Aerated concrete blocks

Abstract

According to Wakili et al. (2015) aerated concrete (AC) is a lightweight concrete having low density and high porosity in comparison with other building materials, where air constitutes 20-90% of the total volume. AC is produced from sand, cementitious material, air-forming chemical, and water. Its parameters vary depending on the production methodology, having a density range of 93-1800 kg/m3. The material is assumed to be commonly used, as it has both good mechanical and thermal characteristics (Jerman, 2013). In general, AC is widely known for its energy-efficient properties, as it has considerably low thermal conductivity. As the thickness of wall in building increase, thermal conductivity value is decreases. If low thermal conductivity material is used, the thickness of wall can be reduced. Aerated concrete offers high level of thermal insulation of buildings at low wall thickness, and low self-weight, respectively (Pruteanu and Vasilache, 2013). Therefore, application of aerated concrete in this project is emphasized by the purpose to reduce building energy consumption as wall blocks.

Aerated concrete is manufactured by entraining air voids deliberately, to come up with lightweight, cellular concrete form. It can be divided into 2 major types based on production method: foamed and aerated concrete (Newman, 2003).

Foamed concrete is produced by injecting a foaming agent into the base mix. In such mixture, no chemical reaction takes place, therefore, it is considered to be the most economical and controllable method of cellular concrete casting (Narayanan and Ramamurthy, 2000). The porosity of the concrete is achieved by adding foaming agent into the mix, which produces air voids that are included in the cement paste (Hamad, 2014). Consequently, foamed concrete characteristics directly depend on the foaming agent properties.

Next wayof pore-formation in cellularconcretes, is based on the formation of gas bubbles by reaction of chemicals, commonly aluminum powder, with the liquid cement mortar. Concentration of air voids and properties of hardened sample from this reaction depend on the alkalinityof mortar mix. Thus, sand with high silicacontent is favorable foraerated concrete production (Narayanan and Ramamurthy, 2000). Aluminum powder based porous concrete manufacturing method is assumed to be the best solution by Hamad (2014). Table 2.8. Concrete blocks characteristics comparison provide better isolation. All three materials are highly reusable, and environmentally conscious, respectively. (Yang and Lee, 2014 & Aggregate Industries, 2016)