scholarly journals TECHNICAL CONDITION OF PRECAST BEAMS WITH THE USE OF EXPANDED LIGHTWEIGHT CONCRETE HOLLOW-CORE SLABS

2019 ◽  
pp. 35-42
Author(s):  
Г. Смоляго ◽  
G. Smolyago ◽  
С. Дрокин ◽  
S. Drokin ◽  
А. Дронов ◽  
...  
Keyword(s):  
Lightweight Concrete ◽  
Significant Proportion ◽  
Physical And Mechanical Properties ◽  
Technical Condition ◽  
Building Structures ◽  
Hollow Core ◽  
Shear Cracks ◽  
Total Load ◽  
Normative Documents ◽  
Methods Of Calculations

The use of expanded lightweight concrete for the production of building structures can significantly reduce the weight, which is important in the manufacture of hollow-core slabs; the weight is a significant proportion of the total load. In the current regulatory documents, the physical and mechanical properties of expanded lightweight concrete differ significantly, and sometimes contradict each other. The defects and damages of expanded lightweight concrete hollow-core slabs are described in the case of the kindergarten built near 50 years ago. They appeared during the manufacture of the slabs - uncompacted concrete and uncovered ribs, or in the course of exploitation of the building - normal cracking, holes for pipes and corrosion of reinforcement. Two slabs in emergency condition have numerous longitudinal and shear cracks and chips of concrete caused by overloading. The differences in normative documents and methods of calculations used at the time of designing the kindergarten building and at the present time are shown. The assessment of the technical condition of the expanded lightweight concrete hollow-core slabs considering defects and damages are carried out

scholarly journals Reliability Assessment and Technical Diagnostics of the Bridge Structure across the Verkhnia Khortytsia River in Zaporizhzhia

2021 ◽  
pp. 51-58
Author(s):  
N. O Dankevych ◽  
M. V Piatnytsia
Keyword(s):  
Service Life ◽  
Survey Methods ◽  
Scientific Research ◽  
Technical Condition ◽  
Technical Diagnostics ◽  
Building Structures ◽  
Bridge Structure ◽  
Normative Documents ◽  
Object Of Study ◽  
Inspection Data

Purpose. The authors aim to assess the reliability and technical diagnostics of the bridge structure, as well as to develop the methods for eliminating defects and restoring the serviceability of damaged building structures, as most accidents occur due to unsatisfactory technical condition of structures and their significant wear due to expiration of the standard service life. Methodology. An important role in the study is played by the formation of knowledge and skills of using a modern engineering approach to the survey of building structures in order to restore their serviceability. Inspections of construction sites are carried out in accordance with the rules set by the relevant regulations. Defects and damages are described in inspection materials with the indication of the possible reasons of their occurrence and forecasting their further influence on reliability and durability of construction. Findings. The analysis of scientific research and normative documents reflecting a problem of the operation safety increase of buildings and structures and estimation of a technical condition of structures is carried out in work. Methods of assessment of reliability and technical diagnostics of bridge constructions are applied. The results of the inspection are substantiated and recommendations are developed to ensure the serviceability and increase the service life of damaged structures of the object of study. Originality. Based on the design and technological documentation, normative base, scientific research, the model of competent systematization of the construction inspection data is obtained. Attention is paid to the timely major, as well as current medium repairs to improve the technical condition of the bridge elements, and in some cases the entire structure. Practical value. Application of the survey methods – visual and instrumental – allowed formulating the conclusions and recommendations aimed at widespread implementation in practice of assessing the reliability and technical condition of structures.

Effects of Loading Percentage of Polyurethane in Lightweight Concrete

2013 ◽  
Vol 357-360 ◽  
pp. 1082-1085 ◽  
Author(s):  
Kamarul Aini Mohd Sari ◽  
Sohif Mat ◽  
Khairiah Haji Badri ◽  
Muhammad Fauzi Mohd Zain
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Lightweight Concrete ◽  
Palm Kernel ◽  
Physical And Mechanical Properties ◽  
Concrete Mixture ◽  
Experimental Program ◽  
Polymer Concrete ◽  
Optimum Level ◽  
Methylene Diphenyl Diisocyanate

An experimental program was performed to obtain the density, compressive strength, and thermal conductivity of palm-based lightweight concrete. Palm-based polyurethane (PU) particles were used as lightweight aggregates in creating concrete systems. Concrete systems contain palm kernel oil-based polyol (PKO-p) reacted with 2,4-methylene diphenyl diisocyanate (MDI). In this study, polymer concrete was improved to achieve the optimum level of PU with the lowest possible density. The PU particles in the concrete mixture comprised of 1% to 5% w/w with density of less than 1800 kg/m3. The PU particles were 5 mm in size. The ratio of PKO-p to MDI was set at 1:1 and the loading of the concrete mixture was set at 3% w/w to produce lightweight concrete. The resulting concrete has excellent compressive strength (17.5 MPa) and thermal conductivity (0.24 W/mK). Results show that the PU particle dosage has the most significant effect on the physical and mechanical properties of concrete.

The concept of calculating the actual limit of fire resistance of building structures

2021 ◽  
pp. 12-17
Author(s):  
Юрий Николаевич Шебеко ◽  
Алексей Юрьевич Шебеко
Keyword(s):  
Fire Resistance ◽  
Fire Safety ◽  
Building Structures ◽  
Safety Level ◽  
Fire Temperature ◽  
Normative Documents ◽  
Software Complex ◽  
Temperature Regimes ◽  
Actual Fire

Проведен краткий анализ понятий, связанных с расчетом пределов огнестойкости строительных конструкций. Дано определение термина «фактический предел огнестойкости», которое отсутствует в нормативных документах по пожарной безопасности. Отмечено, что это связано с использованием на практике значений пределов огнестойкости, определенных для стандартных температурных режимов пожара, в то время как на практике указанные температурные режимы, как правило, отличаются от стандартных. Предложена концепция определения фактического предела огнестойкости, основанная на моделировании воздействия на строительную конструкцию температурного режима реального пожара (например, с помощью программного комплекса FDS 6). The brief analysis of definitions connected with estimation of fire resistance limits of building structures is conducted. There is given the determination of term “actual fire resistance limit” that is absent in fire safety normative documents. It is caused by practical application of the fire resistance limits determined for standard temperature regimes of fires only, but at the same time the temperature regimes of real fires as a rule differ from the standard regimes. There is proposed the method for determination of the actual fire resistance limit based on the modeling of influence of the real fire temperature regime on buildings structures. This modeling can be made by an application of CFD methods (for example, with the help of FDS 6 software complex). The required reliability of the building structure is considered. The proposed method can solve the problem of practical applicability of certain structural unit during designing buildings and structures, for which the use of the resistance limits obtained for the standard fire temperature regimes can lead to unjustified economic expenditures without an appropriate elevation of fire safety level of the object.

scholarly journals Structural Use of Expanded Polystyrene Concrete

2020 ◽  
Vol 5 (6) ◽  
pp. 1131-1138
Author(s):  
Adeniran Jolaade ADEALA ◽  
Olugbenga Babajide SOYEM
Keyword(s):  
Environmental Pollution ◽  
Lightweight Concrete ◽  
Physical And Mechanical Properties ◽  
Consumer Products ◽  
Expanded Polystyrene ◽  
Engineering Properties ◽  
Partial Replacement ◽  
Construction Companies ◽  
Fine Aggregates ◽  
Concrete Matrix

Expanded polystyrene (EPS) wastes are generated from industries and post-consumer products. They are non-biodegradable but are usually disposed by burning or landfilling leading to environmental pollution. The possibility of using EPS as partial replacement for fine aggregates in concrete has generated research interests in recent times. However, since the physical and mechanical properties of EPS are not like those of conventional fine aggregates, this study is focussed on the use of EPS as an additive in concrete while keeping other composition (sand and granite) constant. Expanded polystyrene was milled, the bulk density of EPS was 10.57kg/m3 and particle size distributions were determined. Engineering properties of expanded polystyrene concrete were determined in accordance with BS 8110-2:1985. The result showed that the amount of expanded polystyrene incorporated in concrete influence the properties of hardened and fresh concrete. The compressive strengths of 17.07MPa with 5 % expanded polystyrene concrete at 28 days for example can be used as a lightweight concrete for partitioning in offices. Incorporating expanded polystyrene granules in a concrete matrix can produce lightweight polystyrene aggregate concrete of various densities, compressive strengths, flexural strengths and tensile strengths. In conclusion, this reduces environmental pollution, reduction in valuable landfill space and also for sustainability in construction companies

scholarly journals FIRE RESISTANCE OF BUILDING STRUCTURES OF FLAMMABLE AND COMBUSTIBLE LIQUIDS STORES

Fire Safety ◽  
2019 ◽  
pp. 5-9
Author(s):  
O. I. Bashynskiy ◽  
M. Z. Peleshko ◽  
T. G. Berezhanskiy
Keyword(s):  
Fire Resistance ◽  
Fire Safety ◽  
Theoretical Calculations ◽  
Fire Hazard ◽  
Building Structures ◽  
Safety Measures ◽  
Normative Documents ◽  
Size Number ◽  
Literary Sources ◽  
Combustible Liquids

The article is dedicated to the fire resistance limit of building structures of the objects for the storage of flammable and combustible liquids. Today, oil stores are very important elements of the oil supply system in Ukraine. The analysis of literary sources has shown that fires in oil stores cause extra fire hazard of surrounding objects. Increasing of their scales requires further improvement of fire safety measures during planning and using of oil stores. Fires in such buildings are tricky and large; they cause great harm and often lead to the death of people; their liquidation is very difficult. Theoretical calculations shown that the collapse of structures of the packaged oil stores and, as a result, significant material losses and the threat to people's life and health, were resulted from the incorrect selection of building structures and the discrepancy between the fire resistance of these structures and the applicable norms and requirements for such buildings. Fire Safety, №34, 2019 9 Fire resistance limit of the metal double-T pillar made of steel ВСт3пс4 (profile size number 30) was calculated in the article. Such constructions are used in oil stores. The obtained fire resistance limit of a metal double-T pillar is about 16 minutes (R 16). According to the normative documents for buildings of this type (the degree of fire resistance of the building – III), it should be 120 minutes (R 120). Even if the calculation method has an error due to the choice of another steel grade, objectively none of the double-T profiles from the assortment list would provide proper fire resistance limit.

Assessment and Damage for Building Structures Risk Analysis Methods

2014 ◽  
Vol 899 ◽  
pp. 535-538 ◽  
Author(s):  
Karel Kubečka ◽  
Pavel Vlček ◽  
Darja Kubečková
Keyword(s):  
Risk Analysis ◽  
Technical Condition ◽  
Building Structures ◽  
Analysis Methods ◽  
Alternative Method

The paper introduces an alternative method for damage pricing on buildings in consequence of defects, failures and collapses. The method operates with time-independent price of the structure and following damage on the construction. Using risk analysis methods, the price is reduced depending on technical condition to proper damage and evaluation of the object, building or structure.

Investigation of Physical, Mechanical and Thermal Properties of Building Wall Materials

2017 ◽  
Vol 751 ◽  
pp. 521-526 ◽  
Author(s):  
Jiraphorn Mahawan ◽  
Somchai Maneewan ◽  
Tanapon Patanin ◽  
Atthakorn Thongtha
Keyword(s):  
Compressive Strength ◽  
Thermal Properties ◽  
Water Absorption ◽  
Calcium Silicate Hydrate ◽  
Lightweight Concrete ◽  
Physical And Mechanical Properties ◽  
Mechanical And Thermal Properties ◽  
Thermal Insulating ◽  
Building Wall ◽  
Wall Materials

This research concentrates to the effect of changing sand proportion on the physical, mechanical and thermal properties of building wall materials (Cellular lightweight concrete). The density, water absorption and compressive strength of the 7.0 cm x 7.0 cm x 7.0 cm concrete sample were studied. It was found that there are an increase of density and a reduction of water absorption with an increase of sand content. The higher compressive strength can be confirmed by higher density and lower water absorption. The physical and mechanical properties of lightweight concrete conditions conformed to the Thai Industrial Standard 2601-2013. The phases of CaCO3 and calcium silicate hydrate (C-S-H) in the material indicate an important factor in thermal insulating performance.

Lightweight Concrete Based on Gypseous Binding Materials, Modified with Microcrystalline Cellulose, and Cavitationly Processed Sawdust

2019 ◽  
Vol 945 ◽  
pp. 188-192 ◽  
Author(s):  
A.A. Pykin ◽  
E.Y. Gornostaeva ◽  
N.P. Lukutsova ◽  
J.S. Pykina
Keyword(s):  
Mechanical Properties ◽  
Microcrystalline Cellulose ◽  
Lightweight Concrete ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Water Soluble ◽  
Waste Wood ◽  
Matrix Microstructure ◽  
Calcium Sulfate Dihydrate ◽  
Reducing Substances

The physical and mechanical properties of lightweight constructional heat-insulating concrete (sawdust gypsum concrete) with high-strength gypsum binder, modified by food cotton microcrystalline cellulose and organic fillers of plant origin from the waste wood of coniferous and deciduous species in the form of cavitationly processed pine and birch sawdust have been studied. The dependence of the cavitation extraction time of water-soluble reducing substances (sugars) from sawdust on the strength of sawdust gypsum concrete is established. The changes in microstructure of the gypsum matrix, the mean density, bending tension strength and compression strength, the thermal conductivity coefficient of sawdust gypsum concrete on the basis of the cavitationly processed sawdust with the introduction of microcrystalline cellulose are analyzed. It is proven that microcrystalline cellulose compacts the space between the crystalline hydrates of calcium sulfate dihydrate in the gypsum matrix microstructure and improves the physical and mechanical properties of sawdust gypsum concrete.

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