scholarly journals TECHNOLOGICALITY OF FORM SYSTEMS AT DIFFERENT METHODS OF CONCRETE PREPARATION

2021 ◽  
pp. 17-23
Author(s):  
A.I. BILOKON ◽  
T.A. KOVTUN-HORBACHOVA ◽  
O.A. KАPSHUK
Keyword(s):  
Concrete Strength ◽  
Computational Experiments ◽  
Construction Time ◽  
Scientific Publications ◽  
Design Strength ◽  
Standard Data ◽  
Concrete Mixtures ◽  
Technology Improvement ◽  
The Cost ◽  
Technical And Economic Indicators

It is shown that many scientific publications and researches in the field of monolithic house-building aredevoted to increase of efficiency of use of formwork systems as the most labor and economically expensive area. It isnoted that up to 50 % of the costs are for formwork, including the cost of renting or purchasing, its installation,maintenance, storage and remuneration. It is presented that with the development of formwork systems their technologyis improved, in particular the regulatory framework is improved to reduce the complexity of the work, adjustments aremade to the size of the formwork, it becomes more uniform, reduces the number of connections, increases the turnoverof formwork systems, which also reduces costs.It is shown that a very important issue, inseparable from monolithichousing is the improvement of design with the composition of concrete and concrete mixtures. One of the promisingУкраїнський журнал будівництва та архітектури, № 4 (004), 2021, ISSN (Print) 2710-0367, ISSN (Online) 2710-0375 17 areas of technology improvement is to reduce the time of the set of design strength. The question of the accelerated setof durability by concrete at hardening is very actual in the conditions of the market and high cost of rent of a timbering.Predicting the accelerated growth of concrete strength, respectively, will establish the morning timing of removal offormwork systems. The graph of dependence of time of a set of durability by concrete, for example at activation ofcement suspension in an electromagnetic field in comparison with standard data of hardening is specified. The reductionof the term (days) of keeping concrete in the formwork is shown, it improves the manufacturability of its use,accordingly it causes a reduction of all costs, incl. reduction of construction time and, accordingly, acceleratedmovement of funds and economic profit due to the earlier commissioning of facilities.The area of perspectiveresearches on establishment of interrelation of indicators of efficiency from parameters of object and technology isformulated. This gives a theoretical justification for further computational experiments. The object of research is theproduction processes with the use of collapsible formwork systems for frame-monolithic construction. The subject ofthe study are indicators of manufacturability of the use of formwork systems. The purpose of scientific and appliedresearch is the ability to show the increase of manufacturability of construction by ensuring the normative turnover offormwork by intensifying the hardening of concrete in frame-monolithic construction with a reduction in the duration ofthe strength of concrete. As a result of research the following tasks were defined: the area of further researches isformulated, ways of reduction of the basic technical and economic indicators are offered, the expedient theoreticalsubstantiation of the further computational experiments is proved.

scholarly journals Measures to reduce construction time of high-rise buildings

2018 ◽  
Vol 33 ◽  
pp. 03062
Author(s):  
Leonid Kolchedantsev ◽  
Aleksey Adamtsevich ◽  
Olga Stupakova ◽  
Alexander Drozdov
Keyword(s):  
Concrete Strength ◽  
Concrete Mixture ◽  
Construction Time ◽  
Building Site ◽  
High Rise ◽  
Concrete Mixtures ◽  
Concrete Quality ◽  
Efficiency Increase ◽  
Precast Elements ◽  
Concrete Mixing Station

The organizational and technological solutions for high-rise buildings construction efficiency increase are considered, primarily – decrease of typical floor construction time and improvement of bearing structures concrete quality. The essence of offered technology is: a concrete mixing station and a polygon mainly for load-bearing wall panels with starter bars casting are located on the building site; for reinforced concrete components manufacturing and butt joints grouting the warmed-up concrete mixtures are used. The results of researches and elaborations carried out by the SPSUACE in area of a preliminary warming-up of concrete mixtures are presented. The possibility and feasibility of their usage in high-rise buildings and of excess height buildings construction including cast-in-place and precast execution are shown. The essence of heat-vibro treating of concrete mixture is revealed as a kind of prior electroresistive curing, and the achieved results are: accelerated concrete strength gain, power inputs decrease, concrete quality improvement. It is shown that the location of a concrete mixing station on the building site enables to broaden possibilities of the “thermos” method use and to avoid concrete mixtures warming up in medium-mass structures erection (columns, girders) during the high-rise buildings construction. It is experimentally proved that the splice between precast elements encased with warmed-up concrete mixture is equal with conjugated elements in strength.

scholarly journals Delay and cost overrun in road construction projects in Jordan

2015 ◽  
Vol 4 (2) ◽  
pp. 288 ◽  
Author(s):  
Nabil Al-Hazim ◽  
Zaydoun Abusalem
Keyword(s):  
Construction Projects ◽  
Road Construction ◽  
Weather Conditions ◽  
Public Works ◽  
Fiscal Year ◽  
Cost Overrun ◽  
Construction Time ◽  
Change Orders ◽  
Critical Problems ◽  
The Cost

This study aims to identify the most important factors that cause delay in road construction projects in Jordan, which results in cost and time overrun allocated for this type of engineering projects and cause critical problems for both the developer and the contractor. The gap between the cost at completion and that originally estimated, known as cost overrun, can be regarded as one of the most important parameters reflecting the success of projects. In the public sector, money spent on project change orders results in increased construction time which in return reduces the number and size of the projects that can be completed during any given fiscal year. To achieve this goal, the documents and the final reports for several sample projects implemented over the years 2000 to 2008 were analyzed. All the projects were administered by the same organization taken from Jordan Ministry of Rural and Public Works. The results of this study can assist highway officials in their design, planning, scheduling and projects completions so that necessary actions can be taken to control these overruns in future projects. The study showed that 19 factors might cause delays of road construction projects as defined through a detailed literature review. The analysis of the study indicated that the top causes affecting time and cost overrun in road construction projects in Jordan are Terrain and Weather conditions.

scholarly journals History of buildingand operation of the Nizhny Tulom hydroelectric power plant on the Kola Peninsula.

2020 ◽  
Vol 11 (7-2020) ◽  
pp. 19-32
Author(s):  
Olga E. Konovalova ◽  
◽  
Nikolai M. Kuznetsov ◽  
Keyword(s):  
Hydroelectric Power Plant ◽  
Hydroelectric Power Station ◽  
Hydroelectric Power ◽  
Power Station ◽  
Construction Time ◽  
Current State ◽  
Production And Consumption ◽  
Great Patriotic War ◽  
History Of ◽  
The Cost

The article tells the story of the creation of the Nizhne-Tulomskaya hydroelectric power station (HPP). The main energy parameters of the hydroelectric power station, the layoutof the main structures of the station, and archival photos of the construction time are given. Data on the production and consumption of electricity for own needs, the cost of 1 kW·h during the great Patriotic war are shown. It is told about the reconstruction and current state of the station.

scholarly journals Mechanical Strengths of Sawdust-Ash-Admixed Gum Arabic Concrete

2021 ◽  
Vol 8 (1) ◽  
pp. 12-29
Author(s):  
Augustine Uchechukwu Elinwa
Keyword(s):  
Cement Content ◽  
Gum Arabic ◽  
Strength Ratio ◽  
Design Strength ◽  
Conventional Concrete ◽  
Cement Material ◽  
Cement Ratio ◽  
Setting Times ◽  
Concrete Mixtures ◽  
Mechanical Strengths

Gum Arabic and sawdust ash were used both as an emulsifier admixture and supplementary cement material to address some of the gaps between pozzolanic and conventional concretes. Four concrete mixtures of 1: 2.24: 2.71, with a water-cement ratio of 0.5, and cement content of 370 kg/m3, was used. The concrete mixtures were designated as M-00, M-00GA, M-10GAS, and M-30GAS, signifying the control, control with gum Arabic (GA), and mix with both gum Arabic and sawdust ash (GAS), respectively. The dosage was 0.5 % of GA and the SDA replacement by wt. % was at 10 % and 30 %, respectively. The concrete samples were cured for 90 days, and tested for mechanical strengths. The results showed that adding GA alone to concrete mixture improved the mechanical strengths of the concrete and the gum Arabic acted like an accelerator. When both GA and SDA were used together in the dosage of 0.5 % with 10 % and 30 % proportions respectively, the mechanical strengths of the concrete decreased. The findings also reported that the two-third strength ratio at 28-days of curing which is used for the conventional concrete in stripping the formwork, may not be appropriate for use on pozzolanic concrete. This is because of the delay in setting times and thus, attaining the required design strength. Therefore, it is proposed to be taken at an age beyond 28 days of curing to carter for the pozzolanic effects which starts well above 28-days.

GGBS Use in Concrete as Cement Constituent: Strength Development and Sustainability Effects – Part 1

2021 ◽  
pp. 1-41
Author(s):  
Haotian Fan ◽  
Ravindra K. Dhir ◽  
Peter C. Hewlett
Keyword(s):  
Concrete Strength ◽  
Blended Cement ◽  
Data Matrix ◽  
Strength Development ◽  
Design Strength ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Granulated Blast Furnace Slag ◽  
Data Points ◽  
Class F Fly Ash

This study, third in the series, following from ground limestone and Class F fly ash, evaluates, as a cement constituent, the effect of using ground granulated blast furnace slag (GGBS) on the strength development of concrete, and consequently its embodied carbon dioxide (CO2e). The paper has been built from systematically analysing, evaluating and modelling the extensive data-matrix developed, having 85,099 data points, from the information sourced from 663 studies published in English, during 1974 to 2020, by 1,672 authors, working in 718 institutions in 49 countries, globally. It is shown that, at a given water/cement ratio, in comparison to Portland cement (PC), the use of GGBS results in a reduction in 28-day concrete strength, which increases with GGBS content, at a rate determined by the strength of concrete, GGBS fineness, and curing of concrete. It is also shown that, as to achieve a 28-day design strength, a lower water/cement ratio is required with a PC/GGBS blended cement than PC, this will reduce the actual CO2e savings that can be realised with the use of GGBS as cement constituent in manufacturing concrete. Finally, it is shown that GGBS is more effective in lowering CO2e of concrete than FA and GLS.

scholarly journals Experimental Study of Friction Resistance between Steel and Concrete in Prefabricated Composite Beam with High-Strength Frictional Bolt

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Qi Guo ◽  
Qing-wei Chen ◽  
Ying Xing ◽  
Ya-ning Xu ◽  
Yi Zhu
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Finite Element Model ◽  
Bearing Capacity ◽  
Concrete Strength ◽  
High Strength ◽  
Element Model ◽  
Construction Time ◽  
Friction Behavior ◽  
Friction Resistance

Prefabrication of composites beam reduces the construction time and makes them easily to be assembled, deconstructed, and partially repaired. The use of high-strength frictional bolt shear connectors can greatly enhance the sustainability of infrastructure. However, researches about the concrete-steel friction behavior are very limited. To provide a contribution to this area, 21 tests were conducted to measure the friction coefficient and slip stiffness with different concrete strength, steel strength, and surface treatment of steel. An effective finite element model was developed to investigate the ultimate bearing capacity and load-slip characteristics of bolt shear connection. The accuracy of the proposed finite element model is validated by the tests in this paper. The results demonstrate a positive correlation between concrete strength and friction coefficient and better performance of shot-blasted steel. It is also proved that high-strength frictional bolt has a 30% lower bearing capacity but better strength reserve and antiuplifting than the headed stud.

scholarly journals Effects of microbial agents to the properties of fly ash-based paste

2018 ◽  
Vol 195 ◽  
pp. 01012
Author(s):  
Kiki Dwi Wulandari ◽  
Januarti Jaya Ekaputri ◽  
Triwulan ◽  
Chikako Fujiyama ◽  
Davin H. E. Setiamarga
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Cement Paste ◽  
Construction Material ◽  
Concrete Strength ◽  
Self Healing ◽  
Concrete Mixtures ◽  
Microbial Agents ◽  
Portland Cement Paste ◽  
Geopolymer Paste

Specific microbial agents such as bacteria are often used in concrete to improve its performance. Some microbes act as self-healing agents to close cracks in concrete, and to increase concrete strength. This paper presents a study to observe the effects of microbe addition to two types of concrete mixtures the fly ash-based, as geopolymer paste, and portland cement paste containing fly ash. Furthermore, the investigation was conducted to compare the properties of each paste, such as its compressive strengths, specific gravities, porosity, microstructures, and XRay diffracting properties. The results indicate that microbial activities positively affected the properties of both, portland cement paste and geopolymer paste. The result reported here strongly suggests that fly ash can be used to produce a high quality, but environmental friendly construction material when it’s mixed together with useful microbes.

scholarly journals Influence of various additives on properties of concrete

2020 ◽  
Vol 164 ◽  
pp. 14007
Author(s):  
Zalina Tuskaeva ◽  
Soslan Karyaev
Keyword(s):  
Mechanical Properties ◽  
Water Resistance ◽  
Testing Machine ◽  
Physical And Mechanical Properties ◽  
Air Entrainment ◽  
Strength Characteristics ◽  
Chemical Additives ◽  
Construction Time ◽  
Design Strength ◽  
Multifunctional Additive

A comparative analysis of concrete samples without chemical additives and three concrete samples with additives was carried out The first sample contains the liquid additive, the other two contain the powder additive. The article aims at finding out the effectiveness of additives influence on the physical and mechanical properties of concrete and the basis for the application areas of modified types of concrete. By means of laboratory tests, the physical and mechanical properties of concrete mixtures are determined. To determine the strength characteristics of concrete samples, the IM-1250M testing machine was used. The tests were carried out under the same temperature and humidity conditions. According to the results of the experiments, the samples with the multifunctional additive "D-5" showed the best characteristics of concrete, and the samples with the dolomite flour additive were the cheapest. As a result of the experimental analysis, the effects of three additives on the strength characteristics of concrete and water resistance were determined. Cemplast and D-5 additives are highly effective modifiers of concrete and mortar. They can increase the strength by 20-40% at the age of 28 days at dosages of 1.6-6% with a decrease in water-cement ratio and a decrease of cement amount by 20%. Additives highly increase the workability of the mixture, air entrainment and water resistance. While using the chemical additives an early set of the concrete design strength is observed for the construction time reducing in 7 days.

scholarly journals Technological Indicators of Direct Dumping Zone as a Part of Combined Mining Method

2019 ◽  
Vol 105 ◽  
pp. 01050
Author(s):  
Andrey Sysoev ◽  
Elena Zlobina ◽  
Igor Katanov ◽  
Jurgen Kretschmann
Keyword(s):  
Mathematical Model ◽  
Mining Method ◽  
Transport Costs ◽  
Coal Face ◽  
Mining System ◽  
Bench Height ◽  
Transport Zone ◽  
Subsequent Calculation ◽  
The Cost ◽  
Technical And Economic Indicators

Under the conditions of a combined mining system overburden is developed using a transport and non-transport technologies, specific costs for non-transport technology are lower than transport costs. The change in the non-transport bench height led to the redistribution of the volumes of transport and non-transport overburden. With an increase in the volume of non-transport overburden, the share of more expensive transport overburden is decreases, while the technical and economic indicators of the non-transport zone deteriorate due to an increase in re-excavation volumes. The change in the non-transport bench height affects the recasting ratio and the annual advance coal face line, which determine the cost of developing the overburden. This article presents the results of a study of the laws of change in the recasting ratio and the annual advance coal face line, depending on the non-transport bench height within a combined mining system of flat seam. The obtained patterns were established as a result of solving problems of substantiating typical excavation schemes of the direct dumping method and developing a mathematical model for identifying excavation schemes with the subsequent calculation of their technological indicators.

scholarly journals Understanding Construction Stakeholders’ Experience and Attitudes toward Use of the Structurally Insulated Panels (SIPs) in New Zealand

2019 ◽  
Vol 11 (19) ◽  
pp. 5458 ◽  
Author(s):  
Harris ◽  
Durdyev ◽  
Tokbolat ◽  
Ismail ◽  
Kandymov ◽  
...  
Keyword(s):  
New Zealand ◽  
Current Status ◽  
Common Belief ◽  
Construction Sites ◽  
Construction Time ◽  
Wide Range ◽  
Design Build ◽  
Proper Training ◽  
The Cost ◽  
Time Frames

Abstract: New Zealand faces a housing shortage with construction struggling to meet demand. Structurally insulated panels (SIPs) have been demonstrated internationally as a method of construction which could reduce construction time frames, improve the standard insulation in housing, as well as reduce the amount of waste generated on construction sites. However, anecdotal evidence shows that the SIPs’ adoption is lacking, which is, perhaps, attributed to its industry-wide acceptance level. Thus, in this study, the construction stakeholders, such as architects/designers, builders, territorial authorities and homeowners were targeted to shed light on current status of SIPs use, benefits offered and any barriers inhibiting its industry-wide implementation. This was done through a survey, which was designed to understand the construction stakeholders’ experience levels regarding SIPs use in New Zealand as well as their opinions about any problems associated with the SIPs adoption. Although the stakeholders were happy with the thermal performance offered by SIPs, the results indicate that lack of familiarity and understanding are one of the main barriers to the widespread use of SIPs in New Zealand. Moreover, proper training and clear design information are reported to be crucial to make the building and consenting processes efficient, which will ultimately improve the cost-effectiveness. Despite the barriers (to SIPs adoption) documented by stakeholders, the common belief is that SIPs offer wide-range of benefits to improve performance of the built environment; hence, the stakeholders expressed their willingness to design/build/recommend SIP homes. It is hoped that the findings of this study will guide the industry practitioners in investing their efforts in wider adoption of SIPs in New Zealand.

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