The impact of aeration of concrete based on ceramic aggregate, exposed to high temperatures, on its strength parameters. (30th December 2017)

• Record Type: Journal Article
• Authors: Ogrodnik, Paweł; Szulej, Jacek
• Is Part Of: Construction & building materials. Volume 157(2017)
• Page Start: 909
• Page End: 916
• Publication Date: 2017-12-30
• Subjects: Ceramic cullet -- Concrete -- Fire temperatures -- Strength; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2017.09.155
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: It was demonstrated that there is a correlation between aeration and thermal chipping. It was proven that 10% aeration reduces considerably thermal chipping phenomenon. It was demonstrated that aeration has a favourable impact on compression strength. It was proven that ceramic aggregate can be used to concretes resilient to high temp. It was demonstrated that aeration has a favourable impact on bending strength. Abstract: The modifiers currently being applied enable obtaining cement composites of barely unlimited number of specific features which satisfy the needs of construction market. Due to this fact, it is possible to obtain concretes of increasingly greater strength, frost resistance, in the same time decreasing their absorbability and water permeability. Despite the fact that the concrete is a non-combustible material and considered by a lot of people as resistant to the exposure of high temperatures especially during fire phenomena, there occur many negative processes which weaken its quality and adversely influence strength parameters. From the safety point of view, a particularly hazardous situation concerns the phenomenon of spalling, so-called thermal and explosive chipping of concretes. This particularly refers to damp concretes of compact structure occurring in the places where there are very humid conditions, such as cellars, underground garages, basements or tunnels. The research, conducted by the authors, has shown that it is possible to obtain porous concrete of high porosity and strength (Zegardło et al., 2016) [1]. These studies have inclined the authors to make an attempt to design the concrete on the basis of ceramic aggregate containing aeration admixtures which is in the same time resilient to high temperatures occurring during the fires, as well as the phenomenon of thermal and explosive chipping. In this work, the issue of the impact of fire temperatures on concrete is presented as well as the phenomenon of thermal chipping of concrete cladding is discussed. The main aim of this paper is the assessment of concrete aeration effectiveness as the method for reducing the phenomenon of thermal chipping. Concrete samples based on Portland cement and calcium aluminate cement are used for the research simulating thermal activity of fire. The additive of properties described in the further part of this paper, is applied to aerate a concrete mix. The research is conducted on six, empirically designed concrete mixes, three of which are based on calcium aluminate cement and aeration equal to 0, 5 and 10%. In order to compare the results, three concrete mixes based on Portland cement, which possess precisely convergent aeration of mixes respectively amounting to 0, 5%, 10%, have been prepared. All the types of samples were made with the use of recycled sanitary ceramic aggregates, selected and crushed into two fractions of 0–4 mm and 4–8 mm. This special type of aggregate, as it has been proven by the previous works of authors Halicka and Zegardło (2011) [2], Ogrodnik et al. (2012) [3], Halicka et al. (2013) [4], Zegardło and Ogrodnik (2016) [5], showed very favorable features in the issues of thermal loads impact. The first group of samples is a base one. The second part was exposed only to annealing. The others were subjected to moisture, prior to annealing. Basic research was conducted for particular concrete samples. The compression and bending strengths were also determined.