Proceedings of the Korean Institute of Building Construction Conference (한국건축시공학회:학술대회논문집)
The Korean Institute of Building Construction
- Semi Annual
Domain
- Construction/Transportation > Construction Engineering/Materials/Management
2007.04a
-
This study investigated the applicability of insulation curing method with double layer bubble sheets to the man concrete subjected to cold weather. Temperature history of the mass concrete indicated that the highest temperature of center section was exhibited at
$34^{\circ}C$ while the that of surface section was$25^{\circ}C$ . Difference between center and surface was shown to be less$10^{\circ}C$ when the temperature of center section was peak section, and thereby associated temperature cracking index was calculated 1.5, and occurrence probability of temperature cracking was 5%, so there was no temperature cracking caused by internal restraint. No temperature crack was observed by naked eye. It was clear that early frost demage and temperature cracking could be restrained due to reducing temperature difference between inner part and outside in the case double bubble sheets applied to insulation curing method in cold weather. The maturity of mass concrete is higher than outside about$72\sim89^{\circ}$ DD, so it was demonstrated to prevent early frost demage and ensure strength excellently. Insulation curing method with double bubble sheets was more economic than heating curing method. -
Selection of proper root barrier as destination part of greening is very important in Root penetration resistance plan. To select proper root barrier, it need to understand composition of greening part, size, kind of plant, connection with waterproofing layer. In this point of view, we have establish greening on the roof or concrete structure, not been understand the structural mechanism. It means that we misunderstood about purpose of greening and using it. So, chosen materials and construction method was not proper for greening, it caused water leakage and decrease performance of concrete structure. Therefore, we examine the practical use of copper sheet considering environmental condition for green roof. Watertightness by water of greening part, root penetration resistance test by root penetration, bacteria resistance by must or bacteria in soil, chemical resistance by rain and chemical agent of fertilizer, and load resistance by soil depth, sire of plant. These suggested test methods could be referred as guideline to test in green roof system because of not exist any performance appraisal guideline or standard. Consequently, it should be analysis as technical and institutional subdividing test methods and it need to study constantly as varied angles.
-
Recently, research and development related to high strength concrete for the high rise and large scale reinforced concrete building has been actively promoted in worldwide by national and private research project. But, it is reported that violent explosive explosion would be happened when it was exposed in fire. In the existed study, a explosion in a reinforced concrete structure looses the organism by the different contraction and expansion of hardened cement paste and aggregate, and causes crack by thermal stress. In case of the Europe, Japan and America, they have studied the explosion for a long time. However it would hardly study the explosion in domestic, So it is needed base on mechanical properties of fire deterioration in high strength concrete. Therefore, this study is intend as an mechanical properties of specimen to high heating by heating and load test machine and
$700^{\circ}C$ . As a result, it is willing to propose fundamental data for quick and accurate diagnosis of deteriorated concrete structure by fire damage with experiment according to the design high strength concrete. -
The green roof industry have been developed with Europe, North America, Japan. At the same time, being recognized the important of green roofs in domestic industry and we just start to develop the relative technology as analyzing the future direction of advanced technology. Recently, local self-government including Seoul support the system for green roof which provide 50% of working expenses form of Matching Fund by Seed Money. As years go by, the number of build up the green roof has gradually increased to be proved. At this result caused by management of system in government, unstructured construction system, low development of support technology. In this study as analyzing the present of technical development, supporting by law and system for the advanced waterproofing and root penetration resistance technology, we suggest the development direction of it to be compared with application advanced technology and we could strengthen the international competitiveness to be industrialized the green roof considering system, technology, human infrastructure.
-
In this paper, the period for the strength correction was determined with each region of south Korea based on the meteorological data of KMA(Korea meteorological administration) by applying KASS-5 regulation. In case of 28 days of strength control age, the period for strength correction with 6MPa was calculated to 50-60 days and, with 3 MPa. to around 80 days. The period for the strength correction was shown to be decreased with the rise of altitude. The period to consider the delay of the strength development due to low temperature including the period of cold weather concrete was nearly 7 months around 1 year. References for determining the strength correction factors with each region of south Korea was provided in this paper.
-
In this study we measured the changes according to time respectively on the basis of 0, 30, 60 and 90 minutes, taking into consideration the decline in fluidity of concrete according to elapsed time to analyze manufacturing capability of batcher plant according to elapsed time of ready-mixed concrete manufactured in batcher plant, and offer basic data for mixture design of ultra-high strength concrete. The proportion of water-binder was 23.55, water content was 160kg/m3, proportion of replacement of crushed sand was 0, 20 and 40% at 3 level, and we applied to the same condition of triaxial component using blast furnace slag powder and silica fume as admixture. And to meet the demand of certain fluidity, we measured respectively on property before and after hardening of ultra-high strength concrete using superplasticizer. As a result of experiment, before hardening of ultra-high strength concrete showed the best fluidity in conditions of crushed sand replacement rates of 20% and superplasticizer composition of 1.95%, but it appeared that fluidity drops as time goes by in the same composition condition. And it appeared that when it comes to hardened, the changes of compression strength according to elapsed time by crushed sand replacement rates were within 1MPa. Therefore, it turned out that the difference of strength according to elapsed time was low and compression strength of 280dys in composition mentioned above appeared highly as 88MPa.
-
Building construction in downtown is ever increasing with a strong demand. Top-Down Method is one of suitable construction method for its advantage in minimizing disturbance to neighborhood. Along with these reasons construction site has developed lots of new methods and materials for Time-Cost Trade-off and improving constructability. Opened Slab is one of these method which resist the horizontal force by slab and it has many merit about construction time and unity. We analyze the compression tests on opened slab for the application.
-
In order to select the optimum mix for the required fluidity and strength of mass concrete which is applied to transfer girder and to choose the optimum curing method depending on circumstances through hydration heat analysis of mass concrete, this study examined slump flow, air content and elapsed variation (0, 30, 60, 90) in unhardened concrete properties and reviewed compressive strength characteristics in hardening properties. And hydration heat analysis results through simulation are as follows; 1) Fluidity changes of unhardened concrete showed no significant difference, and those of elapsed variation also showed no difference but a bit of tendency to increase in comparison with the initial properties. 2) The higher the water-binder ratio was, the lower the compressive strength properties were, and the higher the fly ash replacement rate was, the lower the compressive strength development was. 3) In case of
$Fc=40N/mm^2$ , the optimum mix was fly ash replacement rate of 15% from water-binder ratio of 33.0%. 4) Hydration heat analysis results showed that in case of bundle cast, concrete temperature profile characteristics around transfer girder was unfavorable, and in case of separate cast, constant curing for at least seven days guaranteed thermal cracking index of 1.2. -
As a demand for underground structure is increasing with more parking and retail spaces required. Various construction methods are reviewed and selected for each specific site for economical and fast construction. In this study, factors for selecting construction methods were categorized for substructure construction. Construction processes of substructure are consisted of methods for excavation, earth retaining systems, and placement of slabs. Factors for the selection of substructure construction method are the condition of surrounding, geotechnical, information and constraint by comfortness for others nearby. After survey for the construction data of 5 different sites, analysis about reliable substructure construction selection method was suggested.
-
This study dealt with the influence of the replacement ratio of rapidly-chilled steel slag on fluidity and compressive strength of unsaturated polyester polymer concretes. The rapidly-chilled steel slag used in this study, a by-product which is produced by refining pig iron during the manufacture of steel, was controled by a air-jet method which rapidly cools substance melted at a high temperature. Experimental results show that fluidity and compressive strength of unsaturated polyester polymer concretes increase with increasing replacement ratio of rapidly-chilled steel slag. Use of rapidly-chilled steel slag was found to be effective for improving fluidity and compressive strength of rapidly-chilled steel slag.
-
This study investigates the properties of light weight foamed concrete (LWC) designed with various content of fine grains (FG). Test showed that LWC containing diverse powder materials with addition, more than 15% of FG, tended to decrease the fluidity of fresh concrete. 10% of FG content in LWC exhibited 4mm in sinking depth, which is the lowest value. This value dramatically increased at more than 15% of addition. However the concrete incorporating LSP proportionally increased the sinking depth in overall. As for the strength, the values of all specimens were under standardization of KS, except for the concrete adding 5 and 10% of FG. Apparent density of LWC showed the lowest value when used 10% of FG which was satisfied the 0.5 grade in KS. For the thermal conductivity, it was also indicated at 0.5 grade in KS, which is under
$0.160W/(m{\cdot}k)$ . In conclusion, it is demonstrated that adding 10% of FG in LWC was effective in the aspects of recycling of materials, cost effectiveness and quality. -
This study investigates the properties of paste and mortar from different types and forms of silica fume on cement binder for ultra high strength. Although most Silica Fumes distributed in the market fulfill the KS quality standard, each type showed different levels of loss of ignition. When evaluating cement binder for ultra high strength in a form of paste. Flow, viscosity and moving freely time show great difference depending on the Silica Fume's form and type of primary particle's dispersibility. The evaluation of Silica Fume's dispersibility can be possible with the paste test since there is a high correlation of flow quality between paste and mortar. The compressive strength when using Silica Fume was correlated to the SiO2 content. Synthetically, selecting Silica Fume with the most the ideal primary particle is the key to optimizing the formation for cement binder for ultra high strength.
-
Song, Yong-Won;Heo, Young-Sun;Lee, Seong-Yeun;Hann, Chang-Pyung;Yang, Seong-Hwan;Han, Cheon-Goo 55
This study investigates the spatting properties of high strength concrete,$60\sim80MPa$ class, designed with diverse aspect ratios and fiber content of nylon(NY). Test showed that increase of fiber content and aspect ratio in concrete decreased the fluidity of fresh concrete, especially for 1580 and 3000 aspect ratio of fiber. As for the compressive and tensile strength, adding NY fiber did not significantly affect the values In the range of high strength. After completing the fire test, the specimens containing both 750 and 1000 aspect ratios of fiber protected the spatting occurrence even in 0.05vol.% of fiber content. This specimens indicated the residual compressive strength ratio at 37%, showing the most favorable value among other specimens. Therefore, it is demonstrated that to protect the spalling in high strength concrete considering the effective fluidity, strength and economic efficiency altogether, adding 0.05vol.% of NY fiber with 750 aspect ratio Is beneficial. -
Nowadays, polymer-cement mortars are widely used in construction field(floorings and pavements, water-proofings, adhesives, repair materials, deck coverings, anti-corrosive linings) Because of excellent performance such as high tensile and flexural strength, waterproofness, excellent adhesion, good durability, improved wear and chemical resistances. This article presents the results of experimental study that investigates the effect of ambient temperature on the strength properties of polymer-modified cement mortar. Results show that when increasing the polymer proportion in mortar on different ambient temperature, the compressive strength and flexural strength are decreased, and also alkali resistance is decreased.
-
This study investigates the fire resistance properties of high strength concrete, around 60MPa class, designed with various admixture types and fiber content. Test showed that the increase of fiber content decreased the fluidity and slightly inclined the air content of fresh concrete. However, the fiber content in concrete did not affect the compressive strength. For the addition of admixture, specimens adding the shrinkage-reducing-agent (SR) indicated the strength value at 70MPa, which is followed by incorporating silica fume (SF) at 66MPa, the combination of expansive admixture (EA) and SR at 63MPa, only EA at 59MPa, blast furnace slag (BS) at 58MPa and fly ash (FA) at 50MPa in an order. After completing the fire test, all specimens adding 0.05vol.% of polypropylene fiber exhibited protection of spatting, except for the specimens incorporating loft of SF and incorporating 20% of SF with only SR and the combination of EP and SRA, respectively. Therefore the most effective result of this study was shown in the specimens incorporating love of FA and 30% of BS and incorporating 20% of SF with 5 % of EA. It is expected that this test results will be crucial references in near future to develope the spatting resistance method of high strength concrete.
-
As construction industry is requiring competitive power and technique in national construction market with rapid fluctuation of construction environment and development, requirements upgrading performance in construction materials are increasing. But, national lightweight aggregate and lightweight concrete's inappropriateness when produced are also increasing. And there are not international standard of aggregates in using these construction materials because standards and characteristics of aggregate in each countries are different. Therefore, in this study, lightweight aggregate acquired due to wide range of use is tested and mixed for concrete to gain practicality and set the authorized manual in international. Also, basic data will be proposed to set a standard for concrete by analyzing lightweight aggregate characteristics. When lightweight aggregate absorptivity is high, concrete shows low strength and when it's density is low, concrete shows low weight of unit volume. Furthermore, compressive strength of lightweight aggregate is steep in first and longtime material age is tendency to cause low strength increasing rate.
-
This study investigates the fundamental properties of high strength concrete made with various blame values of cement, manufactured by the particle screening method in a pulverizing process. Test showed that concrete using lower blame of cement, such as large particle (L) and both ordinary and large particle (OL), increased the fluidity of fresh concrete. As tine progressive, it was noticeable that the specimens using ordinary cement (OPC) gradually decreased the fluidity, but the other specimens showed the sudden decline until 30 minutes, which is followed by a gradual decrease after 60 minutes. For the setting time, higher blaine of cement accelerated the initial and final setting time, especially concrete using minute size of cement (M) was 10 hours faster than OPC. Compressive strength of L exhibited similar value at 1 days as to that of strength in OPC at 3 days. Importantly, the specimens using M also revealed the similar strength value, regardless of curing temperature between
$-5^{\circ}C$ and$20^{\circ}C$ , which means that using this minute particle of cement in concrete can secure the strength development even in the lower temperature circumstance. Therefore it is clear that using OPC+M simultaneously at cold weather concreting can resist the early frost and develop the early strength of concrete. -
The recycling program about waste concrete is being progressed to national research. But research on waste concrete powder which is occurred in control process of concrete powder is not enough. Waste concrete powder includes in
$SiO_2,\;Al_2O_3$ , and CaO so that the create of tobermorite is possibile through Hydrothermal Syntesis Reaction. Tobermorite have an advantage of high strength, sulphuric acid resistance and the lower drying shrinkage. Accordingly, this study investigate in properties of light-weight foamed concrete made with waste concrete powder. As a results, light-weight foamed concrete made with waste concrete powder is the higher than stone powder sludge of density and porosity, and the tower compressive strength. Therefore, it is thought that light-weight foamed concrete using waste concrete powder is possible. -
PMIS (Project Management Information System) has been applied in the R4-PROJECT This construction project has been controlled and managed by PMIS for the whole process of project. Moreover, this PMIS is updated to the Self-regulation System for Quality and Safety Management which is integrated and developed from PMIS in R4-PROJECT. So, The Self-regulation System for Quality and Safety Management has been delivering effective communication and information distribution with various stakeholders related to project and also brought the achievement of efficient construction management. As the system is successfully utilize, the satisfaction of costumer request and the performance of no accident for 550 million hours could be attained.
-
Since 1960s, advanced constructions have introduced warranty contract which is warranted to quality and performance for need of owner in determined term to ensure the quality of construction. However, the interior of a country encounter another problem result from Defects Liability what indefiniteness of defects standard, excess responsibility period, social recognition of be identical fraudulent work and defects, and contract with ascendancy of owners. etc, so builders concerned more excess defects liability than the quality of construction. The purpose of this study is to analysis of warranty contract in order to solve the problem such as stated above.
-
Steel structure construction is the construction method which is plentifully used with reason of air shortening or the earthquake-proof efficiency improvement back. It is caused by with the feature which is a shop fabrication, it is more accurate than ferroconcrete construction when is a possibility of doing a materials supply and a crane work. From the research which it sees The instance analysis which uses the RFID it leads, A study is proposed an improvement plan of the RFID technology and an application plan of GPS.
-
Recently, A demand on productivity improvement has required innovation of construction industry more than fast with a economy condition. A RFID is technology that can be effectively applied at the administration of physical distribution, labor, construction progress, etc at construction industry. Therefore, At this paper, A survey of staffs that work at construction site is practised to study application possibility of RFID technology at construction industry. It shows use possibility through a survey that investigated Recognition and application, etc at construction site. RFID technology is connected with other technologies by being based on this study construction industry will be advanced.
-
As the proportion of underground construction increases, the impact of inappropriate selection of a underground construction method for a construction size increases. The purpose of this study is to develop an objective way of selecting an excavation method. There have been several attempts to achieve the same goal using various data mining methods such as the artificial neural network, the support vector machine, and the case-based reasoning. However, they focused only on the selection of a retaining wall construction method out of six types of retaining walls. When we categorized an underground construction work into four groups and added more number of independent variables (i.e., more number of construction methods), the predictability decreased. As an alternative, we developed a decision tree by analyzing 25 earthwork cases with detailed information. We implemented the developed decision tree as a computer-supported program called Dr. underground and are still in the process of validating and revising the decision tree. This study is still in a preliminary stage and will be improved by collecting and analyzing more cases.
-
Construction Automation must be founded on the Construction Robot Technology. And Construction Automation is definitely different from Construction Mechanization. This study includes the survey of the thoughts of domestic construction company officer about introducing Construction Robot into domestic construction industry, and the thoughts of recognition related to the Construction Automation currently international trend in construction industry.
-
As buildings become higher, larger, and more complex, safety issues for construction workers working at such environments become more important. We analyzed 140 critical accident cases reported to the KOSHA(Korea Occupational Safety & Health Agency) for construction cranes and lifts by types of cranes and by patterns of accidents and causes. By finding out the accident's types and causes, we expect to develop an efficient measure for preventing similar accidents in the near future. The cases will be studied further and reexamined using the FMEA(Failure Mode and Effect Analysis) as a quantitative analysis method.
-
Now a performance process of Demolition works is 'Before-Removal & After-Classification' method in Korea. This method is short of demolition time, but construction wastes contained substances lower recycling rate of construction, raise expenses of reclamation & treatment. Then the government has decided upon a positive 'Before-Classification & After-Removal' method, and substantially raise a recycling rate of construction wastes. Therefore, this study makes an investigation into state of internal and external demolition field through evaluating technological level, we make a proposal of dismantling method from there. Also, we put dismantling to the test in an apartment by proposed work process. As the result, it made a term of works increased for removing interior material. To solve this problem, we need to develop tools and methods of construction that can remove efficiently. From now on, we continuously need to study a breakdown system of dismantling, analysis of dismantling process and general system by inspecting entire demolition process. And we have to study details for making a specific thesis of method of removing interior material which was based on developing a suitable partial demolition machine and dismantling works.
-
The purpose of this study is to propose development of Schedule based Architectural Construction Simulation System. In this study (or paper), It analyzes the simulation system concept and its characteristics, and analyze the main functions simulation system and the range of functions which are already used currently. Therefore, It could find the limit of the present simulation system, and propose more effective solutions to develop Schedule based Architectural Construction Simulation System.
-
The problem of water leakage due to damaging waterproof in concrete structure, causes the impediment in a long term and shortened the life span of durability. There are a lot of techniques for repair and reinforcement to improve using environment. However, the improper construction which is unconsidered various environmental conditions, could effect to increase the maintenance expenses. Therefore, this study will be compared and estimated the adhesion liquid and sheet integrate waterproofing material, as analyzing the existing problem. For those result, we would like to arrange the alterative plan for the long durability and user needs of concrete structure.
-
In this study, for the establishment of the performance evaluation methods of repair material and method for reinforced concrete structure and the quality control standards of durability recovery method, the quantitative exposure data by exposure experiment under the coastal and normal atmosphere environment is accumulated and analyzed. Investigating and evaluating the result of exposure experiment during 54 months of exposure age under the coastal and normal atmosphere environment, Micro crack, swelling and spatting of surface coating material, crack of repair boundary parts and the great potential difference between repair part and non-repair part were somewhat generated. And the result shown that exposure specimen of coastal environment had lower electrode potential than exposure specimen of normal atmosphere environment.
-
It has been applied the self adhesion waterproofing sheet which is developed from exist asphalt waterproofing sheet by heat and torch in domestic construction field. However, the problem of waterproofing have constantly happened due to air pocket condition and defect of joint part in waterproofing construction. Therefore, in this study, we would like to analyze the field application as testing in side of materials and construction method of self adhesion butyl rubber sheet and study of the materials performance.
-
Recently, the research on durability of concrete proceed rapidly in the building industry. Deterioration due to do-icing salts occurs in practice in bridge structure, dike, barrier and similar structure. This paper reports the results of effect of chlorides on the freeze-thaw properties of concrete bridge deck in winter. The case fresh water condition where the concrete will receives a freez-thaw effect compared to decrease of durability quotient a lot occurs is a possibility of knowing from brine condition.
-
The part in the structure that is most affected by changes of external temperature is the protective concrete layer that protects a waterproofing layer. Also, the waterproofing layer that is situated under or on the back of such a protective concrete layer is affected by temperature and the behavior of the protective concrete layer under the condition of consolidation or close adhesion. In particular, in many cases, the damage is serious mainly around the projection (such as a parapet), crack, and joint (expansion joint). However, there is no proper way of examining again the non-exposed waterproofing layer once it has been constructed. Therefore, there is an assessment only on the physical property of materials and the capability of the layer in construction, and there is no actual assessment in consideration of its environmental condition or the condition of the use of buildings after construction. Therefore, in order to create more pleasant buildings and to enhance the durability of structures, this study conducts research into the change of capability of non-exposed waterproofing material after the application of a static load and moving load on the waterproofing layer situated under or on the back of protective concrete.
-
As recent buildings often use low-quality concrete materials, are constructed defectively, and are put in extreme environmental conditions, many of them show the shortening of life resulting from the corrosion of reinforcing rods by salt damage, carbonization, freezing and thawing, cracking. This in turn raises the cost of repair and maintenance, so it is required to extend the life of structures through enhancing the durability of concrete. In response to the demand, researches on high-durability concrete are being made actively focused on the maximum water-cement ratio, the maximum unit quantity, the minimum cover thickness, the addition of mineral admixtures, etc. With this background, the present study examined the basic physical properties of concrete containing admixtures for enhancing the durability of concrete.
-
To build up the green roofs, it must not adverse effect to durability and structural safety. That is conducted by safety system which consist of waterproofing to form basically, root barrier to protect the waterproofing. The reason why root barrier form is to protect the penetration force of root growth and the root could penetrate concrete surface, move inward so far. It may cause shorten the life span on concrete structure. For this problem, government constantly demand the solution to form the root barrier for waterproofing and concrete structure before the building is service. However, the technical action is not fully prepared. Therefore, in this study, we would like to suggest the workability and suitability of the copper plate to solve not only the side of waterproofing but also root barrier for green roof system and exhibit the mechanism for root penetration resistance and corrosion resistance.
-
The construction industry kept lower level of the technology and productivity improvement than any other kinds of industry. But in most analysis of previous construction work which promoted the productivity of construction, the analysis process has only developed by the economical efficiency or the time studies through work sampling in construction field, So We suggest motion analysis as a tool to solve these problems. Spacially, this study find out productivity improvement method of steel frame fabrication works with using motion analysis. If the result of this study were to be applied to the actual construction field, it will be of great help for Building Construction Automation.
-
We studied the example of various side on effect the aging of exterior materials for concrete structure by analyzing the reason of water leakage in exist serviced skyscraper apartment. For this side, we would like to suggest the proper waterproofing materials and construction methods resulted in the mechanical performance test. So, it could be ensured the leakage safety for using residence facility and crowd utilization after repairing. It may maximize the durability for the concrete structure.