mass lesion has atypical localization, and clinical and laboratory findings suggestive of infection or malignancies. During surgical exploration, macroscopically, a hard, white plaque of varying thickness is seen. Microscopically, fibrous tissue contains extracellular matrix which is organized in thick irregular bundles composed of type 1 collagen fibrils surrounding small retroperitoneal vessels [59] .Typical CT findings, include medially displacement of ureter due to compressive effects of fibroinflammatory mass lesion involving surroundings of aorta and inferior vena cava18-FDG positron emission Tomography (18-FDG PET) is a beneficial and reliable technique for evaluating metabolic or inflammatory activity of disease. Serious complications such as renal failure may occur unless patients are treated promptly [60] .The aim of treatment is to relieve obstruction caused by fibrosis, to halt progression of the fibrotic process and to prevent disease recurrence. If there is an important urinary tract obstruction, this should be eliminated with open surgery, percutaneous intervention or endoureteral approach. As soon as diagnosis is made  steroid treatment should be commenced. If there is no adequate response to steroids following approximately four weeks of treatment, immunosuppressive treatments should be instituted such as mycophenolate mofetil (MMF), azathioprine (AZA), methotrexate, cyclophosphamide, and cyclosporine [61]. Patients who have positive PET findings at the onset of treatment respond better to steroids than those who have negative PET findings [62]. If clinical or radiological improvement is not observed in spite of four weeks of medical treatment, repeat CT investigation and biopsy are recommended in order to corroborate the diagnosis.-related renal involvement, most commonly occurs as tubulointerstitial nephritis (TIN). IgG4-related TIN may be detected during investigations carried out for the suspicion of kidney masses, abnormal urinary analysis, and/or renal failure. Histological findings include lymphoplasmacytic infiltration of the renal interstitium, tubular atrophy and fibrosis. In patients with IgG4-related TIN, low C3 and C4 levels, can be seen especially in patients with active disease. The cause of hypocomplementemia occurring in IgG4-TIN is not entirely clear, since IgG4 itself binds weakly to complement. Hence, it is thought that IgG1 and IgG3 account for hypocomplementemia. CT imaging shows enlarged kidneys and hypodense lesions. Apart from IgG4-TIN, membranous nephropathy and mesengioproliferative glomerulonephritis may also occur, albeit rare in IgG4-related kidney disease [63]. Membranous nephropathy can be concurrent with TIN and presents with nephrotic range proteinuria and hypoalbuminemia [63].IgG4IgG4-RRD may be detected incidentally with symptoms such as cough, dyspnea, and chest pain. Apart from dense lymphoplasmacytic infiltrates, small aggregates of neutrophils may be present in alveolar spaces or within the inflammatory infiltrates.The fibroinflammatory infiltrate typically extends towards perilymphatic region-bronchovascular tree and interlobular septa. Lung manifestations predominantly present as inflammatory pseudotumor, interstitial pneumonitis, organizing pneumonia, and lymphomatoid granulomatosis. IgG4-RD involves not only lung parenchyma, but also pleura, airways, mediastinum, and vasculature. There are four patterns of lung involvement [64] (Table 4).Delayed diagnosis and treatment of IgG4-related interstitial pneumonia can lead to significant pulmonary fibrosis. Many patients exhibit more than one pattern. Visceral and parietal pleura thickening may also take place. In a recently published case-based review, IgG4-related pleural effusion has been reported in 17 patients and in pleural effusion sampling, adenosine deaminase levels were found to be high [65]. The differential diagnosis of IgG4-RRD include MCD, sarcoidosis, lymphoma and inflammatory myrofibroblastic tumor. The solid nodular type may be confused with sarcoidosis. Hilar lymphadenopathy is present in both sarcoidosis and IgG4-RD and they might be discriminated by PET CT, since CT alone is inadequate in this respect. In sarcoidosis fluorodeoxyglucose SUV max uptake on PET is higher. Ga-67 scintigraphy is inadequate in staging of the disease and evaluation of activity and response to treatment in comparison to PET CT [66].In IgG4-RRD, the relation with malignancy depends on the pattern displayed, i.e. while the risk of malignancy is higher in those with interstitial and nodular patterns, it is not seen in those with bronchovascular pattern. In addition, prognosis is poorer in interstitial pattern. IgG4-RD is one of the causes of noninfective aortitis [67]. In retrospective pathological studies of patients undergoing aorta resection, a number of patients with thoracic lymphoplasmacytic aortitis, abdominal periaortitis and inflammatory abdominal aorta aneurysm were identified [68] .Thoracic aortitis can lead to aneurysm formation or dissection, though it is often asymptomatic and detected incidentally by imaging. In a recent prospective study, in 89 out of 587 IgG4-RD patients (15.2%), periaortitis/periarteritis was detected, which was most commonly distributed in infrarenal abdominal aorta and iliac arteries. (83.5%) [69]. IgG4-RD may also involve medium sized vessels such as coronary arteries in addition to large vessels. CT angiography is observed the soft-tissue masses around the proximal segments of the left anterior descending (LAD) and right coronary artery (RCA). The presence “mistletoe sign” in CT angiography is an indicator of IgG4-RD associated coronary artery disease [70]. Mistletoe is a plant attached to the branches of a tree, similar to the perivascular soft, tissue attached to the coronary tree.Riedel thyroiditis, which is a rare form of thyroiditis, is the IgG4-RD of thyroid gland. Stiff thyroid leads to dyspnea, dysphagia and hoarseness. Cytologic examination is not always diagnostic and diagnosis is usually made with thyroid resection, carried out to relieve clinical symptoms and to rule out malignancy. The fibrosing variant of Hashimoto thyroiditis has also been associated with IgG4-RD [71]. In comparison to IgG4-negative thyroiditis, IgG4-RD thyroiditis presents serologically with higher levels of antithyroglobulin and antithyroid peroxidase antibodies.Skin disease ):-RD should be considered as part of the differential diagnosis for nodules, papules, and plaques. Cutaneous lesions are predominantly located on the head and neck in IgG4-RD cases (73.1%) [72]. IgG4-related autoimmune hepatitis and hepatic inflammatory pseudotumor, constrictive pericarditis, sclerosing mastitis, gastritis are included among the rare IgG4-RD manifestations.IgG4The diagnosis of IgG4-RD is currently based on the comprehensive classification criteria proposed in 2019 by Wallace et al. [19] (Table 5).Comprehensive classification criteria issued by 2019 ACR/EULAR involves three steps; in the first step, in a potential case, at least one of the 11 organs consistent with the definition of IgG4-RD should be demonstrated. In the second step, the exclusion criteria step, a total of 32 clinical, serological, radiological and pathological items should be considered. The presence of one of these criteria is enough to rule out IgG4-RD. In third step, 8 important criteria are considered, and serological results, radiological evaluations and pathological interpretations are addressed, scored and interpreted. Overall a score of 20 or more is diagnostic of IgG4-RD. Although comprehensive diagnostic criteria are commonly used, as it is difficult to take biopsy from regions such as pancreas, retroperitoneum and orbita, they can be used with difficulty in diseases of these regions. Thus, organ specific diagnostic criteria have been developed and can be employed instead of comprehensive diagnostic criteria .In many patients, serum IgG4 levels are high. Its level usually correlates with the severity of the disease. However, serum and tissue IgG4 concentrations are neither specific nor sensitive indicator of IgG4-RD. A study demonstrated that almost half of active patients with histologically proven IgG4-RD had normal serum IgG4 levels [4]. Involvement of certain organs or anatomic regions, particularly the retroperitoneum, have lower rates of correlation with serum IgG4 levels. False-negative IgG4 levels due to the prozone phenomenon should be considered in cases with multiorgan involvement and low serum IgG4. In addition, peripheral eosinophilia, high serum IgE levels, polyclonal hypergammaglobulinemia, high CRP, low titer positive antinuclear antibody, rheumatoid factor and hypocomplementemia are common in IgG4-RD. The serum IgG4 level decreases promptly after treatment with glucocorticoids or B cell depletion in most patients despite many patients do not achieve normal levels while they are in clinical remission. In a prospective trial of rituximab in IgG4-RD, higher baseline levels in serum IgG4, IgE and blood eosinophil concentrations predicted greater risk of IgG4-RD relapse and shorter time to relapse, rendering monitoring of these values significant [75]. Apart from IgG4,in a recent study, in the sera of 28 IgG4-RD patients, thymus and activation-regulated chemokine (TARC) levels were measured and were found to be higher than those of patients with Sjögren syndrome and control group. In addition, it was established that they were related to responder index and organ involvement and that TARC stimulated plasmablasts in vitro [76]. Serum plasmablast concentration is a more sensitive marker for the diagnosis of IgG4-RD compared to the serum IgG4 level, however, due to the difficulty of application, it has limited clinical use.Recurrence was observed in 46% of IgG4-RD patients during and after the tapering of the steroid dose [80]. In selected high-risk patients, i.e. those who have high serum IgG4, IGE and eosinophilia at the onset, those with multiple organ involvement and previous history of relapse, remission maintenance treatment should be contemplated [81]. In a recent retrospective study performed with 277 IgG4-RD patients, recurrence was observed more frequently in patients diagnosed at early ages, those who had allergy history and whose treatment was instituted long time after the diagnosis. Cumulative relapse rates were found to be12.86%, 27.84%, and 36.1%, respectively at 12, 24, and 36 months. As to organs affected by recurrence,  recurrence was in de novo organ in 40 patients and in the same organ in 85 patients. The most common de novo recurrence occurred in parathyroid gland. Regarding recurrence in the same organ, the organs where recurrence was most common were lacrimal gland, pancreas and thyroid glands [82]. Following a successful induction treatment, especially some patients with high risk benefited from maintenance treatment [83]. According to international consensus guide, a steroid sparing agent may be administered during maintenance treatment [81]. AZA, MMF, methotrexate, tacrolimus and cyclophosphamide are used as steroid sparing agents [84]. However, there is no agreement on duration of treatment. As active IgG4-RD cases with marked lymphoplasmacytic infiltrationare more likely to respond to pharmacological treatment, in this case the experts recommend immunosuppression. Conversely, in long term stage fibrotic lesions, surgical-debulking should be considered, as they respond poorly to immunomodulatory agents [81]. Spontaneous or at least temporary remissions have been reported [85]. Nevertheless, metachronous nature of the disease suggests that although it may appear to improve transiently in an organ, it may emerge again in a different region month or years later [86]. According to the data obtained in retrospective studies, RTX treatment was effective in cases in which conventional steroid sparing agents were not successful [87]. In patients who are on a steroid regimen when RTX is instituted, the dose of steroid may be reduced following RTX administration [88]. RTX is suitable for maintenance treatment, but the optimal frequency and duration of treatment still remains unclear. Bortezomib (a protease inhibitor) has been used in addition to steroids in recurrent IgG4-RLD [89]. Other biologics, including infliximab, abatacept and tocilizumab, have been reported to be effective in this condition but data are limited to single case reports . As described before, IgG4-RD is a fibroinflammatory condition in which delays in treatment can lead to significant fibrosis and damage.In IgG4-RD, there is a risk of progression from inflammatory and proliferative stage which is responsive to treatments, to fibrotic stage responding weakly to treatments causing severe organ damage. Early diagnosis and treatment are important owing to irreversible organ damage. The aim of treatment is to minimize adverse effects with glucocorticoids and other agents, to produce remission of disease and to preserve organ function. After diagnosis is made, pretreatment evaluation should be made for assessing severity and extension. Routine laboratory tests, whole blood count, kidney and liver function tests, biochemical parameters including amylase and lipase, levels of IgG subtypes, IgE concentration, serum C3 and C4 concentrations, urinalysis (asymptomatic proteinuria may be an indicator of TIN), chest, abdominal and pelvic CT or MRI and PET (for determining the extension of disease) may be ordered. In patients with asymptomatic lymphadenopathy, slight salivary gland enlargement, and incidentally detected lung nodules, watchful waiting policy is recommended. These patients should be evaluated every six months. Patients with symptomatic active IgG4-RD require treatment. Disease activity may be determined by laboratory and imaging methods in addition to symptoms, for example in patients with lacrimal gland swelling, orbital pseudotumor or proptosis. Urgent treatment may be warranted in some patients with pancreatobiliary or renal disease. In addition, patients with aortitis , RPF  pachymeningitis , AIP (due to exocrine and endocrine failure) and pericarditis (due to risk of cardiac tamponade) should be urgently treated. In asymptomatic patients with radiological and laboratory findings in vital organs,  treatment should be initiated, since irreversible sequelae may develop [77]. Glucocorticoids are first line agents for remission-induction in treatment naive patients unless they are contraindicated. Initially, prednisone monotherapy is recommended at the dose of 0.6 mg/kg/day . Almost all patients respond to 40 mg daily prednisone within 2–4 weeks. Many patients respond even earlier. After clinical response is obtained at the involved organ, prednisone dose may be gradually tapered during 3–6 months until it is completely discontinued. Rheumatologists from Asia prefer to maintain low dose glucocorticoids (2.5–5mg/day) for three years [78]. Symptomatic improvement upon response to glucocorticoids manifests with decrease in the size of mass or organ enlargement, improvement in organ functions and reduction in serum IgG4 levels. It has been observed that after glucocorticoid induction treatment, CD4 +T cells decline [79].The outlook of IgG4-RD depends on the organs involved and the severity of fibrosis. It is known that both hematological and solid organ malignancy risk increases in chronic inflammation, as can be seen in stomach cancer caused by H. Pylori and hepatocellular cancer caused by hepatic viruses. Drawing upon this relation, it may be suggested that there may be a close correlation between IgG4-RD and cancer. In IgG4-RD, the most common hematological and solid organ malignancies are diffuse large cell lymphoma and pancreatic cancer respectively. Considering that IgG4-RD is preponderant in subjects population, who are more immunocompromised, it can be considered as a risk factor for both disease and susceptibility to malignancy. Malignancy may occur before, during or after IgG4-RD. In the study of Asano et al. 158 patients diagnosed with IgG4-RD were followed for a mean of 5.95 ± 4.48 years and malignancy was found in 34 of these patients [92], demonstrating that cumulative risk of cancer was higher than that of general Japanese population, with risk being the highest within the first year. In the same study, malignancy was simultaneously diagnosed with IgG4-RD in 12 patients [93]. High serum total IgG, IgG4, SIL-2R (soluble interleukin 2 receptor) and CIC (circulating immune complex) levels pointed to increased risk of malignancy. In the aforementioned study, 8 patients with malignancy achieved cure with chemotherapy and radiotherapy while remission was obtained in IgG4-RD as well, and they did not recur at follow up evaluations [92]. Therefore, it was thought that IgG4-RD may be a paraneoplastic condition. Yamamoto et al. reported that among 105 patients with IgG4-RD the risk of malignancy was increased in comparison to the general population [93]. Shikawo et al. found the same result in 108 patients with AIP [94]. However, Hart et al. did not find any significant increase in the risk of malignancy in 116 patients with type 1 AIP, as compared to 344 control patients [95]. Likewise, in the study of Hirano et al. on 113 patients with IgG4-RD, malignancy risk was not increased [96]. They attributed this result to the exclusion of patients who had coexistent malignancies at the time of diagnosis. Given the results of aforementioned studies, the relation between malignancies and IgG4-RD is controversial.-RD patients regardless of the clinical picture and organ involvement. For patients requiring treatment, prednisone is usually recommended at an initial dose of 0.6 mg/kg/day . In maintenance treatment, steroid-sparing agents are used both to reduce cumulative risks of steroids and to decrease risk of recurrence. Although association is not clear, malignancies are frequently reported in IgG4-RD patients. Therefore, it is prudent to monitor patients for the symptoms of malignant diseases.The aim of the present review was to present a general overview on clinical presentations, physiopathology and treatment of IgG4-RD. As IgG4-RD is a relatively new entity the etiology, prevalence and epidemiologic knowledge is quite limited. Although the clinical picture of the disease varies according to the involved organs, compressive symptoms are common due to the tumefactive nature of the disease. IgG4-RD is diagnosed based on the combination of clinical, radiological and histopathological findings. Typical histopathological features include storiform fibrosis, dense lymphoplasmacytic infiltrates and obliterative phlebitis. Serum IgG4 level is neither specific nor sensitive marker for IgG4-RD, but high values have been found to correlate with the severity and recurrence of disease. Glucocorticoids lead to rapid clinical response in most IgG4


Many studies on Fibre-Reinforced Polymers Reinforced Concrete (FRP-RC) beams tested in flexure have been performed by various researchers around the world. This work presents the results of statistical and mathematical analyses based on experimental data; 102 samples were collected and supplemented from 16 different scientific papers. The load capacity of the beams determined on the basis of the tests was compared with the load capacity calculated on the basis of the recommendations of ACI 440.1R-15. The results obtained from experimental studies showed that for 91.4% of the samples, the underestimation of the load capacity on average was equal to 15.2% of theoretical, and for 33.3% of the beams, the load capacity was overestimated by 26.7%. The paper proposes a new empirical coefficient incorporating material parameters to be implemented into ACI 440.1R-15 flexural design approach in order to improve the accuracy of this model in scope of the nominal flexural strength capacity of FRP-reinforced beams estimation. Modifications to flexural design of FRP-RC beams with the use of ACI 440.1R-15 design code were proposed. As a result, the reliability of the analytical model is increased; therefore, the new model guarantees higher safety and cost efficiency of designed concrete structures reinforced with FRP bars. Design of concrete members reinforced with fibre-reinforced polymers (FRP) bars is based on the design of concrete members reinforced with ordinary steel bars. However, the behaviour of these two materials is significantly different; therefore, to ensure safety and efficiency of FRP reinforcement, a deep understanding of the nature of this material and the adequate use of available design codes is required.An important issue related to FRP bars is their deformation due to creep, which may eventually lead to failure of FRP bar due to creep rupture. The creep effect is initially related to polymer matrix when it occurs; further, this stress is transferred substantially to enhancing fibres. When enhancing fibre is broken, its internal stresses have to be transferred by outer fibres. Very often, such an event works as a chain effect, causing the entire FRP bar to fracture. There are many scientific materials available regarding failure mechanisms of FRP bars since this is one of the key issues in the use of this material as internal reinforcement in concrete structures. Numerous experimental research studies prove that the character of failure of FRP bars is very complex and dependent on a large number of varying factors. It has been observed in tensile tests of FRP bars that various types of FRP bars fracture in slightly different ways.Although higher efficiency of bars is achieved with a smaller diameter (higher strength with relation to cross-section area) due to the shear lag effect, FRP bars with larger diameter fracture in a more gradual manner. Failure of FRP bars with a small diameter has a relatively more sudden character .Steel bars are characterised by generalised values of mechanical properties, which are widely standardized. FRP reinforcement is available in the market in various types and subtypes with a wide range of properties. Material characteristics of FRP bars are guaranteed by manufacturers and usually represent initial values, which undergo (often difficult-to-predict) changes with time and exposure to certain environmental conditions. In the design of reinforced concrete members, these potential degradations of mechanical properties are covered with the use of environmental reduction factorswhich takes into account environmental effects and type of FRP bars ,3,4.In accordance with FIB bulletin 14, the design strength can be obtained by dividing the characteristic strength by a partial safety factor. The partial safety factors applied to the characteristic strength of FRP are mainly based on the observed differences in the long-term behaviour of FRP as well as the application method and on-site working conditions .The design codes and recommendations regarding FRP reinforcement are mainly based on the semiprobabilistic method of limit states. Among the available recommendations addressing the subject of FRP reinforcement can be distinguished a Japanese recommendation JSCE , a set oThe JSCE recommendations define the safety factors related to the FRP-RC members and to the constituent material. The CSA recommendations provide the characteristics of testing strength properties of FRP bars. Recommendations ACI 440 introduces material reduction factors for elements subjected to bending in the ultimate limit state and reduction factors corresponding to the failure mechanism of FRP RC member. Recommendations addressing the subject of FRP reinforcement are based, among other things, on analytical solutions and empirical equations resulting from research carried out on samples of FRP bars and concrete elements reinforced with FRP bars. Due to the different mechanical properties of FRP bars, the recommendations introduce modifications to the coefficients available in existing standards concerning concrete elements reinforced with steel bars.The purpose of strength reduction factors proposed in 440.1R-15 design code is to assure flexural strength reserve of FRP-reinforced beams included in the design capacity of FRP reinforced beam, i.e., in nominal calculated factored bending moment capacity. According to ACI 440 analytical model and considering experimental data from other studies, design flexural strength of FRP reinforced beam with a compression-controlled cross-section is estimated to be 18% higher than for FRP-reinforced beam with a tension-controlled cross-section. Strength reduction factors are applied to values of nominal flexural strength of concrete beam reinforced with FRP, which in most cases  and Carbon FRP (CFRP) bars as reinforcement and consider the influence of defined factors related to concrete beams on material characteristics of these bars.Before proceeding to statistical analysis, the conditionality related to examined specimens was determined and analysed. Necessary considerations, as well as differences and similarities regarding all beams included in current research, are listed in the following parts of the paper.The load capacity of bending concrete elements with FRP reinforcement is determined using methods analogous to the method of determining the load capacity of bending steel-reinforced concrete elements. The load-bearing capacity, unlike for steel-reinforced concrete elements, is influenced by several important factors mainly based on the characteristics of FRP composite reinforcement. The adhesion of composite bars to concrete has a great influence on the load capacity. There are significant differences between the traditional steel reinforcement and the composite reinforcement in the form of FRP bars. The modulus of elasticity of FRP bars is generally lower than that of steel bars, especially in the transverse direction. The shear stiffness of FRP bars is much lower than that of steel. The surface deformation of FRP bars relates to the resin matrix, which has much lower strength than steel bars. At limit loads (when the load capacity is lost), the importance of adhesion and friction between the bars and the surrounding concrete surface decreases. On the other hand, the wedging effect begins to play an important role, as it increases with the increase of concrete compressive strength. The wedging effect in the case of an appropriate braid angle of the FRP reinforcement influences the bending resistance. On the other hand, due to the lack of plastic deformation of FRP reinforcement, a coefficient related to the degree of reinforcement should be used in the bending sections. The value the For experimental testing, a standard four-point loading scheme was applied in all cases. Ratios of middle span length to edge span lengths, as well as reinforcement detailing, did not differ significantly. The dataset used for this research, consisting of 102 positions, included five beams, i.e., 4.9% of all specimens, with square cross-section ; 14 ,12 stockBeam (span) lengths of FRP concrete beams reinforced with FRP bars were analysed and compared due to the economies of scale. The predominant part (82%) of examined specimens were characterised by span length ranging from 1.5 to 2.75 m considering simple supported beams, as well as continuous beams, and span length of 18% of beams reached up to 3.4 m. The slenderness of beams and the relations between the area of cross-section, dimensions of cross-section, and span length of beams were analysed—obtained data were normally distributed—results significantly deviating from average were not found. On the basis of the analysis of geometrical characteristics of FRP-reinforced beams, the possibility of scale effect occurrence was excluded.Various methods of application of load to the beams were used. Thériault, M., and Benmokrane, B.  tested FOn the basis of insightful qualitative analysis of conditionality of examined concrete beams reinforced with FRP bars, no differences were found that could significantly affect the interpretation of data and results.For 32 beams reinforced with CFRP bars, in 2 cases (6.3%), the load capacity was significantly overestimated, while in 4 cases (12.5%), it was significantly underestimated. In the case of 70 beams reinforced with GFRP bars, in 3 cases (4.3%) the load capacity was significantly overestimated, and in 13 cases (18.6%), it was significantly underestimated . More detailed  conclusions can be interpreted using Due to the small number of beams for which significant and unexplainable  deviation occurred, there is the possibility of a significant contribution of factors related to improper specimen preparation or other, e.g., quality-control-related, neglection. For the above reasons, it may be feasible for some positions in the collected data used for statistical and mathematical analysis to be dismissed.The research programme was structured in a hierarchical manner and is discussed in Flexural design of concrete members reinforced with FRP bars can be based on the same assumptions as the flexural design of concrete members reinforced with steel bars. When designing a beam with conventional steel reinforcement, it is assumed that the reinforcement in the tension zone becomes plasticized, and the concrete is crushed in the compression zone at the same time. Then, the beam cross-section is defined as optimally reinforced. The cross-section of the beam is defined as under-reinforced when the amount of reinforcement is less than necessary for the situation described above. However, if the amount of reinforcement applied is greater, the beam cross-section is called a reinforced cross-section.Unlike steel reinforcement, there is no plastic deformation phase in tension in the FRP bar reinforcement. The stress-strain relationship in axial stretching in FRP rebars is linearly elastic until failure.The purely linear elastic nature of this relationship significantly influences the change of the design approach used to determine the load-bearing capacity of concrete elements reinforced with steel bars. The lack of a phase of plastic deformation of FRP bars implies the necessity to change the load capacity design algorithm. In general, the design of steel-reinforced beams avoids the occurrence of concrete crush failure. In the design of FRP beams, this failure mode is preferred because the tied concrete of the beam exhibits a limited level of strength after failure, albeit with a reduced stress level. The method of determining internal forces in reinforced FRP sections is similar to the method used for beams with conventional reinforcement; however, the analysis of the ultimate moment of load capacity of the section is based on taking into account the linearly elastic behaviour of FRP bars.According to ACI 440.1R-15, design flexural strength in a cross-section of concrete member reinforced with FRP bars should not exceed the factored bending moment. The factored bending moment is a function that results from the geometry of the member, location of FRP bars, and mechanical properties of concrete and FRP bars. The strength reduction factor is associated with the failure mode of the member under flexure and characteristics of materials.Nominal flexural strength of concrete member reinforced with FRP bars can be computed on the basis of compatibility of strain, an equilibrium of internal forces and equilibrium of strength limit state, i.e., failure modes.Results of probability analysis are represented in The discrepancy  between the theoretical and test load bearing is marked on the vertical axis. On the horizontal axis, the percentage fractions of beams with the corresponding load bearing divergence are given.Normally distributed data should be visualised on the normal probability plot as a straight line. Deviations from this line are equivalent to divergences from normality . From thThe change of the slope of the linear fit line at 82 specimen per cent is addressed to ACI 440.1R-15, in opposition to the influence of FRP reinforcement ratio and the influence of superposition of high reinforcement ratio and high compressive strength of concrete on the flexural strength of FRP-reinforced beam. This statement cannot be concluded directly from the normal probability plot; at this stage, it is an explanation of the nature of the normal probability plot, which results from statistical and mathematical analysis.−6.Results of probability analysis indicate that the dataset is appropriate for further statistical analysis due to the statistical significance parameter, the compressive strength of concrete, and the degree of reinforcement and the combination of these factors, which meets the significance criterion <160 × 10Regression and ANOVA analysis were performed to investigate the influence of eight variables: 1. static scheme; 2. FRP bar type; 3. concrete strength; 4. reinforcement ratio; 5. failure mode; 6. year of research—based on the theoretical ACI 440 deviation of nominal moment capacity of FRP-reinforced beams in flexural design and the superposition of simultaneous occurrence of two significant variables from the statistical point of view—7. concrete strength with reinforcement ratio; and 8. failure mode with reinforcement ratio, which was investigated to verify the existence of an enhanced interference effect. Statistical analysis was performed on the whole dataset, which includes data on all FRP-reinforced beams listed in −6 and correlation >0.36 were considered appropriate to use. Such significance indicates nearly zero slope of the linear fit line on linear regression plot; the chance that the result was obtained by chance is nearly zero. Corresponding correlation higher than 36% indicates a high possibility of occurrence of positive or negative correlation at certain parts of the dataset.The main conclusions and results of regression and ANOVA analysis are summarised in −6. It is clear that with such constraints, out of the eight variable factors presented, only the concrete strength, the degree of reinforcement, and their combination meet the above criteria (the degree of correlation is highlighted by bold).Therefore, the criteria for accepting or rejecting the studied variables are the degree of correlation (R squared) >0.36 and significance <160 × 10On the basis of the obtained results, three variables, which are presented below, were selected for further study. Regression analysis results related to three variables, which are proposed to be implemented into the analytical model, are summarised in Regression analysis for variables included in Slightly lower values of Adjusted R Square than values of R Square, as well as relatively low values of Standard Error in −6. In other words, for variable concrete strength, the credibility of correlation results obtained in regression analysis is confirmed by ANOVA analysis.According to the results  analysis was performed. A linear relationship was assumed between coefficients related to two investigated variables and their simultaneous occurrence. The objective of GRG analysis was set to maximum, as an average value of the sum of ACI 440.1R-15 nominal flexural strength of FRP reinforced beam in the current dataset and the proposed coefficient The influence of the examined factors on nominal flexural strength of concrete beams reinforced with FRP bars was proposed to be implemented to the ACI 440.1R-15 model by the introduction of new coefficients, Values of proposed coefficients (in Equation (1.3)–(1.5)), resulting from GRG analysis, for the transition zone linear relationship are proposed (Equation (1.2)).The proposed coefficient, where:where:Since the proposed coefficient is primarily related to the influence of material characteristics on nominal flexural strength of FRP-reinforced beams, it is implemented into the formula for the calculation of tensile strength of FRP bar in a longitudinal direction. In the case of compression-controlled sections, it is effectuated by multiplication of a safety factor related to concrete strength, Safety factor related to concrete strength, For these reasons, a modification of safety factor related to concrete strength, Therefore, the parameter β1 is the factor by which the height of the compression zone of the concrete in bending is determined for the rectangular Whitney stress block. A rectangular stress block is a representation of a nonlinear stress distribution in the concrete. The coefficient β1 = 0.70 was adopted due to the distinction between the compressive strength of concrete of 50 MPa.To verify the accuracy and safety aspects of the proposed analytical model, the results were compared to experimental results. The average accuracy of the flexural nominal strength of concrete beams reinforced with FRP bars predicted with the standard ACI 440.1R-15 approach is equal to 87.3%. The newly proposed analytical model guarantees average accuracy equal to 93.1%. An improvement in accuracy is observed for 45.7% of specimens. Moreover, the proposed coefficients were applied in design procedure for beams corresponding to ACI 440 error equal to 7% or more (70.5% of positions with high error); therefore, improvements are significant and observed for most critical situations.For better visualization of the changes in results after the implementation of the new coefficients, results are marked with colour shades: a green background is equivalent to the most accurate result, and a red background indicates the largest theoretical error. Probability analysis was performed for the dataset containing results obtained with the modified ACI 440.1R-15, and the probability plot for results after implementations of proposed changes  is compaThe normal probability plot of theoretical flexural strength of FRP-reinforced beam error related to the results obtained with the use of the proposed model is nearly linear for up to 89.5% of specimens; the theoretical discrepancy for 91 out of 102 FRP-reinforced beams did not exceed 17.2%. For comparison, the discrepancy of ACI 440 results do not exceed 17.2% for 65.2% of specimens.The proposed analytical model was not applied to any CFRP-reinforced beam included in The nominal flexural strength of FRP reinforced beam predicted with ACI 440 design code matches the experimental results fairly well for beams with low and moderate concrete strength or FRP reinforcement ratio.Theoretical results obtained with the use of ACI 440 design code for beams characterised by high compressive strength or high reinforcement ratio are significantly underestimated.Results of the study in this work indicate a positive influence of interference of application of high-strength concrete and high reinforcement ratio in FRP-reinforced beams on their flexural strength.The proposed coefficient, Modifications to the safety factor related to concrete strength, According to regression and ANOVA analysis static scheme, FRP bar type and predicted failure mode does not influence nominal flexural strength of FRP-reinforced beams. However, there may be some restrictions in using these values, as for some other FRP types the values can be not applicable. Authors believe that this method can be generalized, and the values for other types can be defined from other experimental studies and compared with the new model.An extensive research programme was realized to investigate the influence of various factors on flexural strength of concrete beams reinforced with FRP bars, as well as the correlation between the error of analytical results of nominal flexural strength of FRP-reinforced beams obtained with the use of ACI 440.1R-15 design code approach and results obtained experimentally. From the statistical and numerical study covered in this work, the following conclusive remarks can be drawn:Implementation of the proposed coefficient,


Based on N2 adsorption and thermogravimetric analyses, the resulting hybrid porous materials displayed high surface areas (270 m2/g for POSS-TPP and 741 m2/g for POSS-TPE) and outstanding thermal stabilities. Furthermore, as-prepared POSS-TPP exhibited a high carbon dioxide capacity (1.63 mmol/g at 298 K and 2.88 mmol/g at 273 K) with an excellent high adsorption capacity for iodine, reaching up to 363 mg/g, compared with the POSS-TPE (309 mg/g).In this study, two different types of hybrid porous organic polymers (POPs), polyhedral oligomeric silsesquioxane tetraphenylpyrazine (POSS-TPP) and tetraphenylethene (POSS-TPE), were successfully synthesized through the Friedel−Crafts polymerization of tetraphenylpyrazine (TPP) and tetraphenylethene (TPE), respectively, with octavinylsilsesquioxane (OVS) as node building blocks, in the presence of anhydrous FeCl Various instruments, such as Fourier-transform infrared spectroscopy (FTIR), solid state 13C cross-polarization/magic-angle spinning (CP/MAS), nuclear magnetic resonance spectroscopy (NMR), Brunauer–Emmet–Teller theory (BET), XRD, TEM, and SEM were used to examine the chemical structures, morphology, crystallinity, and porous properties for POSS-TTP and POSS-TPE, respectively. The results revealed that the as-prepared POSS-TPP exhibited a high carbon dioxide capacity (1.63 mmol/g at 298 K and 2.88 mmol/g at 273 K) with an excellent and high adsorption capacity for iodine, reaching to up to 363 mg/g.In this work, we designed, synthesized, and applied in CO3, 99.99%), 1,2-dichloroethane , anhydrous magnesium sulfate , ammonium acetate , acetic acid , potassium carbonate , and benzoin (98%) were purchased from Alfa Aesar . Tetrahydrofuran (THF), acetone, methanol (CH3OH), and dichloromethane (DCM) were ordered from Aldrich .Octavinylsilsesquioxane , benzophenone (99%), anhydrous ferric chloride  was added slowly to the reaction mixture at 0 °C, and the reaction solution was refluxed at 80 °C for 18 h. After that, a 10% aqueous solution of K2CO3 was added dropwise to the reaction mixture at room temperature. The reaction mixture was extracted with ethylacetate (EA), dried over MgSO4 and filtered, and the THF solution was removed to yield TPE as a white crystalline solid (yield: 97%)  in dry 1,2-dichloroethane (20 mL) was prepared. The mixture was stirred at room temperature for 0.5 h and then heated under reflux at 60 °C for 24 h. After cooling at room temperature, the solid was filtered and washed three times with THF, methanol, chloroform, and acetone to remove the unreacted monomer and FeCl3. Then, it was dried under a vacuum at 80 °C to get a red-brown solid .A solution of OVS , tetraphenylpyrazine , and FeCl3  in 1,2-dry dichloroethane (20 mL) was stirred at room temperature for 0.5 h and then heated under reflux at 60 °C for 24 h. After cooling at room temperature, the solid was filtered and washed three times with THF, methanol, chloroform, and acetone to remove the unreacted monomer and FeCl3. It was then dried under a vacuum at 80 °C to get a red-brown solid .A solution of OVS , TPE , and FeCl2 solution in hexane. The solution mixture was stirred at different times, and then the UV-Vis measurement was done. The calibration curve of the I2 solution was recorded by using various iodine concentrations.The procedure of iodine uptake by both porous materials (POSS-TPP and POSS-TPE) was carried out as follows: POSS-TPP or POSS-TPE (5 mg) was suspended in 10 mL of an I3COONH4) in the presence of acetic acid at 90 °C. The TPE monomer was prepared by the reaction of benzophenone with zinc in dry THF as a solvent and the presence of TiCl4 at 80 °C under an N2 atmosphere. While the schematic method for the preparation of two different hybrid microporous polymers (POSS-TPP and POSS-TPE) was based on OVS, TPP and TPE are shown in 3 as a catalyst and 1,2-dichloroethane as solvent at 60 °C for 24 h in an N2 atmosphere -TPP units, respectively. While the signals appearing in the range 140.94–129.17 and 39.96–15.17 pm for POSS-TPE (2–CH2-TPE or Si–CH(CH3)-TPE units, respectively. The chemical structures of POSS-TPP and POSS-TPE were confirmed through the solid-state analyses . The solprofiles  of POSS-profiles A which cPOSS-TPE B arising29Si MAS NMR measurement was done to confirm the presence of POSS moiety in both POSS-TPP and POSS-TPE, as presented in 29Si MAS NMR spectra of POSS-TPP and POSS-TPE, two major signals at −66.95 ppm and −78.66 ppm were attributed to the silicon atom of CSi(OSi)3 (T3) from the SiCH2 CH2TPP, Si¬CH(CH3) TPP units and the unreacted SiCH=CH2 group, respectively, and for POSS-TPP and the silicon atom of CSi(OSi)3 (T3) from the SiCH2CH2TPE, SiCH(CH3) TPE units and unreacted SiCH=CH2 group, respectively. In addition, the disappearance of signals arising from the T1 or T2 units (Tn = CSi (OSi)n(OH)3−n) indicated both the remaining structure and the lack of cleavage of the cage structure in the POSS-TPP and POSS-TPE hybrid polymers.The solid state 2 atmosphere, as shown in Td5 and Td10) and char yields were 242 °C, 255 °C, and 3.6% for OVS; 296 °C, 312 °C, and 0% for TPP; 246 °C, 263 °C, and 0% for TPE; 267 °C, 398 °C, and 71% for POSS-TPP; and 378 °C, 475 °C, and 73% for POSS-TPE, respectively. Interestingly, both POSS-TPP and POSS-TPE hybrid polymers displayed high thermal stabilities compared with their corresponding monomers, which was attributed to the introduction of POSS units, which enhanced the highly crosslinked network in the system, preventing the rapid degradation of hybrid polymers and also increasing the cleavage degradation of organic groups in the POSS-TPP and POSS-TPE. The values of Td5 and Td10 and the char yield for the OVS, TPP, TPE, and their corresponding polymers are summarized in The thermal stabilities of OVS, TPP, TPE, POSS-TPP, and POSS-TPE were studied using TGA analysis under an NThe wide-angle powder X-ray diffraction (WAXD) patterns of POSS-TPP and POSS-TPE  showed a2 uptake at a low P/P0 pressure that continued to increase at a high P/P0 pressure, indicating the coexistence of mesopores and micropores in the hybrid polymer network. Based on the International Union of Pure and Applied Chemistry (IUPAC) classification for BET curves, both POSS-TPP and POSS-TPE featured type IV adsorption isotherms. In addition, there were the hysteresis loops in both curves which also confirmed the presence of micropores and mesopores in the polymer framework. The Brunauer–Emmet–Teller (BET) surface area and total pore volume of the POSS-TPP and POSS-TPE were calculated to be 270 m2/g and 0.22 cm3/g, respectively, for POSS-TPP and 741 m2/g, 0.58 cm3/g, respectively, for POSS-TPE. The pore size distributions of POSS-TPP and POSS-TPE were calculated by using non-local density functional theory (NL-DFT), as elucidated in Nitrogen adsorption–desorption experiments at 77 K were measured to examine the porosity parameters for our new POSS-TPP and POSS-TPE . Both of2 capture and iodine adsorption due to their high total pore volumes, BET surface areas, and the presence of mesoporous and microporous structures in the polymer networks. We performed CO2 uptake measurements for POSS-TPP and POSS-TPE at 298 K and 273 K to examine their CO2 uptake abilities, as presented in 2 adsorption capacity, reaching 1.63 mmol/g at 298 K and 2.88 mmol/g at 273 K, while POSS-TPE showed CO2 capture values reaching 0.99 mmol/g at 298 K and 1.97 mmol/g at 273 K. As previously reported, the enhancement of polymeric porous materials for the adsoprtion of acidic CO2 gas can be achieved through the incorporation of basic nitrogen functionalities and oxygen groups into the polymeric network. Interestingly, even POSS-TPP possesses a low BET surface area (270 m2/g) compared with the POSS-TPE. POSS-TPP displayed a higher CO2 uptake than that other porous materials, such as poly) silole (PDMTPAS), (1.02 mmol/g at 298 K), An-CPOP-1 (1.30 mmol at 298 K and 1.40 mmol/g at 273 K), An-CPOP-2 (1.40 mmol/g at 298 K and 1.52 mmol/g at 273 K), and C2M1-Al (1.44 mmol/g at 273 K) [2 molecules and the POSS-TPP. The CO2 adsoprtion capacity performance of POSS-TPP and POSS-TPE, compared with other porous materials, is provided in We applied POSS-TPP and POSS-TPE for COt 273 K) ,73, due 2, have attracted much intention in both academics and industry [2 solution (10−4 M) at different interval times (0 h to 24 h). As shown in 2 was detected at λmax = 523 nm. After the addition of 5 mg of POSS-TPP or POSS-TPE into the iodine solution in hexane, the intensity of the absorption bands of the I2 gradually decreased when the time increased from 0 to 24 h. These results suggest that both POSS-TPP and POSS-TPE could act as good precursors for I2 adsoprtion. The calibration curve  were easily synthesized via simple Friedel−Crafts polymerization of cubic octavinylsilsesquioxane as node building blocks with tetraphenylpyrazine and tetraphenylethene, respectively, in the presence of FeCl


However, existing estimates do not account for the CO2 impact from the capture, transport and utilization of CO2, change in compressive strength in CCU concrete and uncertainty and variability in CCU concrete production processes. By accounting for these factors, we determine the net CO2 benefit when CCU concrete produced from CO2 curing and mixing substitutes for conventional concrete. The results demonstrate a higher likelihood of the net CO2 benefit of CCU concrete being negative i.e. there is a net increase in CO2 in 56 to 68 of 99 published experimental datasets depending on the CO2 source. Ensuring an increase in compressive strength from CO2 curing and mixing and decreasing the electricity used in CO2 curing are promising strategies to increase the net CO2 benefit from CCU concrete.Carbon capture and utilization for concrete production (CCU concrete) is estimated to sequester 0.1 to 1.4 gigatons of carbon dioxide (CO Carbon curing or mixing in concrete is promising for carbon dioxide sequestration. Here, the authors show that the increased use of binder material to compensate the loss in compressive strength and electricity for carbon dioxide curing is more likely to increase carbon dioxide emissions on a life cycle basis for carbon cured or mixed concrete. Among the portfolio of products that can potentially utilize CO2, concrete offers several advantages including (i) a thermodynamically favorable reaction mechanism3 to sequester the CO2 as calcium or magnesium carbonates5 in ordinary Portland cement (OPC)7 (ii) the long term CO2 sequestration in the form of stable carbonate beyond the life-time of the infrastructure (>60 years) (iii) the significant sequestration potential due to the overall and expected growth in global cement production to meet increasing demand8. Concrete along with aggregates and chemicals/fuels are end-products with the potential to sequester the maximum quantity of CO2 (in gigatons)3.The capture and utilization of carbon dioxide , which are by-products of coal electricity and pig iron production; the uncertainty and variability in inventory data and process parameters; and may not always be based on primary experimental data, which is required for a robust life cycle CO2 assessment.A common assumption motivating research and commercial interests in CCU concrete is that the CO2 curing can decrease the compressive strength of CCU concrete when compared to conventional concrete. For example, a review of 99 experimental datasets from existing literature shows that CCU concrete has a lower compressive strength than conventional concrete in 31 datasets  of CCU concrete rely on point values for process parameters rather than parameter distributions that provide a more realistic representation of uncertainty and variability21. The failure to account for uncertainty in the early stages of technology development can hinder research efforts to address hotspots and increase the CO2 benefit from CCU concrete26. An uncertainty assessment in the early stages of technology development can determine process parameters and inventory items that are the most significant contributors to the CO2 burden of CCU concrete and, thereby, help identify research strategies that are most effective in addressing the hotspots.In addition, the CO2 benefit associated with CCU concrete. The net CO2 benefit is defined as the difference between the lifecycle CO2 impact of producing conventional concrete and producing CCU concrete though CO2 curing or CO2 mixing. The net CO2 benefit accounts for the life cycle CO2 impact of the 13 upstream processes to capture, transport and utilize CO2 and produce and transport the materials used in concrete. The net CO2 benefit accounts for any changes in compressive strength when CCU concrete is produced though CO2 curing or CO2 mixing. We conduct a sensitivity analysis consisting of a scatter plot analysis and moment independent sensitivity analysis30 to determine the key processes with the most significant influence on the net CO2 benefit.To address these issues, we review 99 datasets from 19 publications to determine the range of potential net CO31 wherein CO2 is used for curing and OPC is used as binder. Based on the inventory requirements presented in the dataset, the CO2 emissions for the 13 processes  in 10,000 Monte Carlo runs. If the net CO2 benefit is positive, then the total life cycle CO2 emissions from producing CCU concrete (TOTCCU) is lower than conventional concrete (TOTConv). For dataset 1 the likelihood is 0%, which signifies that TOTCCU is greater than TOTConv in all of the 10,000 Monte Carlo runs. Alternately, the distribution for the net CO2 benefit is always negative which indicates that, on a life cycle basis, producing CCU concrete is more CO2 intensive than conventional concrete in the 10,000 Monte Carlo runs.The distribution in Fig. 2 emissions from the 13 conventional concrete (PConv) and CCU concrete (PCCU) processes and the net CO2 benefit. The scatter plot shows the 10,000 net CO2 benefit values on the ordinate and the 10,000 values of the difference between the CO2 emissions from the 13 processes on the abscissa. A visual inspection of the scatter plot reveals a difference in the slopes of the scattered points. A higher slope indicates higher sensitivity of the net CO2 benefit to the contributing process. The scatter plot for dataset 1  has a significant slope. As the difference in CO2 emissions from OPC production are scattered in the lower left quadrant, the CO2 emissions from OPC production for CCU concrete is greater than conventional concrete. Therefore, for dataset 1, the difference between the CO2 emissions from OPC production is the most important reason for TOTCCU being greater than TOTConv .The scatter plot analysis of the 10,000 Monte Carlo runs Fig.  determin30, which determines δ indices for each of the 13 processes contributing to the net CO2 benefit  being lower than conventional concrete (18–18.6 MPa). The mean compressive strength of CCU concrete (16.7 MPa) is 9% lower than that of conventional concrete (18.3 MPa). This implies that in dataset 1 a greater mass of OPC is produced for CCU concrete to achieve the same compressive strength as conventional concrete. In dataset 1, the OPC produced per MPa for CCU concrete is 24.8 kg/MPa and for conventional concrete is 22.6 kg/MPa.This finding is confirmed by a moment independent sensitivity analysisfit Fig. . The δ i2/kg OPC for the life cycle CO2 footprint of OPC . Category 3 has 8 datasets wherein CO2 is used for mixing and the binder consists of only OPC. Category 4 has 21 datasets wherein CO2 is used for mixing and the binder consists of a mix of OPC and SCM.We extend the analysis conducted for dataset 1 to the remaining 98 datasets Fig. . The 99 2 benefit is most sensitive to the amount of OPC produced and used in the design mix  with at least a 50% likelihood in 56 out of the 99 datasets. The compressive strength in CCU concrete decreases due to CO2 curing when compared to conventionally cured concrete. The OPC and SCM consumed to produce the same compressive strength is greater in CCU concrete than in conventional concrete. Therefore, the results demonstrate the CO2 burden of increased OPC and SCM consumption for CCU concrete outweighs the benefit of the CO2 that is captured and used in CCU curing. Additionally, in category 1 datasets, the electricity use in the CO2 curing process is the second key contributor to the increase in the total life cycle CO2 emissions from CCU concrete  in 44 out of the 99 datasets , mass-based (MA), and economic value-based allocation (EA)—to allocate and account for the life cycle CO2 emissions from producing the SCMs  has the most significant influence on the net CO2 benefit  is not significantly impacted by the choice of system expansion SE, MA or EA. CCU is less CO2 intensive than conventional concrete in a minimum of 36 datasets when EA is used and a maximum of 43 datasets when SE is used. However, for category 2 and 4 datasets, the choice of SE, MA or EA impacts the results from the δ indices sensitivity analysis. When SE or MA is used in category 2 datasets, SCM use is a key contributor to the net CO2 benefit of CCU concrete. When EA is used in category 2 datasets, the CO2 emissions from the CO2 curing process is the key contributor. When SE is used in category 4 datasets, SCM use is a key contributor to the difference in the total CO2 emissions between conventional and CCU concrete. When EA or MA is used in category 4 datasets, OPC use is the key contributor. However, the choice of SE, MA or EA is an artifact of the method of analysis—not actually changing real CO2 emissions—and, therefore, is not within the purview of engineering strategies to improve processes and decrease the CO2 emissions from producing CCU concrete.The overall results on the number of datasets in which there is a positive net CO2 curing duration, water to cement and SCM to cement ratios obtained from the 99 datasets 2 curing: a key priority is to determine a CO2 curing protocol that consistently increases the compressive strength of CCU concrete. An increase in compressive strength implies that a smaller quantity of carbon intensive binder material is used in CCU concrete to achieve the same compressive strength as conventional concrete . Fine tuning the curing process such as duration of the pre-hydration and post-carbonation water compensation are promising candidates to restore the reduction in 28-day compressive strength observed for CO2-cured concrete34. For example, a longer duration of pre-hydration may enhance 28-day compressive strength but decreases CO2 uptake at early age. Further investigations are needed for enhancing consistency of CO2-cured concrete production and for implementing the laboratory strategies in field applications.Ensure increase in compressive strength from CO(ii)2 emissions from the CO2 curing process: electricity use, which is the key contributor to the CO2 emitted during the CO2 curing process, can be lowered by streamlining the curing process. Future research can investigate and standardize promising options, such as natural drying or waste heat drying for pre-curing of CO2-cured concrete35 with the end goal of accelerating adoption in industry.Decrease the CO(iii)2 curing on durability: the findings of this research are based on the compressive strength property of CCU concrete, which is limited from a lifecycle perspective. Prior studies show that construction and repair frequencies are key drivers in determining concrete life cycle CO2 impacts37. Therefore, the effect of CCU on concrete durability must be considered when analyzing life cycle CO2 emissions. Preliminary lab scale studies demonstrate that CO2 curing improves durability related parameters such as permeability, sorptivity and sulfate and acid resistance40. However, the variability in the curing conditions and the design mixes used in the studies should be accounted for to ensure that durability gains can be consistently realized when CO2 curing of concrete is adopted at a commercial scale. Future work can prioritize standardizing the CO2 curing protocol , and study the resulting durability impact on different design mixes , with the overall goal of identifying optimal curing conditions and design mixes to maximize durability. This applies to ready-mix concrete and general precast applications with end-products such as masonry units35, pipes22, and pavers41. In addition, CO2 curing for reinforced concrete needs further investigation due to the possibility of increased risk of steel reinforcement corrosion led by concrete carbonation. Moreover, CCU can be potentially synergized with established strategies for concrete crack width control, e.g., engineered cementitious composites with microfiber reinforcement, to further promoting concrete durability43.Improve understanding on the impact of COAn R&D agenda focused on the following items, which are within the control of the CCU concrete production process, can increase the net CO2 captured from the power plant is used for CCU concrete production without any intermediate storage. In practice, the total CO2 captured from a power plant may be significantly greater than the maximum utilization capacity at a CCU concrete production plant. In such cases, the excess captured CO2 may be temporarily stored for future utilization in CCU concrete production or routed towards other utilization pathways. Given that CO2 utilization is an emerging field and in the early stages of commercialization, there is a lack of time-sensitive data on how the captured CO2 feedstock is either temporarily stored or immediately allocated to other utilization pathways. As a result, a system boundary that incorporates the time-sensitive utilization of CO2 captured from a power plant is beyond the scope of this work and is a topic for future research.The system boundary Fig.  assumes 2 through pipelines has a lower CO2 impact than road-based transport using semi-trailer trucks44, which is modeled in this analysis. To quantify the maximum possible gains from shifting to a less carbon intensive mode of CO2 transport, we conduct a scenario analysis with the optimistic assumption that the CO2 impact of CO2 transportation is zero  than alternate approaches such as concrete curing with flue gas47, carbonation of recycled concrete aggregates9, CO2 sequestration in alternative MgO based binders10, and CO2 dissolution in mixing water14. The increased availability of experimental data is necessary to robustly quantify the net CO2 benefit of CCU concrete and account for the impact of data uncertainty and process variability on the results. For example, further experimental research can generate data on the variability in the compressive strength of flue-gas cured concrete properties when the 2-week curing time is reduced47 and the CO2 concentration in the flue gas is varied45. With increased availability of inventory and process data from future experimental research, the life cycle approach presented in this study can be extended to quantify the net CO2 benefit of CCU concrete produced from flue gas and other alternate approaches of CO2 utilization.This analysis focusses on the use of pure CO2 curing or CO2 mixing on the lifetime behaviors and geography specific factors are important practical considerations when using CCU concrete in commercial applications. The lifetime behaviors are impacted by the variations in the geographical sources of raw materials, mix type, product type and the service environment in which the concrete is deployed. For example, the impact of CO2 curing on concrete lifespan would differ substantially between concrete with and without steel reinforcement, due to the heightened steel corrosion48 caused by the CO2-induced pH reduction49. Additionally, geography specific factors such as sulfate-rich soils50, cold regions39, or acidic environments22 can impact the durability of CCU concrete. The findings of this study can be further complemented by future research which quantifies the impact of variations in the lifetime and the geography specific factors on the net CO2 benefit of CCU concrete.The impact of CO59 as they were the only ones to report the following three items (i) the design mix consisting of the energy and material inventory required for the production of conventional and CCU concrete  the quantity of CO2 used in mixing or curing of concrete. This is required to determine the life cycle CO2 impact of capturing, transporting, and utilizing the CO2 used in producing CCU concrete; and (iii) the compressive strength of CCU and conventional concrete at the end of 28 days, which helps account for the change in the material property between conventional and CCU concrete. The 28-day compressive strength is among the most widely used technical parameters for assessing concrete quality, categorizing concrete mix designs60 and forms the basis for concrete structural design62 and is, therefore, chosen as the functional property based on which conventional and CCU concrete are compared. Based on whether CO2 is used in CCU concrete for curing or mixing and if SCM was used in the design mix, the 99 datasets were organized into four categories.(i)2 is used in the curing of concrete and only OPC is used as the cementitious material in the design mix59. This category contains 50 datasets.Category 1: CO(ii)2 is used in the curing of concrete and a combination of OPC and SCM is used as the cementitious material in the design mix55. This category contains 20 datasets.Category 2: CO(iii)2 is used in the mixing of concrete and only OPC is used as the cementitious material in the design mix51. This category contains 8 datasets.Category 3: CO(iv)2 is used in the mixing of concrete and a combination of OPC and SCM is used as the cementitious material in the design mix54. This category contains 21 datasets.Category 4: COWe conducted a literature review to obtain the 99 datasets from 19 studies presenting life cycle material and energy inventory data and process parameters for the production of CCU and conventional concrete. The literature review identified the 19 studies63, or fly ash, which is a by-product of electricity generation in coal power plants.SCM took the form of either ground granulated blast furnace slag, which is a by-product of the pig-iron production2 during mixing or curing changes the compressive strength of CCU concrete when compared to concrete produced through conventional mixing or curing. In addition, an energy penalty (Ep kWh) is incurred for CCU concrete in power plants due to the energy associated with capturing the CO2, which is used in the curing or mixing of CCU concrete . Ep is not incurred when conventional concrete is produced since there is no CO2 capture. Therefore, the net CO2 benefit of substituting CCU concrete for conventional concrete should account for the CO2 impact from the change in the compressive strength and Ep, which is incurred in power plants only when CO2 is captured.The use of CO3 of volume and Ep kWh of electricity.As a result, we use a functional unit of concrete with 1 MPa compressive strength and 1 m3 of CCU and conventional concrete to 1 MPa of compressive strength. The inclusion of Ep kWh of electricity in the functional unit accounts for the difference in CO2 emissions from electricity generation without CO2 capture in the conventional concrete pathway and with CO2 capture in the CCU concrete pathway. Ep is determined based on the mass of CO2 captured from the power plant  the life cycle CO2 emissions from producing the material  and (ii) and the mass of material used in the design mix normalized to the compressive strength of CCU concrete . The material used and the compressive strength are obtained from the literature review , coarse aggregate (CA), fine aggregate (FA), and water (W) production: The COCCU represents the mass of SCM used in the design mix normalized to the compressive strength of CCU concrete .Process 5—SCM production: SCM2 emissions of co-products being generated by a single system.Slag and fly ash, which are co-products of iron-ore production and electricity generation from coal, are used as SCM in the design mix of concrete. Three methods—system expansion (SE), economic value-based allocation (EA) and mass-based allocation (MA)—are widely used in LCA to determine the CO2 emissions from producing a required mass of slag is determined by expanding the system to include the production of a corresponding mass of iron-ore  is determined from Eq. 2The COslag is 1, 0008. or 0.11 when SE, MA or EA is chosen, respectively  is determined from Eq. 3When fly ash is used as the SCM, the COash is 1, 0.02 or 0.06 when SE, MA or EA is chosen, respectively , the CO2 intensity of the mode of transportation used (φM in kg CO2 per kg-km) and the distance over which the materials are transported (DM in km). MCCU represents CCCU, FACCU, CACCU, WCCU and SCMCCU from processes 1 to 5. DM values for road, rail, ocean and barge transport are obtained from the national average values for the US concrete industry (SI Section 7)60. φM for the four transportation modes are obtained from the Ecoinvent database  and the life cycle CO2 emissions from producing a monoethanolamine (MEA) post-combustion CO2 capture system (φMEA). φMEA is obtained from the literature review of 21 studies83 (SI Section Process 7—Monoethanolamine (MEA) Production: The CO2 with a high efficiency (90%)84, capture CO2 from dilute concentrations85, are retrofittable to power plants currently in operation and are a commercially mature technology87. The power sector accounts for 28% of the overall CO2 emissions in the U.S88 and is, therefore, a good candidate for carbon capture. As a result, we consider CO2 capture from power plants. Post-combustion capture is considered as it more commonly deployed than oxy-fuel and pre-combustion systems85. The reader can refer to85 for further details on the underlying physical principles of carbon capture using MEA, which is beyond the scope of this work.MEA systems are considered as they capture CO2 emissions from the power plant is the sum of two components.Process 8—Power plant electricity generation: When CCU concrete is produced, the total COelec quantifies the allocation of CO2 emissions from a coal power plant between the co-products of electricity and fly ash, which is used as SCM in concrete production in certain datasets. Allocelec is 0.98 or 0.94 as economic or mass allocation allocates 0.02 and 0.06 of the total CO2 emissions from the coal power plant to the co-product of fly ash . φNot Cap accounts for the 10% of CO2 which is not captured as the capture efficiency of the MEA system is 90%84.Alloc2 emissions from compensating for the energy penalty (Ep in kWh), which is incurred when CO2 is captured from a power plant. The second component is the product of Ep and the CO2 intensity of the electricity used to compensate for Ep (φAvg in kg CO2/kWh).The second component accounts for the COp is quantified as followsECCU is the mass of CO2, which is captured from a power plant and utilized in CCU concrete production. heatccu represents the heat required to regenerate the MEA ).φ92 to determine the CO2 intensity of the electricity used to compensate for the energy penalty. NETL recommends that the energy penalty is compensated through an external electricity source, which is representative of the grid-mix of the region in which the analysis is carried out92. φAvg varies between 0.38 and to 0.56 kg CO2/kWh, which represents the lower and upper limit of the average CO2 intensity of electricity generated in the different grid regions in the US in 202092.This analysis follows the standards recommended by the National Energy Technology Laboratory (NETL)2 Transportation: This analysis assumes that the captured CO2 is transported in a semi-trailer truck (SI Section 2 Transportation”) as it is necessary to supply the CO2 from the site of capture to geographically disperse concrete curing or mixing facilities, which are primarily accessible by road21. The CO2 emissions from transporting CO2 is the product of the total weight (φCCU plus the tare weight), the distance over which the transport occurs (DCO2 in km) and the CO2 intensity of transportation emissions of a semi-trailer truck  of 0.4 kg in the onward trip to the CCU concrete production facility  and injecting CO2 (φInj) is the product of φCCU (kg CO2), φAvg (kg CO2/kWh) and the electricity required to vaporize 16, respectively. η is the CO2 absorption efficiency and represents the portion of the total CO2 which is absorbed during mixing or curing of concrete (datasets 71 to 99). η varies between 50% and 85% during mixing52. For curing, η is equal to 1  as the curing datasets (datasets 1 to 70) report CO2 utilized as the ratio of the mass of CO2 absorbed to the mass of cement.Processes 10 and 11—Vaporization and injection of CO2 and steam curing: The CO2 emissions from CO2 curing of the concrete sample (φCO2_Cur) is the product of φCCU (kg CO2), φAvg (kg CO2/kWh), the electrical power requirements of the curing chamber (PCO2_Cur = 38.8 kW/m3 of concrete)95 and the duration of curing  is the product of CO2 intensity of steam curing , which is determined from the literature , the CO2 emissions from CO2 and steam curing are assumed to be zero as CO2 curing of concrete is not conducted.When CO2 emissions from producing conventional concrete (TOTConv) are similarly quantified in Eq. The total life cycle CO2 emissions from generating Ep kWh of electricity in a power plant without carbon capture. φPow_Plnt is the CO2 intensity of electricity generated in a coal or NGCC plant  quantifies the COCCU  having the most impact on the net CO2 benefit. The moment independent sensitivity analysis determines the δ index for each of the 13 processes. The δ index quantifies the relative contribution of each of the 13 processes to the probability distribution function of the net CO2 benefit. The moment independent sensitivity analysis offers methodological advantages as it accounts for the correlation between the input parameters for the 13 processes and is applicable when the input parameters and the output are not linearly related98. This study determines the δ indices over 10,000 Monte Carlo runs based on the approach presented in Wei, Lu, and Yuan97.To further verify the results, this analysis conducts a moment independent sensitivity analysisSupplementary InformationPeer Review File