Search

Using recycled concrete aggregates from construction and demolition wastes on structural concrete is a sustainable solution to reduce the consumption of natural resources and the detrimental effects of concrete production on the environment. This paper has collected much data from the literature to study fresh, mechanical properties and durability of concrete made of treated/untreated recycled aggregate (RA). Furthermore, the flexural and shear behavior of recycled aggregate concrete (RAC) beams was studied. This study discussed the distinctions and similarities between reinforced RAC beams and reinforced natural aggregate concrete (NAC) beams. The results of this review's analysis clearly show that reinforced RAC beams with different RAC ratios perform structurally on par with or slightly worse than reinforced NAC beams, demonstrating the viability of RAC for structural applications. Emphasis is placed on carefully choosing and adjusting material models for recycled aggregate concrete. Ultimately, guidelines for future inquiries in this field are delineated and deliberated upon. The review will be advantageous for academics and professionals who aim to acquire a comprehensive comprehension of the behavior of RAC beams. It addresses several practical concerns connected to the numerical modeling of these components, which have not been adequately covered in existing literature. [ABSTRACT FROM AUTHOR]

The reinforced concrete (RC) beams could be upgraded in shear using steel and fiber‐reinforced polymer (FRP) having several shapes (bars, strips, or sheets). Using near‐surface mounted (NSM) Glass FRP (GFRP) bars is still limited compared to carbon FRP (CFRP) elements as shear reinforcement. Moreover, using reinforced high‐strength concrete layers (HSCL) as NSM shear strengthening for the RC beams is still limited. Herein, three RC beams internally reinforced in shear using different shear areas (without, 100 mm stirrups apart, and 200 mm stirrups apart) were experimentally tested as reference beams (CB). Other eight beams strengthened in shear using NSM HSCL, and bars were experimentally tested. Moreover, an extended finite element (FE) simulation was implemented through a verified FE model to study the effect of other NSM aspects on shear‐strengthened beam response. The results explained that, regardless of the internal stirrups area and external NSM characteristics, the shear‐strengthened beams showed higher load efficiency than the corresponding CB. The NSM upgraded shear beam had slightly higher load efficiency than the un‐strengthened beam having the same steel area as internally shear stirrups. Moreover, increasing the internal shear stirrups decreased the total efficiency of the NSM shear strengthening and the internal stirrups regardless of the NSM characteristics. Furthermore, the NSM HSCL was more efficient than the corresponding NSM bars in increasing the load capacity and stiffness of the shear‐strengthened beams. The reported analytical model predicted well the shear capacity of the tested beams. [ABSTRACT FROM AUTHOR]

This study aims to improve the low shear strength of an exterior beam-column joint (BCJ) by using a different reinforcement pattern or ultra-high performance fiber-reinforced concrete (UHPFRC) in the beam-column joint. The main studied parameters were the transverse reinforcement ratio, anchorage of the longitudinal beam reinforcement, beam-column depth ratio, and utilizing UHPFRC. Five specimens with a one-third scale were experimentally tested under one-direction cyclic loading. All the samples were compared to the control sample in terms of crack pattern, mode of failure, hysteresis and envelope behavior, ductility factor, energy dissipation, normalized shear strength, percentage of beam flexural capacity, and stiffness degradation. Compared to the control specimen, the joint shear strength increases by 13%, 25%, 9%, and 38% for specimens that were made better by increasing the transverse reinforcement ratio, increasing the beam anchorage bar length in the joint, lowering the beam-column depth ratio to 0.80, and using UHPFRC instead of normal concrete in the beam-column joint. The UHPFRC in BCJ can be used instead of increasing the anchorage of the beam bars or the transverse reinforcement within the joint to get the same or better shear strength performance. [ABSTRACT FROM AUTHOR]

Background and Objectives: There are few reports on hepatitis C virus genotype 4 (HCV-4) recurrences after orthotopic liver transplantation (OLT). Therefore, we undertook a study to determine the epidemiological, clinical and virological characteristics of patients with biopsy-proven recurrent HCV infection and analyzed the factors that influence recurrent disease severity. We also compared disease recurrence and outcomes between HCV-4 and other genotypes. Patients and Methods: All patients who underwent OLT (locally or abroad) for HCV related hepatic cir-- rhosis from 1991 to 2006 and had recurrent HCV infection were identified. Clinical, laboratory and pathological data before and after OLT were collected and analyzed. Results: Of 116 patients who underwent OLT for hepatitis C, 46 (39.7%) patients satisfied the criteria of recur--rent hepatitis C. Twenty-nine (63%) patients were infected with HCV genotype 4. Mean (SD) for age was 54.9 (10.9) years. Nineteen of the HCV genotype 4 patients (65.5%) were males, 21 (72.4%) received deceased donor grafts, and 7 (24.1%) developed> 1 acute rejection episodes. Pathologically, 7 (24.1%) and 4 (13.8%) patients had inflammation grade 3-4 and fibrosis stage 3-4, respectively. Follow-up biopsy in 9 (31%) HCV genotype 4 patients showed stable, worse and improved fibrosis stage in 5, 2 and 2 patients, respectively. Of the 7 patients in the recurrent HCV group who died, 6 were infected with genotype 4 and 4 of them died of HCV-related disease. Conclusion: This analysis suggests that HCV recurrence following OLT in HCV-4 patients is not significantly different from its recurrence for other genotypes.

Hepatitis C is a systemic disease that has many extrahepatic manifestations in addition to hepatic inflammation and fibrosis, some of which may result in a poor health-related quality of life (HRQOL). Fatigue is perhaps the most frequent and disabling extrahepatic symptom of hepatitis C virus (HCV), reported in almost one-half of all chronically infected individuals. Many other factors are associated with a poor quality of life in patients with HCV, including a number of physical and psychological factors. The objective of this article is to review the association between HCV and impaired HRQOL due to fatigue and psychological disturbances.

Background: Saudi Arabia is a leading country in the Middle East in the field of deceased-donor liver transplantation (DDLT) and living-donor liver transplantation (LDLT). We present out experience with DDLT and LDLT at King Faisal Specialist Hospital and Research Center (KFSHRC) for the period from April 2001 to January 2007. Patients and Methods: We performed 122 LT procedures (77 DDLTs and 45 LDLTs) in 118 patients (4 re-transplants) during this period of time. Results: The number of adult and pediatric procedures was 107 and 11, respectively. The overall male/female ratio was 66/52 and the median age of patients was 43 years (range, 2-63 years). In the DDLT group, the me--dian operating time was 8 hours (range, 4-19), the median blood transfusion was 6 units (range, 0-40), and the median hospital stay was 13 days (range, 6-183). In the DDLT group, after a mean follow-up period of 760 days (range, 2-2085), the overall patient and graft survival rate was 86%. In the LDLT group, the median operating time was 11 hours (range, 7-17), the median blood transfusion was 4 units (range, 0-65), and the median hospital stay was 15 days (range, 7-127). In the LDLT group, and after a mean follow-up period of 685 days (range, 26-1540), the overall patient and graft survival rates were 90% and 80%, respectively with no significant difference in patient and graft survivals between groups. Biliary complications were significantly higher in LDLT compared to DDLT (P< 0.05). Vascular complications were also significantly higher in LDLT compared DDLT (P< 0.05). Conclusions: Both DDLT and LDLT are being successfully performed at KFSHRC with early experience indicating a higher rate of biliary and vascular complications in the LDLT group.

Background: We tested the clinical utility of the platelet count, the aspartate aminotransferase/alanine aminotransferase (AST/ALT) ratio, and the AST to platelet ratio index (APRI) score in predicting the presence or absence of advanced fibrosis and cirrhosis in patients with chronic hepatitis C in Saudi Arabia. Methods: Liver biopsy procedures performed on chronic hepatitis C patients in our gastroenterology unit at King Khalid University Hospital were traced from records between the years 1998 to 2003. The hospital com--puter database was then accessed and detailed laboratory parameters obtained. By plotting receiver operating characteristic curves (ROC), three selected models (platelet count, AST/ALT ratio, and the APRI score) were compared in terms of the best variable to predict significant fibrosis. Results: Two hundred and forty-six patients with hepatitis C were included in this analysis. Overall, 26% of patients had advanced fibrosis. When comparing the three above-mentioned prediction models, the APRI score was the one associated with the highest area under the curve (AUC) = 0.812 (95% CI, 0.756-0.868) on the ROC curves, compared to the platelet count and AST/ALT ratio, which yielded an AUC of 0.783 (0.711-0.855) and 0.716 (0.642-0.789), respectively. Conclusion: The APRI score seemed to be the best predictive variable for the presence or absence of advanced fibrosis in Saudi hepatitis C patients

Background: Hepatocellular carcinoma (HCC) is the second commonest cancer affecting males and the eighth most common one affecting females in Saudi Arabia. Transarterial chemoembolization (TACE) is currently considered the first line therapy for multifocal HCC in selected patients. Objective: To evaluate HCC response to TACE based on triphasic computerized tomography (CT) of the liver obtained 6 weeks after the procedure. Materials and Methods: A retrospective chart review of 15 patients who underwent TACE in King Khalid University Hospital for unresectable HCC. Patients were staged according to the Child-Pugh, Okuda, and CLIP scoring systems. The first triphasic CT of the liver after TACE was evaluated for Lipiodol uptake and interval change in tumor burden. Results: The mean age was 63 years (40-82), 10 were males (66.7%), and five were females. About 11 patients had cirrhosis (73.3%). Eight patients (53.3%) were Child-Pugh class A while seven (46.7%) were Child-Pugh class B. One patient died and two were lost to follow up. Four patients had a complete response to TACE (26.7%), two had a partial response (13.3%), five showed no change (33.3%) and none showed progression of disease. Tumoral Lipiodol uptake in five patients was> 75% (33.3%), in two 75-50% (13.3%) while in four patients it was < 50% (26.7%). Conclusion: Our results show that TACE is an effective method of reducing the tumor burden in selected patients with unresectable HCC.

There are various benefits to ultra-high-performance fiberreinforced concrete (UHPFRC). However, using a lot of cement in this type of concrete has a severe disadvantage since it causes pollution and several environmental concerns. Therefore, another type of concrete that achieves the same superior properties as UHPFRC while using less cement in the mixture should be considered. This research examined replacing cement with fly ash to produce environmentally friendly concrete called Green-UHPFRC. The impact of utilizing G-UHPFRC on the flexural behaviour of thirteen beams was investigated experimentally and numerically under repeated loads. The major parameters of the study were fly ash replacement ratios of 15%, 30%, and 45% and adding steel fiber to mixes with ratios of 1, 2, 3, and 4%. The tested beams were compared to the control beam in their backbone and hysteresis curves, failure load, crack propagation and failure modes, energy dissipation, stiffness degradation, and ductility index. From the results obtained, environmentally friendly concrete (G-UHPFRC) can be produced by replacing cement with fly ash up to 45% and adding 2% steel fiber without affecting the bending performance of beams made of G-UHPFRC compared to those made of UHPFRC. [ABSTRACT FROM AUTHOR]

This research studies and assesses the possibility of employing ultra-high performance fiber reinforced concrete (UHPFRC) in exterior beam-column joints (BCJs). Eight specimens with various concrete material characteristics and steel reinforcing details are cast and examined under repeated loads. Normal concrete with seismic reinforcing details is used as a control specimen. For certain specimens, UHPC, UHPFRC with 1% steel fiber, and UHPFRC with 2% steel fiber are poured into all BCJs, and others are poured into the critical zone only. The consequences of removing stirrups from the joint were studied. All specimens' crack patterns, hysteresis and envelope curves, ductility factor, stiffness degradation, and energy dissipation are assessed and corresponded to the control sample. The results demonstrate that UHPFRC strengthened the joint, prevented crack development and extension and the shear failure in the joint, and formed the plastic hinge in the beams. UHPFRC outperforms normal concrete with seismic reinforcing details and UHPC without steel fiber in bearing capacity, ductility, stiffness, and energy dissipation. UHPFRC with 1% steel fiber enhanced joint behavior, while UHPFRC with 2% steel fiber was better. Casting the whole sample with UHPFRC achieved very little improvement. The presence of stirrups in the UHPFRC beam-column joint has little effect on its properties. It is more economical to cast UHPFRC in the joint zone only and reduce or eliminate these stirrups in the case of UHPFRC. [ABSTRACT FROM AUTHOR]

Due to the depletion of natural aggregates and raw materials for contemporary construction, the construction and demolition waste existing in old concrete structures is an imperative problem. Cutting down on exploiting natural aggregates and reusing construction and demolition waste in the concrete industry are solutions to this problem. This paper investigated the replacement of natural coarse aggregate (NCA) with recycled concrete aggregates (RCA) with different ratios (0%, 50%, 75%, and 100%) in producing self-compacting concrete (SCC). Different components of supplementary cementitious materials (SCMs), such as nano-silica (NS), fly ash (FA), and metakaolin (MK), as well as PVA fibers, were incorporated into the SCC mixtures. The fresh properties (slump flow, V-funnel, and L-box test) and hardened properties (compressive strength, splitting tensile strength, and flexural strength), as well as the flexural behavior of SCC beams (load-carrying capacity, crack pattern, mid-span deflection, and flexural stiffness), were studied for all SCC mixes. The results of fresh and hardened concrete confirmed that it is possible to produce SCC with a 100% replacement of RCA with minimal effects on the concrete properties. The mixture of SCC with 100% RCA replacement, 20% MK, and 22% FA was the optimum mixture with acceptable fresh properties that complied with the EFNARC specifications. For 100% RCA replacement, the compressive strength was reduced by 8.20%, and the ultimate load and flexural stiffness increased by 3.20 and 16.25%, respectively, compared with the control mixture. [ABSTRACT FROM AUTHOR]

Background: Autoimmune hepatitis (AIH) is a relapsing inflammatory disease of the liver of unknown cause. Little is known about AIH in Saudi Arabia. Objectives: Our aim is to [1] identify the special clinical or histological features in our patients[2], describe the initial response to immunosuppressive therapy and long term relapse[3], identify clinical and laboratory predictors of response to therapy, and [4] examine the utility of laboratory markers (platelet count, AST/ALT ratio, and the AST to platelet ratio index (APRI score) in predicting the presence of advanced fibrosis. Methods: Patients were identified using a computer database. Patients responding to initial therapy were compared with patients who did not respond in terms of laboratory and histology parameters. The utility of three fibrosis markers/models were then examined. Results: Thirty-nine patients with AIH were included in this analysis. The mean age was 45.4; 65% of patients were females. Mean ALT at presentation was 268 U/L and AST was 277 U/ L. GGT level was found to be the only statistically significant laboratory or histopathological parameter difference between responders and non-responders. Platelet count and AST/ALT ratio were found to be the best predictors of advanced fibrosis. Conclusion: In Saudi patients with AIH, we found that the GGT level at presentation may serve as a useful predictor for response to therapy. Platelet count and AST/ALT ratio may be used to predict advanced fibrosis.

Objective: To identify laboratory predictors of advanced fibrosis in Saudi Arabian patients with hepatitis B and C. Materials and Methods: Histopathology reports were obtained on all patients who had liver biopsy in the last 5 years, and relevant laboratory data were collected. Results: A total of 328 patients (246 with hepatitis C and 82 with hepatitis B) were included. With logistic regression analysis, four factors were found to be the best predictors of fibrosis, namely, platelet count, ALT, AST and GGT levels. An equation for calculating the risk of advanced fibrosis was developed. The model had a sensitivity of 62%, a specificity of 92.4% and an overall accuracy of 84%. Conclusion: Platelet count, ALT, AST and GGT levels were found to be the best predictors of advanced fibrosis on liver biopsy in Saudi patients with chronic hepatitis B and C. An equation was developed that helps in calculating this risk.

Hepatic encephalopathy (HE) is a disturbance of the central nervous system (CNS) function secondary to porto-systemic shunting. It usually occurs in the setting of advanced liver cirrhosis or acute fulminant hepatic failure. An extensive Medline search was undertaken and all relevant papers found were critically examined. Special emphasis was paid to clinical trials and meta-analyses. All guidelines and conference proceedings related to hepatic encephalopathy were also examined. HE presents with a spectrum of neuropsychiatric manifestations that may be quite subtle (minimal HE) or overt, ranging from disturbance of the sleep pattern to deep hepatic coma. Most patients with HE may be diagnosed on clinical grounds only after excluding other causes of neurological disease, but a wide variety of neuropsychological, neurophysiological, and neuroradiological tests may be utilized. The first step in the management of patients with HE should be supportive care. Following that, a significant effort must be exerted to find and correct possible exacerbating factors which may include: renal impairment, infection, constipation, drugs, gastrointestinal bleeding and other factors. Medications used to treat patients with encephalopathy aim to reduce toxin production, increase toxin elimination, and protect the brain from the harmful effects of these toxins. A critical analysis of the evidence concerning most of the available management modalities is presented. Ultimately, all patients with HE must be considered for liver transplantation. It is concluded that early recognition, positive diagnosis, and a multi-target management plan constitutes appropriate management of patients with HE.

The huge amounts of old and damaged tires spread worldwide has caused many complex environmental risks. The old tires have been converted to crumb rubber (CR) and tire recycled steel fiber (RSF) to facilitate their use. This study used CR to partially replace natural sand in reinforced (RC) columns. Externally bonded (EB) carbon-fiber-reinforced polymer (CFRP) laminates, welded wire mesh (WWM), and RSF were used to enhance the axial behavior of the tested columns to overcome the concrete deficiencies resulting from the inclusion of the CR instead of natural sand. Eighteen columns were prepared and tested to discuss the effects of strengthening type, CR content, RSF, and strengthening area on the axial behavior of the RC columns. Certain columns were internally reinforced with WWM, while others were externally strengthened with EB CFRP laminates. Partially or fully EB CFRP laminates were used to strengthen the columns. Moreover, one column was cast with NC and 0.2% RSF to investigate the role of RSF in confining the column. The results demonstrated a concrete strength reduction for the rubberized concrete (CRC) as the CR content increased. Conversely, the strengthened columns experienced higher load capacities than the corresponding un-strengthened ones cast with the same concrete mix. Moreover, adding 2% RSF to the NC mix could enhance the column capacity, although it decreased the concrete strength. Furthermore, using two CFRP layers increased the load capacity and ductility of the strengthened columns. The strengthened column cast with 50% CR showed the highest load efficiency (334.3% compared to the un-strengthened one). [ABSTRACT FROM AUTHOR]