• Energy Research
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Evaporative losses from reservoirs exacerbate water shortage during dry spells. Notwithstanding the extensive application of self-assembling floating covers for suppressing evaporation, the cover material is often overlooked and limited to available choices such as plastics. The present study is aimed at the production of floating covers using ultra-lightweight alkali-activated slag concrete that offers a range of mechanical and chemical features. Concrete specimens were made with different percentages of ground granulated blast-furnace slag as the binder, sodium metasilicate as the alkaline activator and lightweight perlite aggregates with a density of 100-150 kg/m3. To solve the problem of fracture in the preliminary specimens, slag was partially replaced with 15, 20 and 30% lime. In addition, microsilica (10, 12 and 15%) was introduced to improve the mechanical properties of the samples. In designs without microsilica, 30% replacement of slag with lime resulted in the desirable density, strength and permeability of samples. Results showed that microsilica generally increased the density, resistance and thermal conductivity of samples by 7, 74 and 14%, respectively, while water absorption and permeability decreased by 15% and 14%, respectively. The dry density of samples was obtained between 340 and 516 kg/m3 with a compressive strength of 0.2-0.9 MPa and a conductive heat transfer coefficient of 0.067-0.093 W/mK.

This paper predicts and enhances the hydraulic problems in the Faraskour pumping station. Initially, water could not reach the first and fifth units of the operation. The main hydraulic problem of the suction basin of the new pump station is the sharp rotation of the suction guide from the sharp rotation of the quay station, and that caused the continuous discontinuation of the first and fifth units due to the lack of regular water entering the unit. A numerical simulation was conducted to investigate the hydraulic stability of the station. Computational fluid dynamic (CFD) is used to simulate the flow conditions at different working pumping units to predict the hydraulic problem at the suction side. The results indicate that the geometry of the intake is proper for running five parallel flow pumps with the designed flow rate and use guide walls with a curvature length of 6 m and width of 0.5 m for each pump.

In the biosphere, bacteria can function as geo-chemical agents, promoting the dispersion, fractionation and/or concentration of materials. Microbial mineral precipitation is resulted from metabolic activities of microorganisms. Based on this biomineralogy concept, an attempt has been made to develop bioconcrete material incorporating of an enrichment culture of thermophilic and anaerobic bacteria within cement-sand mortar/concrete. The results showed a significant increase in compressive strength of both cement-sand mortar and concrete due to the development of filler material within the pores of cement sand matrix. Maximum strength was observed at concentration 10(5)cell/ml of water used in mortar/concrete. Addition of Escherichia coil or media composition on mortar showed no such improvement in strength.

{"references": ["Wark, C.G. & Wark, W.W., (2003). Green roof specifications and standards; Establishing an emerging technology. The Construction Specifier, 56, 76-82.", "Centre for the Advancement of Green Roof Technology, (2006). An Introduction to Green Roofs. Retrieved May 15, 2007 from http://commons.bcit.ca/greenroof/download/Green_Roof_pres_06.pdf", "The Green Roof Centre. What are Green Roofs?. Retrieved March 3, 2007 from http://www.thegreenroofcentre.co.uk/pages/what.html", "Greenroofs.com, LLC, (2007). Industry Support. Retrieved March 12, 2008 from http://www.greenroofs.com/Greenroofs101/industry_support.htm", "Barrio, E.P.D., (1997). Analysis of the green roofs cooling potential in\nbuildings. Energy and Buildings, 27, 179-93.", "Barth, K.S., (2004). Green Roofs: Stormwater Management from the\nTop Down. Retrieved July 21, 2005 from http://www.greenroofs.com/pdfs/archives-katrin.pdf", "Baskaran, A., Katsman, R., Sexton, M. & Lei, W., (2003). Investigation of thermally-induced loads in modified bituminous roofing membranes. Construction and Building Materials, 17, 153-64.", "Wong, N.H., Lee, S.E., Cheong, D., Lim, G.T., Yuen, B., Tham, K.W., Sekhar, C., Chen, Y. & Yan, H., (2002). Study of Rooftop Garden in Singapore. Singapore: National University of Singapore.", "Metropolitan Area Planning Council, (2005). Green Roofs. Retrieved June 12, 2005 from\nhttp://www.mapc.org/regional_planning/lid/PDFs/greenroof.pdf\n[10] Chemische Fabrik Gr\u00fcnau GmbH. WOLFIN IB Handbook for Specifiers. (Clark, H. Translated). Unpublished book.\n[11] Marks, B.D. & Tschantz, B.A., (2002). A Technical Manual on the Effects of Tree and Woody Vegetation Root Penetrations on the Safety of Earthen Dams. North Carolina: Marks Enterprises of NC, PLLC."]} Green Roofs offers numerous advantages, including lowering ambient temperature, which is of increasing interest due to global warming concerns. However, there are technical problems pertaining to waterproofing to be resolved. Currently, the only recognized green roof waterproofing test is the German standard FLL. This paper examines the potential of replicating the test in tropical climate and reducing the test duration by using pre-grown plants. A three year old sample and a new setup were used for this experimental study. The new setup was prepared with close reference to the FLL standards and was compared against the three year old sample. Results showed that the waterproofing membrane was damaged by plant roots in both setups. Joints integrity was also challenged.