Papers by Keyword: Ceramic Powder

Abstract: Dredged sediments are a valuable natural resource used in construction and public works, however some dredged sediments do not have the physical and chemical qualities necessary for reuse, necessitating the addition of complementary materials such as ceramic waste powder. The main objective of this study is to improve the technical quality of sediments by adding ceramic waste powder and cement in low content by strengthening its mechanical and geotechnical properties. The present paper reports the treatment and recovery of dredged sediments with varying percentages of ceramic powder (Cp) and cement. Various properties such as maximum dry density, optimum moisture content, and California Bearing Ratio (CBR) are analyzed, the obtained results are compared with limestone Tuff. Investigations are performed using percentages of ceramic powder (Cp) at 2.5%, 5%, 7.5%, 10% and cement 5%. The results showed that there was an appreciable increase in strength and CBR values by the addition of Cp and cement. The research proved the effectiveness of the proposed method for constructing roads and pavements with low thickness.

Abstract: Application of various pozzolanic materials is the current approach to obtain suitable environmental, economic and durability parameters of composites, in which they are used. Considerable interest is focused on the possibilities of finely ground ceramic powder (CP) exhibiting pozzolanic activity. Present paper is aimed at the experimental study on the monitoring of reaction kinetics in lime-ceramic powder system (1:1). Ceramic powders with controlled grading were used. Reaction capacity was assessed in time by means of thermogravimetry. The dominant effect of the finest fractions (up to 0.030 mm) on the pozzolanic reaction was proved; coarser fractions of used CP exhibited approximately the half reaction efficiency after 28 days of curing.

Abstract: Cement is an extremely energy consuming material and its production leads to the emission of a vast amount of greenhouse gases. Cementitious concrete is a universal building material, which is used for the production of various structural elements. The paper describes the problem of cement production and its impact on the environment. This research deals with application of aluminous cement as binder component for the manufacture of refractory composites and with possibilities of further utilization of environmentally friendly materials with pozzolanic properties as a partial replacement of used aluminous cement. These materials are originating as waste in the building industry or by the recycling of cast-off materials. To reduce the costs and adverse effects on the environment was the binder system modified by finely ground ceramic powder and metakaolin. The experimental results present the values of flexural and compressive strength investigated on a series of composite specimens with dimensions of 40×40×160 mm³ and 10, 20 and 30 % of cement replacement. The aim of the present work is to apply the mentioned pozzolanic materials and reach the suitable composite with the sufficient heat resistance and residual mechanical parameters after gradual temperature loading.

Abstract: The aim of this study was to describe mechanical properties decline and macroscopic changes after cyclic thermal load of refractory slabs. Investigated elements were made from refractory cement composite containing natural basalt aggregate, fine ceramic powder, aluminous cement with high volume of Al₂O₃, different dosage of basalt fibres, water and plasticizer. Slabs with dimension 300 x 200 x 38 mm were exposed to elevated temperature 600 °C for three hours (temperature gradient 10 °C/min) and cooled to laboratory condition. This loading cycle was repeated six times. Tensile characteristics were investigated by bending test with clear span of supports 200 mm. Maximum force and displacement increased with increasing amount of basalt fibres. Maximum flexural strength of slabs corresponded to material characteristics measured on specimens 40 x 40 x 160 mm. Slabs with 1% of basalt fibres achieved flexural strength 4.8 MPa (after six loading cycles). The highest weight decline took place after the first loading cycle. Successful design of original fibre-cement composite has been approved by cyclic loading of larger dimension specimens.

Abstract: Presented in this article are the properties of flame sprayed ceramic coatings using oxide ceramic materials consisting of a powdered zirconium oxide (ZrO₂) matrix with 30% calcium oxide (CaO) applied to unalloyed S235JR grade structural steel. A primer consisting of a metallic Ni-Al-Mo based powder has been applied to plates with dimensions of 5x200x300 mm and front surfaces of ø 40x50 mm cylinders. Flame spraying of primer coating was conducted using a RotoTec 80 torch, and an external surface was coated with a CastoDyn DS 8000 torch. Evaluation of the coating properties was conducted using metallographic testing, phase composition research, measurement of microhardness, abrasive wear resistance (acc. to ASTM G65 standard) and erosion wear resistance (acc. to ASTM G76-95 standard).

Abstract: Carbonation is chemical process associated with CO₂ penetration into the material porous structure causing subsequent chemical changes in the structure of cement pastes. In this work, carbonation of several pastes containing varying amount of cement replacement by three waste ceramic powders is studied. Chemical composition of particular tested materials is accessed using XRF analysis. Matrix density, bulk density, total open porosity, compressive and bending strength are measured for all developed pastes with incorporated ceramic materials. Simultaneously, the effect of carbonation on these material properties is researched. The obtained results show significant improvement of materials mechanical strength due to the carbonation. Here, the measured compressive strength is typically about ~ 60% higher for materials exposed to CO₂ rich environment compared to the materials cured in laboratory conditions.

Abstract: In this paper the possibilities of colouring concrete and the use of pigments are presented. There are two groups of pigments with respect to its manufacture (organic and inorganic) and three different forms available on market: powder, granulates and slurry. Next to the influences of other concrete components the effects of fine pigment particles on the properties of fresh and hardened concrete are introduced. Because of the higher need of water the workability of each mixture is affected. With the increasing specific surface area of pigment the flow of fresh concrete decreases. On the other hand this characteristic feature causes slightly higher density of concrete matrix which results in better durability. Optimal dosages differs depending on the form of pigment, for powders it is about 5% of the weight of cement content. Higher amounts don ́t bring about higher tinting strength and in the case of more than 10 % its mechanical properties can be negatively affected. An example of colour evaluation as well as utilization of recycled materials as colouring agents are also mentioned.

Abstract: Waste ceramic powder coming from grinding the ceramic bricks disposed on demolition depot is investigated as partial Portland cement replacement in blended binders. For the milled ceramic powder, measurement of specific surface area (SSA) and particles size distribution is done. Its chemical composition is accessed using X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD) analysis. The blended binders containing ceramic powder in an amount of 8, 16, 24, 32, and 40% of mass of cement are used for the preparation of cement pastes which are then characterized using the measurement of basic physical properties, mechanical properties, hygric and thermal properties. The obtained results show that an application of 8 and 16% ceramic powder in the blended binder provides sufficient mechanical properties of the pastes with relatively low hygric transport properties. From the thermal performance point of view, the incorporation of ceramic powder decreases the heat transport in all the tested pastes. This makes good prerequisites for future research that will be focused on the development of new types of cement-based composites with incorporated ceramic waste powder.

Abstract: The possibilities of utilisation of ceramic powder as supplementary cementitious material are the matter of the presented study. The finely ground ceramic powder originates from the grinding process of thermal insulating brick blocks and shows pozzolanic properties. For the determination of its influence on concrete properties, five mixtures with different percentages of cement replaced by ceramics are designed. The bulk density as well as matrix density are found to decrease with the increasing dosage of waste ceramic material, while the open porosity increases. The compressive strength exhibits a small decrease with the growing amount of cement replacement. The measurement of thermal conductivity shows that by adding ceramic powder the thermal insulating abilities of studied concrete are improved.

Abstract: In this communication, Ag0.9Na0.1(NbyTa1-y)O3 (y=0.5,0.6,0.7,0.9)（ANNT） mixed oxide powder was synthesized by citrate wet chemical method. TG-DTA, XRD and TEM analyses showed that the reaction temperature was 800°C, the calcining time was three hours, and the product was pure ANNT in well-dispersed grain structure (45nm in average).