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This paper summarizes the results of an experimental program aimed at investigating of the mechanical properties of composites based on aluminous cement for high-temperature applications and deal with the influence of high-thermal loading on polycarboxylate superplasticizing (PCSP) additive contained in the composite. The intent of this examination was caused by the suspicion that the action of high-temperatures can lead to burnout of the PCSP additive and thus subsequently affecting the mechanical properties of the final composite. Silica composites based on Portland cement and silica aggregates are not able to resist the effects of high-temperatures [1]. For high-temperature composites was therefore used aluminous cement Secar®71 (Lafarge S.A.) in combination with crushed basalt aggregates of fraction 0/4 and 2/5 mm. The flexural strength was greatly improved thanks combinations of basalt fibers with lengths of 6.35 mm and 12.7 mm. The values ​​of flexural strength and compression strength were investigated on samples dried at temperature 105 °C or loaded for 180 minutes with high-temperature of 600 °C or 1 000 °C.

Development of new composite materials is the worldwide extremely progressive branch of engineering activity. Composite materials are applied in many industries. The principle of composite materials is a combination of different materials providing an entirely new material with specific properties. Fiber-reinforced composites rank to the most frequently used composites because of their suitable mechanical properties. There were studied mechanical properties of fibre reinforced cementitious composites (FRCC) exposed to high temperatures of 600 °C and 1000 °C in the paper. For the production of refractory FRCC were used aluminous cement Secar®71 with 70 % of Al2O3. Various composites differed in the used type of fibers - basalt, carbon and ceramic fibres were applied in doses of 2 % by volume. For the experimental program were prepared prismatic specimens with the total dimensions of 40 × 40 × 160 mm3 and cured for 28 days in humid environment. Residual bulk density, flexural and compressive strength were investigated in the performed experimental program. The results showed the positive effect of the fibers used in refractory composition and the dependence on the length of the used fibers.

Abstract. The aim of our study was to develop a composite material for industrial use that is resistant to the effect of high temperatures. The binder system based on aluminous cement was modified by adding finely-ground ceramic powder and metakaolin to reduce costs and also to reduce adverse effects on the environment due to high energy consumption for cement production. Additives were applied as a partial aluminous cement replacement in doses of 10, 20 and 30 % by weight. The composites were evaluated on the basis of their mechanical properties and their bulk density after gradual temperature loading. The influence of basalt fibers and modifications to the binder system were studied at the same time. Basalt fibers were applied in doses of 0.5 % and 2.0 % by volume. The results confirmed the potential of the mineral additives studied here for practical applications, taking into account the residual mechanical parameters after thermal loading. The addition of ceramic powder reduced the bulk density by 5 % for each 10 % of cement substitution, but the residual values were very similar. The bulk density and the compressive strength were reduced when basalt fibers were applied, and the flexural strength was significantly increased in proportion to the fiber dosages. Metakaolin seems to be a more suitable additive than the ceramic powder that was applied here, because there was a significant increase in the mechanical parameters and also in the residual values of all properties that were studied.

This paper describes the application of lightweight aggregate (LWA) in the creation of fire resistant composite. The effort of the project is the preparation of a light refractory material with good mechanical properties, which would reach technically economical solutions. We initially chose as lightweight aggregate Liaver, which in combination with chamotte aggregate represent the filler of composite. The following observations were focused on partial replacement of binding components with brick dust and its influence on the mechanical properties of the composite. After design process, test composite specimens were produced to determine hardened properties at standard age. On the 28 day were all the mixtures exposed to 105, 600 and 1000 °C. Lastly, the flexural and compressive strength tests were performed on the composite specimens to identify high temperature effect comparing to strength test results obtained from standard laboratory conditions.