Clay Blocks Research Articles

Thermal properties of local Sardinian masonry and insulation materials: experimental assessment on full-scale models

The demand on reducing energy consumption of buildings, recently became tighter and tighter, as well as the need of shortening the building materials’ supply chain. It is generating a growing attention to natural and local construction materials and opening new and interesting research scenarios. The use of novel materials makes necessary reaching a deeper and appropriate understanding of their thermal performances by means of an accurate thermal characterization. The present research has been addressed at testing and verifying the thermal performance of Sardinian local masonry materials (hollow clay blocks and adobe bricks) and three different natural insulations: cork, sheep-wool and reeds. By the use of a dedicated hot box apparatus, working on full-scale wall models, the thermal resistance of eight different samples has been measured and then compared with the theoretical values calculated according to current standards. The results show that the measured values are by far higher than the calculated ones and that the use of local natural materials, if not accompanied by a rigorous standardization of production and installation procedures, can lead to overestimate their thermal performances.

Safety assessment of strengthened floor slab structures in a historic department store in Wroclaw

The subject of the paper are existing intermediate steel/ceramic ceiling structures on four levels from "-1" to "2" in a remodelled historic department store in Wroclaw, which are reinforced with an extra concrete flooring slab cast on a trapezoidal sheet in the post-war period. The purpose of this work is to check the possibility of leaving in these reinforced brick slabs with Förster‘s clay block, ceiling structures, as part of the reconstruction of this building after 2005. The scope of work includes the diagnostics of structural elements for these floor slabs with material tests.

Testing and analysis of masonry hollow clay block prisms filled with mortar

In some design situations, in construction systems with structural masonry, an increase in the capacity of the walls is required, which can be achieved with the filling of empty cells of masonry blocks with grout. The Brazilian technical standard for clay masonry blocks aiming at attaining greater agility and flexibility in the construction process allows the use of bedding mortar instead of grout to fill the cells of the blocks. In this context, the objective of this study was to evaluate the mechanical behaviour of prisms filled with bedding mortar. Six classes of mortar and one type of clay block with nominal resistance of 6 MPa were studied. The results of the compressive strength of the prisms indicate the viability of using bedding mortar with the same structural function as grout. This article presents also an analytical study to evaluate the mechanical behaviour of clay block prisms filled with mortar. Analyses were conducted using general-purpose, nonlinear finite element software that simulates structural behaviour under different loading scenarios. A three-dimensional model of the prisms was developed using eight-node brick elements for both block and mortar with nonlinear properties assigned to each material.

Pipeline–soil–water interaction modelling for submarine landslide impact on suspended offshore pipelines

The submarine landslide is one of the major geohazards in deep-water oil and gas developments. The impacts of glide blocks or out-runner blocks, which carry the geotechnical properties of the parent soil mass before the landslide, on pipelines normal to the direction of slide, are investigated in this study. A computationally efficient numerical modelling technique is developed using a computational fluid dynamics approach, incorporating a strain-rate and strain-softening dependent model for the undrained shear strength of clay sediment, to simulate the lateral penetration of a pipe in a clay block. The role of water in the cavity and channel formed behind the pipe during the lateral penetration on drag force is successfully simulated. Numerical simulations for varying depths of the pipe explain the change in soil failure mechanisms in which the channel behind the pipe and berm play a significant role, especially at shallow depths. As the cavity behind the pipe may not be completely filled with soil, the limitations of smooth/rough and bonded/unbonded interface conditions, as used typically in pipe–soil interaction analysis, are discussed. Based on a comprehensive parametric study, calibrated against centrifuge test results, a set of empirical equations is proposed to calculate drag force for practical applications. The effects of inertia on drag force are examined.

Quaternary Glaciotectonics of the Ural-Siberian North

Abstract This is a review of previous works on glaciotectonics and recent epeirogenesis of the northern West Siberian sedimentary basin and adjacent parts of the Urals and the Siberian Craton. It is supported by the addition of detailed structural profiles of the disharmonic dislocations around Malyi Atlym settlement on the Lower Ob’ never published before. The collected data highlight sources and results of neotectonic phenomena in the north of West Siberia and their impact on distribution of hydrocarbon deposits. The rugged topography of the northern Urals and Mid-Siberian Plateau, discordant with the regional tectonic structure, is generated by compensation uplifts along the margins of thick ice sheets in the West Siberian North. Ice load vacillations were an important factor of geographical separation of hydrocarbons liquid and gaseous phases. This is evident from the west–east zonation of petroleum deposits, discordant with the south–north strike of ancient structures but concordant with thickness zonation of ice sheets. The structure of the alpine-type dislocations penetrating up to 400 m into the sedimentary basin on the Lower Ob’ reveals that the variations of their tectonic style do not fit the mechanical properties of thawed Paleogene rocks. However, they are more understandable assuming their origin from deviatoric stress in pressurized perennially frozen Paleogene rocks. Such conditions are feasible at the base of a growing thick ice sheet. Ice sheets did significant work of glaciotectonic erosion of soft Paleogene rocks of the perennially frozen substrate soldered with glacial ice. This type of erosion is evident in the Ob’ catchment area where whole blocks of intact sand and clay were transported by glaciers over hundreds of kilometers. Glaciotectonic erosion of glacier substrate is sufficient for explaining the well-known stratigraphic hiatus between Quaternary and Upper Cretaceous formations of the Siberian Arctic instead of the popular but illogical tectonic inversion of the sedimentary basin.

Structural condition assessment of a reinforced concrete driveway

The reinforced concrete structure of a driveway built in the eighties of the 20th century is under consideration. It is a single-storey structure with a length of approx. 66.00 m, made in the form of a reinforced concrete skeletal structure, consisting of 7 frames with cantilevers, spaced at 9.00 m: 3 frames in the horizontal part of the driveway are three-span ones, and 4 in the sloping part are single-span frames. The driveway frame main beams have a rectangular cross-section and are based on pillars that have been placed on the spread footing these elements form a monolithic structure. Prefabricated reinforced concrete hollow floor plates were laid on them in the central part of the driveway, and in the outer parts the driveway floor was made of hollow clay slab blocks (Ackerman type). At the time of investigation, the upper layers of the driveway consisted of a surface waterproofing layer, a concrete slab of approx. 10 cm thickness made on a 1 cm sand layer. However, no internal waterproofing layer was found as was in the original design. The paper describes the process of determining the current technical condition of the reinforced concrete driveway structure, paying attention to the design and construction of the object, its operation (including the issues of durability of concrete under the conditions of possible impacts of the marine environment). Static and strength calculations were also performed (supported by concrete and reinforcement tests) and the conditions for further operation of the driveway were analyzed as well as concepts of rehabilitation.

Testing and analysis of masonry hollow clay block prisms filled with mortar

Testing and analysis of masonry hollow clay block prisms filled with mortar

Behaviour of block masonry under in-plane loading

In the design of buildings, the strength of modern masonry under compression and shear is crucial for safety in seismic areas. Modern unreinforced masonry (MURM) built with perforated clay blocks may also be considered adequate in terms of withstanding seismic action. However, the performance of MURM is influenced by many parameters such as solid or perforated units and strength, deformability and thickness of mortar joints. In this paper, the strength of blockwork walls built with two types of perforated clay blocks, lateral surfaces toothed and smooth, and different mortar joints has been experimentally tested under loading in-plane. An extensive investigation based on compression tests and diagonal compression tests of blockwork walls has been carried out. The experimental results are presented and discussed. The response of blockwork walls under diagonal tests have been analysed comparing experimental data with that obtained with finite element method (FEM).

New VDPM leaflet „Mauerwerk mit Dünnbettmörtel”

AbstractThe German associations Verband für Dämmsysteme, Putz und Mörtel (VDPM), Arbeitsgemeinschaft Mauerziegel and Bundesverband Leichtbeton have published a new leaflet „Mauerwerk mit Dünnbettmörtel” [Masonry with thin‐layer mortar] [1]. This compact guide offers 8 pages of helpful tips and important information concerning the application of thin‐layer mortar with high‐precision masonry units or high‐precision blocks of lightweight concrete or clay. The leaflet contains terms and definitions, requirements for the thin‐layer mortar, the units and the masonry and the different forms of delivery of thin‐layer mortar. The main parts of the leaflet are the explanations of laying (levelling layer, blocklaying with thin‐layer mortar, working time, methods of application, head joints…). Notes regarding occupational health and safety protection complete the leaflet. The following article describes the essential content of the leaflet with further information.

Assess of hollow clay block masonry wallets under high temperature

The main goal of this study was the behavioral assessment at high temperatures of masonry wallets built with different geometries of hollow clay blocks. In total, four type of structural wallets were erected; blocks of 15 x 20 x 30 cm nominal dimensions (width x height x length) and compressive strength of 7, 10, 15 and 18 MPa were built, employing laying mortar with compression resistance of 6, 8 ,10 and 12 MPa, respectively. The wallets were submitted to a constant temperature of 900°C, up to 4 hours, while heated gases permeability, thermal insulation and mechanical resistance were assessed. As conclusions, it was possible to observe that some wallets demonstrated the best thermal insulation performance, above 4 hours. Regarding the mechanical resistance and the gas permeability, none of the wallets analyzed reached the flexural criteria established for the work. Keywords: high temperature performance; clay blocks; masonry wallet.

Morphological study of the development of abrasion ring around the edges of the input gunshot wounds subject to the provisions of theoretical mechanics

Background. According to most authors, the mud pies abrasion with gunshot damage is a destroyed epidermis at the edges of the skin defect, which forms the ball onto the path of penetration in the thickness of the layers of the skin and body tissue. Therefore, no complete explanation of the stages and mechanism of formation of the abrasion ring around the edges of the skin defect at the entrance gunshot gunshot wound in contact with the projectile at right angles. Objective. The objects of the study were entrance gunshot wounds, which were formed as a result of shots with bullets of 9 mm caliber, obtained from archival material of the Bureau of forensic medical examination and experimentally obtained gunshot injuries of blocks of sculptural plasticine 9 mm with elastic spherical shells. Methods. Research methods were applied: morphological, medical-criminalistic, visual, analytical and comparative. Data of theoretical mechanics were used to estimate the mechanics of skin destruction. Results. In the study of entrance gunshot wounds, which were formed when a bullet hit the body at a right angle, around its defect was found abrasions in the form of a zone irregular rounded shape, with the bottom of a brownish-brown color. That is, the area of the skin that corresponded to the localization of the abrasion was represented by the naked surface of the dermis, with no reduction in the thickness of the dermis itself. In experimental shots in blocks of sculpted clay elastic shells of spherical shape with a distance of 2 m were formed damage incorrectly rounded in shape, had deepened the crater bottom, with depths ranging from 22.0 mm to end-to-end damage to the block of clay. In not injuries through the clay, formed of the cavity criterion forms on the inner surface was discovered prints bullet round shape. The edges of the walls of the cavity had a thinned appearance, were turned outwards, radially oriented breaks of plasticine were determined at their edges, due to which the damage as a whole took the form of a crown. In the future, the stages of formation of damage to the block of plasticine, which was formed from the action of an elastic spherical projectile, were considered from the standpoint of theoretical mechanics. Conclusion. The formation of the abrasion perimeter is not associated with mechanical contact interaction (friction) of the lateral surface of the bullet and the skin, and its formation is a consequence of the detachment of the epidermis along the edge of the skin defect of the entrance gunshot wounds, due to the complex shock-wave process, which in the initial stages includes the formation of a temporary cavity in the form of a funnel and the further spread of surface Rayleigh waves, accompanied by a detachment of the epidermis.

High‐rise concrete and clay block masonry building in Brazil

AbstractBrazilian structural concrete and clay block masonry construction shares many common features with construction all over the world: blocks of a similar shape are bedded in mortar, vertical and horizontal reinforcement is placed in grouted cells, engineering analysis and design follows universal principles and local design codes mimic those adopted elsewhere. However, loadbearing masonry construction in Brazil has become one of the most preferred high‐rise building systems due to its cost‐effectiveness and ease of construction compared to normal reinforced concrete solutions. This paper provides an overview of loadbearing masonry building in Brazil, including case studies on notable high‐rise masonry structures, with an overview of how Brazilian materials, codes and practices differ from the rest of the world. Finally, the paper explains how the use of high‐strength units assists the growing demand for taller and taller buildings and provides insight into why owners and general contractors often prefer to use structural masonry.

Archeointensity estimates of a tenth-century kiln: first application of the Tsunakawa\u2013Shaw paleointensity method to archeological relics

Paleomagnetic information reconstructed from archeological materials can be utilized to estimate the archeological age of excavated relics, in addition to revealing the geomagnetic secular variation and core dynamics. The direction and intensity of the Earth’s magnetic field (archeodirection and archeointensity) can be ascertained using different methods, many of which have been proposed over the past decade. Among the new experimental techniques for archeointensity estimates is the Tsunakawa–Shaw method. This study demonstrates the validity of the Tsunakawa–Shaw method to reconstruct archeointensity from samples of baked clay from archeological relics. The validity of the approach was tested by comparison with the IZZI-Thellier method. The intensity values obtained coincided at the standard deviation (1σ) level. A total of 8 specimens for the Tsunakawa–Shaw method and 16 specimens for the IZZI-Thellier method, from 8 baked clay blocks, collected from the surface of the kiln were used in these experiments. Among them, 8 specimens (for the Tsunakawa–Shaw method) and 3 specimens (for the IZZI-Thellier method) passed a set of strict selection criteria used in the final evaluation of validity. Additionally, we performed rock magnetic experiments, mineral analysis, and paleodirection measurement to evaluate the suitability of the baked clay samples for paleointensity experiments and hence confirmed that the sample properties were ideal for performing paleointensity experiments. It is notable that the newly estimated archaomagnetic intensity values are lower than those in previous studies that used other paleointensity methods for the tenth century in Japan.

Micro-CT-based identification of double porosity in fired clay ceramics

Optimizing thermal and mechanical properties of clay block masonry requires detailed knowledge on the microstructure of fired clays. We here identify the macro- and microporosity stemming from the use of three different pore-forming agents (expanded polystyrene, sawdust, and paper sludge) in different concentrations. Micro-CT measurements provided access to volume, shape, and orientation of macropores, and in combination with X-ray attenuation averaging and statistical analysis, also to voxel-specific microporosities. Finally, the sum of micro- and macroporosity was compared to corresponding data gained from two statistically and physically independent methods (namely from chemical analysis in combination with weighing, and from mercury intrusion porosimetry). Satisfactory agreement of all these independently gained experimental data renders our new concept for identifying the pore spaces of fired clay as a very promising tool supporting the further optimization of clay blocks.

Experimental study on the contribution of masonry infill in the behavior of RC frame under seismic loading

An experimental investigation is conducted to study the behaviour of masonry-infilled reinforced concrete (RC) frames with various lateral strengths. In addition, we study the behaviour of masonry units when the masonry walls are erected after the RC frame is cast. This construction technique is widespread in Kosovo. Eight 2/3 scale, single-bay, single-story RC frame specimens were tested. Six were infilled with hollow clay block masonry units and combined with RC frames with various strengths, one was infilled with solid clay bricks, and one was without infill (bare frame). The test results showed that the type of masonry unit influenced the failure mechanism of the masonry-infilled RC frames. Further, the results show that the main failure modes of the masonry-infilled RC frames, infilled with hollow clay blocks was the shear failure of the masonry infill, beam column joint failure, and the formation of flexural hinges in the part of RC frame. Whereas, the main failure mode of the masonry-infilled RC frames infilled with solid clay bricks was shear failure of the column and the masonry infill. Based on the experimental results, minimum lateral design strength criteria for RC frames infilled with hollow clay blocks is proposed in order to ensure the controlled ultimate failure mechanism.

Evaluation of the Thermal Performance of the External Walls of Buildings with Hollow Clay Blocks in Temperate and Humid Climate

Evaluation of the Thermal Performance of the External Walls of Buildings with Hollow Clay Blocks in Temperate and Humid Climate

Transparent superhydrophobic coating application to the interlocking clay block for the microbial growth mitigation

Interlocking clay block is of widespread use in many countries due to its less labor-intensive design. The block comprises of considerable amount of pore structures; therefore water can easily penetrate into it causing deterioration by natural weathering as well as the growth of microbes on its surface. In this present work, a transparent, superhydrophobic coating was applied onto the block’s surface to prevent water absorption. The coating which is a poly(methyl hydrogensiloxane) base containing fumed SiO2 nanoparticle was designed to possess surface topographic feature similar to that of the lotus leaf. After coating the block with the superhydrophobic compound, its water absorption decreased from 11.5 to 4.8% and porosity substantially decreased from 22.5 to 9.2%, while bulk and apparent densities did not change. Accelerated weathering test revealed that the coating had good stability. The coated samples exhibited growth inhibition of algae.

Influence of load history on the force-displacement response of in-plane loaded unreinforced masonry walls

Empirical drift capacity models for in-plane loaded unreinforced masonry (URM) walls are derived from results of quasi-static cyclic shear-compression tests. The experimentally determined drift capacities are, however, dependent on the applied demand, i.e., on the loading protocol that is used in the test. These loading protocols differ between test campaigns. The loading protocols applied in tests are also different from the displacement histories to which URM walls are subjected in real earthquakes. In the absence of experimental studies on the effect of loading histories on the wall response, this article presents numerical simulations of modern unreinforced clay block masonry walls that are subjected to different loading protocols. The study shows that the force capacity is not very sensitive to the loading protocol. The drift capacity of walls failing in shear is, however, rather sensitive to the loading history while the drift capacity of walls failing in flexure is not. The largest difference in drift capacity of up to 100% is observed between monotonic and cyclic loading for shear controlled walls under double-fixed boundary conditions and low axial load ratios.

Mechanical Properties of an Artificially Cemented Clayey Material

Abstract As part of an ongoing investigation on the behavior of the brittle cemented sensitive clays of eastern Canada, static penetrometer and vane shear tests had to be performed in the laboratory. Because it was impossible to sample undisturbed blocks of clay of the necessary size, an artificial model material was developed to simulate the response of sensitive clays, namely, brittle response at low stresses and loss of strength upon remolding. The model material consists of a mixture of kaolinite, bentonite, portland cement, and water. Two mixes were produced: a softer 6.25 % cement content and a stiffer 14 % cement content. It is shown that the materials are characterized by stress-strain behaviors similar to those of soft to medium sensitive clays. It is also shown that the artificially bonded materials simulate quite well other mechanical properties of sensitive clays of eastern Canada, such as high water contents and void ratios; brittle failure at low confining pressures; high G u/Su ratios, where Gu=shear modulus and Su=undrained shear strength; and severe collapse of the structure for vertical effective stresses in excess of the materials’ preconsolidation pressures. Specimens cured 21 days were used successfully for laboratory indentation, vane shear, and unconfined and triaxial compression tests, as well as oedometer tests. In addition, the variation of the undrained shear strength of the 14 % cement content specimens was followed for a maximum curing period of one year, by means of vane shear tests and unconfined compression tests.

Study of the block/grout interface in concrete and clay block masonry structures

ABSTRACT This work aims to study the behavior of the block/grout interface for concrete and clay block masonry. This was achieved by push-out and pull-out experimental tests including reinforcement bar in the latter one. The experimental result showed that there is a good bond between the concrete blocks internal faces and the grout, enough to prevent infill-slippage, and that the whole tensile strength of the usual reinforcement bars is achieved provided they are properly anchored. Nevertheless, for clay blocks there is a low bond between the clay blocks internal faces and the grout, allowing the infill-slippage before the reinforcement bars reach their yield stress.