PURPOSES : The purpose of this study is to confirm the thermal expansion characteristics of concrete mixed with 1% waste glass fine aggregates, which is the amount stipulated for recycled aggregates in the current quality standard. METHODS : The coefficient of thermal expansion was measured by applying AASHTOT 336-10 using a LVDT. The results measured were used as physical properties in a finite element analysis to confirm the change in tensile stress and the displacement of the right angle section of the upper slab of a concrete pavement due to admixture substitution. RESULTS : The thermal expansion coefficients of concrete based on the replacement rate of the admixture when the waste glass fine aggregates are replaced are within the range of the thermal expansion coefficients of concrete specified in the Federal Highway Administration report. As the replacement rate of the admixture increases, the thermal expansion coefficient of concrete decreases. As the thermal expansion coefficient decreases, the slab pavement curling displacement and the tensile stress of the center of the upper slab of concrete decrease. CONCLUSIONS : In the short term, the presence or absence of waste glass fine aggregates does not significantly affect the thermal expansion coefficient of concrete. However, in the long term, waste glass fine aggregates are reactive aggregates that causes ASR, which creates an expandable gel around the aggregates and results in concrete expansion. Therefore, the relationship between ASR and the thermal expansion coefficient must be analyzed in future studies.

Polycarboxylic ether-based high-range water reducer (PCE) has been proposed to use due to the operational advantages of reduced water content and increased fluidity of cementitious mixtures. But the concern about using PCE can increase the mobility of radionuclides as well. Nuclear Decommissioning Authority (NDA) showed that the PCE formulations increased radionuclide solubility in free solution. Solubility of U(VI), 239Pu, 241Am with the cementitious materials tested with 3:1 pulverized fuel Ash/Ordinary Portland Cement (PFA:OPC) and 9:1 Ground Granulated Blast Furnace Slag/OPC (GGBS:OPC) with PCE that increased at least one and, in some cases, more than three orders of magnitude (between 10-9 and 10-4 mol dm-3) for these radionuclides in the cement-equilibrated solution. It is possible that the relatively low molecular weight substances present in the PCE cement mixture increase the solubility of radionuclides. In addition, the organic substances that are easily miscible with water can contribute to increase the solubility. In this study, several radionuclides (Nb, Ni, Pd, Zr, and Sn) that may be present in intermediate and low-level waste (LIW) repositories were selected based on the half-life and the estimated dose accordingly, and the solubility tests were conducted with and without PCE in solution. To simulate the field condition of the underground repository, synthetic groundwater was prepared based on the recipe by the KAERI Underground Research Tunnel (KURT) DB-3 GW and used as a solvent. The solubility limiting solid phase (SLSP) of each radionuclide was determined using Geochemist’s WorkBench (GWB) model. The selected solid phases are Ni(OH)2, ZrSiO4, Nb2O5, Pd(metal), and SnO2, respectively, and the solubility experiments were conducted with 1.0wt% of PCE per total weight and 0.5 g / 250 ml of selected radionuclide’s SLSP for 90 days at room temperature (25°C). Compared with and without PCE presence in solution, the selected radionuclides also showed an increased solubility with the presence of water reducing agent like PCE. This results can be used to correctly estimate the mobility of target radionuclides with the presence of PCE in repository environments.

Currently, in Korea, the frequent damage of aged concrete pavements causes route blockages due to maintenance and repair works. Ultra-rapid cement has been used as a measure to solve the economic losses which result from traffic delays, accidents, and civil complaints due to blocked routes. However, now, it couldn’t be used except for urgent constructions because the price is expensive and its onsite application is complicated, hence, fast hardening admixtures are being used in ordinary cement to solve the problem with ultra-rapid cement. In this research, it is intended to develop a material which enables early opening of the road being constructed and cured within 24 hours of closure, to secure durability characteristics of early strength concrete by incorporating admixtures (silica fume, latex, polymer powder), and to find optimal mixing ratio and select the optimal variable for each material.

This document gives a result of experiments on concrete using admixture Sikament® R4 combine with Sikacrete PP1. In developing countries, the development guides to build and set up a new infrastructure. In this case, the schedule of works is very important, which depends on the setting time of concrete structure. Specially, in tropical monsoon climate country, we need to use admixtures to increase the life time of constructions, especially concrete structures. Today, there are thousands of building, roads and bridges will be made. By using admixture, it not only helps to save the waiting time on the work site, but also increase quality of concrete structure. By using these good effects of admixtures, it’s necessary to find an optimal ratio of them in the mix design ingredient of concrete. The concrete strength can be controlled by changing a range of variety ratio of admixture in the mix design. This topic will find out the role of admixture and its relationship with the compressive strength of concrete.

콘크리트 혼화제의 무수축 그라우트에서 산란체와 흡수체의 영향은 빛산란에 의해 파장에 대 한 산란세기로 설명된다. New Austria Tunnel Method의 수지에 대한 산란의 분자특성들은 연구하기 위해 Monte Carlo Simulation하였다. 이는 산란매질에서 광학적 파라미터들(μs, μa, μt)에 의해 조사 되어 그들의 영향을 알 수 있었다. 산란매질에서 광자에 대한 빛 분포에 의한 결과는 광원에서 검출기 까지 거리가 가까우면 무수축혼화제의 산란이 증가하여 산란세기가 크게 나타나는데 혼화제가 첨가함에 따라 무수축 성질이 크게 나타났다. 이는 강구조물의 내구성을 위한 코팅과 부식에서 좋은 모델을 디자 인하는데 도움이 될 것이다.

PURPOSES : The purpose of this study is to evaluate the durability of ternary blended concrete mixtures adding ultra fine admixture. METHODS : From the literature review, crack was considered as the main distress failure criterion on concrete bridge deck pavement. To reduce the initial crack development due to drying shrinkage, CSA expansion agent and shrink reduction agent were used to ternary blended concrete mixtures as a admixture. Laboratory tests including chloride ion penetration test, surface scaling test, rapid freeze & thaw resistance test, non restrained drying shrinkage and restrained drying shrinkage test were conducted to verify the durability of ternary blended concrete mixtures. RESULTS : Based on the test results, proposed mixtures were verified as high qualified durable materials. Expecially initial drying shrinkage crack was not occurred in ternary blended concrete mixtures with CSA expansion agent. CONCLUSIONS : It is concluded that the durability of proposed ternary blend concrete mixture was acceptable to apply for the concrete bridge deck pavement.

건설폐기물의 처리는 국가 사회적 문제로 제기되고 있으며 순환골재의 생산과정에서 발생하는 미분말은 전량 폐기 매립되고 있다. 미분말의 유해성을 분석한 결과 세포독성을 함유하고 있어 토양 및 지하수오염 등 2차 오염을 초래할 수 있다. 본 연구에서는 미분말을 재활용하기 위한 방법으로 콘크리트의 혼화재로 활용하고자 시멘트 대신 미분말을 혼입한 콘크리트의 역학적 특성과 작업성을 비교 분석하였다. 콘크리트의 실험 결과에서, 혼화제를 적절히 사용하면 미분말을 시멘트 대신 20% 이하 치환한 경우 콘크리트에 적용 가능할 것으로 판단된다. 또한 고강도 콘크리트에서도 적용할 수 있다.

Previous researches for increasing the durability of concrete structures examined the characteristics of concrete using glycol ether admixture, and determined the optimal addition rate and evaluated durability of concrete. However, today’ s ready mixed concrete uses various industrial byproducts in order to improve the performance of concrete, and the quality of concrete changes depending on the addition of glycol ether admixture and curing condition. Considering this, we need to understand the characteristics of curing methods according to field condition. Thus, the present study evaluated the effects of replacement with fly ash as a binder and curing conditions (temperature and humidity) on the performance of concrete, and obtained data from a mock-up test for the practical use of concrete containing glycol ether admixture. According to the results of this study, the concrete showed resistance performance of around 30% to carbonation and around 40% to drying shrinkage. In addition, as for resistance to freezing and thawing, the relative dynamic modulus of elasticity was over around 85% through atmospheric curing. These performances prove the effect.

In this study, the impedance of reinforced concrete embedded in concrete was measured and compared with W/B and admixture replacement ratio. As a result, the impedance of rebars increased in all frequency sections with increasing blast furnace slag replacement amount of cement in all W/B Respectively. It is considered that the electro resistance in the concrete increases due to the potential hydraulic properties of the blast furnace slag, and thus the polarization resistance also increases.

In this study, a series of studies is intended to elicit the improvement of the quality of Admixture Substitute Concrete using oil refined for petrochemical work (ERCO). In other words, ERCO is used to analyze the basic properties of Admixture Substitute Concrete by pre-adding the AE liquid solution on its products. As an experimental variable, the method of adding ERCO was added after mixing it with concrete. In addition, the mixing ratio was planned to be 2 levels of 0, 0.5 %, and the total volume of the AEs injection quantity is 5 % that combines 0, 1, 2, and 3 % of the mixed ERCO mass of concrete. As a result, as the pre-injection of AE was increased, the characteristics of the concrete showed that the slump, and air contents were not improved, and the pre-adopting effects of AE agent were also significantly increased in the concrete.

In this paper, Results of mock-up test for mitigating carbonation of high volume mineral admixture concrete by spreading waste cooking oil. Concrete incorporating 60% of BS and 30% of FA with the size of 900×600×200 are discussed. Denatured Silicate paint is also applied to compare the performance. Test results indicate that the application of ERCO and DSP enhance carbonation resistance.

Concrete is a very useful construction material for the sealing disposal of hazardous substances. In general, mass concrete is applied to these structures. And, the mineral admixtures are recommended for the long term performance. Calcium leaching could be happened due to the contact with pure water in underground structures. Thus, it is needed to evaluate the resistance of calcium leaching for concrete mixed with mineral admixtures. From the test results, the mineral admixtures are effective to the improvement of long term compressive strength and chloride diffusion coefficient in concrete members. When calcium leaching is happened, however, the reduction of compressive strength and chloride penetration resistance is severe than OPC case, the micro pore distribution is adversely affected. Consequently, when the mineral admixtures are applied to underground structures which is exposed to calcium leaching environment, it is desirable to reduce water-to-binder ratio, to expose after the sufficient pozolanic reaction, and to use BFS than FA.

This study is to be suggest the optimal mat foundation mixing design of high strength concrete by using fly ash and retarding admixture. This study applied retarding admixture to high strength concrete over 40MPa, and tested the mechanical properties of concrete according to binder content(385∼415kg/㎥), fly ash substitution rate(0~25%), and adding rate of retarding admixture(0~1.2%) As a results, For the concrete to be applied to lower part of mat foundation, it is suitable to substitute FA 25% with binder contents 385kg/㎥ and to apply the mixing with adding retarding admixture 1% in order to repress hydration heat and to cast concrete at once through congelation delay. As a result of experiments of adiabatic temperature rising, coefficients of adiabatic temperature rising K and α were 40.68 and 1.08 for retarding-type concrete and 42.8 and 1.13 for standard concrete, respectively, under the condition of initial concrete temperature about 19℃. In the identical temperature condition, differences of adiabatic temperature rising speed according to use of retarding admixture were not different, and maximum value of adiabatic temperature rising of retarding-type concrete was lower than standard concrete. Keywords: Retarding Admixture, High Strength Concrete, Mat Foundation, Fly Ash, Adiabatic Temperature Rise

본 논문은 강섬유의 일부를 철근집합체로 대체하여 초고강도 섬유보강 철근 콘크리트 I 형보의 연성거동을 유도하는 것을 목적으 로 한다. 강섬유와 철근집합체의 조합을 가진 초고강도 콘크리트 I 형보 대한 휨거동 실험을 수행하였다. 강섬유의 혼입률은 0%, 0.7%, 1%, 1.5%, 2%이다. 철근집합체와 PS강연선 집합체가 압축구역에서 콘크리트를 구속하기 위해 사용되었다. 철근집합체와 강연선 집합체의 길이 도 실험요소 중 하나이다. 이러한 실험요소를 조합하여 9개의 초고강도 철근 콘크리트 I 형보를 제작하였다. 강섬유 뿐만 아니라 종방향의 철근 집합체도 초고강도 철근 콘크리트 I형 보의 연성거동을 유도하는데 효과를 가지고 있다. 강섬유 혼입률 0.7% 또는 1%와 철근집합체를 사용한 조합이 I형 보의 효과적인 연성 거동을 보여주고 있다. 하중과 처짐관계 및 균열양상 등이 좁은 간격을 가진 작은 직경의 종방향 철근 집합체의 유용성을 나타내고 있다.

In this study, chloride penetration of calcium leached concrete according to mineral admixture ratio were compared with OPC. From the results, it showed that chloride diffusion coefficient in calcium leached concrete were increased as calcium leaching period increase. However, the chloride diffusion coefficient of BFS case showed the better resistance than Fly Ash case. And, the distribution of chloride diffusion coefficient was significantly changed by calcium leaching period.

As the usage of supplementary additives such as blast furnace slag and fly ash for concrete was increased, the carbonation of concrete has been a problem. Hence, in this research, as a solution of carbonation of the high-volume supplementary additive concrete, the effect of waste oil based liniment on carbonation and chloride resistivity was analyzed when it applied on the surface of the concrete.

In this study, It was found that replacing a large amount of mineral admixture, we satisfied the target, compressive strength of 30, 50MPa and manufactured lightweight concrete reducing CO2 emissions up to 42.1～52.8% comparing normal concrete

The energy consumption by buildings approximately reaches 25% of total korea energy consumption. The greatest part in the buildings of the energy consumption is building facade. but a few research projects on concrete comprising more than 70% of outsider of buildings has been tried. This research structural insulation concrete what improved insulation performance using Micro Form Admixture.

콘크리트의 취성파괴를 방지하기 위해 강섬유 보강재는 효과적인 복합재료이다. 그러나 시멘트 사용량이 많아지면 건조수축이 증가하고이로 인해, 강섬유 보강재의 연성증가 효과가 제한될 수 있다. 팽창재를 사용한 콘크리트 내부의 강섬유 보강재는 화학적 프리스트레싱 효과가 발생하여 강섬유 보강효과를 증가시킬 수 있다. 본 연구에서는 CSA 팽창재와 강섬유 보강재를 혼입하여 콘크리트의 역학적인 특성을분석하였다. 체적비 1~2%의 강섬유 보강재와 시멘트 중량의 10%의 CSA 팽창재를 혼입하였으며, 다양한 역학적 특성과 휨거동을 분석하였다. 강섬유 보강재를 혼입한 CSA 콘크리트는 인장강도와 초기균열강도의 증가를 나타냈으며, 균열후의 파괴에너지 증가와 같은 연성거동을 뚜렷하게 나타내었다. 적절한 팽창재 사용과 최적의 강섬유 보강재의 혼입률이 도출된다면 이들의 상호작용은 콘크리트의 취성을 더욱 효과적으로 제어할 수 있다.