The Effect of the Composition of a Concrete Mixture on Its Volume Changes
Martin Ťažký,
Lenka Bodnárová,
Lucia Ťažká,
Rudolf Hela,
Milan Meruňka,
Petr Hlaváček
Affiliations
Martin Ťažký
Faculty of Civil Engineering, Institute of Technology of Buildings Materials and Components, Brno University of Technology, Veveri 331/95, 602 00 Brno, Czech Republic
Lenka Bodnárová
Faculty of Civil Engineering, Institute of Technology of Buildings Materials and Components, Brno University of Technology, Veveri 331/95, 602 00 Brno, Czech Republic
Lucia Ťažká
Faculty of Civil Engineering, Institute of Technology of Buildings Materials and Components, Brno University of Technology, Veveri 331/95, 602 00 Brno, Czech Republic
Rudolf Hela
Faculty of Civil Engineering, Institute of Technology of Buildings Materials and Components, Brno University of Technology, Veveri 331/95, 602 00 Brno, Czech Republic
Milan Meruňka
Faculty of Civil Engineering, Institute of Technology of Buildings Materials and Components, Brno University of Technology, Veveri 331/95, 602 00 Brno, Czech Republic
Petr Hlaváček
Department of Material Disintegration, Institute of Geonics of the CAS, Studentska 1768, 708 00 Ostrava, Czech Republic
The presented research aims to clarify the specific effect of the individual components of concrete with Portland cement CEM I 42.5 R on the volume changes of concrete. The effect of the filler component was evaluated from the point of view of the composition and type of aggregate (crushed versus mined) and from the point of view of the mineralogical composition of the aggregate. Concrete formulas with a maximum aggregate grain size of 16 and 22 mm were assessed. The effect of the binder component on the shrinkage of the concrete was monitored on the concrete mixtures produced using the same aggregate and maintaining the same strength class of concrete, C 45/55. The effect of the addition of finely ground limestone, finely ground granulated blast furnace slag and coal high-temperature fly ash was monitored. It was found that the maximum aggregate grain and the type of grading curve do not have a significant effect on the volume changes of concrete. Concretes with mined aggregates showed lower shrinkage than concretes with crushed aggregates. The most significant is the effect of the type of aggregate on the volume changes in the first 24 h. Mineral additives have a positive effect on the elimination of the volume changes of concrete, while the addition of high-temperature fly ash proved to be the most suitable.
