Search Results (15)

Human activities play a key role in landscape evolution. Mining is one of the most important of these since it changes large parts of the Earth’s surface. In abandoned mines and quarries, pit lakes are quite common due to water table blocking. These lakes have remarkable ecological characteristics, but they are still poorly understood. Northwestern Spain has a long tradition in the use of slate for roofs. This exploitation, mostly open-pit, has caused a great transformation in the landscape including the generation of pit lakes. In this work, 27 pit lakes in abandoned slate quarries areas have been analysed using orthophotos of different years, UAV (unmanned aerial vehicle) images and field work. In each lake, the topographic context, geomorphological dynamics, morphometric parameters (including depth), pH, and ecological variables were measured. Other uses for these quarry pit lakes and their significance as a new geo-ecological environment are also discussed. The results show different types of pit lakes and, consequently, different potential uses in each case. Only six offer good conditions for recreational uses, whereas the rest (21) show slope instability or poor water quality. Full article

The detection of asbestos roof slate by drone is necessary to avoid the safety risks and costs associated with visual inspection. Moreover, the use of deep-learning models increases the speed as well as reduces the cost of analyzing the images provided by the drone. In this study, we developed a comprehensive learning model using supervised and unsupervised classification techniques for the accurate classification of roof slate. We ensured the accuracy of our model using a low altitude of 100 m, which led to a ground sampling distance of 3 cm/pixel. Furthermore, we ensured that the model was comprehensive by including images captured under a variety of light and meteorological conditions and from a variety of angles. After applying the two classification methods to develop the learning dataset and employing the as-developed model for classification, 12 images were misclassified out of 475. Visual inspection and an adjustment of the classification system were performed, and the model was updated to precisely classify all 475 images. These results show that supervised and unsupervised classification can be used together to improve the accuracy of a deep-learning model for the detection of asbestos roof slate. Full article

As precious cultural heritage sites, the state of preservation of cave temples is closely related to the geological and climatic conditions in which they are located. This paper constructed an analytical method of sized slate stability based on the equivalent support stiffness method. The stability analysis of the roof slab of Yuanjue Cave was carried out by establishing a three-dimensional numerical calculation model. Through comparative analysis of the results of stress and displacement fields under different conditions, the stress and deformation characteristics of the roof slab of Yuanjue Cave were revealed, as well as the study of the main factors affecting the stability of the roof slab of Yuanjue Cave and the key slate to be monitored. The main research results are as follows. The stress deformation of the roof plate of Yuanjue cave is mainly divided into the initial uniform change stage, the medium-term stable change stage or the medium-term accelerated change stage, and the later rapid change stage. With the increase in the number of overhanging and broken slates and the increase in the damage factor of cracked slates, the vertical stress extremum of the stones increases continuously, and the equivalent support stiffness decreases, which aggravates the uneven stress deformation of the roof of the Yuanjue Cave. This study provides a reliable reference basis for the stability analysis and evaluation of the roof slab of a large number of cave temples existing in the Sichuan and Chongqing areas in China. Full article

This paper presents the results of a laboratory simulation of a subarctic climate carried out in climatic chamber. Realistic daily and seasonal cycles of temperature of a regular subarctic continental climate without dry seasons (Dfc) were simulated and the physical/mechanical properties and performance of the slates were assessed. The slate was selected because of its use as cladding and roofing material in cold regions. Mechanical performances before and after Dfc climate simulation were evaluated through point load index, uniaxial compression, flexural strength and anchor rupture load. A decrease in these mechanical features between 9 and 50% with respect to the initial strengths has been registered. Other physical parameters such as apparent density, open porosity and water absorption were evaluated. The tests showed an increase in open porosity (+72%) and a decrease in bulk density (−0.7%). The results highlighted a predominantly physical decay and mechanical performance decreasing with a relevant lowering in strength without the detection of chemical–mineralogical alterations. Moreover, artificial sun exposure reproduced the weak solar radiation that characterizes the Dfc climate. This was carried out to assess the aesthetic characteristics of the slate, since discoloration under sun exposure was supposed to occur but the slates did not exhibit substantial color changes. Full article

Asbestos is a class 1 carcinogen, and it has become clear that it harms the human body. Its use has been banned in many countries, and now the investigation and removal of installed asbestos has become a very important social issue. Accordingly, many social costs are expected to occur, and an efficient asbestos investigation method is required. So far, the examination of asbestos slates was performed through visual inspection. With recent advances in deep learning technology, it is possible to distinguish objects by discovering patterns in numerous training data. In this study, we propose the use of drone images and a faster region-based convolutional neural network (Faster R-CNN) to identify asbestos slates in target sites. Furthermore, the locations of detected asbestos slates were estimated using orthoimages and compiled cadastral maps. A total of 91 asbestos slates were detected in the target sites, and 91 locations were estimated from a total of 45 addresses. To verify the estimated locations, an on-site survey was conducted, and the location estimation method obtained an accuracy of 98.9%. The study findings indicate that the proposed method could be a useful research method for identifying asbestos slate roofs. Full article

Slate dwellings are known as the “living fossil of primitive dwellings” in China. Energy-saving strategies are crucial to slate dwellings for sustainability as well as maintaining thermal comfort. In this research, a subjective satisfaction analysis on the indoor thermal environment in Daziliang village, China, was conducted. It was found that neutral temperature is 20.92 °C in summer, 8.92 °C in winter, and the actual operating temperature in winter is too low to meet the 80% acceptable range. Therefore, a series of improvement strategies in winter were proposed. The results showed that adding external thermal insulation material—expanded polystyrene board with a thickness of 80 mm on the roof and outside walls—and sunspace depth of 1.5 m are better in terms of energy-saving effects. In addition, the slate dwelling’s daily energy-saving rate of the heating day is 44.26% lower than the original state through these strategies. The air temperature of Bedroom D in winter non-heating days increases by 3.82 °C after improvement and the mean radiant temperature increased by 2.54 °C. Our approach puts forward specific energy-saving improvement measures and provides feasible suggestions for the protection and development of slate dwellings in this area. Full article

Asbestos-cement slate roofs are one of the most common environmental causes of asbestos exposure. However, few studies have examined residential asbestos-cement slate-related exposure and its effects on human health. This study was performed to evaluate cumulative asbestos exposure levels and to calculate the Excess Lifetime Cancer Risk (ELCR) of residents of asbestos-cement slate-roofed houses. We reviewed previous Korean literature to estimate the concentration of airborne asbestos from asbestos-cement slate roofed buildings. Finally, eight studies were selected, and a pooled analysis was performed. The results derived from the pooled analysis were combined with the data from a health impact survey conducted from 2009 to 2016 at the Environmental Health Center for Asbestos (EHCA) of the Yangsan Pusan National University Hospital, and a carcinogenic risk assessment was performed. As a result, the representative value of the indoor exposure concentration related to asbestos-cement slate was found to be 0.0032 f/cc on average, and the representative value of the exposure related to occupational asbestos-cement slate dismantling and demolition was found to be 0.0034 f/cc. In addition, the ELCR of asbestos-cement slate related indoor exposure and occupational dismantling and demolition was found to be of medium risk, and the ELCR of residential dismantling and demolition of asbestos-cement slate was less than 10⁻⁶, indicating that the risk was low. Since there is no threshold for carcinogenicity related to asbestos, this should not be ignored even if the risk appears low, and it would be reasonable to calculate the carcinogenic risk based on total lifetime exposure. More studies on asbestos exposure scenarios and the scope of similar exposure groups through additional data collection and further analysis of risk are needed. Full article

Although exposure to asbestos via various routes has been acknowledged, comprehensive exposure and risk assessment methods have not been developed at the national level. We conducted a study to reconstruct comprehensive past asbestos exposure estimations and to suggest a method to calculate the Excess Lifetime Cancer Risk (ELCR) of Koreans. The past occupational exposure reconstruction was conducted by rebuilding the previous general population job-exposure matrix (JEM). The para-occupational and household exposure estimation was based on the pooled analysis of data from other countries as well as Korea. The neighborhood exposure from occupational sources by distance was estimated by the exponential decay model. As a result, 141 JEM exposure groups across four periods including ~79, the 80s, 90s, 2000s with a ratio of 2.0:1.0:0.5:0.05 were reconstructed. The para-occupational and household exposures were 11% and 1% of the JEM respectively. The environmental exposure source concentration from outside occupational exposure was 2.5% of the inside concentration. The ratio of the concentration of environmental exposure source (C₀) to distance d (C_d) was $ex{p}^{-kd}$ with a decay constant k of 6.834. The mean concentrations (f/cc) were 2.28 × 10⁻³ for outdoor, 4.65 × 10⁻⁵ for indoor, 1.95 × 10⁻² for transportation activity, 4.44 × 10⁻² for agricultural activity, and 4.68 × 10⁻² for daily life activity in naturally occurring asbestos areas. Indoor and outdoor asbestos concentrations from living in a slate roof house were 1.73 × 10⁻⁶ and 2.70 × 10⁻⁸, respectively. For improved generalizability, validity, and applicability of the proposed method, further studies on each route with real assessments and experiments are required. Full article

Roofing slates are a category of building stones which have a very distinctive feature: High fissility, which allows them to be split into tiles that are thin, regular and large. There are several types of roofing slates, depending on their lithology. The four main lithologies are low-grade slates, slates stricto sensu, phyllites, and mica-schist. Occasionally, other rocks such as quartzites, serpentinites, or shales, can also be used as roofing slates. Roofing slates must ensure waterproofing, a quality that depends on both the rock and the installation. Installation must therefore take into account parameters such as the pitch, orientation, and overlap of the tiles in order to avoid capillarity, which could jeopardize waterproofing. These parameters are usually included in installation manuals. However, despite the fact that roughness is a parameter known to have an important effect on capillarity, it has never been thoroughly analyzed. Roughness varies depending on the type of roofing slate, but installation manuals do not take this factor into account. This study has measured surface roughness in different types of roofing slates using a laser scanner and determined the capillarity values along and across the grain direction. Furthermore, the role of dissolved salts in capillarity has likewise been studied. Full article

Roof and wall slates are fine-grained rocks with slaty cleavage, and it is often difficult to determine their mineral composition. A new norm mineral calculation called slatecalculation allows the determination of a virtual mineral composition based on full chemical analysis, including the amounts of carbon dioxide (CO₂), carbon (C), and sulfur (S). Derived norm minerals include feldspars, carbonates, micas, hydro-micas, chlorites, ore-minerals, and quartz. The mineral components of the slate are assessed with superior accuracy compared to the petrographic analysis based on the European Standard EN 12326. The inevitable methodical inaccuracies in the calculations are limited and transparent. In the present paper, slates, shales, and phyllites from worldwide occurrences were examined. This also gives an overview of the rocks used for discontinuous roofing and external cladding. Full article

In view of problems with roadways with a compound roof, such as the occurrence of instability in the roof strata, ease of separation of the layer caving, difficulty of maintenance, and poor safety, we established a mechanical calculation model of a roadway with compound roof using the elastic mechanics theory, taking the stability control of a roadway with compound roof at a coal mine in Guizhou Province, China as the research background, and based on the actual characteristics of the coal seam and the roof and floor slate. Expressions of the separation layer and instability limit load of compound roof were derived, and the calculation and verification were carried out in combination with the actual conditions. By means of numerical simulation, the distribution and evolution laws of stress, displacement and plastic zone of roadways with a compound roof were studied, and the deformation characteristics and instability mechanism of roadways with a compound roof were revealed: (1) in early stage deformation of roadway, the amount is large, the speed is fast, and the scale is wide; (2) compound roofs are vulnerable to abscission and instability, the bearing capacity of the two sides is low due to softness and cracking, the shear failure of side angles and vertex angles weakens the strength of surrounding rock, and the self-bearing capacity of surrounding rock is low; (3) the bolt and anchor bear relatively large tensile force, and the support structure is easy to be broken up. On this basis, the stability control principle of a roadway with compound roof tunnel was put forward: fast and timely support; high-strength bolt strong support; improving the stability of the roof and the bearing capacity of the two sides; restraining the shear failure of the key bearing parts such as the side angles and the bottom angles, and targeted stability control technology for roadways with a compound roof was developed. The field industrial test showed that the deformation of this roadway with a compound roof was effectively controlled and the overall stability of the roadway was effectively improved. The results of this study could provide useful reference for a roadway with a compound roof under similar conditions. Full article

Slate is a natural rock usually used in roofs, façades, and for tiling. In spite of this broad use, the production process of slate tiles requires substantial improvements. An important quantity of slate from the quarry is wasted during the manufacturing of the final product. Furthermore, processes are not automatized and the production lead times can be considerably shortened. Therefore, new processing methods to increase productivity, reduce costs and to provide added value to the final slate product are required. Drilling is an important part of these manufacturing processes. Conventional drilling processes usually cause the breaking of the slate tiles; then, even a higher quantity of material is wasted. To overcome these problems, lasers emerge as a feasible tool to produce holes in this material, since mechanical stresses are not induced on the workpiece. In this work, we have studied the CO₂ laser microdrilling of slate tiles. We used a Design of Experiments (DOE) methodology to determine the influence of the laser processing parameters on the hole quality. This work demonstrates the capability of a CO₂ laser to produce holes in slate with less than 100 microns in diameter, avoiding any fracture, and with a processing time of less than 50 ms per hole. Finally, this process demonstrates the viability of the production of high-density micron-sized holes in a slate tile for water draining purposes. Full article

This study aimed to evaluate the relationship between various asbestos exposure routes and asbestos-related disorders (ARDs). The study population comprised 11,186 residents of a metropolitan city who lived near asbestos factories, shipyards, or in slate roof-dense areas. ARDs were determined from chest X-rays indicating lower lung fibrosis (LFF), pleural disease (PD), and lung masses (LMs). Of the subjects, 11.2%, 10.4%, 67.2% and 8.3% were exposed to asbestos via occupational, household, neighborhood, and slate roof routes, respectively. The odds ratio (OR) of PD from household exposure (i.e., living with asbestos-producing workers) was 1.9 (95% confidence interval: 0.9–4.2), and those of LLF and PD from neighborhood exposure, or residing near asbestos factories) for <19 or >20 years, or near a mine, were 4.1 (2.8–5.8) and 4.8 (3.4–6.7), 8.3 (5.5–12.3) and 8.0 (5.5–11.6), and 4.8 (2.7–8.5) and 9.0 (5.6–14.4), respectively. The ORs of LLF, PD, and LM among those residing in slate-dense areas were 5.5 (3.3–9.0), 8.8 (5.6–13.8), and 20.5 (10.4–40.4), respectively. Substantial proportions of citizens residing in industrialized cities have potentially been exposed to asbestos, and various exposure routes are associated with the development of ARDs. Given the limitations of this study, including potential confounders such as socioeconomic status, further research is needed. Full article

Building-integrated photovoltaic (BIPV) systems have improved aesthetics but generally cost far more than conventional PV systems because of small manufacturing scale. Thus, in the short and medium term, there is a need for a BIPV mounting system that utilizes conventional modules. Such a design is provided here with a novel modification of conventional photovoltaic (PV) modules to allow them to act as BIPV roofing slates. The open-source designs for the mechanical components necessary to provide the post-consumer conversion for a conventional PV module are provided, and prototypes are fabricated and installed on a mock roof system along with control modules mounted conventionally. The approximately U.S.$22/module BIPV roof-mounted system is direct mounted on the roof to eliminate the need for roofing shingles or other coverings, which effectively provides a 20% total cost reduction from conventional racking systems that demand a roof to mount upon without considering the savings from the rack itself. The results of the outdoor system testing found no water leaks. An increased operating temperature was observed, which would reduce the output from a silicon-based PV module by less than 10%. The results found significant potential for this design to further reduce total PV systems costs. Full article

In this study, we evaluated a two-step process for detoxification of waste roofing slate, involving cement hydrate removal and low temperature detoxification using oxalic acid. These treatments were conducted on raw material and intermediate product, respectively. Cement hydrate removal effectively eliminated most Ca-containing cement hydrate components from the raw material under the following conditions: HCl to solid ratio: 0.456 g/g, reaction time: 2 h, and solid to liquid ratio: 0.124 g/mL. Following low temperature (~100 °C) detoxification of intermediate product obtained after cement hydrate removal, chrysotile in waste roofing slate was effectively transformed to Mg-oxalate under conditions of oxalic acid to solid ratio of >0.67 g/g. Full article