• Journal of Soil and Groundwater Environment
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• v.9 no.4
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• pp.15-23
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• 2004

Deicer operations provide traffic safety during winter driving conditions in urban areas. Using large quantities of de-icing chemicals (i.e., $CaCl_2$ and NaCl) can cause serious environmental problems and may change behaviors of heavy metals in roadside sediments, resulting in an increase in mobilization of heavy metals due to complexation of heavy metals with chloride ions. To examine effect of de-icing salt concentration on the leaching behaviors and mobility of heavy metals (cadmium, zinc, copper, lead, arsenic, nickel, chromium, cobalt, manganese, and iron), leaching experiments were conducted on roadside sediments collected from Seoul city using de-icing salt solutions having various concentrations (0.01-5.0M). Results indicate that zinc, copper, and manganese in roadside sediments were easily mobilized, whereas chromium and cobalt remain strongly fixed. The zinc, copper and manganese concentrations measured in the leaching experiments were relatively high. De-icing salts can cause a decrease in partitioning between adsorbed (or precipitated) and dissolved metals, resulting in an increase in concentrations of dissolved metals in salt laden snowmelt. As a result, run-off water quality can be degraded. The de-icing salt applied on the road surface also lead to infiltration and contamination of heavy metal to groundwater.

• Polymer(Korea)
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• v.33 no.4
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• pp.342-346
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• 2009

The effects of the monomer ratios on the typical properties of polymer modified mortars that contain styrene and butyl acrylate latexes was investigated. Basic data was also obtained that is necessary for the development of appropriate latexes for cement modifiers. Polymer modified mortars that contain styrene and butyl acrylate latexes polymerized with various monomer ratios were prepared for different polymer-cement ratios. They were then tested to obtain the particle size of the polymer latexes, air contents, water-cement ratios, flexural and compressive strengths, water absorption, and chloride-ion penetration. From the test results, the polymer modified mortars that have styrene and butyl acrylate latexes (with the mix proportions of synthesis having monomer ratios of between 40:60 to 60:40 for the appropriate mix proportions) could be recommended for practical applications. The basic properties of the polymer modified mortars were more affected by the polymer-cement ratio than by the monomer ratio, and were improved over unmodified mortar.

• Polymer(Korea)
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• v.32 no.6
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• pp.603-609
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• 2008

The purpose of this study is to clarify the effect of the monomer ratio on properties of the polymer-modified mortars using methyl methacrylate-butyl acrylate (MMA/BA) latexes, and to obtain basic data necessary to develop appropriate latexes for cement modifiers. From the test results, the total pore volume of polymer-modified mortars using MMA/BA latexes is linearly reduced with an increase in the bound MMA content and increased in the polymer-cement ratio. In general, the superior flexural and compressive strength of polymer-modified mortars using MMA/BA latexes is obtained at a bound MMA content of 70 or 80 percent and a polymer-cement ratio of 15%. And, the water absorption and chloride ion penetration depth are greatly affected by the polymer-cement ratio rather than the bound MMA content.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.375-381
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• 2017

Recently, due to the increasing of interest about the eco-friendly concrete, it is being increased to use concretes containing by-products of industry such as fly ash, ground granulated blast furnace slag, silica fume, and etc. Especially, these are well known for improving the resistance to reinforcement corrosion in concrete and decreasing chloride ion penetration. The purpose of this experimental research is to evaluate the resistance to corrosion of reinforcement and critical chloride content of high volume fly ash concrete(HVFAC) which is replaced with fly ash for approximately 50% cement content. For this purpose, corrosion monitoring of reinforcement by half cell potential method was carried out for the cylindrical test specimens that the upper of reinforcement in concrete was exposed to detect the time of corrosion initiation for reinforcement. It was observed from the test result that the the time of corrosion initiation for reinforcement of HVFAC by the accelerated corrosion tests increased 1.2~1.3 times than plain concrete and the critical chloride contents of plain concrete and HVFAC were found to range $0.80{\sim}1.20kg/m^3$, $0.89{\sim}1.60kg/m^3$, respectively.

• Journal of the Korea Concrete Institute
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• v.18 no.6 s.96
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• pp.785-791
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• 2006

The purpose of this study is to clarify the effect of the monomer ratio on properties of the polymer-modified mortars based on styrene and butyl acrylate latexes, and to obtain basic data necessary to develop appropriate latexes for cement modifiers. This paper deals with the effects of monomer ratio on the typical properties of the polymer-modified mortars with styrene and butyl acrylate latexes. The polymer-modified mortars using the styrene and butyl acrylate latexes polymerized with various monomer ratios are prepared with different polymer-cement ratios, and tested for the particle size of polymer latexes, air contents, water-cement ratios, flexural and compressive strengths, water absorption, and chloride-ion penetration. From the test results, the polymer-modified mortars using styrene and butyl acrylate latexes with the mix proportions of synthesis having monomer ratios of 50:50 to 60:40 for the appropriate mix proportions can be recommended for practical applications. Their basic properties are greatly affected by the polymer-cement ratio rather than the monomer ratio, and are improved over un-modified mortar.

• Journal of the Korea Concrete Institute
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• v.14 no.3
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• pp.307-314
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• 2002

Utilization of demolished-concrete as recycled aggregate has been researched for the purpose of substituting for insufficient natural aggregate, saving resources and protecting environment. There, however, are some Problems not only the large difference of dualities in recycled aggregates but also a little deterioration of mechanical properties in recycled aggregate concrete in comparison with that of natural aggregate concrete. In this study, the test results of freez and thaw durability of concrete with demolished-concrete recycled aggregate(DRA) arc as follows. Improvement of crushing process is an important assignment because that adhered mortar on source-concrete recycled aggregate(SRA) and DRA highly affects thc qualifies of recycled aggregate. The compressive strength of recycled aggregate concrete was not highly different in comparison with that of control concrete. But the resistance to penetration of Cl in recycled aggregate concrete was shown smaller than that of control concrete because of adhered mortar on recycled aggregate. The resistance to frcezing and thawing of recycled aggregate concrete was highly different due to adhered mortar on recycled aggregate, and durability factor of concrete with NA-SRA and DRA was more decreased than that of control concrete. On the other hand, durability factor of concrete with AA-SRA was larger than that of control concrete. It, therefore, is necessarily required that recycled aggregate including adequate entrained air should be used for satisfying the freez and thaw durability of recycled aggregate concrete.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.4
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• pp.289-296
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• 2018

In this study, we evaluated the feasibility and performance of LCD waste glass as a replacement for cement by using LCD waste glass powder which is generated from manufacturing process due to development of LCD industry. Experiments were carried out by replacing 10% and 20% cement of LCD waste glass with particle size of $12{\mu}m$ of LCD waste glass with OPC and particle size of $5{\mu}m$, respectively. Through experiments, basic properties, mechanical properties and durability of concrete were evaluated. Experimental results show that the compressive strength is high at 10% replacement ratio compared to 20%. The lower the particle size, the higher the strength. The durability test evaluated the chloride penetration performance through the chloride ion diffusion coefficient. The higher the substitution rate and the smaller the particle size, the lower the chloride ion diffusion coefficient and the better the OPC than the all substitution rate. As a result, LCD waste glass concrete with low granularity and proper replacement ratio is considered to be advantageous for durability under salt environment.

• International Journal of Highway Engineering
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• v.4 no.2 s.12
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• pp.1-8
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• 2002

Latex modified concrete(LMC) became to be applied as a new material for newly constructed bridge deck overlays in Korea due to its excellent bond strength, flexural strength and impermeability against water and chloride. However, it could not be adopted at repair job site because of its long curing time required. Thus, a research on latex modified concrete with rapid-setting cement(RSLMC) is necessary if it could develope the sufficient strength for early opening to traffic. This study focused on the durability of latex modified concrete with rapid-setting cement mainly on water permeable resistance and freeze-thaw resistance. The main experimental variables were latex contents(0, 5, 10, 15 and 20%) and antifoamer contents (0, 1.6, 3.2, 4.8 and 6.4%). Test results show that the permeability of RSLMC is very low indicating below 100 coulombs at 15% of latex contents at all antifoamer contents. The freeze-thaw resistance of RSLMC maintains above 90% of relative dynamic modulus at 3.2% of antifoamer content until 300 freezing-thawing cycles.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.3
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• pp.243-249
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• 2016

The present work is for an evaluation of resistance to corrosion in steel coated with cementitious repair material, so that 3 cases of steel plate(Normal, Welding, Welding & coating case) are subjected to ICM(Impressed Current Method) for acceleration of corrosion for 7days. Tested and estimated corrosion ratio through Faraday's Law are compared, and the related flexural strength are evaluated. In Normal and Welding cases, similar level of corrosion ratio(70%) is evaluated, however only 17% level of corrosion ratio is evaluated in the Welding & coating case, which indicates that cementitious repair material is effective to anti-corrosion due to a block of chloride penetration. The flexural test results are consistent with those in accelerated corrosion test, which shows a significant flexural strength in Welding & coating case by 3.4times greater than the others. The cementitious material repair coating is evaluated to be effective to anti-corrosion in welding of steel plate.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.3
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• pp.195-202
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• 2006

Deterioration of sewer concrete is representative that biochemical corrosion according to the $H_2S$ has growth by inhabit sulfur-oxidzing bacteria because of special environment in sewer. But in case of domestic, fundamentally, sulfur-oxidzing bacteria could moderate development of repair material method is need because of corrosion prevent method is inconsideration with carry out to improve project. In this paper, after development of spread type antibiotic with antibio-metal, antibacterial performance about sulfur-oxidzing bacteria of antibiotic and tested to estimate fundamental properties of bonding strength, abrasion contents, contents of water absorption, contents of air permeability, carbonation depth, chloride ion penetration depth and chemical resistance of spread with antibiotic restorative mortar.