Effect of water absorption on frost resistance of clay roofing tiles

Abstract

clay was also applied as an admixture. In addition, the Vuppor organic admixture 6 was used to modify the pore H igh f rost resistance is one of the signs of good quality structure of test specimens. in clay roo ng tile products. T he present paper deals with the question of whether the water absorption of clay roo ng tiles aVects f rost resistance. T he results PREPARATION OF SPECIMENSshow that clay roo ng tiles with high water absorption Mineral admixtures were added to the brick clay in doses can be just as f rost proof as tiles with lower absorption.of 1 or 10 wt-% referred to the weight of dried clay, along M edian pore radius is found to be an important factor with Vuppor admixture at a constant dose of 1 wt-% of in determining f rost resistance: increasing the median dried admixture to dried clay. Test specimens (100Ö pore radius increases frost resistance. BCT /561 50Ö 20 mm) were manufactured from a plastic mass (upsetting height 24 mm according to PfeVerkorn test), held T he author is in the Department of Materials for 48 h at laboratory temperature (20°C), and then dried Engineering, Faculty of Civil Engineering, Slovak at 110°C to constant weight. Specimens were red in an University of T echnology, R adlinského 11, SK -813 68 electric laboratory furnace at 900°C with a dwell time of 1 h. Bratislava, Slovak R epublic ( sveda@svf.stuba.sk). M anuscript absorption N V (wt-%) is de ned as 100(m n m s )/m s , where the Institute of M aterials, M inerals and M ining.m n is the saturated weight of the specimen after 4 h submersion in boiling water and m s is the dry weight of the specimen.

Influence of firing temperature on frost resistance of roofing tiles

“…For all freezing temperatures, the density increased with temperature up to 1100 • C, but it dropped above 1100 • C. On the other hand, both porosity and water absorption decreased monotonically up to 1100 • C, but these rose for the freezing temperatures of −10 and −30 • C and dropped for room temperature and the freezing temperature of −50 above 1100 • C. It is reported that there is a correlation between pore distribution and frost resistance. [2][3][4][5][6]16 was measured by the mercury intrusion method. The results are plotted with the diameter of pore as abscissa against pore volume per unit weight, which was calculated from the data of accumulated pore-size distribution, as ordinate.…”

“…But, when they are used in cold districts, frost damage which is caused by the freezing of water which has permeated into the numerous pores existing in that material become a serious problem. [1][2][3][4] To describe in details, when water contained in some of these pores following rainfall freezes into ice due to a decrease of temperature, local high tensile stress will arise around these pores, and micro-cracks will be generated. These micro-cracks will grow and join with each other until the final fracture occurs.…”

“…[2][3][4][5][6] The roofing tile is a complex, heterogeneous material consisting of quartz, feldspar, and numerous pores. It is considered that the change of the constituent minerals and microstructure of the bodies with a densification process influences the frost resistance.…”

Determination of suitable raw materials for preparation of frost resistant brick body and its evaluation according to pore size distribution

“…For this parameter, a principle applies, that if its value grows, the frost resistance also increases. 23) Frost resistance value can be, however, affected by properties of the input material and the firing temperature. If the input material contains substances whose presence radically increases the volume of pores in the brick body then an increase of frost resistance is significantly slowed.…”

“…The literature, 23) for example states the knowledge about the influence of pore volume on the frost resistance of a brick body. Here it was found that at almost the same water absorption or the same pore volume in the brick body, the author obtained different frost resistance values.…”