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.
- SourceAvailable from: Sukmin Kwon
- "The housing industry has also been required to reduce its environmental footprint and save energy; house production (including sales and distribution ), structural methods, and methods of construction give positive incentives to reduce CO 2 . For example, high levels of insulation and airtight construction are known to save energy (Khedari et al. 2005; Demirboğa 2007). In general housing, organic building materials such as urethane and polyurethane foam have been used to increase insulation. "
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- "It also contributes to concrete strength by pozzolanic and filler effects   . Fly ash is characterized by its cheapness which reduces the unit cost of cement and concrete, and its positive effects, such as lower water demand , lower hydration heat  , reduced bleeding , and satisfactory durability   . "
ABSTRACT: This works aims to study the effect of partial substitution of ordinary Portland cement (OPC) by silica fume (SF) and fly ash (FA) on the physico-mechanical properties of the hardened OPC–FA–SF composite cement pastes. The OPC was partially replaced by 20% and 30% fly ash along with 5% and 10% silica fume. The phase composition of the hydration products was investigated using XRD and DTA techniques. It was found that, the increase of FA content in OPC–FA–SF composite cement decreases the water consistency values and increases the setting times. On the other hand, the increase of SF content leads to increase the water of consistency and decrease the setting times. The partial substitution of OPC by FA and SF leads to higher porosity values with a consequent decrease in the compressive strength values especially during the early ages of hydration. At the later ages of hydration, however, the OPC–FA–SF cement pastes possess total porosity and compressive strength values close to those of the neat OPC paste. The lower of free lime contents were obtained for OPC–FA–SF composite cement pastes with the formation of further additional amounts of CSH as a result of the pozzolanic reaction. The results showed also that, the physico-mechanical properties of composite cement paste [OPC (65%)–FA (30%)–SF (5%)] were improved at later ages.08/2014; 11(1). DOI:10.1016/j.hbrcj.2014.02.003
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- "Mineralogical character of the aggregate quite influences the TC of concrete composites. The less conductive concrete can be produced by using aggregate with less TC; similarly more conductive concrete can be produced with more TC aggregates  . The thermal conductivity coefficient of traditional concretes ranges between 0.8 and 1.65 W/m K . "
ABSTRACT: In this study, the influence of waste PET as lightweight aggregate (WPLA) replacement with conventional aggregate, on thermal conductivity, unit weight and compressive strength properties of concrete composite was investigated. For this purpose, five different mixtures were prepared (the control mixtures and four WPLA mixtures including 30%, 40%, 50%, and 60% waste PET aggregate by volume). Thermal conductivity (TC) coefficients of the specimens were measured with guarded hot plate apparatus according to TS ISO 8302 . The thermal conductivity coefficient, unit weight and compressive strength of specimens decreased as the amount of WPLA increased in concrete. The minimum thermal conductivity value was 0.3924 W/m K, observed at 60% WPLA replacement. From this result, it was concluded that waste PET aggregates replacement with conventional aggregate in the mixture showed better insulation properties (i.e. lower thermal coefficient). Due to the low unit weight and thermal conductivity values of WPLA composites, there is a potential of using WPLA composites in construction applications.Composites Part B Engineering 02/2013; 45(1):721-726. DOI:10.1016/j.compositesb.2012.09.012 · 2.98 Impact Factor