This study investigated the properties of foamed concrete by using surfactant foaming agent and synthetic foaming agent. The effects of foaming agent types on the compressive strength, density and pore structure of the concrete were investigated. The samples were assessed by XRD analysis and simultaneous SEM was used to study their pore distribution. This study showed the improvement of important properties of foamed concrete. Lower pore distribution and correspondingly higher compressive strength values were reached. Also, synthetic foaming agent had more positive effect on the strength of foamed concrete

NaCl과 LiNO2의 첨가량에 따른 콘크리트에 매립된 철근의 부식거동을 전기화학적 임피던스 분광법을 이용하여 고찰하였다. 부식 가속 방법중 하나인 건습반복법을 이용하여 단기간 내에 부식현상을 촉진하였으며, 측정된 임피던스 값을 통해 등가회로를 제안할 수 있었다. NaCl 1.2 kg/m3이 첨가된 콘크리트에 매립된 철근의 부동태 피막이 빠르게 파괴되는 것을 확인할 수 있었으며, 염화물 첨가량 대비 0.6M의 LiNO2를 첨가한 경우 부식진행속도가 크게 저하하는 것을 확인할 수 있었다. 또한 염화물 첨가량 대비 1.2M의 LiNO2를 첨가한 경우 부동태 피 막이 부식가속시간이 지나도 파괴되지 않고 성능이 유지되는 것을 확인할 수 있었다.

Recently, Advanced water treatment facilities with Ozone are being introduced domestically. However, waterproofing/corrosion prevention construction method of concrete structure for existing advanced water treatment makes waterproofing/corrosion prevention materials and concrete deteriorated because of strong oxidation of ozone. Therefore, in this study, It was evaluated in ozone resistance and bond strength of metal spraying coating.

In order to study carbonation progress after surface repair of carbonated concrete, each carbonation penetration velocity from different repair materials of concrete structure is compared through the experiment of carbonation accelerating CO2 concentration to 100%

This study is corroborated as a fundamental resource to develop lightweight foamed concrete. Weight of unit volume decreased until 0.8% dosage of foaming agent is put cement paste. After that, Mechanical properties of cement paste with foaming agent is verified to use FEM analysis based on picture image. Finally, It is compared with compressive strength of experiment and estimation from picture image.

Chloride ions ingress continuously in reinforced concrete through pores of it by Cl-. Recently, new materials removing harmful anions have been developed. Layered double hydroxides(LDH) has an excellent ability to remove harmful anions because various anions can be adsorbed in the interlayer space between divalent and trivalent cations. In this study, Ca/Al-NO3 and Mg/Al-NO3 LDH were prepared by using a co-precipitation method. Experiments for binding chloride ions of LDH were conducted by using potentiometric method.

Recently, Advanced water treatment facilities with Ozone are being introduced domestically. However, waterproofing/corrosion prevention construction method of concrete structure for existing advanced water treatment makes waterproofing/corrosion prevention materials and concrete deteriorated because of strong oxidation of ozone. Therefore, in this study, As a one of studies for improving durability of advanced water treatment plant applied by metal spray system, electrochemical corrosion protection of metal spraying film according to surface treatment in pH 5 acid solution which is similar to pH concentration in real ozone treatment was evaluated..

In this study, Corrosion behavior in mortar was observed by the passage of time by using EIS method. As a result of EIS experiment, equivalent circuit and changes of Impedance parameter could be observed. In addition, it was confirmed that impedance of rebar in mortar and corrosion rate according to the amount of NaCl were different.

Palm Oil Fuel Ash(POFA), Agricultural by-product, has been studied in especially ASEAN countries. However studies about effects of superplasticizers on early compressive strength of concrete with POFA are insufficient. Therefore, in this study, the effects of superplasticizers were evaluated in terms of compressive strength.

The properties of bubble in lightweight concrete shows a difference depending on the ingredient and amount of foaming agent. To select foaming agent which is suitable for the purpose, it is essential to conduct a basic study to find the right properties of bubble.

본 연구는 고강도 섬유보강 시멘트 복합체(UHSCC) 접착성능을 평가하는 것이 목적이다. Direct shear test를 통해 압축전단접착강 도를 측정한 결과 NC(보통강도콘크리트)+ NC 실험체(150×150×150)에서는 모든 수준에서 유사한 압축전당접착강도를 나타내었고, 반 면 UHSCC+UHSCC에서는 지연타설 30분 후부터 0분에 비해 압축전단접착강도가 낮아지는 것을 확인할 수 있었다. 이를 통한 접착면의 파괴 모드를 분석한 결과 NC+NC 에서는 모든 수준에서 비계면 파괴를 보였고 UHSCC+UHSCC에서는 30분, 60분, 90분 시험체에서 계면파괴가 일 어났다. NC 및 UHSCC의 타설면을 XRD 시험을 통해 분석한 결과 NC 시험체에 비해 UHSCC의 시험체 에서 많은량의 SiO2의 성분이 검출되 는 것을 알 수 있었고 UHSCC에서 나타난 코팅막의 주성분의 대부분은 SiO2로 사료된다. 따라서 본 연구에서 사용된 UHSCC는 지연타설 30분 후 부터는 접착성능의 저하로 구조체로서의 사용이 어렵다고 판단된다. 금후 연구에서는 콜드조인트 발생 부위의 면처리 방법을 통한 접착성 능 향상이 필요하다고 사료된다.

This study is corroborated as a fundamental resource to develop structural lightweight foamed concrete. Mortar using foaming agent decrease over 0.3 g/㎤ of weight of unit volume and increase over 27 MPa of compressive strength available structural purpose. After that, it is compared with Young's modulus of experiment and analysis from FEM analysis using SEM image.

This study is, when we pour the concrete, doing bonding shear performance evaluation to search the influence about an adhesive interface by a generated cold joint with a retardation time. In conclusion, this experiment shows that the higher a compressive strength of the concrete is, the higher a reduction ratio of the bonding shear strength is, and the instance of a none agitation and a compaction with 15 minutes of a retardation time are the lowest influence in a whole of the results; each of the reduction ratio of the bonding shear strength is approximately 4.5%.

Recently, Advanced water treatment facilities with Ozone are being introduced domestically. However, waterproofing/corrosion prevention construction method of concrete structure for existing advanced water treatment makes waterproofing/corrosion prevention materials and concrete deteriorated because of strong oxidation of ozone. Therefore, in this study, using a metal spraying system was evaluated for bond strength between concrete and metal spraying coating.

Currently, a technique to subdivide the process refining is introduced, can be divided into the steel slag. In this study, Free-CaO in the electric arc furnace slag by the ethylene glycol method for the quantitative analysis for the expansion to proceed with construction materials.

Concrete with blast furnace slag (BFS) shows varied strength development properties different from normal concrete. Therefore, a precise prediction of compressive strength using a full maturity model is desired. The purpose of this study is to predict the compressive strength of concrete with BFS by calculating the apparent activation energy (Ea) and rate constant (kT) for each BFS replacement ratio. The method of Carino Model is used in this study for predicting compressive strength of concrete with BFS.

Concrete with blast furnace slag (BFS) shows varied strength development properties different from normal concrete. Therefore, a precise prediction of compressive strength using a full maturity model is desired. The purpose of this study is to predict the compressive strength of concrete with BFS by calculating the apparent activation energy (Ea) and rate constant (kT) for each BFS replacement ratio. The method of Carino Model is used in this study for predicting compressive strength of concrete with BFS.

Reaction degree of ground granulated blast furnace slag(GGBFS) in cement paste was measured by water-binder ratio and GGBFS replacement ratio, curing temperature with ages using selective dissolution. In result of experimental, when water-binder ratio and curing temperature were high and replace ratio of GGBFS was low, reaction degree was estimated high.

In this study, the concrete compressive strength test conducted according to the replacement ratio of electronic arc furnace oxidizing slag. As higher substitution rate of the electronic arc furnace oxidizing slag aggregates, early concrete compressive strength development is effective and the higher the concrete compressive strength as too.

This study was conducted for investigating effect of retardation time of secondary placement on shear bonding strength. Evaluation experiment on the shear bonding performance of UHPC(180MPa level concrete) was conducted according to retardation time and size of specimen. As a result, the smaller the size of specimen, the weaker the measured bonding performance of specimen. Also, comparing specimen which is o minute occurrence time of cold joint with specimen which is after 15 minutes, it showd 70% lesser shear bonding strength.