Clay Roof Research Articles

Chocolate clays of the Northern Caspian Sea Region (distribution, position and structure)

Chocolate clays are one of the most common facies of Lower Khvalynian sediments of Northern Caspian and Lower and Middle Volga region. After more than a hundred years of research, there are still a number of unresolved issues related to the conditions of its bedding, structure, facial structure and colority. Chocolate clays are confined solely to pre-Khvalynian relief depressions: terraces, paleo down cuttings and junctions of large tributaries at river valleys, and varied in form and origin paleoravines, estuaries, saline-dome depressions (Elton Baskunchak) and ancient deflationary depressions (Kalmykia) at watersheds. Chocolate clay roofing according to the general slope of the surface of the Lower Volga and Northern Caspian gradually decreases from north to south. The highest level of occurrence of clays in the Caspian depression is usually noted at levels +20-25 m. To the north, within the valley of the Volga, clay roof rises to a level35 mand above. There are two types of chocolate clay by the pattern of its distribution: continuous and intermittent (mosaic). Continuous distribution prevails in the Volga River valley and is observed in ancient estuaries and junctions of Volga River’s major tributaries: the Large and Little Irgiz, Large and Little Karaman, Torgun etc. Depending on structure features facies (macrofacies) of chocolate clay are divided into subfacies: monoargillaceous, stratified, sand-clay and silt-clay. The most common monoargillaceous subfacies have total clay composition. It’s massive unstratified or hidden-stratified dark chocolate brown clay with a large block jointing, sometimes interbedded with lighter silt varieties.

Optimisation of concrete mixtures made with crushed clay bricks and roof tiles

The main purpose of this paper is to show the possible applicability of concrete made using partial replacement of natural aggregate with crushed bricks and roof tiles in load-bearing structures. In total, 62 different concrete mixtures with crushed bricks and roof tiles were made based on Box–Behnken design and experimentally tested. The selection of acceptable concrete mixtures was chosen according to experimental results and mathematical models of required properties (density, slump, compressive strength, tensile strength and modulus of elasticity). An optimal concrete mixture for a precast concrete beam and block floor system was chosen according to multi-criteria decision process. The applicability of concrete mixtures for precast concrete block and beam floor systems was tested regarding the requirements set out in standards HRN EN 15037-1:2008 and HRN EN 15037-2:2009.

Experimental Heat Transfer Study on Green Roofs in a Semiarid Climate during Summer

An experimental study was conducted on green roofs under the semiarid summer climatic conditions of West Texas to investigate the effect of soil type, moisture content, and the presence of a top soil grass layer on the conductive heat transfer through the roof. Two soil types were investigated: uniform sand and local silt clay. Tests were also conducted on a control roof. A dual-needle heat-pulse sensor was used to conduct thermal property tests on the soils. The tests reveal that unlike sand, the thermal conductivity of silt clay did not increase continuously with soil moisture. Better heat transfer conditions were achieved when the sand and silt clay roofs were watered to a water depth of 10 mm per day rather than double the amount of 20 mm per day. The roof with silt clay soil had the lowest fluctuation in inner temperature between daytime and nighttime. Green roofs with silt clay soil required more than twice the amount of soil moisture than green roofs with sand to achieve similar roof heat transfer rates. The best net heat flux gains for vegetated green roofs were 4.7 W/m2 for the sand roof and 7.8 W/m2 for the silt clay roof.

PENYERAPAN GAS KARBONDIOKSIDA (CO 2 ) DALAM BIOGAS DENGAN LARUTAN Ca(OH)2

<p>Abstract: Carbon dioxide content in biogas produced by fermentation is still high. Because of<br />that, biogas need a process purification to reduce carbon dioxide content. In this work, Ca(OH)2<br />solution was contacted with biogas in a column for reducing the CO<br />2<br />content. This research<br />studied the effect of packing type used in absorber column on the rate of CO<br />2<br />reduction. Based<br />on experimental data and modelling, it was found that the reaction between CO<br />2<br />followed first order reaction. The constant of rate reaction was affected by the packing type<br />which using glass ball, plastic pipe, ceramic, wood, and clay roof, the constant rate were 0.781,<br />0.464, 0.916, 0.637, and 0.987 min<br />Keywords: Biogas, CO<br />2<br />, Ca(OH)2<br />-1<br />, respectively.<br />, absorber, rate of reaction</p>

Using remote sensing to assess the relationship between crime and the urban layout

The link between place and crime is at the base of social ecology theories of crime that focus in the relationship of the characteristics of geographical areas and crime rates. The broken windows theory states that visible cues of physical and social disorder in a neighborhood can lead to an increase in more serious crime. The crime prevention through environmental design (CPTED) planning approach seeks to deter criminal behavior by creating defensible spaces. Based on the premise that a settlement's appearance is a reflection of the society, we ask whether a neighborhood's design has a quantifiable imprint when seen from space using urban fabric descriptors computed from very high spatial-resolution imagery. We tested which land cover, structure and texture descriptors were significantly related to intra-urban homicide rates in Medellin, Colombia, while controlling for socioeconomic confounders. The percentage of impervious surfaces other than clay roofs, the fraction of clay roofs to impervious surfaces, two structure descriptors related to the homogeneity of the urban layout, and the uniformity texture descriptor were all statistically significant. Areas with higher homicide rates tended to have higher local variation and less general homogeneity; that is, the urban layouts were more crowded and cluttered, with small dwellings with different roofing materials located in close proximity to one another, and these regions often lacked other homogeneous surfaces such as open green spaces, wide roads, or large facilities. These results seem to be in agreement with the broken windows theory and CPTED in the sense that more heterogeneous and disordered urban layouts are associated with higher homicide rates.

Quantifying Slumness with Remote Sensing Data

The presence of slums in a city is an indicator of poverty and its proper delimitation is a matter of interest for researchers and policy makers. Socio-economic data from surveys and censuses are the primary source of information to identify and quantify slumness within a city or a town. One problem of using survey data for quantifying slumness is that this type of data is usually collected every ten years and is an expensive and time consuming process. Based on the premise that the physical appearance of an urban settlement is a reflection of the society that created it and on the assumption that people living in urban areas with similar physical housing conditions will have similar social and demographic characteristics (Jain, 2008; Taubenb¨ock et al., 2009b); this paper uses data from Medellin City, Colombia, to estimate slum index using solely remote sensing data from an orthorectified, pan-sharpened, natural color Quickbird scene. For Medellin city, the percentage of clay roofs cover and the mean swimming pool density at the analytical region level can explain up to 59% of the variability in the slum index. Structure and texture measures are useful to characterize the differences in the homogeneity of the spatial pattern of the urban layout and they improve the explanatory power of the statistical models when taken into account. When no other information is used, they can explain up to 30% of the variability of the slum index. The results of this research are encouraging and many researchers, urban planners and policy makers could benefit from this rapid and low cost approach to characterize the intra-urban variations of slumness in cities with sparse data or no data at all.

The effect of firing temperature on the irreversible expansion, water absorption and pore structure of a brick body during freeze-thaw cycles

The paper deals with the monitoring of brick body in the process of volumetric freezing and thawing. The samples were fired at temperatures of 900, 1000 and 1060 °C. Attention is focused on monitoring of the irreversible expansion, water absorption and pore structure of a brick body. We found that in all cases the endpoints take place continuously, where the amount firing temperature plays a crucial role. The greatest influence of freeze/thaw cycles on the change of the pore structure was also observed at the lowest temperature. The change of the pore system during the freeze-thaw cycles occurs in such a way, that the pore volume of small pores further decreases and conversely, the pore volume of large pores increases. The knowledge gained can be used not only in the production of new but also in predicting the remaining durability of older clay roofing tiles. DOI: http://dx.doi.org/10.5755/j01.ms.19.4.2741

A Study on the Estimation Method of the Environmental Load Intensity for Analyzing GHG Reduction Effect of Han-Ok

The Korean government recently has rediscovered the potential value of Han-Ok, the Korean traditional house, as an eco-friendly building. In order to objectively verify the environmental performance of Han-Ok as a low carbon green building, this paper suggests the analysis method of GHG emission load of Korean traditional house, based on Life Cycle Assessment, which is commonly abbreviated to “LCA”. The environmental impacts caused by building construction and operation can be analyzed through the sum of input and output data from every phase. The study particularly describes the GHG reduction effect by using traditional building materials such as wood products, traditional clay roof tiles, and mud, which are mainly used to construct Han-Ok. Also the study proposes the method for comparative analysis of quantity of GHG emissions in building’s entire life cycle so that the data can be used as a reliable basis to optimize the environmental performance of building.

Photocatalytic effects of TiO2 mesoporous coating immobilized on clay roofing tiles

Abstract The objective of this study was to examine the effect of the hydroxyl radicals (free and bound) produced by a TiO 2 mesoporous coating immobilized on the surface of clay roofing tiles. The efficiency of the coating was determined by microbiological and photochemical tests. In the microbiological test (pour plate method), use was made of the test bacteria Pseudomonas aeruginosa , while the photochemical test involved the degradation of para-chlorobenzoic acid, monitored by HPLC method. Both experiments were carried out without and with a scavenger (methanol and tert -butanol). The results of the measurement of the photocatalytic efficiency, and the observed changes in the measured contact angle (sessile drop method), imply the existence of a photo-induced hydrophilicity of the TiO 2 coated porous substrates. The newly designed coating represents a medium which efficiently hinders bacterial adhesion. The experiments demonstrated the existence of self-cleaning and slight self-disinfecting properties of the mesoporous coating.

Mössbauer and X-ray study of the firing process for production of improved roofing tiles

The effects of firing atmosphere parameters on the microstructural characteristics and physical properties of clay roofing tiles were studied. For these investigations, 57Fe Mossbauer spectroscopy, X-ray diffractometry and dilatometry were used. XRD of the raw material exploited from the clay pit belonging to the roofing tile factory “Potisje-Kanjiza”, revealed the presence of montmorillonite, kaolinite, illite and some chlorite clay minerals, as well as, quartz, albite, calcite and dolomite. Gradual changes were observed both in the 57Fe Mossbauer spectra and X-ray diffractograms with samples fired in reducing CO/N2 gas atmosphere at temperatures between 700 and 1060 °C. These changes reflect the dehydroxylation processes, oxide (Fe3O4) formation, carbonate decomposition, densification and new silicate (plagioclase) formation. The firing conditions in reducing atmosphere were determined to produce roofing tiles with improved properties.

Effects of Firing Conditions on the Properties of Calcareous Clay Roofing Tiles

AbstractThe effects of firing conditions on the microstructure and physical properties of clay roofing tiles are studied. This research presents the effects of oxidizing and reducing atmosphere on Kanjiža clay material with carbonate content up to 22% by weight and the characterization of the final products. The firing was done both in the laboratory and under industrial conditions. The Fe2+/Fetotal ratio played a decisive role in the sintering process under a reducing atmosphere. The formed glassy phase, with the presence of Fe2+, attacked the earth-alkali oxides after the carbonate decomposition and more effectively filled smaller pores. The obtained results justified the benefits of the reducing firing atmosphere with 5% CO, lower porosity, higher frost resistance values, and changed microstructural characteristics

Embodied impacts of traditional clay versus modern concrete houses in a tropical regime

The environmental impacts of typical residential houses in Indonesia have not been assessed, although the expanding use of material – both locally fabricated and imported – has potentially created damage locally and regionally. This study focuses on two commonly used building envelope materials in Indonesia, the more traditional clay roof and clay bricks, and the more recently popular concrete block and concrete roof. The direct and indirect emissions resulting from the material use in buildings derived from the production process, transportation and construction are calculated. Cement-based houses are seen to be higher impact in the categories of abiotic depletion, global warming and human toxicity, whereas clay-based houses perform worse on acidification, eutrophication and photochemical oxidation. The analysis indicates that the reduction of weathering and the improvement of small-scale production processes in clay buildings could significantly improve the embodied impacts, making clay a more environmentally benign material across the life cycle. Furthermore, the analysis shows that if current trends continue, by 2030 the global warming impact from cement-based houses is predicted to contribute an additional 9 million tonnes CO2-eq compared to if all houses used traditional clay materials.

Titanium Dioxide Photocleans Polluted Air

Titanium Dioxide Photocleans Polluted Air

Frost Action Mechanisms of Clay Roofing Tiles: Case Study

Clay roofing tiles fired at five different temperatures (900, 920, 960, 1,000, and 1,020°C) were subjected to the investigations of textural characteristics and frost resistance prediction. The closed container and hydraulic pressure mechanisms proved to be dominant at lower firing temperatures (900 and 920°C), whereas micro-ice-lens formation mechanism have significant role at higher temperatures (960 and 1,000°C). The highest resistance is noticed for the samples fired at 1,020°C where the frost action mechanisms are balanced because the porous structure that compensates the local stresses developed during freezing. The prediction of frost action durability of clay roofing tiles, the appearance of the first cracks, and the prediction of frost action mechanisms given by the statistical model, showed a high level of agreement. The statistical model contains capillary pores (P0.1), and the ratio of frozen and unfrozen water (I) as significant parameters for describing susceptibility to closed container mechanism and micro-ice-lens formation mechanism, respectively.

Major Earthquakes of the Past Decade (2000-2010): A Comparative Review of Various Aspects of Management

Objectives:This article sought to review and compare data of major earthquakes of the past decade and their aftermath in order to compare the magnitude, death toll, type of injuries, management procedures, extent of destruction and effectiveness of relief efforts.Materials and Methods:A retrospective study of the various aspects of management and aftermath of 5 major earthquakes of the past decade (2000–2010) was undertaken. This included earthquakes occurring in Bam Iran, Sichuan China, Port-au-Prince Haiti, Kashmir Pakistan and Ica Peru. A literature search was done via computer of published articles (indexed in Pubmed). The issues assessed included: 1)Local magnitude,2)Type of building structure 3)Time of the earthquake (day/time/season), 4)Time to rescue, 5)Triage, Transfer, and Treatment 6) Distribution of casualties (dead/ injured), 7)Degree of city damage, 8)Degree of damage to health facilities, 9)Field hospital availability, 10)International aid, 11)Air transfer, 12) Telecommunication systems availability, 13) PTSD prevalence, 14) Most common injury and 15) Most common disease outbreak.Results:The Bam earthquake had the lowest (6.6 Richter’s) and the Sichuan earthquake had the greatest magnitude (8.0 Richter’s). Mortality in Haiti was 212,000 and it was the deadliest earthquake of the past decade. Collapse of heavy clay roofing structures was a major cause of death in Iran and Pakistan. Earthquakes occurring at night and nonworking days carried a high death toll. The time to rescue and treat was the lengthiest in Haiti (possibly contributing to the death to injured ratio). However, the worst dead to injured ratios were in Bam (51%) and in Pakistan (47%); the best ratio was in China (15%). Iran and Pakistan suffered the highest percentage of damage to the health facilities (90%). Field hospital availability, international aid and air transfer were important issues. Telecommunication systems were best in China and worst in Pakistan. PTSD prevalence was highest in Iran. Respiratory infection was the most common infection following all 5 earthquakes.Conclusions:Earthquake damage, death toll, managerial protocols etc. vary in different countries and are influenced by many factors including the hour the earthquake hits and the day of the week. Additionally, social, structural and geographic factors as well as the medical, governmental and NGO respondents are influential. Engineered residential construction remains to be of importance in reducing mortality in developing countries. It is essential that hospitals, fire departments and police stations, water, telephone and electrical facilities be made earthquake proof.

Taquezal Buildings in Nicaragua and Their Earthquake Performance

Taquezal is a common earthen building type in Nicaragua. It is constructed by building a wood frame and then packing the frame with mud to create thick earthen walls. The wood frame allows the structure to be constructed without the formwork (which is required for rammed earth buildings) and without first constructing blocks (which is generally required in adobe construction). The wood frame also allows a thinner wall than other earthen building types. Commonly, taquezal roofs are made of timber framing and heavy clay tile roofs. Taquezal buildings are not engineered and therefore are difficult to analyze with modern structural engineering methods. During the 1972 Managua earthquake, nearly 10,000 people died, and most of them were in taquezal buildings. This paper discusses taquezal as a structural system and applies engineering methods to this nonengineered structure. It was found that taquezal buildings perform well during low-to-moderate earthquakes if well maintained. However, if the wood is not maintained and allowed to rot, this degrades the roof diaphragm and wall supports, and the performance is considerably diminished.

Impregnation and superhydrophobicity of coated porous low-fired clay building materials

The imperative needs of energy saving during the latest years indicate the necessity of producing hydrophobic building materials in order to increase their durability. In the frame of this experimental work, low-fired clay (roof tiles and facing bricks) have been subjected to impregnation to make them water-repellent. To achieve this, water- and solvent-based silanes/siloxanes have been selected enriched with Si nanoparticles. Generally the mechanism of these coatings is to reduce the water capillary absorption of the building materials which has penetrated, but does not clog pores or capillaries, therefore little or no impairment of the building material's ability to “breathe”. Different tests have been performed in the laboratory in order to test the efficiency of the tested solutions such as capillary elevation and water absorption. Additional the measurement and the evaluation of the thickness and the retention of the applied coating on the LFCM were performed using acoustic microscopy. This evaluation can be made in a repetitive way during the lifetime of the material targeting to the continuous monitoring of this effect.

Influence of freezing test methods, composition and microstructure on frost durability assessment of clay roofing tiles

Clay roofing tiles are sensitive to frost action and require testing by repeated freezing and thawing cycles. The research purpose is to predict frost durability, taking into account the effect of clay mineralogy, microstructure (studied by DRX, FRX and mercury porosimetry) and manufacturing parameters, drawing an empirical comparison between methods C and E suggested by the European Standard. Method E is more severe and selective than method C, showing earlier failure and smaller dispersion, which may be explained due to the different saturation process, cooling kinetic and the presence of cloth. The damage increased with the number of cycles, it is substantially affected by the fired clay porosity and calcium content, being consistent with the thermodynamics and kinetics of the mechanisms that lead to failure. The findings provide guidance to improve frost durability based on clay characterisation and industrial process control.

Introduction of Clay Roof Tile Recycling System to Evaluate Environmental Impact Reduction Effect

Introduction of Clay Roof Tile Recycling System to Evaluate Environmental Impact Reduction Effect

Silicon thin film solar cells on commercial tiles

Nanostructured silicon single junction thin film solar cells were deposited on commercial red clay roof tiles with engobe surfaces and earthenware wall tiles with glazed surfaces, with a test area of 24 mm2. We studied the influence of the type of substrate tile, back contact, buffer layer and SiOx passivation layer on the optoelectronic performance of the solar cells. Despite the fact that typical micrometre-sized defects on the surfaces of the tiles and the porous nature of the ceramic substrates make deposition of homogeneous thin films on them quite challenging, we have been able to achieve a cell efficiency of 5% and a quantum efficiency of 80% on non-fully optimized cells on commercial tiles. The method is industrially employable utilizing pre-existing plasma-enhanced chemical vapour deposition technologies. The cost-effectiveness and industrial feasibility of the technique are discussed. Our study shows that photovoltaic tiles can combine energy generation with architectural aesthetics leading to significant implications for advancement in building integrated photovoltaics.