Failure Mechanisms of Structural Bamboo Using Microstructural Analyses

Bamboo is deemed an emerging constructional material with promising application projections due to the reliable natural properties and advantageous structural characteristics. However, there is a lack of systematic studies on the mechanical characteristics of the bamboo species from a microstructural scale. Hence, this paper investigated the primary mechanical properties of the bamboo specimens (Dendrocalamus asper) with further microstructural analysis on the bamboo failure. The direct tensile strength of bamboo specimens was about 226.45 MPa, while the final splitting tensile modulus was found to be 2.88 MPa. Microstructural characterisation of the failed tensile specimens indicates that fibre debonding is the main failure mechanism under tensile conditions. On the other hand, splitting and end bearing failure were found on compression test specimens. In addition, nanoindentation tests were carried out on different cell structures to articulate the hardness and Young’s modulus. The elastic modulus of the fibre cell walls is three times that of the parenchyma cell walls, yet the hardness values are comparable. This confirms that the specimen failure of previous macromechanical testing is due to crack propagation along the parenchyma cells, instead of the cell walls. Based on the experimental studies discussed in this paper, the conclusion can convey a positive message regarding the ability of bamboo as a primary sustainable substitute for conventional construction materials.

Stabilization of the Dispersed System of Halloysite Nanotubes for Silicate Constructional Material

The stabilization of the dispersed system of halloysite nanotubes (HN) obtained by ultrasonic treatment (UST) in the aqueous medium of the stabilizers of sodium polynaphthalene methylene sulfonate stabilizers (S-3) and a synthetic compound based on polycarboxylate ether (MG) is considered. The morphology of halloysite is studied. Various mechanisms of aggregate stability connected with the spatial obstacles to aggregation due to the action of electrostatic, adsorption-solvate, and structural-mechanical stabilization factors are established. Three variants of introducing S-3 and MG stabilizers into the dispersed system of halloysite nanotubes are considered. It has been found that the most preferred method is the one with the stabilizer added in two steps. In this variant halloysite nanotubes are of minimum size and with maximum specific surface area. The maximum ζ-potential values of 52.9 mV and 43.8 mV are obtained for the dispersed system stabilized with S-3.

Influence of Coconut Fiber and Shell on Concrete

Concrete is a Composite material which is composed of Cement, fine aggregate, coarse aggregate binded together with a definite proportion of water. Concrete is widely used in every single construction work around the world. Due to large scale construction activities using conventional coarse aggregate such as granite as a constructional material extreme reduction in the natural stone deposit has been encountered and is affecting the environment, hence causing ecology imbalance. In current situation of construction, price factor and the wide range of extraction and processing of materialsis matter of great concern for the people as well as environment. Therefore, introduction of alternate waste material in place of natural aggregate in concrete production not only protects environment but also make concrete a suitable, economical and environment friendly construction material. Different material like Coconut Shell and Fiber can also be used alternatively. In this project Coconut Shell and fiber are used as partial replacement for coarse aggregate as well as fine aggregate, respectively. To study characteristic properties of concrete 10% and 20% for coarse aggregate and 1%, and 2% for fine aggregate are replaced by its weight with coconut shell and fiber.

Quarry waste for the production of sustainable and innovative constructional materials

<p>In Canton Ticino, Switzerland, the exploitation of natural stone, mostly gneisses, is an important activity of valley’s economies but in the last decades the local quarries are facing severe economic difficulties. The current rules on the disposal of quarry wastes and the territorial planning that regulates the structure of quarries and inert landfills, is putting pressure on the economy and profitability of quarries, as the wastes represent up to 40% of the extracted material and disposal costs are huge given the important volumes. Therefore, the sustainable development of the quarry sector needs new and effective strategies, in particular in the management of quarry waste to reduce its disposal costs and possibly to re-enhance this material. Here, we propose an example of an environmentally friendly circular economy based on crushed aggregates of quarry waste for the building of high added value constructional elements.</p><p>In this applied study, we characterized the waste materials (different types of gneisses) and evaluated the crushed aggregates for their use in traditional concretes and in innovative geopolymers to use in 3D printing systems. The results showed that the concretes produced with 100% quarry waste (crushed aggregate) have good mechanical properties but moderate durability. However, it has been observed that even by simply mixing these crushed aggregates with a part of fluvial sand (allochthonous) it is possible to improve the performance of the concrete in all respects. Hence, this environmentally friendly material is suitable for many applications in the concrete industry. The aggregates were also tested for powder bed 3D printing that uses geopolymers as a binder. The first tests with this printed geopolymer suggest that this innovative constructional material may be used in non-structural architectural elements, however, further investigation is needed.</p><p>In this project it has been mapped, within the construction industry, how the economic supply chain could be configured for the reuse of this material. In particular, the usability in the production of concretes, geopolymers and mortars was highlighted, both in traditional applications and with innovative applications such as 3D printing. The analysis was carried out with particular attention to the concepts of circular economy and sustainability, identifying the main actors and their potential interests within the supply chain.</p>

ASSESSMENT OF WOODEN BUILDINGS IN TERMS OF CONSTRUCTION WASTE GENERATION

Construction industry creates an environment for people's lives. On the other hand, construction activities have a negative impact on various aspects of the environment. It consumes natural raw materials, significantly contributes to carbon footprint, waste, etc. Appropriate choice of constructional, material, technical, technological and environmental parameters of buildings can partially reduce this negative impacts. By designing, implementing and using wood-based constructions it is possible to reduce the negative impact in the area of construction waste generation. Currently, the construction market offers a large number of construction systems of wooden buildings, which have both strengths and weaknesses. In this paper are identified construction systems of wooden buildings offered on the Slovak construction market. The aim of the paper is a detailed identification of construction waste generation during the realization of particular wooden structures and monitoring of waste generation in production factory (off site) and on construction site (on site) during the construction of wooden buildings. Based on the obtained information, the individual construction systems of wood-based constructions are compared in terms of construction waste generation

Influence of Constructional-Material Parameters on the Fire Properties of Electric Cables

The significant number of cables of different materials and construction used extensively in building objects increases their fire load and, therefore, strongly influences safety in the case of fire. The purpose of the study was to identify relevant factors related to the construction of electrical cables, and perform a qualitative and quantitative assessment of their influence on specific fire properties, such as heat release and smoke production. Fifteen cables of different construction and materials were studied using the EN 50399 standard test. The analysis was focused on cable constructional-material parameters related to the chemical composition of non-metallic elements and the number and shape of conductors in the cable, as well as the concentric barrier as armor or the copper concentric conductor. The conclusions drawn from the experiments were: (1) Construction, the number of conductors, and the presence of armor or concentric metallic conductors improve the fire properties by forming a barrier against flame penetration through the cable; (2) the use of copper conductors resulted in a decrease of fire parameters compared to cables with aluminum conductors (peakHRRav parameter even four times lower for copper cable); (3) construction material based on non-plasticized poly(vinyl chloride) (PVC) significantly reduced the fire properties of cables more than halogen-free materials (LS0H) (peakHRRav parameter more than 17 times higher for the fully halogenated cable), which is due to the decomposition process of the material; and (4) no clear relationship between the fire parameters and the cable parameter, χ, was found.

Improve Light Weight Concrete Characteristics by Adding Paraffin Wax as Moisture Proof

The development of structural materials used in the building process is certainly subject to the local and temporal potentials and to how the extent to which the human thought made in the scientific and industrial field. Where the constructional methods that depend on pottery, bricks were and still essentially adopted. The advanced human thought attempted making more efforts to find constructional materials of certain specifications. Porous concrete Light Weight Concrete (LWC) is considered a good alternative constructional material in addition to its light weight and good thermal isolation. It is currently used in Iraq as concrete block to form breakers only. This research includes essential information about LWC and developing it through the adding paraffin wax to generate a material of high moisture isolation, low absorption rate and high bearing for compressive forces especially after overflowing it with wax.

Corrosion Effect of 65% Nitrate Acid on X4CrNi1812 at 333 K

Austenitic stainless steels are often used for a materials in the construction of machines and equipment for agricultural and for industrial construction. One of the most important factors constructional material is corrosion resistance. Equipment with austenitic stainless steel can be easy join by quickly welding at a not to high construction price, but one with the serious problem in aggressive environment is their corrosion resistance. A few corrosion processes in crevices and awkward corners can be avoided at the design stage (low roughness parameters, round-section and other). But still the construction material is exposed to corrosion. These steels often come into contact with an aggressive environment based on nitric acid. The main aim of this research is to investigate corrosion resistance in different time (48, 96, 144, 192, 240, 288, 336 hours). For this used weight loss of test samples and its profile roughness. The research was conducted on austenitic stainless steel in grade in Nitrate acid at 333 K. Corrosion tests confirmed that the research this steel in 65% nitrate acid as a corrosive environments is characterized through proportionate to time corrosion process whose measure may be surface roughness. In industrial practice roughness parameters for all the research times can be used for determine the stage and size of steel corrosion.

Textiles and Fabrics for Enhanced Structural Glass Facades: Potentials and Challenges

The use of textiles in architecture can cover a wide set of solutions and functions, spanning from buildings, towards geotechnical, aeronautic or automotive fields, etc. Special applications involve textiles in the health care or dressing scenarios. A multitude of other functions can then be found relatively for the use of textiles in building engineering and facades. As far as traditional facades or roofs composed of glass are taken into account, textiles offer a relevant number of potential uses that are specifically focused on energy, acoustic, insulation and even structural goals, in addition to pure architectural objectives. It is known that glass is relatively versatile, but has intrinsic needs and thermo-physical and mechanical features that require dedicated design methods, towards safe design purposes. Glass itself, in the form of constructional material, cannot be directly compared to other consolidated solutions for buildings. The same concept applies to textiles, and to their use to enhance other building components. Besides the key advantages deriving from the use of textiles in glass facades and envelopes—in the form of light, thermal or acoustic insulation, or energy efficiency—special care must be spent for specific structural requirements and performances. In some cases, textiles can in fact offer enhanced resistance to ordinary glass structures. In other conditions, textiles in combination with glass can ensure also enhanced acoustic and thermal performances. A multidisciplinary design approach able to properly fit several objectives should be considered. This paper aims at exploring the actual knowledge on glass textiles, with a focus on available tools and research trends, with careful consideration for structural glass facade applications.

ІМПЛЕМЕНТАЦІЯ МЕТОДІВ ПОРОШКОВОЇ МЕТАЛУРГІЇ ДО ПРОЦЕСІВ СЕРІЙНОГО ВИРОБНИЦТВА ЖАРОМІЦНИХ ТИТАНОВИХ ЛОПАТОК ГТД

The questions associated with improvement of efficiency of aircrafts and engines manufacture are considered. In the given context when new aircraft engines are developed, the growth of a share of easy materials such as heat resistant titanium alloys is observed. This is explained by successful complex of physical-mechanical properties, where the mechanical properties to weight ratio is the principal ones. It is noticed, that serial production’s technology of such alloys has high power inputs (double vacuum arc re-melting) and requires a strict composition control of alloying elements, impurities and uniformity of their distribution in the ingot structure. Significant difficulties are attributed to multi-stage deformation processing of large-tonnage ingots from multi-doped titanium alloys, such as ВТ8 alloy. This processing is needed in the operation chain for obtaining the small-sized rod-shaped half-products for production of GTE series blades billets. For elimination the shortcomings of serial technology, such as a large number of operations, the application of the powder metallurgy methods (PM) with technical-economical advantages is offered. The analysis of research results of composition, structure and physical-mechanical properties of an experimental alloy as ВТ8 shows that it is possible to gain the half-finished products of multi-doped titanium alloys with controlled chemical composition after sintering by methods of powder metallurgy. Mechanical properties of such alloy are approximated to serial alloy ВТ8 and thus it is permitted to use the experimental alloy as ВТ8 as constructional material for components which are not subjected to impact and cyclic loadings at the work temperatures like for serial alloy prototype. Received alloy is differed by presence of residual porosity and structure typical for two-phase sintered titanium alloys. For reducing of experimental alloy as-ВТ8 to requirements of the normative documentation (ND) for serial alloy ВТ8 and further implementation, investigation of influence of deformation processing on its structure and mechanical properties was carried out.