• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.352-359
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• 2003

Portland cement concrete (PCC) pavements are more durable and have superior surface friction compared to most dense-graded asphalt. However, data collected to date generally show PCC pavements to create more noise than asphaltic surfaces. Recent research has shown that some of the new concrete pavement textures are worthy of further examination. One of these, exposed aggregate surfaces, appear to provide better noise quality characteristics as well as good frictional characteristics and durability. In this paper, we considered the relationship between noise level and various textures of exposed aggregate concrete (EAC) pavement by tire impact noise measurement. As the results of that, it was suggested that optimum surface texture and manufacturing condition of EAC in order to reduce tire and pavement interaction noise. Conclusively, we would like to recommend optimum condition of EAC pavement at the respects of materials and treatment. Furthermore, Frequency spectrum as well as A-weighted noise level was also evaluated to analyze properties of noise between PCC and EAC.

• Journal of the Korea Concrete Institute
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• v.15 no.3
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• pp.504-511
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• 2003

Environmental noise at high intensities directly affects human health by causing hearing loss. Although scientific evidence currently is not conclusive, noise is suspected of causing or aggravating other diseases. Environmental noise indirectly affects human welfare by interfering with sleep, thought, and conversation. Noise emission from motorized vehicle includes power unit noise, tire/pavement noise and aerodynamic noise. Among them, tire/pavement noise is noise emission from interaction of the tire and road surface when the vehicle cruises over the surface of pavement. In general, portland cement concrete(PCC) pavement is known to create more noise than asphaltic surfaces though it has the advantage of durability and superior surface friction. However, the results of preliminary laboratory test showed exposed aggregate concrete(EAC) has and effect on reducing tire/pavement noise. Based on the laboratory test. pilot construction of exposed aggregate concrete pavement was completed and series of in-situ measurements were conducted for noise analysis including the pass-by noise measurement and the close-proximity method. Conclusively, it is expected that tire/pavement noise represent significant portion of noise levels at higher frequencies and it would be reduced on special textures of pavement such as exposed aggregate concrete.

• Korean Journal of Construction Engineering and Management
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• v.13 no.2
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• pp.48-57
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• 2012

A variety of studies on concrete have been performed to examine the advantages for structural material, but less attention has been paid to the contribution of concrete to finishing. Due to this matter, specific management guidelines for construction and quality on exposed concrete have not been clearly established despite more construction cost and quality control are required. This study analyzed a impact factors on the quality by survey of the existing research and practice. Field tests were performed using mock-up models to analyze the quality of exposed concrete according to form manufacture method, concrete mix proportion, and concrete placing method. Results indicate that the quality of exposed concrete was determined by concrete mix proportion and construction managements. Guidelines of quality control on exposed concrete in construction stages were proposed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.165-167
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• 2011

This study is to evaluate the feasibility of the mix design for exposed concrete. Mock-up sized specimens were prepared, and a flowing concrete method was selected for placement. Results showed that the fluidity and air content of fresh concrete achieved target values, the compressive strength at 7 days was 27 MPa, and surface roughness was in the range of between around 1.53 and 1.68 ㎛, which was in the quality level. Therefore it is concluded that the proposed mix design for exposed concrete can be applied in practice.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.1067-1070
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• 2003

The effects of traffic noise are a serious concern in many urban communities throughout the world. Environmental noise at high intensities directly affects human health by causing hearing loss and indirectly affects human welfare by interfering with sleep, thought, and conversation. In general, portland cement concrete(PCC) pavement is known to create more noise than asphaltic surfaces though it has the advantage of durability and superior surface. However, the results of preliminary laboratory test showed exposed aggregate concrete(EAC) have an effect on reducing traffic noise. Based on the laboratory test, pilot construction of exposed aggregate concrete was performed and series of in-situ measurements were conducted for noise analysis which included the pass-by noise measurement and the close-proximity method. Conclusively, It is expected that tire/pavement noise which is represented much noise levels at higher frequencies would be significantly reduced on special textures of pavement as like exposed aggregate concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.173-174
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• 2014

In this research, the effect of the amount of retarder and the washing timing on the quality of aggregate-exposed concrete produced by water-jet washing method is evaluated as a series of test to develop the aggregate-exposed concrete as a concrete finishing method. As a result, the amount of losing aggregate and surface mortar was increased as the dosage of retarder was increased because of the hydration retarding effect of the retarder. Furthermore, as the washing timing was extended, the mortar on the surface of the concrete was not blown by water jet with 8 to 24 ml of retarder because of hydration of cement, hence the surface quality was poor. Therefore, washing timing of one day after concrete placement showed 90 % of aggregate exposed rate and 24 ml of retarder showed the most favorable result of aggregate exposure.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.555-560
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• 2002

The structure of Chosun-ilbo Boopyung factory was desined as exposed concrete. The self compacting concrete(non-vibrating concrete) must be applied to this case because the exposed concrete wall is very thin(200mm) and high(6m), Laboratory tests and semi mock-up test were performed for optimum mix design of the self compacting concrete. As a result, the optimum mixes were observed at the 3-component types(ope, fly-ash, slag powder) that Vp$\geq$0.175, Vw/Vp$\geq$0.95, W=170~175$kgf/m^3$ and B=500~540$kgf/m^3$ Based on this result. we make plan that the pilot productions of batcher plant, the full-scale mock up tests and site application.

• 레미콘
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• no.7 s.68
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• pp.9-16
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• 2001

Execution of exposed concrete has some problems such as segregation, surface honey comb and insufficient surface flossing due to unsuitable mix proportion and unfavorable construction in our field. Therefore, in this paper, field application of exposed concrete at training center building of Chongju university in Daecheon are carried out based on the mixing data obtained from laboratory test. Base concrete are made in accordance with mixing data. Segregation reducing type superplasticizer developed are applied in order to flow the vase concrete with out segregation of materials. According to test results, air content shows to be reduced after flowing. Compressive strength of flowing concrete is higher than that of base concrete about 7%. Surface glossing is reducing as the age goes on. It is improved about 10% compared to that of vase concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.157-160
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• 2004

If concrete structure is exposed to high temperature such as long-term fire, damages affecting partial or whole structure system may occur. Therefore accurate diagnosis of deterioration is needed based on mechanism of fire deterioration in general concrete structures. Fundamental information and data on the properties of concrete exposed to high temperature are necessary. Especially, the amount of fire damage done to concrete depends on the materials, the standard design compressive strength of concrete, and heated temperature. So, the object of this study is to present data for supposed heated Temperature of deteriorated concrete by fire.

• Magazine of the Korean Society of Agricultural Engineers
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• v.16 no.3
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• pp.3472-3476
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• 1974

This test was attempted to investigate the effects of some mix designs of concreteon the compressive strengths and corrosive rates when exposed to sea water of the West Sea. In this test, concrete mixes consisted of an ordinary concrete, a pozzolan concrete and concretes with different admixtures such as fly ash, pozzolith and vinsol resin. Compressive strengths of the concrete were measured at ages of 1-year and 2-years when exposed to both sea water and fresh water. Corrosive rate was tested at ages of 1-year and 2-years when exposed to sea water only. The results obtained from the test may be summarized as follows: (1) When all of concretes were exposed to fresh water, compressive strength of an ordinary concrete was the lowest at all mixes of concretes, and all of them showed higher strength as the exposing age is longer. It was evidance that the uses of pozsolan cement, fly ash, pozzolith and vinsol resin in mix design of concrete had an effect on increasing compressive strength and that fresh water also had an effect on curing concretes even though at a long-time age. (2) When concretes were exposed sea water, a concrete with fly ash was the highest in compressive strength and its strength was increasing as the exposing age is longer, but the other concretes were decreased at 2-year exposure. It was found that a concrete with fly ash was the most effective on compressive strength of all concrete, but the other concretes were attacked by action of the sea water. (3) The use of vinsol resin admixture was the most resistant to corrosion by sea water, while the use of pozzolith was the most serious at corrosion and the others were corroded to almost same extent. (4) The relationship between corrosions and compressive strengths of concretes was not clearly correlated yet. It was known that the corrosive rate of concretes could not affect to compressive strengths by 2-year exposure of the sea water. (5) Pozzolan concrete was the most effective in compressive strength when exposed to fresh water only, However, the use of a fly ash admixture was available for compressive strength when exposing to both fresh water and sea water. It was also noticed that the use of vinsol resin was not available for strengths of concrete but for resistance to corrosion when exposed to sea water. (6) It was found that the use of pozzolith was so defective in compressive strengths and corrosiive resistance when exposing to sea water that it was only available for fresh water.