Petrography of roofing slates

Cation Exchange Capacity (CEC), texture, consistency and organic matter in soil assessment for earth construction: The case of earth mortars

This paper provides general introduction to the subject of constructional geomaterials and to the special issue entitled “Challenges to supply and quality of geomaterials used in construction”. Constructional geomaterials are understood as any kind of inorganic mineral raw material which can be derived from the Earth’s crust, processed, and used in construction. Mineral raw materials to be used in construction present the largest part of extractive industries, contributing to more than 70% of annual world production of mineral commodities. Therefore, extraction and processing of constructional geomaterials can be considered as serious environmental and social issues. Proper use of new materials according to their physical properties and to the ability to withstand the weathering process can contribute to lower impacts on the surrounding environment. Constructional geomaterials have been used for many objects of world cultural heritage; understanding of their nature and properties can help in the saving of these heritage objects for future generations.

Constructional geomaterials: versatile earth resources in the service of humankind—introduction to the thematic set of papers on: challenges to supply and quality of geomaterials used in construction

Investigation results of the influence of weathering process on the residual shear
 strength and durability of fine grained lithological flysch components in the area of
 north Istria, Rjecina Valley and Vinodol Valley are presented in this doctoral theises.
 Physical and mechanical properties of incompetent, fine grained flysch lithoilogcal
 members significantly change due to weathering. Landslide occurrences in flysch
 deposits are frequent and slip surface is formed at the contact of surficial deposits and
 flysch rock mass or inside the weathered flysch rock mass. Rock mass defragmentation
 at the slip surface occurs due to sliding and shear strength decreases from peak to
 residual values thorugh occured displacements. These residual strength values of the
 slip surface material are competent for the dormant landslide reactivation along the
 same slip surface. Weathering effect on the residual shear strength values of fine
 grained lithological flysch components are investigated by laboratory tests on samples
 of different weathering grades in direct shear and ring shear apparatus. Also uniaxial
 compressive strenth and durability of fine grained lithological flysch rock mass
 samples with different weathering grades are investigated. Mineralogical composition
 of the same fine grained lithological flysch components of different weathering grades
 is determined. Numerical simulation of the Krbavcici II landslide in north Istria and
 Valici landslide in the Rjecina Valley reactivation are conducted with residual strength
 parameters of different weathering grades of fine grained lithological flysch
 components. It is proved that weathering process has significant effect on the residual
 shear strength decrease of fine grained lithological flysch components and that
 weathering of those materials causes the dormant landslide reactivation in the flysch
 rock mass.

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The Buddhist sacred site of Taya Caves is a gem hidden underground in Yokohama, Japan. The caves were excavated and sculpted into bare rock by Shingon Buddhist monks from the Kamakura until the Edo period (thirteenth–nineteenth century), and dedicated to ascetic training, rituals, and pilgrimage. They are a maze of halls and galleries decorated with hundreds of rock-cut reliefs, picturing deities and masters of Buddhism, temples and shrines, real and fantastic animals, vegetal motifs, mandalas, zodiac signs, family crests, etc. The history and rock art of Taya Caves and the urge to preserve their cultural value led to this first-ever scientific investigation, dealing with the stone properties, deterioration, and environmental setting. Textural, mineralogical, geochemical, and petrophysical investigations were combined with a microclimate monitoring and chemical analyses of groundwater and rainwater. The caves are excavated into a clay-rich fossiliferous siltstone, extremely soft and porous and highly susceptible to water-driven weathering. Water represents a constant in Taya Caves, either flowing, dripping, and stagnant; or rising from the subsoil; or related to the extremely high relative humidity. Crusts and efflorescences represent important indicators of mineral dissolution and mobilization. The crusts are made of gypsum, crystallized from the dissolution of calcareous bioclasts and oxidation of pyrite, with minor calcite. The efflorescences are composed of chlorides, phosphates, sulfates, and carbonates, possibly deriving from agrochemicals and the surface vegetation cover. The salt weathering is strictly related to the microenvironmental variables and physico-chemical properties of the phases and waters involved. Rock-water interaction is particularly damaging even considering just the physical mechanisms. The stone is strongly sensitive to water absorption, hygroscopic adsorption, and slaking: the stresses generated by in-pore water and air movement and the swelling clay minerals may lead to rapid disintegration, especially during cyclic processes. This research is expected to raise concerns about the safeguard of Taya Caves and support future monitoring and conservation plans, and to foster a wider promotion and valorization of this heritage site.

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Taya Caves, a Buddhist marvel hidden in underground Japan: stone properties, deterioration, and environmental setting

This paper is intended as a contribution to the discussion of the reliability of assessing the state of weathering of rocks by visual inspection. The study was made by using both shales and greywackes belonging to the Baixo Alentejo Flysch Group, in the south of Portugal. Samples of these two rock materials, with different states of weathering, were collected during a fieldwork programme. This was followed by a laboratory testing programme, which included mineralogical analysis by X-ray diffraction and physical tests. The authors asked a group of qualified people to classify the rock samples under study by ordering them in a sequence according to their state of weathering. A comparison was then made between the qualitative classification of those assessors and that obtained by using the void ratio given by the quick absorption test, a quantitative index parameter which is usually seen as a good way to characterize the state of weathering of the rock material. The conclusions that are made in the paper about the results of the study show many divergent opinions among the assessors. It emphasizes the qualitative feature of visual evaluations of the state of weathering of rocks usually makes them quite subjective. This subjectivity becomes more important as the heterogeneity of the rock material increase, giving rise to quite different evaluations, even for a rock with the same state of weathering.

Overview of the evaluation of the state of rock weathering by visual inspection

After many years of war, great efforts have been made for the socio-economic development of Angola, particularly in the construction industry. Among the construction techniques, adobe is one of the most used in the province of Huambo, especially by low-income families, which constitute the majority. This technique was established as an intangible heritage in the culture of that population. Huambo province is located in the central region of Angola (Central Plateau). Adobe blocks are building elements with potential degradation by the action of water. Due to the subtropical climate, hot and humid, and geomorphology of the province, located at about 1000–2000 m of altitude and with an extensive river system, these buildings can be vulnerable and may present premature degradation, exacerbated by the lack of knowledge concerning the properties of the geomaterials used and techniques/solutions that allow their stabilization and conservation. This paper aims to present the main results of the study to investigate the influence on adobe performance in regard to the mineralogy and geochemistry of soils used in the production of adobes used in the construction of dwellings. The knowledge gained with this research can support the development of solutions for the common anomalies and problems in this construction, as well as to improve the strength and durability of the adobe units. For this purpose, soil samples were collected and mineralogical, geochemical, and physical tests were performed. Durability and erodibility tests were also performed on selected adobes, following the Geelong method. The results obtained with this research may contribute to the development of the knowledge concerning this sustainable building solution, which has a strong presence in the province of Huambo and neighbouring regions.

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Soil mineralogical composition effects on the durability of adobe blocks from the Huambo region, Angola

The main role of a communication framework in distributed autonomic management is to support the dissemination of management information between network nodes In distributed autonomic management, each network node intelligently self-adapts its behavior through collaboration and cooperation between the several nodes In this paper, we propose a set of communication mechanisms between self-managed network nodes, comprehending the several stages of communication, including a bootstrapping, discovery and election of entities, and ensure the base of communication of information between nodes to perform the collaborative decisions and to enforce these decisions We propose a bootstrapping and discovery mechanism that uses the concept of Hide & Seek, where the entities change their role dynamically according to events in the network, with dynamic probing intervals according to the number of Seekers entering or leaving the network We compare our discovery approach with current solutions, and we show that our mechanism is more efficient both in terms of control messages overhead and convergence time

Nodes Discovery in the In-Network Management Communication Framework

The use of dimension stones in architecture and civil engineering implies the knowledge of several mechanical, physical, and chemical properties. Even though it has been usual practice to measure physical and mechanical properties of dimension stones the same is not true for thermal properties such as thermal conductivity, thermal diffusivity, specific heat capacity, and heat production. These properties are particularly important when processes related with heating and cooling of buildings must be considered. Thermal conductivity, thermal diffusivity, and specific heat capacity are related with the way thermal energy is transmitted and accumulated in stones; heat production has to do with the amount of radioactive elements in the rocks and so with the environmental impact of radioactivity and public health problems. It is important to start to measure on a routine basis those four thermal properties in rocks and, in particular, in dimension rocks so that their application can be improved and optimized. With this is mind three sets of different rock types (granites, limestones, and marbles) were collected to measure the thermal conductivity, the thermal diffusivity, and the specific heat capacity with the objective of characterizing them in terms of those properties. Since the same set of rocks has also been studied for other physical properties, a correlation amongst all the measured properties is attempted. For each rock type several samples were used to measure the thermal conductivity, the thermal diffusivity, and the specific heat capacity, and average values were obtained and are presented. As an example, for granites the thermal conductivity varies between 2.87 and 3.75 W/mK; for limestones varies between 2.82 and 3.17 W/mK; and for marbles varies between 2.86 and 3.02 W/mK. It is hoped that measuring thermal properties on dimension stones will help to better adequate them to their use in civil engineering as well as to adequate their use in terms of a CE product.

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António Pinho

Papers

Overview of the evaluation of the state of rock weathering by visual inspection

Soil mineralogical composition effects on the durability of adobe blocks from the Huambo region, Angola

Nodes Discovery in the In-Network Management Communication Framework

On the Use of Thermal Properties for Characterizing Dimension Stones

The Baixo Alentejo (Portugal) Flysch Rocks: Physical Properties And Correlations