Table of contents

3^rd - 4^th November 2022, Brașov, Romania

Selected, peer reviewed papers from the International Conference Civil Engineering and Building Services CIBv2022

Edited by:

Ioan TUNS

Transilvania University of Brasov, Romania

Radu MUNTEAN

Transilvania University of Brasov, Romania

Dorin RADU

Transilvania University of Brasov, Romania

Teofil-Florin GĂLĂȚANU

Transilvania University of Brasov, Romania

Christiana Emilia CAZACU

Transilvania University of Brasov, Romania

FOREWORD

The International Scientific Conference CIBv represents one of the most important and traditionally scientific events of Civil Engineering and Building Services in Romania, enjoying increasingly higher visibility at the international level.

The aim of the CIBv conference is to provide a platform for researchers, engineers, academicians as well as professionals from all over the world to present their research results and development activities. It also provides opportunities for the participants to exchange new ideas and application experiences, to establish business or research relations and to find other partners and even friends for future collaboration.

List of International Conference CIBv2022 Civil Engineering and Building Services, Honorary Committee, International academic scientific committee, Organizing committee are available in this pdf.

All papers published in this volume have been reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

• Type of peer review: Single Anonymous

• Conference submission management system: Morressier

• Number of submissions received: 32

• Number of submissions sent for review: 25

• Number of submissions accepted: 17

• Acceptance Rate (Submissions Accepted / Submissions Received × 100): 53.1

• Average number of reviews per paper: 2

• Total number of reviewers involved: 50

• Contact person for queries:

Name: Radu Muntean

Email: radu.m@unitbv.ro

Affiliation: Transilvania University of Brasov

Global concerns about climate change have led to the development of building materials that use plant biomass with the added benefit of sequestering carbon from the atmosphere. Lightweight concrete made with hemp, is a material with huge potential in terms of its ability to achieve hygro-thermal performances close to those of polystyrene. This ecological material, referred to in the literature as hemp concrete, is made of some components that, depending on the chosen combination, can generate different results of the physic-mechanical properties. The method is based on a series of experiments that are generated using a program called Design of Experiments (DoE). This program uses statistical analysis of a series of experiments performed by varying one of the input parameters, like the amount of hydrated lime or cement. Following this analysis, it is possible to identify those elements used in the composition, which produced a significant influence on the physical-mechanical properties of hemp concrete. Moreover, this method also allows a quantification of the influences so that the parameters can be ranked, with a minimum number of experiments. The method is, in the same time, a modern and an economical technique used for experimental planning. The aim of the research is to quantify numerically the influence of each component element of the mixture that determines variations of the physical-mechanical properties in hemp concrete. This study will contribute in the future to the optimization of compositions, which will be differentiated on the basis of mechanical performance or thermal insulation criteria.

It is common practice for government agencies to fix signs – and indeed even official temporary notices – onto masonry structures using steel nails. This method of fixing is destructive; it causes irreversible damage to the material fabric, which has a bearing on the overall aesthetic of the building, a scenario which is more acute if the site is of cultural heritage significance. Stones and concrete blocks (locally referred to as concrete bricks), the latter introduced in the 1950s, are the main materials used in masonry construction in Malta. Clay bricks are not utilized, as in Malta there is a blanket prohibition on the extraction of local clay. The main building material used in Malta since time immemorial is Lower Globigerina Limestone. This article puts forward the case for a non-destructive, reversable method to fix notices to building which respects the integrity of the dimension stones. Instead of being hammered into masonry blocks, the proposed removable plugs are installed in the mortar. Their size is relative to the thickness of the mortar bed and the load they are designed to carry, the latter being of negligible importance in the case of lightweight placards. The proposed solution applies equally to other masonry structures, whether erected in dimension or randomly placed stones, concrete blocks or clay bricks, as long as the construction in question uses mortar in the joints between the units.

The thermal resistance of concrete significantly influences the energy consumption of the building. Consequently, concrete with high thermal resistance can contribute to the envelope's energy efficiency. In order to obtain the thermal conductivity performance required for the passive house standard using the principles of sustainable development, it is essential to analyze the thermal improvement solutions of the concrete with a low impact on the environment. For this reason, it is necessary to analyze methods of improving concrete's thermal performance by replacing aggregates with ecological materials like perlite. Perlite is a common term used for a glassy natural volcanic rock used in construction in various mixtures for its fire resistance, low density, and thermal and acoustic improvement properties. While processing raw perlite (cutting, grinding, and fractionation to various sizes), large amounts of powder are collected and stored as waste. Currently, only limited amounts of waste perlite powder are recycled in the construction industry, which urges the efficient use of this waste to limit the impact on the environment. There are various studies about concrete mixtures with perlite from the point of view of structural strength. However, the results are contradictory, influenced by the size of used particles and the replacement levels in the mixture. This article aims to present the current state of knowledge regarding the characteristics of the mixture between concrete and perlite.

The paper studies the influence of light weight aerated autoclaved concrete (AAC) partitioning walls to a medium height reinforced concrete structure, in Bucharest (Romania). The building is designed as a framed structure with non-bearing AAC walls placed in certain bays. There is a bearing full bricks masonry wall in one of the bays. Full bricks are used because of its high strength compared to AAC. The aim is to determine the importance of the masonry walls placement, both full bricks and AAC, for the building's behavior. The analysis points out the structure's elastic and plastic behavior and also the efforts developed in the non-bearing walls. The bearing masonry wall's behavior is very important, because the structure is built in a high seismic area. To extend the study, the full bricks wall is replaced with a reinforced concrete one. This is done to see how it impacts the building's behavior, for both the elastic and plastic stage. The paper concludes that AAC, full bricks and concrete walls placements have a significant influence on the structure.

Considered the issues of environmental protection with the simultaneous use for the neutralization and disposal of urban waste containing substances of organic origin, due to solar energy and atmospheric precipitation. At present, in the Russian Federation, waste makes up 90–98% of all extracted natural resources, that is, the industry works mainly for the production of waste. Already 8 billion m³ of industrial and municipal waste has accumulated. Landfills are 50–90% full on average across the country. The volume of waste from livestock enterprises and poultry farms in the form of manure, droppings and sewage is about 700 million m³ per year, and more than 2 million hectares of land are occupied for storing this waste. Therefore, it is planned until 2020–2025 to introduce a complete ban on the storage of municipal solid waste at more than 200 landfills and dumps, where they have accumulated 31 billion tons

Steel fiber reinforced concrete (SFRC) for industrial floors has become a state-of-the-art construction method in all industries worldwide, including the construction of port platforms. The first patent that refers to a dispersed reinforced concrete element with steel fibers there exists since 1874 and was patented in the USA (California) by A. Bernard who proved the improvement of the strength of the concrete by adding some uneven steel scraps. Steel fibers have been created to improve the durability and flexibility of concrete under high loads, over long periods of time, providing three-dimensional reinforcement of concrete. Steel fibers can be used as the sole form of reinforcement or in combination with reinforcement bars or welded wire mesh.

The building materials branch of the construction industry is continuously developing due to occurrence of new products which seek to improve the "green" character of buildings by using different types of wastes. Prefabricated products of different sizes such as blocks, panels, beams and other spatial elements can now be obtained with eco-materials. Concrete is the most used material in the building industry and thus it is necessary to diminish its environmental pollution. There are different ways for improving the "green" character of concrete, such as the addition of waste products of different types (fly ash, silica fume, slag, shredded tyre rubber, agricultural powder wastes, etc.) or by replacing some of the components (i.e. cement, aggregates) with eco-materials. Materials with pozzolanic properties (fly ash, silica fume, banana leaves powder, volcanic tuff, etc.) can, in certain proportions, replace the cement. In order to replace the aggregates, the substitution materials are obtained with sizes which are corresponding to the aggregate sort (polystyrene granules, shredded plastic recipients, agricultural wastes, etc). In the current article, the experimental results obtained on types of eco-concrete used for producing reinforced concrete beams are presented. The eco-concrete used for pouring the reinforced concrete beams contains the following materials: fly ash as replacement for the cement, metalic fibers, polyester fibers and hemp fibers. The beams models were tested in two point bending. The strength capacity and type of failure were analysed and compared as a function of the type of eco-concrete.

Floods, induced partly by climate change and partly by the negative impact of human actions, may be regarded as the most common type of natural catastrophe in Montenegro, causing significant economic, ecological, social, and health damage yearly. Therefore, the focal point of flood risk assessment is reflected in properly determining flood hazards. However, within the Montenegrin National flood risk assessment, which is entirely scenario-based, the hazard is treated only by estimating the occurrence probability of a specific scenario. The paper provides an overview of recent efforts to overcome the potential weaknesses of scenario-based risk assessment by constructing hazard maps for all areas of potential significant flood risk in Montenegro. Hazard maps are intended to visualise different flood intensities (e.g., flood depth, velocity, etc.) for selected return periods. Such outputs are generated by two-dimensional hydraulic modelling, which requires extensive work on gathering the available field data, calculating hydrological inputs, building and calibrating the model, and defining uncertainties that may affect the results. The final production of the hazard maps is conveyed by post-processing the computation results in GIS-based software.

One of the major problems we face today is the correct management of waste generated in all spheres of activity. Thus, the concept of sustainable development aims to develop strategies that prevent and solve problems already generated. Domain construction is the one that generates the most waste worldwide, according to recent studies, which requires the imposition of clear, effective, and future-proof measures to improve the environment and the health of the population. This paper is the continuation of a research program in which 3 types of mortar recipes are analyzed. The study involves replacement of aggregates, in different percentages (10% and 15%), with plaster waste from historic buildings. The obtained results show that the values fall within the limits stipulated in the norms in force, so the study will continue with the analysis of the samples using the state-of-the-art method: nuclear magnetic resonance. The paper aims to analyze the properties of the proposed mortars at the nanoscopic level, following the relationship between the plaster mortar matrix and the plaster waste introduced in different percentages in the samples. In addition, the impact of these wastes on the hydration of the cement and on the porosity of the composition of these mortars is also observed, being noticed that the relationship between the porosity of the samples and the mechanical resistances is inversely proportional, that is, the resistances decrease as the porosity increases. It will also be identified the location of hydrogen in the structure: in hydrated mineralogical compounds of cement and in large, medium and small pores. For each studied sample, the investigations were conducted at the age of 7, 14 and 28 days (even at 3 days for samples with 10% and 15% substitution of aggregates with old plastering mortars). The results for the proposed samples will be compared to the standard recipe.

Because of its multiple advantages such as durability, flexibility in use, fire resistance and low production and maintenance costs, concrete is, by far, the most popular building material currently in use. However, cement – one of the base ingredients of concrete – requires large quantities of raw materials and fossil fuels in order to be produced. In fact, in terms of pollution, it is one of the most environment-damaging products of the construction industry. A relatively recent trend in the problem of mitigating cement-related pollution is the possibility to substitute a certain percentage of cement with reactive powders, which are considered to be waste products of other industries. Concurrently, another trend is to try and obtain better performance of plain concrete, by using so-called "disperse reinforcement". Thus, in the present article, a laboratory study is presented, regarding the obtainment and performance of concrete in which cement has been partially replaced with ultrafine silica and fly ash. Furthermore, in the case of the fly ash recipe, a percentage of metallic fibers was added, in order to study the potential performance gain with respect to plain concrete. The obtained results in compression were encouraging, in the sense that, for all recipes of concrete (plain concrete – used as reference sample versus concrete with fly ash, concrete with ultrafine silica, concrete with fly ash and fibers), the desired concrete strength class was attained. Even more, in the case of obtained results in tension by bending and splitting, the concrete with fly ash and fibers attained almost twice the tensile strength of the plain concrete. The obtained results suggest that concrete with reactive powders and/or metallic fibers can successfully substitute the plain concrete normally used in the construction industry.

In the present paper, the design of a steel warehouse structure was investigated. After establishing the base sections for the beams and columns through the design for ultimate resistance and buckling strength, an optimization procedure was applied to the beam-to-column connection. Three types of connections were studied: a bolted connection with end plate, a welded connection and a bolted connection with web and flange angles. The detailed analysis of the components of the connections was performed with the help of the software "IdeaStatica". The advantages and disadvantages of the three joint solutions are presented. The results were compared and the best solution was proposed in view of costs, structural performance, inspection difficulties, joint stiffness, and the installation and safety process.

The horizontal shaft of rotary table is an important rotating part of drilling rig. The vibration caused by the mass imbalance of the horizontal shaft will seriously affect the normal operation of drilling rig and lead to faults. Therefore, taking the horizontal shaft rotor system of rotary table of the drilling rig as the research object, the unbalanced vibration characteristics of the rotor are extracted by the improved all-phase fast Fourier transform method. Through the cross-correlation operation of the signal, the data of the discrete signal is weighted and superimposed, the vibration amplitude, time delay of the phase and the spectrum analysis can be obtained. The experimental results show that the accuracy and stability of the vibration amplitude and phase extracted by the improved all-phase fast Fourier transform method are better, and the accuracy of the vibration phase extraction can reach 98%, which verifies the effectiveness of the proposed method.

Grinding robot is used in building construction to replace manual grinding of concrete components. Bearing in grinding system under high-speed conditions has friction violently with the inner and outer ring, and generates a lot of heat. This will cause thermal failure of grinding system. In order to explore the thermal characteristics of rolling bearings, a numerical analysis model based on bearing heat transfer mechanism was established to study the influence of different working conditions on bearing temperature. The results provide a reference for reducing the thermal failure of rolling bearings in grinding system of grinding robot.

According to Eurostat statistics, the volume of waste collected is constantly increasing, the amount of waste produced in Europe in 2020 reaching 2151 million tons. In the European Union, the most waste-producing activity is construction and demolition, accounting for 37.1% of the total waste produced in 2020. This type of waste has a high occupancy rate. This article proposes the reuse of mixed masonry waste in the production of plaster mortars. The maximum amount of mixed masonry waste used in the experiment was 35%, partially replacing the aggregate component. The physical and mechanical characteristics that have been measured in the experimental program may be divided into two categories: characteristics of mortars in fresh state (apparent density, consistency) and in hardened state (bending strength, compressive strength and adhesion to the support layer). In order to highlight the influence of the addition of waste on the composition and on the evolution of the mechanical properties of the studied mortars, the experimental program was distributed over 3, 7 and 28 days. The results showed an increase in the mechanical strength of mortars containing mixed masonry waste compared to standard mortar. Mixed masonry waste can be a substitute for raw materials in the production of new types of plaster mortars and contributes to the reduction of the resulting waste by recycling and reuse. The experimental program will be continued with microscopic investigations using modern investigation methods, to highlight the behaviour of mortars with masonry waste, and to identify the correct proportion of waste that can be used in mortar networks so as not to affect the characteristics required by the acting norms.