Thermal conductivity and compressive strength of concrete incorporation with mineral admixtures
ABSTRACT In this study, the effect of silica fume (SF), class C fly ash (FA), blast furnace slag (BFS), SF+FA, SF+BFS, and FA+BFS on the thermal conductivity (TC) and compressive strength of concrete were investigated. Density decreased with the replacement of mineral admixtures at all levels of replacements. The maximum TC of 1.233 W/mK was observed with the samples containing plain cement. It decreased with the increase of SF, FA, BFS, SF+FA, SF+BFS, and FA+BFS. The maximum reduction was, 23%, observed at 30% FA. Compressive strength decreased with 3-day curing period for all mineral admixtures and at all levels of replacements. However, with increasing of curing period reductions decreased and for 7.5% SF, 15% SF, 15% BFS, 7.5% SF+7.5% FA, 7.5% SF+7.5% BFS replacement levels compressive strength increased at 28 days, 7- and 28-days, 120 days, 28- and 120 days, 28 days curing periods, respectively. Maximum compressive strength was observed at 15% BFS replacement at curing period of 120 days.
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ABSTRACT: In the autoclaved aerated concrete production, aluminum powder is used to create pores which lead to high thermal insulation property. In the present technique developed, snow or crushed ice is added to fly ash over optimum moisture content and compacted to obtain an increased porosity and a stronger matrix. The main objective of this study is to investigate the effect of various practical mix percentages of snow into fly ash and evaluation of their insulation properties. The optimum water content of fly ash was determined and additional snow with percentages of 10, 20 and 30 by weight are added to type C fly ash samples. Thermal conductivity tests were performed on samples to evaluate the insulation capability of the snow added fly ash samples where information is not readily available in the literature. The highest improvement in the thermal conductivity is obtained by adding 20 per cent snow to fly ash samples over optimum moisture content. Higher percentages of snow addition resulted in interconnected voids, causing lower thermal conductivity performance. These findings can be utilized for nonstructural insulating construction blocks and also as an insulation layer for embankments in permafrost areas.Energy and Buildings 11/2011; 43(11):3236-3242. · 2.47 Impact Factor
Conference Paper: DEVELOPMENT AND APPLICATION OF LIGHTWEIGHT CEMENT-BASED COMPOSITES[Show abstract] [Hide abstract]
ABSTRACT: The purpose of this study is to suggest the material design method of lightweight mortar that reduces the mass of building components and provides them with better insulation. To achieve this, we applied a number of special lightweight aggregates and applied the packing density model, porous mortar, and a combination of both methods. A series of experiments were carried out in order to investigate the mechanical properties and examine the thermal conductivity of mortar. The study identified that the adopted material design methods were effective in reducing the density of mortar and in obtaining sufficient insulation. Furthermore, compressive strength sufficient for structural purposes was also achieved in certain types of mortar. Finally, by combining the packing density model and porous mortar, lightweight insulation blocks were developed for achieving not only sufficient bearing capacity but also high insulation performance.First International Conference on Concrete Sustainability, Tokyo; 05/2013
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ABSTRACT: The work aims to study the effect of substitution of micro-silica (SF) and fly ash (FA) on the behavior of composite cement pastes exposed to elevated temperature. The composite cements are composed of 80 mass% OPC with variable amounts of SF and/or FA. The fire resistance of composite cement pastes was evaluated after firing at 250, 450, 600, and 800 °C with rate of heating 3 °C/min for 3 h soaking time. The physico-mechanical characteristics such as total porosity, bulk density and compressive strength of cement pastes were determined at each firing temperature. Moreover, the phase composition, free lime and microstructure for some selected samples were investigated. Cement pastes containing 10 and 15 mass% have higher firing resistance than all SF-pozzolanic cement pastes at 600 °C. It can be also, concluded that the composite cement pastes made from 10% of SF and 10% FA have good fire resistance in comparison with cement pastes made from only SF-pozzolanic cement pastes up to 450 °C.Construction and Building Materials 01/2013; 38:1180–1190. · 2.27 Impact Factor