State of the art on pre-tensioning steel straps confinement: literature review

This paper presents the state-of-the-art of the current research development on pre-tensioning steel straps confinement. Critical review was conducted based on careful selection of references to provide in-depth overview in the development of this confining technique. The paper was started with highlighting the features of such confining technique, then an extensive description of the connection clip systems was presented. The experimental and numerical investigations performed on steel-strapped concrete structures were discussed at length in the paper. The potential usage of pre-tensioning steel straps confinement in increasing the bond properties of confined concrete and as a repairing technique of damaged concrete were also covered in this paper

State of the art on pre-tensioning steel straps confinement: literature review

This paper presents the state-of-the-art of the current research development on pre-tensioning steel straps confinement. Critical review was conducted based on careful selection of references to provide in-depth overview in the development of this confining technique. The paper was started with highlighting the features of such confining technique, then an extensive description of the connection clip systems was presented. The experimental and numerical investigations performed on steel-strapped concrete structures were discussed at length in the paper. The potential usage of pre-tensioning steel straps confinement in increasing the bond properties of confined concrete and as a repairing technique of damaged concrete were also covered in this paper

The Arab world's contribution to solid waste literature: a bibliometric analysis

BACKGROUND: Environmental and health-related effects of solid waste material are considered worldwide problems. The aim of this study was to assess the volume and impact of Arab scientific output published in journals indexed in the Science Citation Index (SCI) on solid waste. METHODS: We included all the documents within the SCI whose topic was solid waste from all previous years up to 31 December 2012. In this bibliometric analysis we sought to evaluate research that originated from Arab countries in the field of solid waste, as well as its relative growth rate, collaborative measures, productivity at the institutional level, and the most prolific journals. RESULTS: A total of 382 (2.35 % of the overall global research output in the field of solid waste) documents were retrieved from the Arab countries. The annual number of documents published in the past three decades (1982–2012) indicated that research productivity demonstrated a noticeable rise during the last decade. The highest number of articles associated with solid waste was that of Egypt (22.8 %), followed by Tunisia (19.6), and Jordan (13.4 %). the total number of citations over the analysed years at the date of data collection was 4,097, with an average of 10.7 citations per document. The h-index of the citing articles was 31. Environmental science was the most researched topic, represented by 175 (45.8 %) articles. Waste Management was the top active journal. The study recognized 139 (36.4 %) documents from collaborations with 25 non-Arab countries. Arab authors mainly collaborated with countries in Europe (22.5 %), especially France, followed by countries in the Americas (9.4 %), especially the USA. The most productive institution was the American University of Beirut, Lebanon, with 6.3 % of total publications. CONCLUSIONS: Despite the expected increase in solid waste production from Arab world, research activity about solid waste is still low. Governments must invest more in solid waste research to avoid future unexpected problems. Finally, since solid waste is a multidisciplinary science, research teams in engineering, health, toxicology, environment, geology and others must be formulated to produce research in solid waste from different scientific aspects

Load-deformation behaviour of eccentrically loaded SSTT-confined high strength concrete columns

The application of steel-straps confinement or better known as steel-strapping tensioning technique (SSTT) has been proven to be effective in increasing the strength and ductility of High-Strength Concrete (HSC) column comparable to Fiber-Reinforced Polymer (FRP). However, most of the research of confined HSC column has mainly concentrated on concentric loading. In actual practical condition, most of the columns are subjected to eccentric loading. The scarcity of the experimental data for eccentric loaded confined HSC column has prevented the potential use of this type of structure element. In this paper, five HSC columns were tested. The specimens were SSTT-confined and tested with 25mm and 50 mm eccentric loading. The results show that SSTT confinement can increase the strength and deformability of high-strength concrete column, although the strain gradient reduces the confining efficiency. Therefore, smaller capacity enhancement factor should be used in eccentrically loaded SSTT-confined HSC columns compared to concentrically loaded columns. Furthermore, the non-linear theoretical model established in this study can be used for templates for future work on SSTT-confined HSC columns

Effect of Addition of Palm Oil Biodiesel in Waste Plastic Oil on Diesel Engine Performance, Emission, and Lubricity.

This research was aimed to examine the diesel engine's performance and emission of secondary fuels (SFs), comprising waste plastic oil (WPO) and palm oil biodiesel (POB), and to analyze their tribological properties. Their compositions were analyzed by gas chromatography-mass spectrometry (GC-MS). Five SFs (10-50% POB in WPO) were prepared by mechanical stirring. The results were compared to blank WPO (WPO100) and Malaysian commercial diesel (B10). WPO90 showed the maximum brake power (BP) and brake torque (BT) among the SFs, and their values were 0.52 and 0.59% higher compared to B10, respectively. The increase in POB ratio (20-50%) showed a negligible difference in BP and BT. WPO70 showed the lowest brake-specific fuel consumption among the SFs. The brake thermal efficiency (BTE) increased with POB composition. The maximum reductions in emission of hydrocarbon (HC, 37.21%) and carbon monoxide (CO, 27.10%) were achieved by WPO50 among the SFs. WPO90 showed the maximum reduction in CO2 emission (6.78%). Increasing the POB composition reduced the CO emissions and increased the CO2 emissions. All SFs showed a higher coefficient of friction (COF) than WPO100. WPO50 showed the minimal increase in COF of 2.45%. WPO90 showed the maximum reduction in wear scar diameter (WSD), by 10.34%, compared to B10. Among the secondary contaminated samples, SAE40-WPO90 showed the lowest COF, with 5.98% reduction compared to SAE40-WPO100. However, with increasing POB content in the secondary contaminated samples, the COF increased. The same trend was also observed in their WSD. Overall, WPO90 is the optimal SF with excellent potential for diesel engines

Behaviour of lightweight foamed concrete with pre-tensioning steel straps confinement

Due to its low compressive strength and ductility, lightweight foamed concrete (LFC) cannot be used in structural members such as beams, slabs and columns. One way to improve the strength and ductility of LFC is by confining the concrete laterally by using active external confinement. This research therefore aimed to investigate the effectiveness of external confinement by using low cost steel straps tensioning technique (SSTT) to the LFC columns. A total of 36 cylindrical specimens with 100 mm diameter, 200 mm height and density of 1500 kg/m3, 1650 kg/m3 and 1800 kg/m3 were prepared in this study. The strength of the LFC columns was significantly improved with the increase in number of layers and decrease in spacing of the SSTT confinement. This paper also presents the axial compression stress-strain relationship of the SSTT-confined LFC. SSTT confinement is proven to be effective in increasing the performance of the LFC columns, especially in the specimens with the density of 1500 kg/m3

Bond Between SSTT Confined Concrete and Ribbed Steel Reinforcement Bar

A study about bond strength of normal strength concrete (NSC) and Steel Strap Confining Technique (SSTT) confined NSC was presented. A series of 8 specimens pull-out test were carried out to investigate the bond strength of short embedment (5Db) in SSTT confined NSC. The concrete compressive strength was about 45 MPa meanwhile the 12mm diameter reinforcement tensile strength was about 500 MPa were used in the pull-out specimens. In order to determine the effects of lateral confinement pressure of steel strapping, three groups of different steel strap gap distance pull-out test were conducted and compared with control specimens and previous theoretical bond stress equation. It was found that SS-B pull-out specimen exhibited highest bond strength and about 40 percent higher compared with Cont-B specimen as lowest bond strength pull-out specimen in this study

Behaviour of lightweight foamed concrete with pre-tensioning steel straps confinement

Due to its low compressive strength and ductility, lightweight foamed concrete (LFC) cannot be used in structural members such as beams, slabs and columns. One way to improve the strength and ductility of LFC is by confining the concrete laterally by using active external confinement. This research therefore aimed to investigate the effectiveness of external confinement by using low cost steel straps tensioning technique (SSTT) to the LFC columns. A total of 36 cylindrical specimens with 100 mm diameter, 200 mm height and density of 1500 kg/m3, 1650 kg/m3 and 1800 kg/m3 were prepared in this study. The strength of the LFC columns was significantly improved with the increase in number of layers and decrease in spacing of the SSTT confinement. This paper also presents the axial compression stress-strain relationship of the SSTT-confined LFC. SSTT confinement is proven to be effective in increasing the performance of the LFC columns, especially in the specimens with the density of 1500 kg/m3

Subdermal contraceptive implant in post partum women: a prospective study in a single tertiary centre in Pahang, Malaysia: a preliminary study

Objective: The aim of the study was to evaluate the menstrual patterns and the effects of subdermal contraceptive implant, implanon®on breast feeding in post partum women during the first six months of insertion. Materials and methods: A prospective study was conducted over a one year period, from 1st July 2010 untill 30th June 2011 at outpatient gynecology clinic, Hospital Tengku Ampuan Afzan, Pahang, Malaysia. Thirty-three post partum patients requested for implanon as contraceptive method participated in the study. All patients had implanon inserted between 4 to 10 weeks of pospartum and were follow-up after 3 months and six months after the insertion. Results: There were 33 women enrolled in the study. Mean age of the patients was 30 years (range 24-41 years). Of those, 17 patients delivered by caesarean section while 16 patients had vaginal delivery. During first visit, 57.6% had amenorrhoea, 21.2% had prolonged bleeding while the incidence of normal, and irregular bleeding were 15.1% and 6.1% respectively. In second visit, 63.6% had amenorrhoea, 6.1% had prolonged bleeding while the incidence of normal and irregular bleeding were 21.2% and 9.1% respectively. Only two patients seek medical treatment due to prolonged bleeding. 28 patients continue to breast fed their babies while 5 patients stopped breast feeding while on implanon. The majority of women expressed satisfaction to her implanon® use, only three patients were not satisfied mainly due to side-effects of prolonged or irregular bleeding. There was no removal after six months follow-up Conclusions: Implanon® is a good, well accepted long-term contraceptive method for post partum women and lactating mothers. Dissatisfaction of its use is mainly due to abnormal menstrual bleeding pattern

Microwave irradiation-assisted transesterification of ternary oil mixture of waste cooking oil – Jatropha curcas – Palm oil: Optimization and characterization

Palm oil is an incredibly efficient crop, but our dependence on this crop as a primary biodiesel feedstock has threatened food insecurity as it is still perceived as the main source for vegetable oil throughout the world rather than being utilized for fuel. Therefore, the idea of utilizing non-edible food crops and waste vegetable oils could help to overcome the major problems faced by the first generation of biodiesel feedstock. In this study, a ternary oil mixture comprises 50 vol% of waste cooking oil, 15 vol% of Jatropha curcas oil and 35 vol% of palm oil were premixed and developed into biodiesel via esterification and microwave irradiation-assisted transesterification using a modified household microwave in the presence of methanol and potassium hydroxide catalyst. The parameters affecting biodiesel yield were optimized via response surface methodology based on central composite design. The operating parameters were optimized at 0.78 wt% of catalyst concentration, 9.86:1 of methanol/oil molar ratio, 10.5 min of reaction time and 478 rpm of stirring speed with the predicted and experimental yields are at 96.81 and 96.91 %, respectively. The results indicate that the synergistic mixture of ternary oil in WJP biodiesel gives better cold flow properties as well as improves oxidation stability and cetane number