Marcel Jogl

Basic and Hygric Properties of Concrete Containing Fine Ceramic Powder

The motivation for utilization of active admixtures in concrete lies primarily in a positive effect on properties of hardened concrete with regard to its durability. Fine parts complement the grain size distribution curve, but also due to subsequent hydration arise phases with better resistance to aggressive substances from surrounding environment. Process of pozzolanic reaction is also associated with a reduction in open capillary porosity, causing a gradual reduction of the permeability of concrete. The paper presents an experimental program focused on the monitoring of evolution of basic and hygric properties of concrete with fine ceramic powder addition.

Physical and Mechanical Properties of Composites Made with Aluminous Cement and Basalt Fibers Developed for High Temperature Application

Present paper deals with the experimental study of the composition of refractory fiber-reinforced aluminous cement based composites and its response to gradual thermal loading. Basalt fibers were applied in doses of 0.25, 0.5, 1.0, 2.0, and 4.0% in volume. Simultaneously, binder system based on the aluminous cement was modified by fine ground ceramic powder originated from the accurate ceramic blocks production. Ceramic powder was dosed as partial replacement of used cement of 5, 10, 15, 20, and 25%. Influence of composition changes was evaluated by the results of physical and mechanical testing; compressive strength, flexural strength, bulk density, and fracture energy were determined on the different levels of temperature loading. Increased dose of basalt fibers allows reaching expected higher values of fracture energy, but with respect to results of compressive and flexural strength determination as an optimal rate of basalt fibers dose was considered 0.25% in volume. Fine ground ceramic powder application led to extensive increase of residual mechanical parameters just up to replacement of 10%. Higher replacement of aluminous cement reduced final values of bulk density but kept mechanical properties on the level of mixtures without aluminous cement replacement.

Differences in the Mechanical Properties of Lightweight Refractory Cementitious Composites Reinforced by Various Types of Fibers

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.

RESIDUAL PROPERTIES OF FIBER-REINFORCED REFRACTORY COMPOSITES WITH A FIRECLAY FILLER

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.

Long-term resistance of HPC to action of deicing salts

Present paper deals with investigation of deicing salts resistance of high performance concretes. Durability of concrete is one of the fundamental principal which defines ability of material to resist severe condition. In order to increase concrete durability combination of high efficient plasticizer and some mineral additive is often used. Impact of metakaolin and silica fume as a partial replacement of Portland cement on concrete properties was investigated. Resistance of studied concrete mixtures dramatically increased during two years of measurement thanks to pozzolanic reaction what was declared by mechanical parameters.

Refractory Cement Composite Reinforced by Various Types of Fibers

Following article deals with experimental investigation of elevated temperatures influence on mechanical properties of refractory cement composite, which seems to be very progressive and interesting field of material science. Specimens 40 x 40 x 160 mm3 were exposed to 600 °C and 1000 °C for three hours. Using of aluminous cement, in this case Secar®71 with70 % of Al2O3, means the basic premise for refractory composites. Natural crushed basalt aggregate of two fractions 0-4 mm and 2-5 mm works as filler. Metakaolin MefistoL05 in amount 225 kg/m3 represents the fine filler, commonly used in refractory concrete production. Ceramic fibers or combination of two lengths of basalt fibers significantly improve the flexural characteristics. The goal of this research is to quantified influence of basalt fibers and ceramic fibers on flexural strength, compressive strength and bulk density of cement composite in high temperature conditions.

Effects of High Temperature Treatment on the Mechanical Properties of Basalt Fiber Reinforced Aluminous Composites

Article presents the results of an experimental program aimed at investigating of the mechanical properties of composites based on aluminous cement with the addition of basalt fibres, which could be used in the manufacture of components resistant to high temperatures, including the retention of mechanical properties. Silica composites based on Portland cement and silica aggregates are not able to resist the effects of high temperatures [1], therefore a heat resistant mixtures in this experiment includes only components that are able to resist the effects of high temperatures.

Fracture and Mechanical Properties of Fire Resistant Fibre Composites Containing Fine Ground Ceramic Powder

Significant advances in the field of building materials leads to increasingly frequent enforcement of these high performance materials in real constructions. Efforts to maximize the efficient use of non-renewable resources and especially energy-intensive materials lead to efforts to achieve maximum efficiency and usability [. Paper presents results of an experimental program focused on development of fire-resistance composites based on aluminous cement with fine ground ceramic powder (FGCP). Studied fibre composites were loaded by temperature 600 °C and 1000 °C. The influence of applied thermal load on composites was evaluated by means of fracture energy, compressive strength, bending strength and modulus of elasticity in bending.

Application of Granulated Cable Plastic Waste for Soil Stabilization

Paper deals with the assessment of practical utilization of granulated cable plastic waste (GCPW) for the production of stabilized soil layers in transport engineering. The main goal of the experimental work was the evaluation of the influence of GCPW on mechanical properties of soil stabilization based on the fluidized fly ash. Mechanical properties were investigated using standard procedures in soil mechanics. GCPW was dosed as a partial replacement of fluidized fly ash up to 30 %. It was concluded, that the studied level of replacement performs critical level, additional increasing of GCPW would lead to a decline of required mechanical properties. Besides, replacement by studied waste material caused lower values of the bulk density.

Performance of Dosage of Ceramic Chopped Fibers in Aluminous Cement-Based Composites after Exposure to High Temperatures

The results of an experimental investigation of the influence of chopped alumina-silica bulk fibers on residual mechanical properties of lightweight cement-based composites for high temperature application are obtained. The matrix of studied specimens is based on aluminous cement, because of its sufficient temperature resistance over 1000 °C. Thermal ceramic bulk fiber offer a maximum temperature range of between 1200° to 1500 °C. They also provide excellent chemical stability and resistance to chemical attack. If wet by oil or water, thermal and physical properties will be fully restored after drying. The benefits of using ceramic bulk fibers were evaluated by the results of physical and mechanical testing; compressive strength, flexural strength and bulk density were determined on the different levels of temperature loading. The prismatic specimens, having dimensions of 40×40×160 mm3, are cured 28 days in humid environment and after that time dried and subjected to temperatures of 600 °C and 1000 °C for 3 hours. The experimental composites differed in doses of fibers, which are 0.0 %, 0.5 % and 2.0 % by volume.