• Journal of the Korea Institute of Building Construction
• /
• v.7 no.2 s.24
• /
• pp.99-106
• /
• 2007

The purpose of this study presents in Relations between cracks in self-leveling material and quality of floor groundwork surface are experimentally examined. As the first stage, the experiment to observe cracks in self-leveling material constructed on floor groundwork made from various kinds of concrete was carried. As a result, following basic findings were obtained. First, observation of cracks should be continued until an increase in width of cracks stop, without constructing any finishing material. Second, degree of cracks may be indicated quantitatively by the product of length and width. Finally, Cracks and separation is not be influenced by specimen size. Based on these findings, the method of predicting cracks by evaluating surface layer quality of floor groundwork will be established.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2002.11a
• /
• pp.67-76
• /
• 2002

Self-leveling material(SLM) is one of the floor finishing materials which make flat surface like as water level by itself in a short time. So it is possible to increase construction speed and enhance economical efficiency. In this study, author intended to develop SLM for the industrial warehouse and factory loading heavy weight machinery and vehicles. The demanded properties for this type of SLM are above 20mm of flow value and above 300kgf/cm2 of 28-days compressive strength. To possess demended strength and fluidity, SLM have to be composed of many types of binders and chemical additives. So it is difficult to decide suitable mixing proportion of composition materials. In this study, author investigated the weight percentage effect of main composition materials for high-strength self-leveling material, by experimental design such as tables of orthogonal arrays and simplex design, and by statistical analysis such as analysis of variance and analysis of response surface. Variables of experiments were ordinary portland cement(OPC), alumina cement(AC), anhydrous gypsum(AG), lime stone(LS) and sand, and properties of tests were fluidity of fresh state and strength of hardened state. Results of this study are showed that suitable mix proportions of binders for the high strength self-leveling materials are two groups. One is 78~85.5% OPC, 7.5~9.5% AC, 9~12.5% AG and the other is 72.5~78% OPC, 9~12.5% AC, 13~l5% AG.

• Journal of the Korea Institute of Building Construction
• /
• v.7 no.4
• /
• pp.125-132
• /
• 2007

The use of Self-Leveling material is increasing recently. This paper assesses the quality of surface layer of concrete floor when Self-Leveling material is defective. The paper shows how to predict the defect of SL material before construction begins. The relationship between the quality of surface layer of concrete floor and the defect of SL material was determined and the quality of surface layer of concrete floor was then estimated. The relations between the quality of surface layer and the defect of SL material were determine considering surface strength, moisture, and consistency of surface layer. Absorbing amount was used as the indicator of consistency and the absorbing amount of test material was measured. Then the relations between the test material and surface strength were determined. Generally concrete floor with greater consistency has greater surface strength, however in this study, we hound that high impact concrete floor could have lower surface strength as the consistency gets bigger. The relations between the level of defect occurred in SL material and the quality of surface layer were examined and we clarified that the surface layer with lower consistency gets higher possibility to occur exfoliation in early stage, one or two weeks after constructing SL material. When the consistency is sufficient, the occurring situation of defect depends upon the moisture of surface layer. Little amount of moisture gets higher possibility not to occur the defect. As the amount increases, fissure generates and early exfoliation may occur. In addition, the level of fissure is highly related with the surface strength.

• Journal of the Korea Institute of Building Construction
• /
• v.2 no.4
• /
• pp.89-98
• /
• 2002

Self-leveling material(SLM) is one of the floor finishing materials which make flat surface like as water level by itself in a short time. So it is possible to increase construction speed and enhance economical efficiency In this study, author intended to develop SLM for the industrial warehouse and factory loading heavy weight machinery and vehicles. The demanded properties for this type of SLM are above 200mm of flow value and above 300kgf/$cm^2$ of 28-days compressive strength. To possess demended strength and fluidity, SLM have to be composed of many types of binders and chemical additives. So it is difficult to decide suitable mixing proportion of composition materials. In this study, author investigated the weight percentage effect of main composition materials for high-strength self-leveling material, by experimental design such as tables of orthogonal arrays and simplex design, and by statistical analysis such as analysis of variance and analysis of response surface. Variables of experiments were ordinary Portland cement(OPC), alumina cement(AC), anhydrous gypsum(AG), lime stone(LS) and sand, and properties of tests were fluidity of fresh state and strength of hardened state. Results of this study are showed that suitable mix proportions of binders for the high strength self-leveling materials are two groups. One is 78~85.5% OPC, 7.5~9.5% AC, 9~12.5% AG and the other is 72.5~78% OPC, 9~12.5% AC, 13~15% AG.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05b
• /
• pp.505-508
• /
• 2006

Self-leveling mortar is walkable bottom mortar which can maintain the horizontality of self fluid and have the the quick-setting quality, the low-human-effort practicable material of high-quality bottom in construction. In accordance with more adhesive strength with bottom side and absorption control, Primer is used for purpose to prevent pin-hole occurrence by self leveling mortar application prior to construction. This study is composed measurement of absorption, adhesive strength. Used material is NP-40 as nonionic emulsifying agent, uses SA-210L as negative ion emulsifying agent, uses APS, SBS as ridical initiator. A result of test, in accordance with image of Primer, as low temperature and application frequency, indicates low absorption rate and adhesive strength, as solid powder and dryness time is increse, absorption rate and adhesive strength lowly shows figure.

• Journal of the Korean GEO-environmental Society
• /
• v.10 no.5
• /
• pp.11-18
• /
• 2009

When underground pipe is installed, backfill materials need proper compaction. But in case of circular underground pipe, compaction of backfill material is difficult and compaction efficiency is poor at beloe the pipe. It caused the stability of underground pipe is reduced and various damages occurred. One of the solutions to solve this problem for underground pipe is to use controlled low strength material (CLSM). CLSM is made by concept of low strength concrete, which is applied to geotechnical engineering field. The representative characteristics of CLSM are self-leveling, self-compacting and flowability. In addition, its strength can be controlled and its construction method is simple. The behavior of underground pipe was investigated by finite element analysis for various backfill materials under same condition. As a result, in case of using the CLSM as backfill material, surface settlement and displacement of pipe are reduced comparing with those in case of using field soil or sand.

• Nuclear Engineering and Technology
• /
• v.45 no.3
• /
• pp.323-334
• /
• 2013

During a hypothetical core-disruptive accident (CDA) in a sodium-cooled fast reactor (SFR), degraded core materials can form roughly conically-shaped debris beds over the core-support structure and/or in the lower inlet plenum of the reactor vessel from rapid quenching and fragmentation of the core material pool. However, coolant boiling may ultimately lead to leveling of the debris bed, which is crucial to the relocation of the molten core and heat-removal capability of the debris bed. To clarify the mechanisms underlying this self-leveling behavior, a large number of experiments were performed within a variety of conditions in recent years, under the constructive collaboration between the Japan Atomic Energy Agency (JAEA) and Kyushu University (Japan). The present contribution synthesizes and gives detailed comparative analyses of those experiments. Effects of various experimental parameters that may have potential influence on the leveling process, such as boiling mode, particle size, particle density, particle shape, bubbling rate, water depth and column geometry, were investigated, thus giving a large palette of favorable data for the better understanding of CDAs, and improved verifications of computer models developed in advanced fast reactor safety analysis codes.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2010.03a
• /
• pp.338-350
• /
• 2010

As existing materials for ground reinforcement, chemical grout material using cementitous materials and waterglass was used. But many problems in terms of ground reinforcement effects were implicated. In this study, for development and applicability verification of new materials, viscosity, fluidity, permeability, Self-Leveling, keeping of drilled hole, antiwashout underwater, resistance of water (groundwater dilution and minimize material eluting) and the early strength and long-term strength characteristics of developed materials was confirmed, and material standards, and establishing construction standards for the various model tests were conducted. As a result, high viscosity, flowability, permeability and keeping of drilled hole characteristics are excellent, in addition to the early strength properties, dilution does nat occur to groundwater, including groundwater is available for dealing with environmental issues. Application of basic and reinforcement method by Filler function in addition to structure can also or development of a new concept can be expected. In addition, middle and large-diameter drilled shaft, micropile, ground anchors, soil-nailing, steel pipes multi-grouting reinforcement for cement injection process could be used enough to even be considered.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2011.05b
• /
• pp.105-109
• /
• 2011

This study is concerned with the development of the SL inorganic floor covering. First, volatile organic compounds, inorganic test profile on the SL through the flooring is environment-friendly inorganic noncombustible floor finishes the event of fire toxic gases (such as volatile organic compounds) emissions have been identified as not at all. Second, SL-breathable material, the concrete floor to prevent aging, long life, which are three levels of noise, shock-absorbing function was decreased. Third, SL economic analysis of mineral flooring terrazzo tile floors compared with the normal material. On a terrazzo tile cost 13,500 won ~ 24,500 won, but It have found that, in terms of labor SL 36,899 won ~ 38,899 won flooring mineral balance. Occurs in the total amount when compared with terrazzo tile floors and 25,399 won 3T, 5T and economical analysis concludes that the original 12,399 won.

• Journal of the Korea Institute of Building Construction
• /
• v.18 no.1
• /
• pp.41-49
• /
• 2018

The purpose of this study is to develop a floor mortar construction technique which has high strength and inherent mechanical properties and does not cause cracks due to shrinkage after construction. It has been demonstrated that compressive strength, bending strength, flow with floor mortar, and crack reduction performance. As a result, it was confirmed that the developed floor mortar had the same or better performance comparing with the existing foreign products. The results of this experiment can be used as a validation material for high performance and high flowable mortar construction technology with excellent material performance, economical efficiency and construction ability by securing the required performance as floor mortar and selecting the optimal formulation.