Study on production of Aerated concrete block in Bangladesh

The main objective of this paper is the presentation of the potentiality and formation techniques of aerated concrete in the context of Bangladesh. In this experiment, generation method of hydrogen gas was used for the aeration process. In this gasification method, a finely powdered aluminium powder was added to the slurry of Ordinary Portland cement with different percentages such as 0.05%, 0.1%, 0.15%, 0.2%, and 0.25%. To determine the effect of aluminium powder on the final product properties, some test has been conducted such as density, water absorption and compressive strength test. However, it was observed that the concrete having 0.15% aluminium powder contributes in the strength gaining process of aerated concrete. KeywordsAutoclaved Aerated concrete, Aluminium powder. INTRODUCTION Conventional building materials are beyond the reach of majority population of Bangladesh due to their poor affordability. Besides the escalation in the cost of building materials, rising environmental concerns due to the extensive exploitation of natural resources connected with general construction and other housing development activities urge the search for alternative technological options. This paper attempts to identify a sustainable and affordable alternative material to replace the conventional bricks for the primary building applications. On this purpose a study on aerated concrete has been conducted. Aerated concrete, also known as Autoclaved Aerated concrete (AAC), Autoclaved cellular concrete (ACC), or Autoclaved light weight concrete (ALC) , was invented in the mid-1920s by the Swedish architect and inventor Johan Axel Eriksson (2) . Autoclaved Aerated concrete (AAC) is a popular building material which is used all over the world. It has a history of 50 successful years can be used in all environments for all types of buildings (Wittmann, 1983, 1992) (4) . It is a light weight, pre-cast building material that simultaneously provides structure, insulation, fire and mold resistance. Depending on its density, up to 80% of the volume of an AAC block is air. AAC's low density also accounts for its low structural compression strength. It can carry loads of up to 8 MPa (1160psi), approximately 50% of the compressive strength of the regular concrete . AAC was first produced commercially in Sweden in 1923. Since then, the production and use of aerated concrete have spread to more than 40 countries of all continents, including North America, Central and South America, Europe, the Middle East, the Far East and Australia. This wide experience has produced many case studies of the use in different climates and under different building codes. In the United States, modern uses of AAC began in 1990 for residential and commercial projects in the Southeastern states. U.S. production of plain and reinforced AAC started in 1995 in the Southeast and has since spread to other parts of the country. A nationwide group of AAC manufacturers was formed in 1998 as the Autoclaved Aerated Concrete Products Association (AACPA, www.aacpa.org). Design and construction provisions for AAC masonry are given in the MSJC Code and Specification. The AACPA includes one manufacturer in Monterrey, Mexico, and many technical materials are available in Spanish. AAC is approved for use in Seismic Design Categories A, B and C by the 2007 Supplement to the International Building Code, and in other geographic locations with the approval of the local building official . Many researchers have been carried out on AAC. Johan Alexanderson (1979) studied the relations between structure and mechanical properties of autoclave aerated concrete and he found that the strength of aerated concrete specially cement and lime mixing, increased with increasing amount of hydrates and with decreasing porosity. P.G. Burstrom (1980) studied sealants between elements of aerated concrete and reported that because of the low tensile strength of aerated concrete, the sealing of joints between such elements causes special problem. Cabrillac R et al (1996) reported problems about optimization of porosity and properties of aerated concrete. N. Narayanan, K. Ramamurthy (2000) studied about micro structural investigation on aerated concrete and reported that the reasons for changes in compressive strength and drying shrinkage are explained with reference to the changes in microstructure. Hulya Kus and Thomas Carlsson (2003) studied about micro structural investigation of naturally and artificially weathered autoclaved aerated concrete. Hulya Kus et al (2004) reported about In-use performance assessment of rendered autoclaved aerated concrete walls by long term moisture monitoring. A. Laukaitis and B Fiks ( 2006) reported about acoustical properties of aerated autoclaved concrete and found that the evaluation of acoustic qualities of AAC is based on the material's air permeability and porosity. A. Laukaitis et al (2009) reported on influence of fibrous additives on properties autoclaved aerated concrete forming mixtures and strength characteristics of products. Autoclave treatment performed under high temperature and high pressure is economically IJISET ‐ International Journal of Innovative Science, Engineering & Technology, Vol. 2 Issue 3, March 2015.