THE USE OF DIATOMACEOUS EARTH IN PRODUCTION OF FOAMED FINE-GRAINED CONCRETE

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7408-13-3 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 62, 449-456 pp, DOI: 10.5593/sgem2017/62/S26.057

ABSTRACT

The buildings energy performance is becoming increasingly important, because of environmental restrictions connected with CO2 emission and rising costs of fuel end energy. Respecting sustainability issues, design of buildings with improved thermal properties and optimum energy performance is preferred, whereas specific attention has to be paid not only to the design of building envelopes, but also to the thermal insulation of buildings subsoil. To obtain buildings with high thermal resistance and sufficient thermal stability, the use of materials possessing advanced thermal insulation properties should be taken into consideration. Traditional buildings materials such as concrete and mortar are produced from natural raw materials and in addition with large energy consumption with respect to today’s economic standards. Here, their proper modification with supplementary cementitious materials (SCMs) brings positive binder saving while strength maintaining. In comparison with ordinary concretes, foamed composites show several advantages including low weight resulting in better manipulation, possibility of treatment and improved thermal insulation properties. Low specific density together with the saving of input material, as well as environmental aspect, which are the important characteristics of these materials, are ensured by encased character of air voids within their porous structure. By the use of SCMs combined with supporting effect of chemical additives, foaming agents, it is possible to achieve advanced materials having low weight, sufficient mechanical strength and high thermal insulation properties. On this account, the paper is aimed at modification of common fine-grained composite based on Portland cement, silica sand and water in mass ratio 1/3/0.5. At first step, diatomaceous earth powder was used as a cement substitution in 20 vol. %. Then, foaming agent was added into concrete mix in order to develop material with beneficial thermal insulation parameters. Used raw materials were characterized by their chemical composition, particle size distribution and specific surface area. For hardened composites cured 28 days in water, basic physical characteristics, dynamic moduli, mechanical and thermal properties were accessed. Obtained results pointed to an increase in the mechanical resistivity of concrete modified with diatomite admixture. On the other hand, incorporation of foaming agent resulted in a significant decrease in strength parameters. However, improvement of thermophysical properties that what was of the primary importance was achieved. Newly created light-weight concrete was found applicable for construction industry, for example for floor or flat roof structures, facing panels, sheeting, components of light-weight envelopes, etc. Moreover, the developed concrete mix brought both the environmental and economic benefits comparing production costs and functionality of concrete of common composition.

Keywords: foamed concrete, diatomaceous earth, cement substitution, improved thermal performance.