Influence of fibrous additives on properties of aerated autoclaved concrete forming mixtures and strength characteristics of products

The influence of fibrous additives of non-hydrophilized and hydrophilized carbon, polypropene, basalt and kaoline fibre on properties of aerated autoclaved concrete (AAC) forming mixture, as well as on properties of final product was investigated. All these fibrous additives, both non-hydrophilized and hydrophilized, have effect on fluidity and swelling of forming mixtures and increase plastic strength. Along with growing content of each fibrous additive within limits from 0.1% to 0.4% of mass of solid components, the fluidity and swelling of forming mixtures decreases, while the plastic strength increases. All investigated fibrous additives, both hydrophilized and non-hydrophilized, increase the compression- and flexural strengths of AAC. The optimal content of all fibrous additives to be added for obtaining of greatest compression- and flexural strengths is 0.3% counting of dry material in the forming mixture. By capacity to increase the compression- and binding strengths, the fibrous additives may be lined up in the following order: carbon fibre > polypropene fibre > basalt fibre > kaoline fibre. All fibrous additives increase flexural strength more than that of compression. Hydrophilized fibres increase compression- and flexural strengths of concrete more than the respective non-hydrophilized ones. Basing on the results of investigations performed as to fibre-rein forced AAC structure by scanning electron microscope, as well as on the results of earlier performed investigations with fibres used for reinforcement to find out their chemical resistance to treatment of them in the autoclave by alkaline solutions, the pH value of which corresponds to that of hardening alkaline binding medium of concretes, the influence of properties of fibrous additives on efficiency of reinforcement was explained. (C) 2009 Elsevier Ltd. All rights reserved.