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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korea Institute of Building Construction
Journal Basic Information
Journal DOI :
The Korean Institute of Building Construction
Editor in Chief :
Volume & Issues
Volume 8, Issue 6 - Dec 2008
Volume 8, Issue 5 - Oct 2008
Volume 8, Issue 4 - Aug 2008
Volume 8, Issue 3 - Jun 2008
Volume 8, Issue 2 - Apr 2008
Volume 8, Issue 1 - Feb 2008
Selecting the target year
A Study on the Engineering Properties of Ultra High-Strength Concrete Utilizing Crushed Sand
Lee, Sang-Soo ; Rho, Hyoung-Nam ; Song, Ha-Young ;
Journal of the Korea Institute of Building Construction, volume 8, issue 4, 2008, Pages 45~51
DOI : 10.5345/JKIC.2008.8.4.045
Recently, the demand of ultra high-rise building is on the increase in korea due to the rapidly changing movement in economic growth and the expansion of national infrastructure. At the same time, the tendency toward the amount used of concrete has greatly increased every year. In addition, as the seriousness of quantity demanded of aggregate is gathering strength, the active areas of research proceeds to do actively in every place in order to review the usability of crushed sand as a part of the countermeasures. And, it needs to establish the quality standard and service guide, etc. for the practical use. Accordingly, this study was to establish the ratio of water-binder materials as three levels like 23.5, 27.5, and 31.5%, and the replacement ratio as three levels like 0, 50, and 100% in order to define the engineering properties of ultra high-strength concrete using the crushed sand. This study was to examine it after establishing the combined condition by the substitute of the fine aggregate percentage and admixture. From the result of this research above, it may be summed up as follows. 1) The more the replacement ratio of crushed sand and the ratio of water-binder materials increased, the mon the fluidity decreased due to the decrease of irregular grain shape of sand and unit combined discretion. 2) This study found out that 100% of replacement ratio of crushed sand was almost similar level to the compressive strength of concrete using the natural sand.
A Study on the Key Factors Influencing the Reliability of Conceptual cost estimates in Building Construction Projects
An, Sung-Hoon ; Park, U-Yeol ;
Journal of the Korea Institute of Building Construction, volume 8, issue 4, 2008, Pages 53~59
DOI : 10.5345/JKIC.2008.8.4.053
Cost estimates are very important to their decision-making in the early stages of a construction project. So Clients have wanted not only to know the results of conceptual cost estimates but also to assess their quality Conceptual cost estimates process is very complex process, so the results of cost estimates are influenced by various factors. So the purpose of this study is to reveal the key factors which influence the reliability of conceptual cost estimates in building construction projects. The analytic hierarchy process is used to determine the relative important weights of elements influencing the conceptual cost estimates. And factor analysis is used to reveal the key factors from the elements that influence the conceptual cost estimates. The results showed that the key factors is an experience level, available data level, level of will for winning the bid, difficulty level of conceptual cost estimate, uncertainty level.
A Study on the Sub-elements of the Top-down Construction Method Selection Model using Weighting Factor in Downtown Area
Park, Chang-Wook ; Moon, Seung-Yun ; Yun, Seok-Heon ;
Journal of the Korea Institute of Building Construction, volume 8, issue 4, 2008, Pages 61~69
DOI : 10.5345/JKIC.2008.8.4.061
The size of the construction projects become huge and complex, and the depth of excavation for the underground structures become deeper. Also the working area is not enough for loading materials and temporary facilities. This is the most case of recent construction projects in downtown area. Top-down is the most useful method for this kind of construction projects. Top-down construction method consists of supporting method, retaining wall type, foundation type and construction direction such as up-down or up-up. construction managers have to select sub-elements for top-down construction method in planning phase. This study is to suggest the sub-elements selection model for the top-down construction method, and the case study is conducted for evaluating this model.
Development of Core Technology for Object Detection in Excavation Work Using Laser Sensor
Soh, Ji-Yune ; Kim, Min-Woong ; Lee, Jun-Bok ; Han, Choong-Hee ;
Journal of the Korea Institute of Building Construction, volume 8, issue 4, 2008, Pages 71~77
DOI : 10.5345/JKIC.2008.8.4.071
Earthwork is very equipment-intensive task and researches related to automated excavation have been conducted. There is an issue to secure the safety for an automated excavating system. Therefore, this paper focuses on how to improve safety for semi- or fully-automated backhoe excavation. The primary objective of this research is to develop the core technology for automated object detection in excavation work. In order to satisfy the research objective, a diverse sensing technologies are investigated and analysed in terms of functions, durability, and reliability. The authors developed detecting algorithm for the objects using laser sensor and verified its performance by several tests. The results of this study would be the basis for developing the automated object detection system.
A Study on the pH Reduction of Cement Concrete with Various Mixing Conditions
Jo, Young-Kug ;
Journal of the Korea Institute of Building Construction, volume 8, issue 4, 2008, Pages 79~85
DOI : 10.5345/JKIC.2008.8.4.079
The purpose of this study is to evaluate the mix design of pH reducing cement concrete which can be used for environment-friendly concrete. Cement pastes and concretes are prepared with water-binder ratios and various admixtures such as blast-furnace slag, fly ash and recycled cement, and tested for compressive strength and pH. pH is measured through pore solution expressed from hydrated cement paste by special apparatus. From the test results, regardless of water-binder ratio, The pH of expressed pore solution from hydrated cement paste which is made of ordinary portland cement with blast-furnace slag, fly ash is decreased with increasing of admixtures content, and compressive strength is also slightly improved. The compressive strength of cement paste made of recycled cement which is burnt at
, for 2 hours is considerably increased compared with that of none-burnt recycled cement due to restoration of hydraulic property, but pH is a little higher. Porous concrete with ordinary portland cement has high pH in the range of 12.22 to 12.59, however, that is reduced to the range of 8.95 to 10.39 by carbonation at the surface of porous concrete. The pH reduction of porous concrete is possible by various admixture addition, however their degrees are very slight. Therefore, to reduce the pH considerably, carbonation method of porous concrete is better in pH reduction methods for plant survival condition of pH of 9.0 or less. In this study, it is apparent that pH for the environment-friendly porous concrete products used in the construction field can be suppressed by this carbonation method and various admixtures addition.
A Study on the Chemical Admixture According to Target Slump Value by Crushed Sand Replacement Rate
Ryu, Hyun-Gi ; Cho, Myeong-Ken ;
Journal of the Korea Institute of Building Construction, volume 8, issue 4, 2008, Pages 87~93
DOI : 10.5345/JKIC.2008.8.4.087
With an increased use of alternative aggregate due to exhaustion of quality aggregate resources, the amount of used crushed aggregates have been increased and as a result, development of admixture materials has also been improved and its amount of use is increasing from day to day in order to secure quality in concrete. Accordingly, the purpose of this study is to make concrete of good quality by using chemical admixture developed in this study by replacement rate of fine aggregate. At first, susceptibility, compressive strength ratio and length change ratio in both fresh and hardened concrete were evaluated according to corresponding regulation. As for high performance related regulation, APC NO.3 and PC series were going to rule, and as for AE agent regulation, replacement ratio of fine aggregate of high performance chemical admixture was 10:0 and other chemical admixture met quality regulation for AE agent.
Study on the Analysis of Present Situation and Improvement Direction of Construction Safety Empirical Education
An, Yong-Seon ;
Journal of the Korea Institute of Building Construction, volume 8, issue 4, 2008, Pages 95~103
DOI : 10.5345/JKIC.2008.8.4.095
Construction safety should be considered prior to any other factors to execute construction projects smoothly and reduce the social expenses. Especially, the safety education is very important to the lives of labors and to control the four resources such as time, money, quality and safety. On this research, the present situation and related regulations of safety education are reviewed and the education contents and realities of the safety empirical education places are surveyed. Also questionnaire to education lecturers is performed to understand the satisfaction level of the education programs of the education places. Finally, the improvement directions are suggested to inspire trainees based on the results of the research.
A Study for Improvement of the Testing Methods for Quality Control of Recycled Aggregate
Jaung, Jae-Dong ; Lee, Do-Heun ;
Journal of the Korea Institute of Building Construction, volume 8, issue 4, 2008, Pages 105~114
DOI : 10.5345/JKIC.2008.8.4.105
This study investigates the saturation level of surface dryness, quantity of adhesive mortar, and the alien substance content of recycled aggregates for concrete to develop an adequate quality testing method for understanding the properties of recycled aggregates, which differ greatly from preexisting aggregates. For tests that measure the saturation level of surface dryness, where detail methods are applied differently according to the tester, various testing methods from across world were compared and analyzed. This study revealed that when measuring the saturation level of surface dryness of a certain sample, aggregates must be supplemented immediately whenever the height of the sample becomes lower than the measuring mold, and allowing the tamper to free fall on the sample will provide the most accurate results. When measuring the quantity of adhesive mortar of recycled aggregates for concrete, an acid solution was used, and since the quantity of adhesive mortar increases as the particle sizes gets smaller, the sample for testing should represent the entire granularity. Sulfuric acid solution is adequate for immersion, and the concentration should be 20% for best results. According to the alien substance content measurement, which was examined by the naked eye, the error range caused by the difference in particle size was neglectable, and therefore the sample should be
in size concerning the accuracy and measuring time. Also, for coarse recycled aggregates, the sample should amount to 1kg for measuring alien substance content by the naked eye, which proves that assortment by the naked eye is the most adequate method for measuring the alien substance content of a recycled aggregate.
An Effects of the Strength Development of High Strength Mortar under Temperature History by Steam Curing
Kwon, Hee-Sung ; Choi, Eung-Kyu ; Lim, Nam-Ki ; Lee, Young-Do ; Jung, Sang-Jin ;
Journal of the Korea Institute of Building Construction, volume 8, issue 4, 2008, Pages 115~121
DOI : 10.5345/JKIC.2008.8.4.115
The present study performed low-pressure steam curing with mortar specimens in order to examine the temperature profile and strength development of steam curing in high-strength specimens of 100MPa. In addition, as a basic research to utilize PC products, we examined the effects of curing temperature and time in steam curing cycle on strength development resulting from the hydration of cement within the range of high strength by changing four factors affecting the quality of PC displacement time, peak curing temperature, peak temperature duration, and ascending and descending gradient of temperature - in various patterns, and analyzed the optimal strength development characteristic based on the relation between temperature profile and strength development. With regard to the high-temperature curing characteristic of PC, we performed an experiment on the strength characteristic according to the temperature profile of high-strength mortar, and from the results of the experiment according to curing characteristic, displacement time, peak curing temperature, peak temperature duration, and ascending and descending gradient of temperature, we drew conclusions as follows.
Fundamental Study for Establishing the Research and Development Encouragement Strategy in Construction Area
Kim, Kyoon-Tai ;
Journal of the Korea Institute of Building Construction, volume 8, issue 4, 2008, Pages 123~129
DOI : 10.5345/JKIC.2008.8.4.123
The final objective of this study is to establish the research and development (R&D) encouragement strategy in construction area. For this, this study deals with the survey of current status of Korean construction industry. The result of this study is as follow; First, it is necessary for strengthen the R&D infrastructure to establish R&D cooperation system between industry, university, government and public institute. Second, private sector's should do its role as one of the four performing sectors in R&D network, not just assisting role. We will apply the result for establshing the national strategy as basic data.