Ceramic tiles have traditionally been used as wall cladding and flooring materials, primarily because of their technical characteristics, but also because of their aesthetic qualities. High-porosity tiles (1018% water absorption) are typically used for wall cladding: these are known as earthenware tiles. In contrast, tiles with a low-porosity body (< 3% water absorption), known as stoneware tiles, are generally used for flooring. In recent years, moreover, the ISO 13006 standard, which sets out ceramic tile classification criteria, has incorporated a new group of tiles with very low porosity (<0.5% water absorption), called porcelain tiles.
JDF-503 general ceramic tile adhesive is a powder made of cement modified by polymer. It has features such as strong water-resistance, good durability, convenient operation and low price, commonly used for laying and pasting ceramic tiles.
Bi-component SF-1 type decorative stone adhesive is processed with certain techniques by taking soluble silicate as main raw material added with modifying agent, hardening agent, additive and filler. It is applied specially to decorative stones.
CTW and Portland cement X-ray diffractograms are shown in Fig. 11.3. In the case of CTW, a material with a mainly crystalline structure is observed; quartz and mullite are its most abundant phases. In addition, other phases such as albite, anorthoclase, and hematite are present. Phases such as Hatrurite, quartz, Larnite, gypsum, calcite, and brownmillerite (ferrous phase) can be observed in the cement diffractogram.
The presence of quartz, in CTW, causes a series of bands located at 1084, 796778 (double band), 693, 522, and 463cm1 in the IR spectrum.20 The presence of aluminum octahedron in mullite is responsible for a series of bands located between 1180 and 1130cm1, in the range from 560 to 550cm121,22; and at 630cm1, it is possible to find a characteristic band of Al-O-Si.23 The band corresponds to the internal vibrations of primary structural units; in other words, SiO4 and AlO4 tetrahedrons, and Si-O-Si and Si-O-Al bridges are found in the wave number 470cm1.24 The band, also intensive, associated with the vibrations of deformations of T-O bonds (internal vibrations of the tetrahedrons) is located at 466cm1.25 In addition, the bands associated with the vibrations of O-H asymmetrical tensions can also be observed in the spectrum in a range from 3200 to 3700cm1, as well as vibrations of H-O-H deformation of water in the region of 23002500cm1, between 1600 and 1650cm1, and around 1800cm1 and 2000cm1, which is in agreement with the research carried out by Mozgawa et al.26 Xu et al.27, and Komnitsas et al.18 In this material, it is possible to observe the low intensity of bands associated to water; this is because CTW are materials that have undergone a sintering process, and are mainly porcelain stoneware, construction elements that have a low water absorption (below 5%).
In the Portland cement spectra, bands between 31003700cm1 can be observed, and are associated with the presence of H2O and OH because the cement can have some residual humidity. The water absorbed by gypsum is associated with the band located at 3550cm1.28 Two bands, one at 1623cm1, and a smaller one at 1684cm1, come up in the spectrum of the anhydride cement due to the presence of water absorbed by sulfates. The bands located at 1796, 2513, 2875, 2983, and 13501550cm1 are caused by the presence of calcium carbonate in the cement,28 in the same way that the presence of carbonates is associated with bands located at 1428cm1, 714cm1, and 878cm1. Furthermore, two main bands, intensive and sharp (926 and 878cm1) are associated with stretching/tension vibrations Si-O cm1 of the Alite, and the 523cm1 band is associated with deformation vibrations O-Si-O of the main silicates in cement.29 The characteristic bands of sulfates are generally found in the range of 11001200cm1. It is difficult to interpret this area of the spectrum because sulfates generate many peaks, thus generating overlaps. The band located at 1092cm1 corresponds to sulfate of anhydrous calcium (CaSO4), while the bands located at 602 and 660cm1 are associated with semihydrated calcium sulfate (CaSO4H2O).30
Traditionally ceramic tiles took several days to make as the clay base was fired first and then fired again, after the glaze and any decoration had been applied. Modern methods use a single firing and can be completed in as little as 20 minutes. To achieve a very low and uniform firing shrinkage the bodies of modern tiles are made from finely ground, evenly mixed refractory clays with minimal fluxing agents. A typical recipe would consist of 35% ball clay, 15% china clay, 10% limestone, and up to 15% ground tile waste (Prentice, 1990). The remaining 25% would comprise silica, usually as finely ground quartz sand but frequently including a proportion of cristobalite. Tile glazes are essentially silica, with nepheline syenite or feldspar added as a flux, coloured by metallic oxides, and fused in a furnace. Optical microscopy may be employed to investigate the composition and condition of ceramic tiles and can be complemented by SEM and microanalysis (Kopar & Ducman, 2005). Figures 357 and 358 show a section through the outer surface of a modern ceramic tile. This consists of a fired clay base with an underglaze containing a coloured crystalline aggregate, over which a transparent silica wet glaze has been applied to seal the tile surface.
357. Ceramic tile with a fired clay base (left) comprising vitified clay (brown) with angular inclusions of ground quartz (white). Opaque underglaze applied to clay base (grey) includes fine particles of a crushed aggregate for colour. The outer glaze (right) is glassy and transparent (white); PPT, 150, 1mm across.
358. Same view as 357 in cross-polarized light. The fired clay base appears red with grey/white quartz inclusions (left). The underglaze containing fine-grained colouring aggregate appears grey and the glassy outer glaze is isotropic (black, right); XPT, 35, 4.5mm across.
Ceramic tiles are fixed to walls and floors using tile adhesive (359). The failure of tiled surfaces may involve loss of adhesion or cracking often caused by a lack of provision for movement, use of inappropriate bedding materials, or poor workmanship (Jornet & Romer, 1999). Petrographic examination can provide information helpful to the identification of failure causes, by checking the composition and condition of the bedding/jointing materials and in the assessment of crack morphologies (Wong et al., 2003).
359. Ceramic floor tile (left) and tile adhesive (right). The tile consists of fired-clay matrix (reddish-brown) with very fine quartz sand inclusions (white). The adhesive comprises natural sand fine aggregate (white) bound by a cement matrix consisting of HAC mixed with Portland cement (brown); PPT, 75, 2.5 mm across.
Homogenous ceramic tiles were collected from 5 construction sites in the state of Perak and Penang, Malaysia. The tiles were broken manually using a hammer and then fed into a jaw crusher (Model: Retsch BB-200) to acquire aggregates of mesh size 20mm (Plate 1 and 2). Other materials including ordinary portland cement (OPC), locally available river sand (specific gravity 1.73) and natural crushed stone aggregates of maximum size 20mm (specific gravity 1.62) were also used for the production of concrete block. In the case of homogenous ceramic tiles waste aggregates, five concrete mixes were prepared by varying the content of ceramic tiles coarse aggregates from 20% to 100%. The concrete block were then demoulded and cured under water at 272C until the test age. The samples were demoulded 24 hours after casting and cured. The blocks were then tested for compression strength at different curing time in days (7, 14 and 28days). In this study, the percentage of placement, the water/cement (W/C) ratio, compacting factor, and compressive strength at 7 and 14days were used as inputs and the values of the compressive strength for curing time of 28days was used as an outputs for fine and coarse aggregates respectively. Herein, all the data were divided into 3 categories which are training, testing and validation data because early stopping criteria were used in the neural network training. Then, all data are resampled through bootstrap re-sampling approach to make it 72 data in each category.
The production of ceramic tiles with fly ash was not only to save the high disposal costs per annum but also to profit from ceramic tile sales. Therefore, from the point of view of the utilization of waste and the perspective of high demand for building materials which meet the requirements of the domestic and international markets, ceramic tile production has brought considerable economic benefits and has profound social significance. Specific cost accounting is shown in Table 7.35.
From the table it can be seen that the total cost was 2.574 million RMB/100,000m2, which means the unit cost was 25.7RMB/m2. The sale price was 35RMB/m2. The profits were 9.3RMB/m2. The total annual output value was 3.5million RMB. The total profit was 0.93 million RMB. In addition, ash consumption quantity amounted to 2000t/y, which means saving 5.4 million RMB for fly ash disposal.
Thermal characterization and use in ceramic tile making of fly ash is presented. Differential temperature analysisthermogravimetric analysis analysis, elementary component variation, chemical component, radical component transformation, mineralogical component transformation, microstructure transfer, leaching toxicity and speciation transformation, as a function of temperature for fly ash, are provided. Use of fly ash in ceramic tile making is explored. 11 major elements in fly ash with contents over 1% and a sequence of O >Ca >Si >Cl >Al >Fe >Na >S >C >Mg are found in fly ash. Main elementary content and chemical component of the ash changes with increase of sintering temperature. It is inferred that heavy metals should be stabilized in the sintered fly ash due to generation of crystal and glass phases which constitute occluding body of these heavy metals. Microstructure of fly ash is strengthened with the increase of temperature, and porosity reduces. In addition, content of glass phases increases and particles are more closely cemented together as sintering temperature increases from 1000 to 1300C, which is conducive to solidification of heavy metals. The leaching toxicity and speciation of heavy metals are also influenced by the increase of temperature.
The use of MIBA in the production of ceramic tiles has been explored to a limited extent (Andreola etal., 2001; Appendino etal., 2004; Barbieri etal., 2002; Baruzzo etal., 2006; Johnson and Barclay, 1973). The production procedure is very similar to what has been previously described for general ceramic products, with the additional step of pressing. A dry pressing process is the most common method used and typically includes the addition of an organic binder. MIBA has been used in different ways in ceramic tile production, including as a minor component:
Appendino etal. (2004) used 75% MIBA along with other waste materials (corundum-based waste and ceramic powder waste from kaolin ore extraction) and a minimal amount of ethyl alcohol to produce glass-ceramic tiles.
Porcelain stoneware tiles incorporating MIBA by up to 20% by weight into a porcelain stoneware body were found to have good mineralogical, thermal and rheological compatibility with the pure porcelain stoneware product (Andreola etal., 2001). An in-depth study was recommended on the mechanical and aesthetic properties of these MIBA tiles, which would be useful in evaluating whether the incorporation of MIBA into a porcelain stoneware body is feasible.
Glass-ceramic tiles have also been successfully produced from mixes containing 75% MIBA, with the rest either corundum-based waste or kaolin ore ceramic powder. Tests on the physical and mechanical performance of the resulting tiles (results in Table 7.10) showed that the optimum sintering temperature was 950C, beyond which an overall decrease in all aspects of performance started to show, attributed to density reduction as a result of the beginning of the bloating process. With a sintering temperature of 950C, the MIBA-based glass-ceramic tiles demonstrated high mechanical performance capable of satisfying ceramic wall tile requirements (i.e., bending strength>12MPa and thermal expansion coefficient<9106/C) (Schneider, 1991).
As shown in Table 7.11, the introduction of frits comprising either 100% MIBA or 50% MIBA+50% glass cullet as sintering promoters had a beneficial effect on the properties of ceramic tiles (Barbieri etal., 2002), in addition to potentially decreasing the maximum firing temperature (Rambaldi etal., 2010). Apart from decreases in the water absorption and linear shrinkage with the introduction of frits, the bending strength was comparable to that of the control mix and within the requirements of UNI EN 100 for porcelain stoneware (i.e., bending strength>27MPa). Furthermore, the addition of MIBA improved the tile spot resistance from class C to class B, based on the UNI EN 100 classification (class A, completely clean, varying to class E, very dirty). However, the high iron content of MIBA did have a worsening effect on the tile aesthetics. The resulting tiles were darker and some slight surface defects were also evident. Similar findings concerning the aesthetic appearance of tiles were also observed when applying plasma-based glazes made of MIBA (Schabbach etal., 2012b).
Some of the same researchers (Barberio etal., 2010) later carried out a life cycle assessment on the use of MIBA for frit production, compared to landfill disposal. Apart from witnessing a drastic reduction in heavy metal leachability with vitrification of MIBA, the authors also showed that it is environmentally advantageous for all of the evaluated impact categories relating to global warming. The main advantages are associated with metal recovery (i.e., aluminium and iron) from MIBA treatment, the use of secondary materials instead of primary raw material in frit production and the prevention of landfill disposal. Johnson and Barclay (1973) also reported that the use of glass from the vitrification treatment of MIBA in ceramic tiles was an attractive prospect from an economic point of view. However, slight concerns were raised regarding possible negative effects on the tiles aesthetics.
Using the 50/50 blend of MIBA and dredging soils, it was shown that ceramic tiles with low leachability and sufficiently high bending strength were achievable (Table 7.12), satisfying the requirements for ceramic wall and floor tiles, though high shrinkage upon firing was recorded and, as has been reported previously, visual defects were evident (Baruzzo etal., 2006).
Bricks are popular envelope materials for buildings while ceramic tiles are used for floor and wall finishes. The high primary energy demand in the production of brick and tiles is associated with the high consumption of fossil fuel during the manufacturing stage. It is estimated that firing of the bricks and tiles in the kiln consumes about 80% of the total energy of production (Bribian et al., 2011). In addition, some raw materials for brick and tiles manufacture are transported over long distances, which add to the transportation component of material production. Embodied energy of fired clay bricks and that of ceramic tiles have been estimated to be about 3 GJ/ton and 12 GJ/ton, respectively (Hammond and Jones, 2011).
Weathering reduces the natural durability of western red cedar roofing shakes by leaching fungitoxic thujaplicins from wood.6 Because weathering is confined to wood surface layers, the mechanical properties of wood, assuming decay to be absent, are largely unaffected by prolonged exposure of wood to the weather.6 The mechanical properties of wood composites, however, which depend in part on the strength of wood-adhesive bonds, can be significantly reduced by moisture-induced dimensional changes.6
Artificial accelerated weathering slightly reduces the solar reflectance of cool roof coatings, and its influences on the cooling effect of cool roof coatings are negligible within the experimental error.8
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(Swipe left to see more) Model ConveyorCapacity (m /h) Hoisting Speed (m/s) Main Shaft Speed r/min Diameter Of Material (mm) Hoperp Volume(L) Width(mm) Distance(mm) NE15 15 0.5 15.54 <40 2.5 250 203 NE30 30 0.5 16.45 <50 7.8 300 305
(Swipe left to see more) Model Design Pressure (Mpa) Set Tempreture Working Medium Opening Method Annual Capacity m/year 231m 1.6 204 Saturated water vapor Open the door on both ends 150000 2.531m 200000-250000 2.6839m 300000
The effect of coal fly ash and borax solid waste (TW) on the properties of wall tile was investigated. The properties examined include firing strength, firing shrinkage, water absorption and microstructure. A number of wall tile compositions were prepared by the replacement of potassium feldspar with the fly ash and TW in the range of 210%. Further on, the wall tiles were produced by replacing potassium feldspar (in the presence of fixed quantity of 2% TW and 5% TW) with the fly ash in the range of 210%. The results showed that firing strength of the wall tile increased when the fly ash and TW used in the preparation of the standard tile composition. In particular, the improvement of strength was observed when the TW up to 6wt.% was introduced as potassium feldspar replacement. Results indicate an interesting potential for the coal fly ash and TW recycling to produce useful materials.
Nepal, country of Asia, lying along the southern slopes of the Himalayan mountain ranges. It is a landlocked country located between India to the east, south, and west and the Tibet Autonomous Region of China to the north. Its territory extends roughly 500 miles (800 kilometres) from east to west and 90 to 150 miles from north to south. The capital is Kathmandu.
Nepal, long under the rule of hereditary prime ministers favouring a policy of isolation, remained closed to the outside world until a palace revolt in 1950 restored the crowns authority in 1951; the country gained admission to the United Nations in 1955. In 1991 the kingdom established a multiparty parliamentary system. In 2008, however, after a decadelong period of violence and turbulent negotiation with a strong Maoist insurgency, the monarchy was dissolved, and Nepal was declared a democratic republic.
Wedged between two giants, India and China, Nepal seeks to keep a balance between the two countries in its foreign policyand thus to remain independent. A factor that contributes immensely to the geopolitical importance of the country is the fact that a strong Nepal can deny China access to the rich Gangetic Plain; Nepal thus marks the southern boundary of the Chinese sphere north of the Himalayas in Asia.
As a result of its years of geographic and self-imposed isolation, Nepal is one of the least developed nations of the world. In recent years many countries, including India, China, the United States, the United Kingdom, Japan, Denmark, Germany, Canada, and Switzerland, have provided economic assistance to Nepal. The extent of foreign aid to Nepal has been influenced to a considerable degree by the strategic position of the country between India and China.
Nepal contains some of the most rugged and difficult mountain terrain in the world. Roughly 75 percent of the country is covered by mountains. From the south to the north, Nepal can be divided into four main physical belts, each of which extends east to west across the country. These are, first, the Tarai, a low, flat, fertile land adjacent to the border of India; second, the forested Churia foothills and the Inner Tarai zone, rising from the Tarai plain to the rugged Mahbhrat Range; third, the mid-mountain region between the Mahbhrat Range and the Great Himalayas; and, fourth, the Great Himalaya Range, rising to more than 29,000 feet (some 8,850 metres).
The Tarai forms the northern extension of the Gangetic Plain and varies in width from less than 16 to more than 20 miles, narrowing considerably in several places. A 10-mile-wide belt of rich agricultural land stretches along the southern part of the Tarai; the northern section, adjoining the foothills, is a marshy region in which wild animals abound and malaria is endemic.
The Churia Range, which is sparsely populated, rises in almost perpendicular escarpments to an altitude of more than 4,000 feet. Between the Churia Range to the south and the Mahbhrat Range to the north, there are broad basins from 2,000 to 3,000 feet high, about 10 miles wide, and 20 to 40 miles long; these basins are often referred to as the Inner Tarai. In many places they have been cleared of the forests and savanna grass to provide timber and areas for cultivation.
A complex system of mountain ranges, some 50 miles in width and varying in elevation from 8,000 to 14,000 feet, lie between the Mahbhrat Range and the Great Himalayas. The ridges of the Mahbhrat Range present a steep escarpment toward the south and a relatively gentle slope toward the north. To the north of the Mahbhrat Range, which encloses the valley of Kathmandu, are the more lofty ranges of the Inner Himalaya (Lesser Himalaya), rising to perpetually snow-covered peaks. The Kathmandu and the Pokhar valleys lying within this mid-mountain region are flat basins, formerly covered with lakes, that were formed by the deposition of fluvial and fluvioglacial material brought down by rivers and glaciers from the enclosing ranges during the four glacial and intervening warm phases of the Pleistocene Epoch (from about 2,600,000 to 11,700 years ago).
The Great Himalaya Range, ranging in elevation from 14,000 to more than 29,000 feet, contains many of the worlds highest peaksEverest, Knchenjunga I, Lhotse I, Maklu I, Cho Oyu, Dhaulgiri I, Manslu I, and Annaprna Iall of them above 26,400 feet. Except for scattered settlements in high mountain valleys, this entire area is uninhabited.
The Kathmandu Valley, the political and cultural hub of the nation, is drained by the Bghmati River, flowing southward, which washes the steps of the sacred temple of Paupatintha (Pashupatinath) and rushes out of the valley through the deeply cut Chhobar gorge. Some sandy layers of the lacustrine beds act as aquifers (water-bearing strata of permeable rock, sand, or gravel), and springs occur in the Kathmandu Valley where the sands outcrop. The springwater often gushes out of dragon-shaped mouths of stone made by the Nepalese; it is then collected in tanks for drinking and washing and also for raising paddy nurseries in May, before the monsoon. Drained by the Seti River, the Pokhar Valley, 96 miles west of Kathmandu, is also a flat lacustrine basin. There are a few remnant lakes in the Pokhar basin, the largest being Phewa Lake, which is about two miles long and nearly a mile wide. North of the basin lies the Annaprna massif of the Great Himalaya Range.
The major rivers of Nepalthe Kosi, Nryani (Gandak), and Karnli, running southward across the strike of the Himalayan rangesform transverse valleys with deep gorges, which are generally several thousand feet in depth from the crest of the bordering ranges. The watershed of these rivers lies not along the line of highest peaks in the Himalayas but to the north of it, usually in Tibet.
The rivers have considerable potential for development of hydroelectric power. Two irrigation-hydroelectric projects have been undertaken jointly with India on the Kosi and Nryani rivers. Discussions have been held to develop the enormous potential of the Karnli River. A 60,000-kilowatt hydroelectric project at Kulekhani, funded by the World Bank, Kuwait, and Japan, began operation in 1982.
The rivers and small streams of the Tarai, especially those in which the dry season discharge is small, are polluted by large quantities of domestic waste thrown into them. Towns and villages have expanded without proper provision for sewage disposal facilities, and more industries have been established at selected centres in the Tarai. The polluted surface water in the Kathmandu and Pokhar valleys, as well as in the Tarai, are unacceptable for drinking.