Investigation on properties of autoclave aerated concrete using different pre-curing and curing techniques

Abstract

AAC (Autoclave aerated concrete) is a porous and lightweight concrete that is produced through the molding process and can be used to make blocks, cladding, and flooring by autoclaving a variety of raw materials. The primary focus of this work is to assess various pre-curing and curing methods for AAC blocks. Autoclave curing is used in the conventional process of manufacturing AAC blocks, which increases the overall manufacturing cost of AAC blocks. For the production of AAC block, coarse aggregates are not used. The density of the AAC block ranges from 600 to 800 kg/m3. For achieving lesser density, cement, fly ash, sand, and aluminum powder was used. The chemical reaction between aluminum powder and lime in presence of water is exothermic and releases hydrogen gas in the form of bubbles, which results in a lower density. In the present study, various mixture design of AAC block was developed consisting of fly ash, cement, lime, aluminum powder, and water. Samples for determining the mechanical properties of AAC were developed using various mixing methods such as hand mixing, pan mixing, and high-speed hand-drill mixing. The impact of several curing techniques, including air drying and water curing, on the compressive strength and density of the AAC block was examined. Sodium chloride and calcium nitrate were used to increase the setting time of the AAC block. The compressive strength of the AAC block was obtained in the range of 0.2 to 1.5 Mpa and the density of the block was obtained between 512.3 kg/m3 to 750.2 kg/m3. The compressive strength of AAC obtained after autoclave curing is more than the compressive strength obtained after air curing as well as water curing. An attempt has been made in the present investigation to develop AAC blocks without using an autoclave process, so that overall production cost of AAC blocks can be reduced.