Influence of partial replacement of sand with copper slag on the thermal properties of hardened concrete

The article presents the results of testing the effect of partial replacement of sand with fine copper slag waste on the thermal properties of hardened concrete. The impact of the replacement on mechanical properties (ie. compressive and tensile strength of concrete) was also investigated. The thermal properties of the concrete were determined using the non-stationary method with the ISOMET 2114 device. Tests were performed on concrete containing three different types of cement (CEM I, CEM II and CEM III). A total cement content of 360 kg/m3 was assumed in the compositions of all concrete mixes with a water-cement ratio of 0.45. Replacing 66% of the sand volume with copper slag waste caused a decrease in thermal conductivity by about 4–8% in relation to the reference concrete. In addition, the compressive strength of concrete containing copper slag increased by about from 4–21% in relation to the reference concrete.

Mechanical performance of biodegradable hemp shivs and corn starch-based biocomposite boards

For the production of traditional building materials, excavated natural resources are used. The production process of such materials requires high-energy demands, wherefore, high amounts of CO2 gases, which have a great impact on climate change, are emitted. Only a small part of such materials is effectively recycled and reused. Generally, they are transported to landfills, which rapidly expand and may pollute the soil, groundwater and air. Currently, a great attention is paid to the production of novel building materials. The aim is to use as less excavated materials as possible and replace them by natural renewable resources. Therefore, the recycling and utilisation at the end of life cycle of such materials would be easier and generation of waste would reduce. This way, the efforts of switching to circular economy are being put. One of the approaches – wider application of vegetable-based raw materials (cultivated and uncultivated agricultural plants). The usage of fibre hemp shives (HS) as an aggregate and corn stach (CS) as a binding material allows development of biocomposite boards (WPCs) which could contribute to the solution of the before mentioned problems. Bio-sourced materials combined with a polymer matrix offer an interesting alternative to traditional building materials. To contribute to their wider acceptance and application, an investigation into the use of wood-polymer composite boards is presented. In this study, biocomposite boards for the building industry are reported. WPCa are fabricated using a dry incorporation method of corn starch and HS treatment with water at 100 °C. The amount of CS and the size of the HS fraction are evaluated by means of compressive, bending and tensile strength, as well as microstructure. The results show that the rational amount of CS, independently on HS fraction, is 10 wt.%. The obtained WPCs have compressive stress at 10% of deformation in the range of (2.4–3.0) MPa, bending of (4.4–6.3) MPa and tensile strength of (0.23– 0.45) MPa. Additionally, the microstructural analysis shows that 10 wt.% of CS forms a sufficient amount of contact zones that strengthen the final product. The obtained average density (~319–408 kg/m3) indicate that, according to European normative document EN 316, WPCs can be classified as softboards and used as self-bearing structural material for building industry. Based on the requirements, WPCs can be applied in dry and humid conditions for the internal and external uses without loading (EN 622-4, section 4.2) or as load-bearing boards in dry and humid conditions for instantaneous or short-term load duration (EN 622-4, section 4.3).

Evaluation of investing in real estate in EU and non-EU countries based on MCDM

Investment in real estate is a zoning issue as the real estate market is closely related to economic development and trends in real estate market are considered to be indicators of trends in the whole economy of the country. The goal of this paper is to analyse the main aspects and considerations when investing in real estate, evaluate investment in real estate situation in different EU and non-EU countries and introduce MCDM methods that could be used for selecting a state for investment in real estate. It is identified that when investing in real estate various political, social, economic, environmental and other factors have to be taken into consideration. Analysed examples of EU (Lithuania, Romania, UK) and non-EU (Turkey, China, Russia) countries show different risks and opportunities for investments in real estate. MCDM methods are applicable to evaluate which countries are most attractive for investment in real estate. Described TOPSIS and ARAS methods could be used for assessing states as alternatives when selecting where to invest

Analysis of second-order effects of constructions behaviour

This paper presents the importance of the second-order effects in behaviour of steel frame structures. EN 1993-1-1 were distinguished three main methods: taking / without taking into account second order effects depending on the sensitivity of horizontal design effects and tolerance. Using these methods, the susceptibility of steel frame structures to second-order impacts is considered in accordance with EN 1993-1-1. The study was performed taking into account also the rotational stiffness of the joints of the frame structure. In this way, trying to determine the effect of the joint on the rotational rigidity makes the frame structure more sensitive to second order impacts. It is also considered a semi-rigid joints effects the general frame-tailed P-Δ and the second row stress. This establishes the link between the effects of the second-order and the semi-rigid joints in the overall (general) analysis. Frame-building sensitivity makes it possible to compare and measure the importance of such dependencies.

Experimental investigation on foamed concrete produced using a planetary ball mill

The experimental study is devoted to investigation on foamed concrete produced applying innovative intensive mixing technology by using a planetary ball mill. Modern type of foamed concrete represents cementitious composite material group which may be competitive with traditionally used autoclaved aerated concrete. Innovative mixing method makes possible stabilizing of foamed concrete mixture and improving the microstructure of material. The aim of this study is to investigate physical and mechanical properties of non-autoclaved concrete such as density and compressive strength, and capillary water absorption depending on intensive mixing time. In this research microstructure, such as pore size diameters, depending on mixing time is also analysed.

Big data in construction industry: systematic literature overview

Technological advancement has led to tremendous increase of data. Many industries utilize big data to become more efficient or even to create new products or services. Applications of big data in construction industry has been extensively researched in Asia that can be explained with huge construction volumes in the area. This study is aimed at identifying big data applications in construction industry in time period beyond 2016. Research object is construction industry, research subject is big data applications. Research methods used in this research are systematic literature overview and meta-analysis. Novelty of the research is classification of big data applications based on systematic literature overview. Authors conclude that existing categorization (Bilal et al., 2016b) can be applied to researches about big data applications in construction industry published in 2016 and later. However, potential for new applications is identified in category of emerging trends triggered by big data and authors propose to perform cross-industry analysis to identify solutions that can be adopted to construction industry.

Strengthening of steel structures with fatigue cracks using adhesively bonded non-prestressed and prestressed CFRP lamellas

In comparison to classic strengthening methods of fatigue-damaged steel structures, adhesively bonded CFRP lamellas show several advantages. Compared to bolted reinforcement measures and the drilling of the crack tip, crosssectional weakening is avoided. Heat-induced, negatively acting residual stresses and distortions, usually occurring during repair welding, can also be excluded. Therefore, the effectiveness of adhesively bonded CFRP lamellas to enhance the remaining lifetime of fatigue damaged steel structures is examined in a German research project. Selected results are presented in this paper. To characterize the steel, CFRP and adhesive materials, different tests on small scale specimens are carried out. With the help of fatigue tests on CT-samples the remaining fatigue lifetimes of specimens strengthened with adhesively bonded CFRP lamellas is compared to the remaining lifetimes of specimens strengthened by established methods such as drilling the crack tip and repair welding. Based on the evaluation of the crack propagation after the rehabilitation measures, the great potential of adhesively bonded CFRP reinforcements can be deduced. By prestressing the lamellas, the remaining lifetime can generally be increased further. The combination of adhesively bonded CFRP lamellas together with established rehabilitation methods shows a particularly high positive influence on the remaining lifetime of the CT-specimens.

New model for the selection of effective wall solutions for residential buildings

Currently, the construction sector is facing requirements for higher quality and efficiency standards as well as objectives related to value creation. In construction, rational decision-making problems often involve creating a unique complex of criteria, which must consider multiple requirements and conditions. The paper presents the developed model for the selection of multi-layered external walls of a residential building. The model considers the following aspects and parameters: time, cost, quality, environmental conditions, aspects of sustainable development, and problemsolving benefits received from the assessment of alternatives and the development of the model. Game theory was used to calculate the defining rational decision. For the calculations was used game theory: Bayes, Wald’s rule, Savage criterion, Laplace’s rule. This study presents the developed model for the selection of multi-layered external walls of a residential building and calculation results based on game-theory rules, which are effective tools for rational decisionmaking.

Conceptual model of productivity bot for smart construction planning

One of the most important tasks in modern construction is to build a building according to the desired time schedule. This requires a timetable for the construction stages processes. The schedule is also easy to adapt and to plan the renovation of a building or maintenance works. Without a good schedule site manager cannot effectively handle construction area processes. The solution to this problem is the proposed productivity bot concept based on metaheuristic algorithms. Metaheuristic algorithms allow to improve the construction planning process schedules compared with conventional planning methods and equipment. The results of testing with construction planning data has shown that the metaheuristic algorithm achieved the main improvements during the first planning optimization stages. The proposed concept is expected to present results that are close to the optimal timetable and surpass classical methods for scheduling. Productivity bots act as a software engine complementing with the organization of construction or automation functionality. Productivity bot is designed to manage building processes. It is intended for automated planning of construction stages schedules according to construction technologies.

Analysis of the impact of water flow rate of selected Turbo type nozzle on the distribution of sprinkling intensity

In the work, the distribution of the sprinkling intensity for a selected nozzle with the trade name Turbomatic was tested and analysed. The device meets Polish legal requirements, has a CNBOP approval certificate and is classified as a TURBO type nozzle. The research was aimed at extending the knowledge about spray jets generated by nozzles, in particular analysing the impact of water flow rate on selected parameters of the sprinkling surface. These dependencies can in practice save water and more effectively extinguish during rescue and firefighting operations. The tests were carried out in the laboratory of the Rescue and Fire-Fighting Equipment of the Main School of Fire Service partly in field conditions. Two different water flow rates of 200 and 400 dm3/min were assumed at a set operating pressure at the nozzle outlet of 0.4 MPa. The position and methodology of conducted research was discussed. Selected results were presented in tabular and graphical form. Their analysis was carried out and conclusions were made based on it. They shows that the flow rate of the nozzle has a significant impact on sprinkling surface parameters such as: its size and shape, range projection, maximum value of sprinkling intensity, location of maximum, etc.