ABSTRACT
The paper presents the results of tests of the impact of the addition of fly ashes or metallurgical cement (CEM III) admixture on the degree and stability of aeration and on selected physical and mechanical properties of SCC concrete mix. The results were compared to those obtained for SCC concrete made solely with the use of Portland cement (CEM I). Tests were performed on fresh concrete mix (spread, viscosity and air content by pressure method). The aeration parameters of fresh concrete mix were determined by AVA (Air Void Analyzer) method. Total air content A, content of micropores A300 and spacing factor were determined. For hardened concretes the following characteristics were determined: compressive strength (after 2, 7, 28 and 56 days), water absorption, water tightness and frost resistance. The analysis of the results demonstrated that the addition of a large amount of fly ashes to CEM I or their use for preparing SCC CEM III concrete practically have no negative impact on basic physical and mechanical characteristics of concrete. Both the compressive strength of concrete and water absorption as well as water tightness are very similar for all formulations tested. Also spread and viscosity of the fresh mix are comparable. It was observed that both the addition of fly ashes and of metallurgical cement to SCC concretes have a clearly negative impact on the stability and quality of their aeration characteristics and, as a consequence, significantly reduces their frost resistance and thus durability.
