Application of Fibers in Refractory Composites Marcel JOGL, Pavel REITERMAN, Ondřej Holčapek, Petr KONVALINKA Experimental Centre, Faculty of Civil Engineering, CTU in Prague, marcel.jogl@fsv.cvut.cz

Content Introduction Experimental investigation Results of measurement The components and mixtures Production and treatment of test specimens Thermal loading The examined properties Results of measurement Conclusion

Introduction Development of materials with higher strength and durability Low fire resistance of elements The instability of the silica aggregates and Portland cement-based composites (over 500 °C) Decrease in strength of constructure steel (over 400 °C) Creation of composite material for high temperature applications Required resistence Excellent workability Homogenous behavior

Experimental program The components and mixtures Production of refractory composites by mixing selected components Within the experiment were designed 6 mixtures Chamotte filler was compared with the crushed brick aggregate Program was also focused on the assessment of various doses of fibers   Components [kg/m3] Basalt fibres Aluminous Cement Fireclay Plast. Water 6.35 mm 12.7 mm 0/1 mm 1/2 mm 2/4 mm Ref-0 900 520 140 320 16.20 200 Ref-0.5 1.45 13.05 Ref-2.0 5.8 52.2 Recycled aggregate 0/4 mm RA-0 1016 RA-0.5 RA-2.0

Experimental program Production and treatment of test samples 9 specimens made of each mixture with the dimensions of 40x40x160 mm Stored in a humid environment for 28 days Drying at 105 °C for 24 hours Divided into three groups of three samples: 1. group of samples dried at 105 °C 2. group of samples fired at 600 °C 3. group of samples fired at 1000 °C

Experimental program Thermal loading Thermal loading was preformed in an automatic electric furnace The temperature increase of 10 °C/min Samples were left to cool down spontaneously

Experimental program The examined properties Flexural strenght [MPa] Compressive strenght [MPa] (fragments after bending test) Bulk density [kg/m3] Mechanical testing was carried with the use of the loading device EU 40 for all applied thermal levels

Evaluation of the experiment The average values of the examined properties Relative values of bulk density Significant decline of the bulk density due to thermal loading Effect of the increasing application of basalt fibers Lower bulk density of applied recycled ceramic aggregate

Evaluation of the experiment The average values of the examined properties Relative values of residual flexural strenght Influence of fibers application is visible only on the non-loaded composites

Evaluation of the experiment The average values of the examined properties Relative values of residual compressive strenght Negative effect of high doses of basalt fibers Measurement well correspond with the results of the bulk density

Conclusions In term of mechanical properties, the most suitable values are achieved when the 0.5 % of fibers by volume was applied However, the reference mixtures with no fibers exhibited higher or similar values of mechanical properties Decreased quality of recycled aggregate led to the reduction of studied parameters The program has confirmed the potential of ceramic grit for aluminous cement based composites production Further application of various waste materials can help to reduce environmental impacts and total costs

Thank you for your attention This work was carried out with financial support of the grant GAČR P104/12/0791