High-Strength and Heat-Insulating Cellular Building Concrete Based on Calcined Gypsum

Adrian Ioana; Lucian Paunescu; Nicolae Constantin; Valeriu Rucai; Cristian Dobrescu; Vili Pasare; Alexandra Istrate

doi:10.3390/ma16010118

High-Strength and Heat-Insulating Cellular Building Concrete Based on Calcined Gypsum

Materials (Basel). 2022 Dec 22;16(1):118. doi: 10.3390/ma16010118.

Authors

Adrian Ioana¹, Lucian Paunescu², Nicolae Constantin³, Valeriu Rucai³, Cristian Dobrescu³, Vili Pasare¹, Alexandra Istrate³

Affiliations

¹ Engineering and Management of Metallic Materials Obtaining Department, Science and Engineering Materials Faculty, University Politehnica of Bucharest, 060042 Bucharest, Romania.
² Cosfel Actual SRL Bucharest, 021619 Bucharest, Romania.
³ Materials Science Department, Science and Engineering Materials Faculty, University Politehnica of Bucharest, 060042 Bucharest, Romania.

Abstract

A cellular concrete with a fine porous structure was experimentally made using the corrosion technique for aluminum powder as an expanding agent in an aqueous solution of Ca(OH)₂. The originality of this paper was the use of our own production method for the fine aluminum powder through atomizing the recycled molten waste of this metal using concentrated jets of nitrogen. Additionally, the waste melting technique involved our own microwave heating method. A high weight proportion of calcined gypsum (maximum 82.3%) represented the main concrete binder. Using moderate contents of coal fly ash (3.6-11.1%) together with perlite (4.6-6.4%) to reduce the pore size and silica fume (0.3-1.2%) with pozzolanic properties, the aim was to obtain a macrostructure characterized by a very low pore size and to increase the compressive strength (by up to 4.1 MPa), despite the relatively low density (below 641 kg/m³). An industrial method of increasing the mechanical strength by steam curing fresh concrete was applied.

Keywords: aluminum powder; calcined gypsum; cellular concrete; lightweight; mechanical strength.

Grants and funding

This work was supported by Programul Operaţional Capital Uman, Axa prioritară 6—Educaţie şi competenţe, Proiect: Pregătirea doctoranzilor şi cercetătorilor postdoctorat în vederea dobândirii de competente de cercetare aplicativă—SMART Cod MySMIS: 153734, and the authors would want to thank University “Politechnica” of Bucharest for the chance to publish this paper.