[en] This study was undertaken to examine the influence of residual stresses on porcelain tile behaviour under cutting. To do so, two samples of glazed industrial porcelain tiles that exhibited different behaviour under cutting were selected. Using these industrial tiles, cutting tests were performed and the macroscopic residual stresses were determined by the strain relaxation incremental slotting method. The influence of the cooling rate on the arising residual stresses and their effect on tile cutting were also studied. For the porcelain tile with appropriate cutting behaviour, the residual stress profile in the body was symmetrical and could be fitted by just using the second- degree Legendre polynomial. This was the expected behaviour for homogenously cooled ceramic materials (same cooling rate at the proper surface as at the rib). For pieces with inappropriate cutting behaviour, it was necessary to use more terms of the series, which suggested that cooling had not been homogeneous. With regard to the influence of cooling, the temperature range in which residual stresses were generated was determined and it was verified that pieces with a greater level of stresses exhibited worse cutting behaviour. (Author)

[en] This work provides a novel method for increasing the mechanical strength of porcelain materials. To achieve this was used a ceramic powder prepared from sodium feldspar and clay. This powder was wetted up to 8wt.% with water and pieces of rectangular section are formed by uniaxial pressing at 21MPa. The dried specimens were then sintered in a laboratory furnace (1,218°C). These specimens were subjected to a chemical ion exchange treatment in order to increase their mechanical properties, also known chemical tempering. Temperature and time were varied during chemical treatment according to a factorial design. The results showed an increase of ∼74% in breaking force of porcelain material, providing a reduction of the material thickness greater than 15%. Therefore, the process of chemical tempering can be used to increase the breaking force and consequently decreasing the thickness, saving raw materials and energy in the production process.(Author)

[en] This review has been written in a somewhat unusual form to facilitate the separation of experimental facts from theory and theory from opinion. For the purposes of this paper cohesive failure has been taken as the criterion of a good bond, i.e., the fracture surface does not coincide with the interface

[en] This paper presents an original procedure to determine the softening curve in concrete from a diametric Brazilian test and a three point bend test. An inverse procedure is proposed combining experimental results, numerical finite element computation and an iterative algorithm, called algorithm AMS-UPM, developed expressly for this research. The starting point of the algorithm is a bilinear softening curve, on which a successive transformations are applied decreasing the difference between the experimental and numerical results in each step. The procedure has been applied successfully to two conventional concretes. The final result is a softening curve that adjusts almost perfectly experimental data of the three point bending test.

[en] The present work investigates the possibility of adopting a new kinematics at the industrial polishing lines of porcelain stoneware tile. An alternative motion of the transverse oscillation of the polishing heads is proposed, in which no radical changes in the industries facilities are required. The basic idea is to replace the purely sinus motion of the polishing heads by a rather trapezoid wavelike motion. In theory this could be achieved simply by adopting regular delays at the transverse oscillation motion. Consequences of this alternative kinematics were quantitatively analyzed considering the spatial homogeneity of polishing expected for tiles. Such homogeneity was represented by the coefficient of variation of the distribution of polishing time over the surface, which was in turn determined by means of computational simulations, taking into account the effect of multiple polishing heads. (Author) 10 refs.

[en] In order to reduce production costs, the ceramic tiles have been produced in ever faster firing cycles. One of the undesirable consequences of the acceleration of the firing cycles is the anticipated overfiring, when the tiles stop shrinking and start to expand before the water absorption reaches the required values. The present study evaluated, through statistical analysis (DOE), the effects of the main characteristics of the firing cycle and the green bulk density of the compacts of porcelain tiles on this phenomenon. The results showed that the main factors responsible for porcelain tiles anticipated overfiring are very short holding periods on firing and relatively low green densities. The results also suggest that these factors contribute to the expressively heterogeneous development of the microstructure of the products, which may contribute to the development of the anticipated overfiring.

[en] Epoxy and polymers played a significant role in the world of construction and repair in the past few decades. The major problem in using epoxy for construction repair is its high cost. The current study aims at confronting this problem, and attempting decrease cost by adding waste materials without affecting it’s properties.

Window glass and porcelain tile waste were chosen to add to the epoxy at different percentages (10, 20, 30, and 40 %) to create composites that could be used as new repairing materials. The experiment will attempt to find out the suitable percentage of mixing. Such percentage is not used when bonding the concrete to decrease the cost of concrete repairing. Accordingly, the new composites were tests for compression and bond strength to measure the adhesion strength. The final results showed a general improvement in the properties of the new composite when adding glass and porcelains, yet the porcelains results were much better than glass as filler with epoxy, which achieved the main objective of the current work in finding a developed and better repair material used for cracks and construction with a less cost. (paper)

[en] This paper reports the results about the PIXE analysis of major, minor and trace elements of Chinese ancient greenish white porcelain and blue-and-white porcelain produced in Hutian Kiln (Jingdezhen district, Jiangxi province) during 10th-14th centuries. The porcelain body and greenish white glaze from northern Song (AD 960), southern Song (AD 1037-1276), early Yuan (AD 1279-1320), later Yuan (AD 1320-1368) were investigated together with white-and-blue glaze from Ming dynasty (AD 1368-1644). The obtained data were further analyzed by factor analysis

No abstract available

[en] The porcelain stoneware tiles production needs high whiteness clays in order to be competitive in the ceramic sector. In the present work, Spanish clays used in the porcelain stoneware tiles production have been characterized in physic, chemist and mineralogical terms, in order to reduce its content of chromophore oxides (Fe2O3 and TiO2). These reduction processes are concerned with different physical and chemical treatments, as sieving at 150mm, magnetic separation using a 0.6T permanent magnet, or acid treatment with HCL and later neutralization with NH3. With these treatments, due to siderite elimination, chromophore oxides as Fe2O3 have been decreased from 2,36% to 1,66% in the chemically treated clay. (Author).