Influence of some industrial wastes as a heavy aggregate on durability of concrete upon utilization in the special constructions

The aim of this study is to investigate the effect of some industrial wastes as a heavy aggregate on durability of the concrete after exposure to different effects. The coarse aggregates used to perform the concrete were dolomite (control) and lead slag, while fine aggregate were sand and lead slag aggregate. The physical and mechanical properties of use draw aggregates were determined also the physical and mechanical properties of different types of concrete were studied. The linear attenuation coefficients (μ) and half value layer (HVL) of gamma rays measurements have been carried out using γ-rays sources of Cs173 and Co60. Effect of sea water on the mechanical properties of high performance concrete; in addition, corrosion behavior of reinforcing steel embedded in concrete incorporating different aggregates upon exposure to sea water were studied. It was found that, the compressive strength for all concrete mixes made with dolomite and lead slag coarse aggregates satisfy the requirements of compressive strength for high performance concrete (grade-M60) after 28 days of curing in tap water. The results indicate that, the compressive strength values and gamma radiation shielding properties of concrete mix containing lead slag aggregate enhances upon replacing sand by fine portion of lead slag aggregate. The concrete mixes made with lead slag coarse aggregate proved their high endurance and could sustain sea water exposure, achieving compressive strength values exceeding grade M-60 concrete even after 6 months exposure. Lead slag concrete- in spite of its efficient durability-requires the incorporation of a corrosion inhibitor to counteract the hostile effect of the high sulfate concrete in the aggregate

Effect of silica fume on the chloride and sulphate attack of sulphate resisting and high alumina cement composite

228-234The present investigation aims to study the chloride as well as sulphate attack on the composite of 85% SRC and 15% HAC. The effect of substitution of HAC with silica fume on the aggressive attack was also studied. The results indicate that the free lime contents decrease with silica fume and curing time in sulphate as well as chloride solution. The XRD results are in a good agreement with the compressive strength and chemical analysis. The substitution of HAC with SF improves the attack of chloride and sulphate ions on cement pastes. It can be concluded that superplastecizer must be added to the silica fume blended cements

Role of GeneXpert in extrapulmonary tuberculosis

Background Tuberculosis (TB) commonly affects the lung (pulmonary TB). Extrapulmonary TB (EPTB) can involve many systems. Diagnosis is often difficult. EPTB may be misdiagnosed with many other inflammatory, granulomatous, and neoplastic disorders. GeneXpert mycobacterium tuberculosis /rifampicin is a valuable test in diagnosis of pulmonary TB. There is limited research about its diagnostic role in EPTB. Patients and methods The aim of this study was to assess the diagnostic value of GeneXpert in EPTB. Samples from EPTB cases were sent for standard mycobacterial culture and GeneXpert assay. The sensitivity and specificity of GeneXpert were calculated. Results A total of 100 patients were included. Overall, 61 cases were definitely diagnosed as EPTB, whereas 39 cases were negative according to culture. GeneXpert was positive in 40 cases, which represent 65.6% of EPTB cases, and negative in 21 (34.4%) cases. Sensitivity and specificity of GeneXpert was 65.6 and 97.4%, respectively. The positive predictive value and negative predictive value were 97.4 and 64.4%, respectively. Conclusion GeneXpert is a rapid, valuable tool in diagnosis of patients with EPTB. It is a highly specific test with fair sensitivity. A multicenter study with larger sample size is needed to evaluate the diagnostic role of GeneXpert in different sites of EPTB

Effect of silica fume on the slag cement containing wet cement dust

274-278The present work aims to study the effect of various amounts of silica fume on the physico-mechanical properties of slag cement with 5% raw cement dust. Slag cement is substituted by 4, 8 and 12% silica fume. The results reveal that the increase of silica fume tends to increase the water of consistency. On the other side, 4% silica fume decreases the setting time (initial and final) . 8 and 12% silica fume tend to lengthen the setting time due to the increase of mixing water. The free lime content increases up to 7 days then decreases for all mixes. As the amount of silica fume increases the free lime content decreases. Also, the combined water content increases with the amount of silica fume. The compressive strength of cement paste decreases with silica fume due to the increase of mixing water

Not sick enough to worry? "Influenza-like" symptoms and work-related behavior among healthcare workers and other professionals: Results of a global survey

10.1371/journal.pone.0232168PLoS ONE155e023216