Influence of Micro additives on Macrostructure of Autoclavedaerated Concrete

Abstract

Autoclaved aerated concrete (AAC) is a construction material with porous macrostructure prepared of finely milled siliceous aggregate, lime, water and Portland cement with the addition of aluminium powder and being steam-cured under the pressure in an autoclave. Today AAC (light construction material) is a widely used in the constructions as a material that is compared to concrete or conventional stone material, which has a high insulation properties and fireresistant. Previous studies have shown that application of microadditives in AAC enhances physical-mechanical properties of AAC samples. Most of these changes are duo to an even distribution of pores. The influence of such additives, as amorphous SiO2 (AS) and carbon fibres (CF), reduced to microsizeparticles, on formation of AAC macrostructure was investigated. The investigations were carried out with AAC forming mixture where 10% lime was replaced by equivalent content of Portland cement. Research results have showed, that the optimal replacement of sand by AS was 1.0% and by CF – 0.1%, and resulted in an equal distribution of pores and optimal macrostructure formation (higher amount of small pores, lower amount of merged pores) which leads to highest compressive and flexural strengths of modified AAC samples.