In this study, the resistance of chloride penetration and sulfate attack of mortar substituted heavyweight waste glass were evaluated. As a result, chloride penetration depth and diffusion coefficient decreased with the substitution of waste glass, chloride penetration resistance is increased. For sulfate attack resistance, the effect of heavyweight waste glass was little.

철근콘크리트 구조물의 대표적인 열화현상인 염해를 억제하고자 여러 가지 연구가 진행되었는데, 그 중에서 혼화재료를 콘크리트에 혼입하여 사용하는 방법이 대표적으로 알려져 있다. 본 연구에서는 대표적인 콘크리트 혼화재료인 플라이애시를 혼입한 콘크리트와 OPC 콘크리트에 대하여 3가지 수준의 물-결합재비(37%, 42%, 47%)를 고려해 내구성능 평가를 실시하였다. 각 목표 재령일에서 Tang's method에 준하여 촉진 염화물 확산계수 측정 실험을, ASTM C 1202에 준하여 통과전하량 측정 실험을, KS F 2405에 준하여 압축강도 실험을 실시하였다. 또한, 기존의 연구결과인 재령 28일의 실험결과를 참고하여 확산계수에 대한 시간의존성지수(m)를 도출하여 고찰하였으며, 장기재령의 압축강도와 시간의존성지수 간의 상관관계를 평가하였다. 재령 49일부터 플라이애시 혼입 콘크리트에서 OPC 콘크리트 대비 개선된 염해저항성능을 나타내었으며 이는 포졸란 반응에 의해 생성된 불용성의 수화물이 원인으로 사료된다. 플라이애시 혼입 콘크리트에서 OPC 콘크리트 대비 약 1.5배 높은 시간의존성지수를 나타내었으며, 압축강도와의 상관관계 평가 결과, OPC 콘크리트는 압축강도가 증가할수록 선형적으로 시간의존성지수가 증가하는 경향을, 플라이애시 콘크리트는 압축강도가 증가할수록 선형적으로 시간의존성지수가 약간 감소하는 경향을 나타냈다.

Chloride attack is one of the most critical deterioration due to rapid corrosion initiation and propagation which can cause structural safety problem. Extended service life through repairing is very important for determination of maintenance strategy. Conventionally adopted models for estimation of LCC (Life Cycle Cost) have shown step-shaped elevation of cost, however the extension of service life is much affected by quality of construction and repairing materials, which means engineering uncertainties in residual service life. In the paper, RC (Reinforced Concrete) column with three different mix proportions exposed to chloride attack are considered, and repairing numbers with related costs are evaluated through probabilistic technique for maintenance. When calculating repair frequency for intended service life through probabilistic model, the required repair frequency is evaluated to be 6.71 times for OPC, 4.09 times for SG30, and 2.95 times for SG 50, respectively. The probabilistic model for repairing cost is evaluated to be effective for reducing the repair frequency reasonably with changing the intended service life and design parameters.

In this study, the absorption protection agent was applied to the surface of fiber reinforced concrete to evaluate the chloride ion penetration resistance. The evaluation was based on the method presented in KS F 2711. It was confirmed that the resistance performance against chloride ion was improved by 56∼71% when the coating material was applied.

This study investigated the durability performance of concrete to which Polydimethylsiloxane (PDMS) was applied for penetrating water repellency. As the results of study, From test of the resistance to chloride ion penetration, superior salt-resistance was shown in comparison to plain concrete, by the application of PDMS. Experimental results of SM and IM showed more than twofold improved salt-resistance compared to plain concrete.

In this study, sodium chloride is directly mixed with binders in order to simulate harsh environments by promoting the corrosions of fibers and cement-based matrix including UHPC (Ultra High Performance Concrete). The experimental variables are the amount of sodium chloride and material composition such as UHPC, high strength mortar, and normal mortar. The experimental results show that UHPC has the superior capability to resist chloride ions due to its dense microstructures.

In this study, poly-silicon sludge was used in replacement with Portland cement as SCMs. Poly-silicon sludge has an ability to improve the durability to the concrete system. Thus, the chloride penetration test of PS specimens was conducted for the confirmation of the durability. From the results, The penetration depth of the plain specimens is deepest, and gradually decreases as PS substitution rate increases.

The method of lowering the diffusion coefficient of concrete are widely used by mixing blast furnace slag(BFS) and fly ash(FA) in order to prevent the steel corrosion. In this study, the NaCl solution was supplied and the potential of the reinforced steel was monitored to measure the critical chloride contents of the reinforced concrete according to the type of concrete. In case of using BFS and FA, it showed that the corrosion of the steel was progressed rapidly, which is considered to be related to the decrease of the pH of the concrete.

C-S-H phase is one of the main hydrates in hardened cement paste and binds chloride ions. The purpose of this study is to quantify equilibrium amount of chloride adsorption bound by C-S-H phase with various Ca/Si ratios. C-S-H phase can absorb chloride ions with 3 steps. In the C-S-H phase with low Ca/Si ratios, momentary physical adsorption could not be expected. Physical adsorption is strongly dependent on electro-kinetic interaction between surface area of C-S-H phase and chloride ions. In previous research, C-S-H phase showed binding behavior with 3 stages including the stage of instantaneous physical adsorption other stages. Thus, this study examined the equilibrium amount to express chloride binding isotherm of C-S-H with various Ca/Si ratio.

In this study, chloride penetration in a repaired concrete using magnesium polymer ceramic (MPC) was assessed based on the NT BUILD 492. To investigate the effect of repaired material on chloride penetration, a cylinder OPC concrete specimen was fabricated and attached on the surface with MPC. Then, chloride penetration test was carried out on the combined concrete sample at a constant applied voltage (30 V) for 6 hours. It was found that most of chloride sources was passed though the interface between OPC and MPC, resulting in a loss of chloride in the material. Thus, it is needed to modify the conventional chloride penetration test for the repaired concrete specimen.

The aim in this study was to remove Cl−, which can be problematic in the recycling of bottom ash, by identifying the optimum operating conditions for a soil electrolysis apparatus with spiral paddles and to use these as the base data in removing contaminants from various polluted soils using electrolysis. Unprocessed bottom ash collected from the openair storage yard at thermoelectric power plant H in Gyeong sang nam - do Province was used as the experimental material. The experimental methodology was to identify the optimum operating conditions to remove Cl− contained in the bottom ash using the following variables: use or not of spiral paddles, application or not of electrolysis, change of concentration of the electrolyte solution, electrolysis application time, and the voltage level during electrolysis. From the results, the highest removal efficiency of 91.4% was shown under the following conditions: use of the spiral paddles, use of 0.3% NaOH electrolyte solution, 20 min of electrolysis; and a voltage level of 5 V during electrolysis. It is evident that application of the soil electrolysis apparatus for removal of Cl− from bottom ash could be valuableas base data for purification of polluted soils in the future.

염해에 따라 발생하는 보수시기와 보수로 유지되는 내구수명은 보수비용 평가에 매우 중요한 요소이다. 일반적으로 사용하는 결정 론적 보수비용 평가는 사용기간의 연장에 따라 계단식으로 증가하게 되며, 보수로 인해 변동되는 내구수명의 변화를 고려하지 못한다. 본 연구 에서는 확률론적인 보수시기 및 비용을 평가하기 위해, 염해에 노출된 콘크리트 교각을 선정하였다. 두 가지 배합과 염화물에 노출된 외부 환 경조건을 고려하여 염화물 거동을 평가하였으며, 도출된 내구수명과 수명에 대한 확률변수를 변화시키면서 보수시기 및 비용 변화를 분석하 였다. 변동계수의 변화에 따른 보수회수는 큰 차이가 발생하지 않았으나, 초기의 내구수명 연장이 구조물의 보수시기 및 비용에 큰 영향을 미 치고 있었다. 또한 확률론적 보수비용 산정 모델은 결정론적 모델과 다르게 연속적인 보수비용이 평가되므로 목표내구수명에 따라 보수회수 를 감소시킬 수 있는 효과적인 기법임을 규명되었다.

Concrete structure for nuclear power plant is mass concrete structure with large wall depth and easily permits cracking in early age due to hydration heat and drying shrinkage. It always needs cooling water so that usually located near to sea shore. The crack on concrete surface permits rapid chloride intrusion and also causes more rapid corrosion in the steel. In the study, the effect of age and crack width on chloride diffusion is evaluated for the concrete for nuclear power plant with 6000 psi strength. For the work, various crack widths with 0.0~1.4 mm are induced and accelerated diffusion test is performed for concrete with 56 days, 180days, and 365 days. With increasing crack width over 1.0mm, diffusion coefficient is enlarged to 2.7~3.1 times and significant reduction of diffusion is evaluated due to age effect. Furthermore, apparent diffusion coefficient and surface chloride content are evaluated for the concrete with various crack width exposed to atmospheric zone with salt spraying at the age of 180 days. The results are also analyzed with those from accelerated diffusion test.

시공지연 등으로 발생한 콜드조인트는 전단력에 취약하며 염화물 침투 및 확산을 촉진시킨다. 본 연구는 압축 및 인장하중과 콜드 조인트 조건을 고려한 1년 양생된 콘크리트의 염화물 확산계수를 분석하였으며 선행연구인 91일 재령의 결과와 비교하였다. 91일 재령결과와 비교할 때, 하중을 재하하지 않은 일반적인 경우에는 건전부에서는 10.7%, 콜드조인트에서는 10.5%로 낮게 평가 되었다. 건전부와 콜드조인 트의 감소율의 차이는 비슷하지만 염화물 확산계수는 콜드조인트에서 크게 발생하였다. 압축력 30%의 경우 건전부는 하중재하시 발생된 공 극압밀로 인하여 확산계수가 감소하였다. 콜드조인트 콘크리트의 경우 365일 재령은 91일 재령보다 압축력 30%일 경우 10.9%, 압축력 60%일 경우 5.8% 확산계수가 낮게 평가되었는데, 이는 장기간 수중양생에 따른 지속적인 수화반응에 의해 확산계수가 낮게 평가되었기 때문이다. 인 장력의 경우 압축부와는 다르게 동일 수준의 인장하중과 재령, 콜드조인트 유·무에 따른 확산계수의 차이가 비교적 크지 않았다. 이는 콘크리 트가 1년 재령임에도 불구하고 인장력에 취약한 재료적 특성인 미세균열이 지배적인 영향으로 작용하였기 때문이다.

The present study was conducted for the purpose of analyzing the growth response of Dracaena braunii treated with chloride ions and to evaluate its salt tolerance. Distilled water (CON) was spiked with 1 (C1), 2 (C2), 5 (C5), 10 (C10) and 15 g/L (C15) CaCl2, respectively. Acidity (pH) and electrical conductivity of hydroponic solution, and leaf width, leaf length, root length, number of leaves, fresh weight, dry weight and the water content of Dracaena braunii were measured. Acidity and electrical conductivity remarkably increased commensurate with increasing concentrations of CaCl2. Growth in the C1 treatment was better than that in CON, whereas the C10 or C15 treatments caused either slow growth or withering of the plants. Fresh weight, dry weight and water content were significantly decreased in response to CaCl2 concentration, compared with those in the control. These results showed that CaCl2 concentration less than 1 g/L may be used as a hydroponic solution for D. braunii, as long as the water quality is not too saline. The chlorine ion has a negative effect on the growth.

The main cause of corrosion in reinforced concrete is diffusion of degradation factors such as chloride ions, carbon dioxide, and sulfate ions. To monitor the extent of the corrosion in reinforced concrete, it is necessary to recognize and track the diffusion of degradation factors. In this paper, we suggest thin-film iron sensorto measure the penetration of chloride ions. The sensor indicates results as electrical resistance and change in electrical resistance. The sensor and contact pad are connected by an anisotropic conducting film (ACF) bonding in order to reduce the influence of the contact electrical resistance. The sensor’s electrical resistance increases with corrosive behavior and external chloride ion concentration. Use of these thin-film iron sensors enables measurement and monitoring of the depth of chloride ion diffusion in concrete.

화력발전의 부산물인 플라이 애쉬는 포졸란 반응을 통하여 조직구조를 개선하고 장기 강도 및 염화물 저항성에 매우 효과적이다. 본 연구에서는 28일 및 180일 재령의 보통 포틀랜트 시멘트 및 FA를 혼입한 콘크리트에 대하여 압축강도 및 염화물 저항성을 평가하였으며, 재 령의 증가에 따른 상관성을 평가하였다. 이를 위해, 물-결합재비(W/B)를 37%, 42%, 47%의 3가지 수준, Fly Ash를 시멘트 중량의 0%, 30%, 50%의 3가지 수준으로 나누어 총 9가지 배합을 설정하였으며, 28일 및 180일 재령 시, 압축강도, Tang‘s method에 의한 촉진확산계수, 그리고 ASTM C 1202, KS F 2711을 통한 통과전하량을 측정하였다. Fly Ash 혼입율이 클수록, W/B가 낮을수록 염화물 저항성(확산계수 및 통과전하 량)이 개선되었는데, 모든 FA 50 배합에서 염화물 저항성은 재령 28일 대비 재령 180일에서 약 15% 수준으로 감소하였다. 이는 FA의 포졸란 반응으로 인해 공극구조가 더 치밀해져 나타난 결과이며, 염해 저항성이 강도보다 시간에 더욱 의존적임을 알 수 있다. 재령 180일 이후, FA를 혼입한 배합에서 강도와 염해저항성의 뚜렷한 선형관계가 관측되었다.

In order to determine the short-term impact induced by chloride ionic, CaCl2 was used to study the chloride ionic effects of salinity on substrate and growth of Dracacena braunii grown in ornamental hydro-culture. A distilled water (control) was enriched with 10, 20, 50, 100, and 150 g･L -1 of CaCl2, respectively. Before planting, acidity and electronic conductivity values remarkably increased with increasing concentration of CaCl2. However, 4 weeks after planting, acidity values decreased to a slightly acidic pH, while there were not significant differences among electronic conductivity values obtained. Number of root, fresh weight, and total chlorophyll content were significantly decreased in response to CaCl2 concentration in comparison with control, whereas dry weight, water content, and color of stem were no significant effect of CaCl2 concentration less than 20 g･L -1 . These results showed that initial CaCl2 concentrations above 20 g･L -1 is considered to be the threshold value that will sustain the Dracacena braunii in the growth condition and above which plant growth will be retarded.

This research developed eco-friendly UHPC using industrial by-products (Ground Granulated Blast Furnace Slag, Bottom Ash) by replacing cement and silica powder. The Chloride Penetration Resistances of the developed eco-friendly UHPC were evaluated. It is found that the developed eco-friendly UHPC shows adequate compressive strength and enhanced chloride durability.