• Journal of the Korea Institute of Building Construction
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• v.13 no.6
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• pp.594-601
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• 2013

One of the important problems associated with building demolition is the dust generated during the work. The only way to reduce the demolition dust is to use a dust net during water spraying. However, it is difficult to supply the necessary amount of water to remove demolition dust, thus making it difficult to apply this method on a demolition site. This work attempted to find an alternative approach to dust removal by incorporating surfactant and high range AE water reducer in the water being sprayed. Through the experiment, it was found that the addition of surfactant did not contribute to the removal of demolition dust. However, the use of high range AE water reducer showed better performance than spraying plain water, indicating that some amount of demolition dust had been adsorbed on the high range AE water reducer.

• Magazine of the Korea Concrete Institute
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• v.15 no.5
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• pp.39-44
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• 2003

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.247-250
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• 2000

As construction technology advances, most of concrete structures are becoming larger and taller. Therefore, high strength and high quality concrete is necessary for them. Nowadays, the proposal of using type IV(belite cement) is investigated to satisfy high flowing, low heat, and ho호 strength. In this study, the flow value and compressive strength of mortar were investigated according to usage of AE high range water reducer. And the slump flow value, falling time and heigth difference of concrete with beilte cement and ordinary cement were examined depending on water cement ratio, sand ratio and unit water weigth, and compressive strength to checked depending on age.

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.111-120
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• 2000

In case of constructing concrete structure under water, generally concrete mixed with antiwashout admixture, high range water reducer, or AE-water reducing agent etc has been manufactured to ensure the quality of antiwashout underwater concrete because of being difficulty in ascertaining construction situation by the naked eye. The properties of high quality antiwashout underwater concrete that were aimed at affluent fluidity, workability and the compressive strength of 450 kgf/$\textrm{cm}^2$ at 28 ages using two types of blended cements are following as;(1) Setting time of antiwashout underwater concretes using blended cements was more greatly delayed than that of control concrete, however, was satisfied with criteria value of "Quality standard specification of antiwashout admixture for concrete".(2) As a test results of slump flow, efflux time and box elevation of head, it was found that workability of high quality antiwashout underwater concrete was improved. (3) Heat evolution amount of OPC was 1.5 times as high as that of two types of bended cements in 72 hours. (4) Suspended solids of antiwashout underwater concrete using blended cements was more than that of control concrete, also compressive strength of high quality antiwashout underwater concrete was very low in early age, but was better than that of control concrete as to increasing ages.

• International Journal of Concrete Structures and Materials
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• v.19 no.1E
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• pp.41-48
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• 2007

Addition of latex to concrete is known to increase its durability and permeability. The purpose of this study is to analyze air void systems in latex-modified concretes using a reasonable and objective method of image analysis with such experimental variables as water-cement (w/c) ratios, latex contents (0%, 15%) and cement types (ordinary portland cement (OPC), high-early strength (HES) cement and very-early strength (VES) cement). The results are analyzed by spacing factor, air volume (content) after hardening, air void distribution and structure. Additionally, air void systems and permeability of latex-modified concrete (LMC) are compared by a correlation analysis. The results are as follows. The LMC of the same w/c ratio showed better air entraining (AE) effect than OPC with AE water reducer. The VES-LMC showed that the quantity of entrained air below $100{\mu}m$ increased more than four times. For the case of HES-LMC, microscopic entrained air between the range of 50 to $500{\mu}m$ increased greater than 7 times even in the absence of anti-foamer. Although spacing factor was measured rather low, the permeability of latex-modified concrete was good. It is construed that air void system does not have a considerable effect on the property of latex-modified concrete, but latex film (membrane) has a definite influence on the durability of LMC.

• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.695-702
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• 2005

It is known that latex-modified concretes were increased their durability and permeability by added latex. The purpose of this study was to analysis the air void systems in latex-modified concretes using a reasonable and objective image analysis method with main experimental variables such as water-cement ratios, latex contents(0%, 15%) and cement types(ordinary portland cement, high-early strength cement and very-early strength cement). The results are analyzed spacing factor, air volume after hardened, air distribution and structure. Also, air void systems and permeability of latex-modified concretes were compared with correlation. The results are as follows; The same w/c ratio LMC showed better air entraining effect than OPC with AE water reducer. The VES-LMC showed that the number of entrained air below $100{\mu}m$ increased more than four times. In the HES-LMC, micro entraining air having range from 50 to $500{\mu}m$ increased above 7 times without antifoamer. Though spacing factor was measured low, latex-modified concretes were showed that permeability was good. It is considered that air void system does not have an effect on the property of latex-modified concretes but latex film is more influenced in the their durability.