Effect of Iron Ore Tailing on the Properties of Concrete

Experiments were conducted to determine the suitability of iron ore tailing (IOT) as fine aggregate replacement of sand (RS) for concrete used for rigid pavement. The use of iron ore tailing (IOT) from Itakpe mines near Okene in north-central Kogi state of Nigeria will ensure economy in concrete production as well as a better way of disposing the tailing. Mix design was carried out for concrete of grade 35 using standard practice for selecting proportions for normal weight, and mass concrete [ACI 211.1-91, 1997]. The constituent materials were batched by weight. The mix with only sand as fine aggregate served as the control mix, while sand was replaced in the other mixes by 20%, 40%, 60%, 80% and 100% iron ore tailing (IOT). Consistency and Strength test were conducted on both concrete specimens. It was observed that concrete workability reduced with increase in the percentage of iron ore tailing in the mix. Twenty-eight (28) days compressive strength and indirect tensile strength values of 43.67N/mm2 and 2.69N/mm2 respectively, were obtained for concrete when 20% iron ore tailing (IOT) was used, Values comparable to 28days compressive strength and indirect tensile strength values of 45.02N/mm2 and 2.64N/mm2 respectively, obtained using only sand as fine aggregate. Keywords: concrete; sand (RS); iron ore tailing (IOT); compressive and tensile strength

Laboratory Experiment on the Effect of Carbibe Waste and Metakaolin on Strength and Durability Properties of Blended Concrete

The versatility of concrete makes it the most desirable construction material in the construction industry. The increase in global population growth and urbanization leads to a high demand for more basic infrastructure. The high cost of concrete structures is largely influenced by cost of the constituent materials and it is an important constituent in the making of concrete There are other cementing materials which have shown the ability to improve the properties of concrete and also presents both environmental sustainability and economic benefits. For this study investigation into the suitability of using calcium carbide waste and metakaolin in concrete production, this investigation involves the replacement of cement with blend of calcium carbide waste and metakaolin in an increment of 0, 5, 10, 15 and 20%. Concrete cube containing CCW-MK was tested for strength at 3, 7, 14, 28 and 56 days of curing age. The optimum compressive strength was recorded at 10% CCW-MK content. 5% concentration of H2SO4 was used to cure the concrete for 28 days. Oxide composition test was done on the CCW and MK. The results revealed that CCW had a CaO content of 86.43% and MK had a sum of Al2O3, SiO2 and Fe2O3 as 98.6%. The workability of CCW-MK increases with increase as the dosage of CCW-MK increase. The compressive strength of CCW-MK concrete increased with an increase in the dosage of CCW-MK and curing period respectively. The retained compressive strength of CCWMK concrete cured in H2SO4 with an increase in the dosage of CCW-MK. Furthermore, the water absorption increases with an increase in the dosage of CCW-MK. Microstructural analysis of CCW-MK concrete was done with the aid scanning electron microscope equipment. The microstructure of the maximum compressive strength sample shows a denser, more homogenous and compact hardened concrete with respect to the control. It was concluded that blended concrete with sufficient strength can be achieved with the addition of CCW and MK blends can as supplementary cementing materials in concrete production

Strength Properties of Asphalt Mixture Produced with Polyvinyl Chloride (PVC) Modified Bitumen

In recent time, more polyvinyl chloride (PVC) plastic are produced than what is currently being recycled, that contributes to the volume of waste. This occurrence prompted the exploration of polymer modified bitumen (PMB) to address the waste concern and thereby cuts cost in bituminous mix and improves pavement performance. This research evaluated the strength properties of asphalt mixture produced with polyvinyl chloride modified bitumen. Marshall method of mix design was used in the production of hot mix asphalt (HMA). Scanning Electron Microscopy (SEM), Fourier Transform Infra-red (FTIR) and Energy Dispersive X-Ray Spectrometry (EDS), used for microstructural examination and elemental analysis. These materials conform with its physical properties and characteristics. The shredded, grinded plastic revealed high binding properties when blend with bitumen. The percent incorporated was 2 - 10% PVC content and the Optimum Bitumen Content obtained was 10%, at 9.57kN for stability. The modified bitumen for penetration recorded at 68mm, which conformed with 60/70 grade bitumen, softening point recorded at 52oC, ductility was recorded at 107cm, specific gravity at 1.02, flash and fire point at 294oC and 306oC, solubility at 97% respectively. The properties were satisfactorily for grade 60/70 bitumen at 4% PVC by weight and be used as bitumen modifier for heavy traffic condition. Polyvinyl Chloride modified at 8 - 10%, be used at cold climates, while 2, 4, 6% PVC modified be used in warm regions. Therefore, the experiment proved these materials with characteristics, stability and stiffness be used for pavement constructions

Fermentation of deproteinized cheese whey powder solutions to ethanol by engineered Saccharomyces cerevisiae : effect of supplementation with corn steep liquor and repeated-batch operation with biomass recycling by flocculation

The lactose in cheese whey is an interesting substrate for the production of bulk commodities such as bio-ethanol, due to the large amounts of whey surplus generated globally. In this work, we studied the performance of a recombinant Saccharomyces cerevisiae strain expressing the lactose permease and intracellular ß-galactosidase from Kluyveromyces lactis in fermentations of deproteinized concentrated cheese whey powder solutions. Supplementation with 10 g/l of corn steep liquor significantly enhanced whey fermentation, resulting in the production of 7.4% (v/v) ethanol from 150 g/l initial lactose in shake-flask fermentations, with a corresponding productivity of 1.2 g/l/h. The flocculation capacity of the yeast strain enabled stable operation of a repeated-batch process in a 5.5-l air-lift bioreactor, with simple biomass recycling by sedimentation of the yeast flocs. During five consecutive batches, the average ethanol productivity was 0.65 g/l/h and ethanol accumulated up to 8% (v/v) with lactose-toethanol conversion yields over 80% of theoretical. Yeast viability (>97%) and plasmid retention (>84%) remained high throughout the operation, demonstrating the stability and robustness of the strain. In addition, the easy and inexpensive recycle of the yeast biomass for repeated utilization makes this process economically attractive for industrial implementation.Fundação para a Ciência e a Tecnologia (FCT)LACTOGAL-Produtos Alimentares S.A.Companhia Portuguesa de Amidos, S.A

Successful and unsuccessful approaches to imaging carcinoids: Comparison of a radiolabelled tryptophan hydroxylase inhibitor with a tracer of biogenic amine uptake and storage, and a somatostatin analogue

A mouse mastocytoma model was used to determine the biodistribution and tumour uptake of four radiopharmaceuticals developed to target the serotonin synthetic pathway in carcinoid tumours. Three of the compounds were competitive inhibitors of the rate-limiting enzyme of serotonin synthesis, tryptophan hydroxylase. Radiolabelled iodo- dl -phenylalanine (iodine-131 PIPA) was found to have the highest uptake and tumourto-liver ratio. Four patients with known carcinoid tumours were then injected with 0.5 mCi 131 I-PIPA and imaged at 1, 4, 24 and 48 h post-injection. The radiopharmaceutical, however, failed to localize in the known tumour sites. This result was in contrast to the authors' experience of 131 I- and 123 I-MIBG imaging of carcinoid tumours. Seven patients with known metastatic carcinoid tumours, two patients with symptoms of recurrence following tumour resection, one patient with completely resected disease, and two patients with a flushing syndrome of uncertain aetiology were studied with 131 I-MIBG. Three of the seven patients with known metastatic disease had positive 131 I-MIBG scans. Both patients with clinical evidence of recurrent disease had negative scans, as did the patient who was considered to have had complete resection of her primary tumour. The two patients with idiopathic flushing syndrome also had negative scans. Among seven patients imaged with 123 I-MIBG there were four true-negative scans and one falsenegative, the latter in a patient with biochemical and CT evidence of recurrence. In a seventh patient with distant metastases there was variable uptake in some of the lesions. Four patients were studied with indium-111 penetetreodide. Two patients with metastatic carcinoid disease had positive scans, although hepatic metastases were not seen in one. Another two with idiopathic flushing syndrome had normal studies. The literature suggests that up 50% of carcinoid tumour cases are detected with 131 I-MIBG, compared to a sensitivity of 87% reported with somatostatin receptor imaging using 111 In-pentetreotide. The experience with 123 I-MIBG is much less extensive. The mechanisms of carcinoid tumour localization for each of the three classes of radiotracers are discussed and contrasted to their varying sensitivities. The relative success of 131 I-MIBG and 111 In-pentetreotide relative to 131 I-PIPA may be related to the fact that 131 I-MIBG is actively taken up and stored by the enterochromaffin cells of the tumours and 111 In-pentetreotide binds to cell surface receptors, whereas 131 I-PIPA binds to tryptophan hydroxylase, which may be present in quantities too small to permit tumours to be imaged.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46840/1/259_2005_Article_BF01731835.pd

Comparative Elemental Analysis of Rice Husk Ash Calcined at Different Temperatures Using X-ray Flourescence (XRF) Technique

Abstract In this study, the effect of the calcination temperature of rice husk on the pozzolanic properties of the resulting rice husk ash (RHA) especially its silica content was investigated. Rice husk was collected from a rice milling plant and washed to remove sand and other impurities, beneficiated using the water beneficiation method and calcined at temperatures of 400, 500, 600, 700and 800°C, respectively for three hours. Samples were taken for XRF analysis, setting time determination and specific gravity test. The result of XRF analysis revealed that RHA calcined at temperatures between 400°C and 800°C contains more than 70% silica as stipulated by ASTM C618 for pozzolanas. The silica content though varies slightly with different calcination temperature of the rice husk ash. Also, calcination removed impurities present in the rice husk. Besides that, the specific gravity of RHA decreases with increasing calcination temperature from 2.00 at 400°C to 1.05 at 800°C. Setting times of RHA mortars at 15% replacement of OPC with RHA shows no definite pattern with increasing temperature. However, the initial and final setting times of OPC-RHA mortars at all calcination temperatures were higher than that of OPC mortar. As a whole, calcination improves the silica content of rice husk ash for use as a pozzolana as well as removes mineral impurities that may affect the pozzolanic properties of the rice husk ash