Papers by Keyword: Blocks

Abstract: Sustainable building materials have been developed to reduce the polluting emissions and the exploitation of natural resources of the building sector. Among these materials, an outstanding category is that of nature-based solutions which are produced recovering waste or by-products of agricultural cultivations and using them as vegetal aggregates to replace the traditional ones. This paper focusses on hempcrete which is produced mixing the by-product of industrial hemp cultivation (i.e., shives) and lime to obtain a sustainable, breathable and insulating material. The strength of hempcrete develops through carbonation of the binder that, leading to the formation of calcium or magnesium carbonates and mineralization of shives, determines the microstructure and hence most of the characteristic properties of the material. The aim of this research is to investigate how carbonation influences the microstructure of hempcrete when different recipes are used for blocks production. This study consists in the characterization of the material through techniques such as XRD (X-ray Diffractometry), SEM (Scanning Electron Microscopy) and TG-DTG (thermogravimetric analyses). Moreover, the evolution of carbonation is studied analyzing samples at different maturation times. The investigation of the carbonation reaction degree is also crucial to evaluate the environmental performances of the material because it allows the quantification of the carbon dioxide uptake. Also, periodic characterization allows to assess the durability of hempcrete and to select the best formulation according to the designed application and the corresponding service conditions.

Abstract: Clay fired bricks are commonly encountered in the construction sector as infill between structural frames. This system has been favoured by builders due to familiarity, ease of manufacture, and they also do not require skilled labourers to erect. Produced from moulded clay and hardened by firing in a kiln, brick production is both energy intensive and high in CO₂ emission. Fired bricks are typically held together by cement mortar at the bed and perpend joints which provide very minimal resistance against shearing or flexure. This meant brick walls often require additional wind posts or stiffeners to provide stability. Compressed earth masonry offers an alternative to the conventional brick walling system in that, besides having the advantages of conventional bricks, they also confer higher compressive strengths due to the high-pressure compaction manufacturing process. The high strength allows the system to be adapted into load-bearing masonry system for use in low-rise buildings as an alternative to the more expensive reinforced concrete or steel framing system. The high-pressure compaction process along with high quality moulds also give fair-faced finished to the bricks, allowing them to be used as facing bricks and eliminating the need for surface finishing such as plastering. Additionally, compressed bricks featuring interlocking key holes along the bed joints allows for simplified and faster wall erection process. This review paper aims to document the research progress thus far in adopting the compressed interlocking bricks as a sustainable alternative to current building materials.

Abstract: The authors offered a method for manufacturing concrete mixture with preliminary mixing of bonding material, modifying agent and basalt fibers in AC electromagnetic field using steel fiber as ferromagnetic component. The obtained fiber concrete was used for fencing with improved thermal characteristics.

Abstract: In this paper, a variety of blocks were grouped into the autoclaved blocks and fired blocks as far as the productive technology is concerned. In order to compare the life cycle impacts of the two kinds of the blocks, a life cycle assessment of two products on the functional unit 1m³ was carried out through the exploitation of mineral stage, transportation stage and the production of the blocks stage on the considering of the resource and energy consumption and the pollutant discharges. The results demonstrated that the fired blocks appeared to have less impact than autoclaved concrete blocks on human health, marine ecotoxicity toxicity and terrestrial ecotoxicity toxicity nearly 30%. The raw coal led to the serious impacts on the fossil depletion through the cement production stage of the autoclaved concrete blocks accounting for 45.86% and the gangue exploitation stage of the fired blocks accounting for 42.5%. Assessment of the data quality that the data was of pretty high or within the permission. The sensitivity analysis and contribution analysis assessment showed that the conclusion were robust.

Abstract: The objective of the study is to investigate the potential of using Porous Concrete Paving Blocks (PCPB) as a part of paving surface. Laboratory tests were conducted to compare and examine the effect of particle sizes of coarse aggregate. Two coarse aggregate sizes were selected; passing 8 mm retains 5 mm and passing 10 mm retains 8 mm. The fine aggregate was eliminated from mixes. The water to cement ratio used was 0.35. Compressive strength and skid resistance tests were performed to evaluate the properties of PCPB. The test results indicated that there was a reduction in the strength when coarse aggregate at different size was used. Scanning electron microscopy showed that voids, poor bonding and lack of adhesion at the boundaries of the aggregate with cement paste contributing to the low PCPB strength. However, both PCPB specimens provide 30 % to 40 % increase in skid resistance compared to Concrete Paving Blocks (CPB).

Abstract: Bulk high temperature superconductors are usually used as arrays due to the limited size and performance of a single bulk. To find a reasonable array pattern for the superconducting maglev vehicle, we studied the levitation force of four multi-seeded rectangular YBaCuO blocks with three possible arrays above a permanent magnet guideway (PMG). Experimental results show that the levitation force can be improved through an optimal array pattern of the bulk superconductor. The method is to avoid the joint gaps of bulk arrays in a strong magnetic field area of the PMG thus improving the utilization rate of the applied magnetic field. The optimal array pattern will be helpful to improve the levitation performance and reduce the quantity of onboard superconductors.

Abstract: As a powerful simulation tool, simulink being increasingly used in modern design, yet one distinctive feature of modern design is that they need to be updated frequently [1,2]. Take the control strategy blocks for example, the paper present a method to update the blocks including mdl files and m files automatically by writing script using Matlab. After the update work it will record the work log automatically, during the update process it also checks the potential errors made by human to make sure the update work is correct. It is a convenient and reliable method to update the simulink blocks.

Abstract: Properties of Porous Concrete Paving Blocks (PCPB) were investigated in this study. Two groups of coarse aggregate sizes were performed; passing 8 mm retains 5 mm and passing 10 mm retains 8 mm. For mixture design, 100 % of coarse aggregate were used. However, fine aggregate was eliminated in this investigation. The density, water absorption, flakiness index and elongation index test were performed to determine the properties of the coarse aggregate used in this study. Compression test and skid resistance test were used to evaluate the performance of PCPB. The results show that PCPB containing coarse aggregate size 5 8 mm give high compressive strength compared to others PCPB specimen. In addition, both PCPB specimens give an in increasing in skid resistance approximately 30 % compared to Concrete Paving Blocks (CPB).

Abstract: Constructional engineering was always faced with the threaten of earthquake and the problem of large energy consumption. As a new type of green building material, straw concrete has better ductility than normal concrete. In the straw concrete multi-ribbed slab structure, as the filling material of wall board, straw concrete improved the energy dissipation and deformability of wall board. When the load was applied, the filling blocks, grid frame and outer frame in straw concrete wall board work cooperatively, have good mechanical properties. The straw concrete wall board has advantages that light, high strength, energy conservation and seismic resistance. Considering the effect of different components in straw concrete wall board, this paper proposes the formula of vertical bearing capacity of straw concrete wall board to provide the basis for engineering application. The construction of straw concrete multi-ribbed slab structure include three processes that steel bar bind, blocks prefabrication and integral pouring, which fits for field fabrication in the building construction site.

Abstract: In order to confirm the calculation model of multi-ribbed slab structure and transmission of earthquake action, this paper improved existing multi-ribbed slab structure. The calculation model of improved multi-ribbed slab structure confirmed the stress relationship among three seismic fortification lines, and the transmission of earthquake action became clear, the same calculation model could be applied in structural analysis. For studying the features of characteristic parameters of restoring force changing in the first seismic fortification line, blocks, and correcting the parameters, the experimental study was carried out. The experiment shows that when a unidirectional horizontal load was applied, that blocks in grid frame could be regarded as a slanted strut that with specific section and elasticity, the ideal slanted struts nominal elastic modulus is roughly in 20~60 N/mm2.