Hydraulic Conductivity of Compacted Lateritic Soil Partially Replaced with Metakaolin

The study investigates the potentials of using metakaolin (MK) to improve the properties of compacted lateritic soil for hydraulic barrier system for containment of municipal solid waste (MSW). Oxide compositions determined by the X-ray fluorescence (XRF) show that MK contains Silicon oxide, SiO2 (53.4 %), Aluminium oxide Al2O3 (34.2 %), Titanium oxide, TiO2 (5.97 %) and Iron oxide, Fe2O3 (3.84 %) in high proportion. The soil was replaced with 0 %, 5 %, 10 %, 15 % and 20 % MK and compacted using four compaction energy levels namely: the Reduced British Standard Light (RBSL), British Standard Light (BSL), West African Standard (WAS) or “Intermediate” and British Standard Heavy (BSH) over a range of molding water contents (10 - 25 %). Unconfined compressive strength (UCS) and hydraulic conductivity tests were conducted and the results obtained were used to evaluate whether the lateritic soil partially replaced with MK conforms with the specifications for barrier systems for MSW containment. The results of this study show a general improvement in UCS of the soil specimens with increase in the percentage replacement of MK. Results of the study also show that hydraulic conductivity values of the specimens permeated with leachate are better than the results of hydraulic conductivities obtained when de-ionized water (DIW) was used as the permeant fluid. The specimens replaced with 5-20 % MK and compacted using the BSH compaction energy yielded hydraulic conductivities on the orders of 6.3 x 10-10 m/s to 2.2 x 10-10 m/s when DIW was used as the permeant fluid. On the other hand, the specimens compacted using the WAS and BSH compaction energies and permeated with leachate yielded hydraulic conductivity values in ranging from 6.8 x 10-10 m/s to 3.6 x 10-11 m/s. These hydraulic conductivity values met the regulatory maximum hydraulic conductivity (i.e. ? 1 x 10-9 m/s) for construction of liner and cover systems for MSW containment. Keywords: Compaction energy, Metakaolin, Hydraulic conductivity, Unconfined compressive strength, Municipal solid waste leachate, De-ionized wate

A review of tertiary BIM education for advanced engineering communication with visualization

SPECT with Tc-99m-labeled agents is better able to detect viability after nitrate administration. Nitrates induce vasoclilation and may increase blood flow to severely hypoperfused but viable myocardium, thereby enhancing tracer delivery and improving the detection of viability. Quantitative data on the changes in blood flow are lacking in SPECT but can be provided by PET. The aim of the present study was to use PET to evaluate whether nitrate administration increases blood flow to chronically dysfunctional but viable myocardium. Methods: N-13-Ammonia PET was used to quantitatively assess blood flow, and F-18-FDG PET was used as the gold standard to detect viable myocardium. Twenty-five patients with chronic ischemic left ventricular dysfunction underwent N-13-ammonia PET at rest and after nitrate administration. Results: A significant increase in nitrate-enhanced blood flow was observed in viable segments (from 0.55 +/- 0.15 to 0.68 +/- 0.24 mL/min/g, P <0.05). No statistically significant change in blood flow was observed in nonviable segments (0.60 +/- 0.20 vs. 0.55 +/- 0.18 mL/min/g). A ratio of at least 1.1 for nitrate-enhanced flow to resting flow allowed optimal detection of viable myocardium, yielding a sensitivity of 82% with a specificity of 100%. Conclusion: N-13-Ammonia PET showed a significant increase in nitrate-enhanced blood flow in viable myocardium, whereas blood flow remained unchanged after nitrate administration in nonviable myocardium. Nitrate use during myocardial perfusion imaging will lead to improved assessment of myocardial viability

Application of wood waste ash in concrete making: revisited

Portland cement production is a carbon dioxide trigger responsible for almost 5% of the worlds CO2 emissions. Pozzolanic inclusions could contribute to sustainability particularly if they are derived from waste. Managing solid waste is increasingly becoming a global challenge as a result of increasing volume of accumulated waste from industrial and agricultural by-products. Environmental concerns as well as economic implications related with disposal of these wastes have prompted many researches in order to provide viable solutions. Recycling of these waste materials into the construction industry seems to be a more promising and viable alternative most especially in the manufacturing of greener and sustainable concrete material. Wood ash (WA) is a by-product derived from incineration of wood as well as its products such as sawdust, wood bark and chips. This paper presents an overview on investigations performed on the applicability of this material in mortar and concrete making. Specifics on physical, chemical, mineralogical and elemental characteristics of the waste material are discussed. It highpoints the impact of wood ash on workability, compressive and flexure strengths, water absorption, drying shrinkage, carbonation, alkali–silica reaction (ASR) and chloride permeability of concrete

Desvios de custos e prazos em empreendimentos da construção civil: categorização e fatores de influência

Desvios de custos e prazos s&#227;o desafios recorrentes na constru&#231;&#227;o civil. Neste artigo, os autores objetivaram revisar sistematicamente a literatura relacionada a desvios de prazos e custos para determinar uma estrutura de categoriza&#231;&#227;o e respectivos fatores respons&#225;veis por esses desvios. Foi empregada a abordagem Systematic Literature Review (Revis&#227;o Sistem&#225;tica de Literatura - RSL) de maneira met&#243;dica, para proporcionar acompanhamento e reprodu&#231;&#227;o futura. Informa&#231;&#245;es relevantes foram extra&#237;das dos artigos selecionados e posteriormente sintetizadas para a obten&#231;&#227;o da proposta de categoriza&#231;&#227;o e respectivos fatores respons&#225;veis pelos desvios. Nove categorias foram identificadas e definidas com base em seus determinantes: rela&#231;&#245;es governamentais; contratos; organiza&#231;&#227;o; gerenciamento; financiamento; projeto e documenta&#231;&#227;o; altera&#231;&#245;es de escopo; aspectos ambientais e econ&#244;micos; e atividades e equipamentos. Al&#233;m disso, 95 fatores de influ&#234;ncia foram identificados e anexados &#224;s categorias pertinentes. Apesar de a literatura ser heterog&#234;nea em rela&#231;&#227;o a contextos e regi&#245;es globais, o que dificulta a condu&#231;&#227;o da RSL, houve boa sustenta&#231;&#227;o para os fatores identificados. Escassez de evid&#234;ncias foram identificadas na Am&#233;rica Latina, particularmente no Brasil. A literatura existente em desvios de prazos e custos at&#233; o momento se mostrou multifacetada, com 92 artigos publicados em 46 fontes diferentes no intervalo de tempo de 1985 a 2014. A maioria das pesquisas teve como foco o estudo de alguns desses fatores em particular, enquanto esta pesquisa classificou-os e sintetizou-os de forma a possibilitar uma vis&#227;o nova e mais abrangente sobre o fen&#244;meno