Aptness of nano alumina (Al₂O₃) with high range water reducer-incorporated concrete

Abstract

Purpose The purpose of this paper is to study the effect of nano alumina (Al2O3) on the properties of fresh concrete, hardened concrete and microstructure of concrete incorporated with high range water reducer (HRWR). This initiative was taken to improve characteristic properties of concrete using nano alumina because nano alumina can be easily be manufactured from a scrap of industrial aluminum products, so its incorporation in concrete will not only reduce industrial aluminum waste but will also change the morphology of concrete at the microstructural level. Design/methodology/approach To accomplish the objectives of the research, four different concrete mixes with the constant water–cement ratio (W/C) and superplasticizer (SP) content 0.4 and 0.6% by weight of cement, respectively, were prepared, whereas nano alumina content was altered by 0.3% and 0.4% by weight of cement. Fresh property of concrete was analyzed by using slump cone test, whereas hardened properties of concrete were analyzed through compression test and flexural strength test. The interaction of nano alumina with concrete composite was evaluated using an X-ray diffraction test. Findings It was observed that 0.6% superplasticizer by weight of cement increased workability by 22% but with the addition of 0.3%, nano alumina by weight of cement workability decreased by 31%. Compressive strength increased by 4.88% with the addition of 0.6% superplasticizer but with the addition of 0.3% nano alumina by weight of cement compressive strength increased by 18.60%. Also, flexural strength increased by 1.21% with the addition of 0.6% superplasticizer by weight of cement but with the addition of 0.3% nano alumina by weight of cement flexural strength increased by 8.76%. With the addition of superplasticizer, alite and belite phases remained un-hydrated but with the addition of nano alumina alite phase was hydrated while belite phase was un-hydrated. The size of belite crystals in mixes having nano alumina was less than that of mix having 0.6% superplasticizer. Also with the addition of nano alumina, a calcium aluminum silicate phase was formed which was responsible for the increment of strength in mixes having nano alumina. Originality/value Incorporation nano alumina (Al2O3) in concrete will not only reduce industrial aluminum waste but will also reduce CO2 emission. Nano alumina (Al2O3) also changes morphology of concrete at micro structural level.

Characteristics of Silica Fume Nano Alumina Ternary Blended Mortar

“…Adding SF or nano-silica [1][2][3] to blended concrete causes lower early strength development and consistency due to its fineness and dilution effect in the nucleation sites. Recently, the incorporation of nano-additives such as titanium oxide, nano-silica, zinc oxide, or nano alumina (nA), has gained prominence in facilitating the production of binders with different strength and durability performances [4][5][6][7]. However, it is necessary to further improve the characteristics of silica fume (SF) blended mortar by investigating the effect of nA on the setting time, workability, strength, and thermal resistance.…”

“…Moreover, alumina is a very reactive oxide that can react with silica to produce a binder with good strength, improved morphology [4], and thermal and chemical resistant characteristics due to its refractory properties [8]. Aluminum shavings were recently applied in small quantities to achieve significant thermal resistance, reduction in apparent porosity, and attainment of lightweight mortar due to the effervescence of hydrogen gas [9].…”

“…Aluminum shavings were recently applied in small quantities to achieve significant thermal resistance, reduction in apparent porosity, and attainment of lightweight mortar due to the effervescence of hydrogen gas [9]. Moreover, the use of nA in OPC-based binders reportedly enhances early strength and reduces porosity, particularly in the presence of lime (CaO), such as in GGBFS, due to the possible formation of calcium aluminosilicate hydrate (CASH) [4] and low ettringite [Ca 6 Al(SO 4 ) 3 (OH) 12 •26H 2 O] composition [10]. Ashok et al [7] also reported improved fresh and hardened properties of concrete of different grades following the incorporation of nA.…”

“…Carmo et al [20] asserted that 2% nA contributed to the bond strength of steel fiber-reinforced concrete. In addition, Peerzada et al [4] affirmed that the incorporation of nA increased the strength of concrete by enhancing alite hydration (not belite), however, interfered with the efficiency of the superplasticizer, such that 0.3% nA together with 0.6% superplasticizer (SP) could reduce the workability by 31%. Moreover, Atiq Orakzai [5] reported that the presence of nA and nano titanium oxide provided favorable nucleation sites for calcium silicate hydrate (CSH), controlled the growth of portlandite, and enhance the microstructural density.…”