This research investigated the effects of matrix strength on the direct tensile behavior of high performance hybrid fiber reinforced cementitious composites (HPHFRCCs) at high strain rates. 3 different type matrixes were used (56 MPa, 81 MPa and 180 MPa). And macro fiber was long hooked fiber (H, =0.3 mm,=30 mm) and micro fiber was short smooth fiber (S, =0.2 mm,  =13 mm). The volume content of macro fibers was 1.0% and the volume content of micro fibers was 1.0%. The high matrix strength clearly increased the tensile strength and peak toughness of HPHFRCCs even at high strain rates (74 ~ 161 /sec).

In this study, freezing and thawing test of secondary product was performed using the Fiber Reinforced polymer Cement composites. From the test result, it was found that fiber reinforced polymer cement composites resistance of freezing and thawing were better than that of conventional products.

The innovation in this study is the complexation of Erianthus fibers (Erianthus arudinaceus) with compatibilizer inPP by extrusion, to produce a material with an improvement in mechanical properties. The aim is to provide a general-purpose material from biomass that does not compete with food as an alternate material from the petroleum base.Erianthus is a cellulose resource crop which is a source of bio fuel, is inedible, highly productive and promising energyresource, there has been little report on its use as a material. It also is a cellulose resource crop with a high productivityas a fiber reinforcement material with low environmental load. Development of Erianthus fiber reinforced polypropylene(PP) composite material was reviewed. Erianthus fiber was pulverized and the powder was sorted by sieve size, whichwas put through the process of complexation with polypropylene using a twin-screw extruder. The mechanicalcharacteristics of the obtained composite material were evaluated by conducting a tensile strength test and a bendingtest. As a result of using the classified fiber as the filler, it is found that the difference in the surface area of the fiberhas a great effect on the mechanical properties and the thermal decomposition properties. It is found to be sufficientlyfeasible to make Erianthus function as a polypropylene fiber reinforcement element by controlling the size of Erianthusfiber.

전복 음료를 개발하기 위하여 전복에 식물류를 혼합한 전복 복합물의 in vitro 항산화능을 측정하였으며, 정상군, 대조군, 전복 복합물의 성인 1일 1회분(APM-1) 급이군(EAPM-1) 및 3회분(APM-2) 급이군(EAPM-2)으로 구분하여 4주간 실험사육하였다. 전복 복합물의in vitro 항산화능과 총 페놀 및 플라보노이드 함량은 APM-2가 유의적으로 높았다. 혈중 총 지질 함량은 대조군에 비해 운동과 전복 복합물을 병행급이한 EAPM-2군이 유의적으로 감소되었다. LDH 활성 및 BUN 함량은 대조군에 비해 전복 복합물 급이군에서 유의적으로 감소되었다. AST 활성은 전복 복합물 급이 시 대조군과 유의차가 없었으며, ALT 및 ALP 활성은 대조군에 비해 유의적으로 감소되었다. 혈청 및 간 조직에서 지질과산화물 함량은 대조군에 비해 전복 복합물 급이군에서 유의적으로 감소하였다. 간 조직의 라디칼 소거능은 대조군에 비해 전복 복합물의 급이 시 유의적으로 증가하였다. 따라서 전복 복합물은 항산화능 및 페놀 화합물에 의존하여 트레드밀 운동에 의한 산화적 스트레스 해소 및 피로 회복 에 도움이 될 것으로 예상된다.

본 연구는 폴리비닐 알코올 섬유 및 강섬유를 체적비율로 1.5% 혼입한 고인성 섬유보강 시멘트복합체에 대한 비상체의 고속충돌시험을 실시하고, 충돌조건에 따른 파괴특성을 실험적으로 검토하는 것을 목적으로 하였다. 비상체의 충돌에 의한 고인성 섬유보강 시멘트복합체의 파괴특성을 평가하기 위하여 화약압력식 충격시험장치를 활용하였으며, 충돌속도의 범위는 약 150 ~ 1,000m/s로 설정하였다. 파괴특성에 대한 평가결과, 고인성 섬유보강 시멘트복합체는 섬유를 혼입하지 않은 Plain시험체의 약 3배 이상의 비상체 운동에너지가 작용하는 범위에서도 표면관입의 파괴등급으로 평가되었으며, 시험체가 파단되지 않는 내충격성능이 확인 되었다. 또한, 충돌시험 전후에 대한 시험체의 질량감소율의 경우, Plain시험체는 비상체의 운동에너지의 증가율과 비례적인 관계를 보였지만, 고인성 섬유보강 시멘트복합체는 비상체의 운동에너지의 영향을 크게 받지 않는 것으로 나타났다. 특히, 이와 같은 경향은 시험체 배면의 파괴특성과 밀접한 관계를 가지며, S시험체에 비해 PVA시험체의 배면박리 억제효율이 큰 것으로 평가되었다. 한편, 국부손상에 대한 표면관입깊이 및 배면박리깊이의 관계를 검토한 결과, 고인성 섬유보강 시멘트복합체는 Plain과 달리 시험체 단면의 중앙선을 기준으로 배면에 가까운 영역에서 배면박리가 발생하는 것을 알 수 있었다. 본 연구를 통해 비상체의 충돌에 대한 고인성 섬유보강 시멘트복합체의 주요 파괴거동이 검토되었으며, Plain과 비교하여 내충격성능의 향상을 명확히 확인하였다.

충돌 또는 폭발 하중 하의 콘크리트는 정적 하중에서 가지는 재료물성과 다른 거동을 보이게 된다. 즉, 고변형율 하의 콘크리트의 재료물성은 크게 변화하게 되며, 이를 시험평가하기 위한 방법 중 압축강도와 관련된 시험법으로는 SHPB(Split Hopkinson Pressure Bar) Test가 있다. 그러나, SHPB Test는 금속과 같은 인성재료를 위해 개발된 시험방법으로서 취성재료인 콘크리트에 적용이 가능한지에 대한 검토가 추가적으로 필요하며, UHPC와 같은 섬유보강 초고성능 콘크리트에 대한 연구는 미미한 실정이다. 이에 본 연구에서는 콘크리트 시험체를 위해 제작된 SHPB Test 장비를 사용하여 일반 콘크리트 및 UHPC 시험체에 대한 시험평가를 수행하였으며, SHPB Test의 적용 적정성을 파악하기 위하여 초고속카메라를 활용한 변위영상 분석을 통한 검증을 수행하였다.

The purpose of this research is to investigate characteristics of cementitious composites containing lathe scrap to use it as a alternative materials of steel fiber. For this purpose, the cementitious composites containing lathe scraps were made according to 5mm, 10mm, and 20mm in lengths for their widths of 2mm and 4mm, respectively. It was observed from the test result that the cementitious composites containing lathe scraps were most largely increased than plain mortar in the compressive and flexural strengths when its width is 2mm and its length is 5 to 10mm.

Recently there are many study on the effect of improving the compressive strength of MWCNT-cement composites. However study related to MWCNT-cement yet insignificant to the domestic. The MWCNT have excellent mechanical characteristics which are mixing cement. MWCNT-cement composites can be expected improving compressive strength. This parametric experimental study have verified to increasing compressive strength of mortar composites mixing MWCNT as W/C, curing age.

This study investigate mechanical properties of alkali-activated slag fiber-composites according to water to binder ratio. A series of experiments were carried out to find the mechanical properties including compressive strength, uniaxial tensile tests. The result of tests exhibited strain hardening behavior and high ductility under direct uniaxial tensile load test.

This study was aimed to investigate the difference in strength of Carbon Nanotube (CNT) reinforced cement mortars with different types of surfactants and doses. In the experimental program, CTAB, SDBS and TX10 which were common surfactants adopted to improve CNTs dispersion in fabricating CNT composites in many industrial fields were included and superplasticizer which was revealed to be effective to disperse CNTs especially in CNT reinforced cementitious composites were added as well. Superplasticizer presented less strength reduction in cement mortar and more strength gain by adding CNTs among four types of surfactants. Higher dosage of superplasticizer caused lower strength of cement mortar. Adding CNTs of 0.4 wt.% or less to cement didn’t show strength enhancement by adding CNTs but 0.8 wt.% of CNTs resulted in strengthening effect after all. Finally, a combination of 0.1 wt.% of CNTs, superplasticizer and sonication treatment could lead to strength improvement by adding CNTs in cement mortar.

본 연구에서는 국내기상자료를 대상으로 극한기상현상의 발생원인을 단일재해와 복합재해로 발생하는 시기로 구분하여 특성을 비교 및 분석하여 이를 바탕으로 복합 재해에 대한 정의 및 특성 분석을 수행하였다. 30년 이상의 자료를 보유한 기상청 산하 기상관측소를 대상으로 전기간 자료를 구축하고 극한기상 현상의 발생원인을 강우-강풍, 강설-강풍 등 복합재해로 발생하는 시기의 자료와 단일재해로 발생하는 시기로 구분하여 지속시간별 연최대치계열을 추출하였다. 일반적으로 지표를 이용하여 지수를 계산하는 경우 반드시 표준화(normalization), 가중치부여(weighting), 집계(aggregation) 등의 방법이 필요하다. 지표들의 평가 기준 및 형태 등이 상이하므로 이를 평가할 수 있도록 표준화 과정을 거쳐야 한다. 본 연구에서는 Z점수 방법을 사용하여 적용하였다. 최근 2003년~2013년 11년간의 기상자료에 대한 Z 점수값의 상위 10%이내 해당되는 기상관측소의 지역에 대해서 분석하였다. 분석된 결과값을 이용하여 강우, 강풍, 적설이 각 지역별로 나타나는 표준화 점수를 통해 기후변화 영향을 받은 정도를 분석할 수 있다.

In this study, we intended to estimate the heat of hydration of carbon nanotubes-cement composites. It was tried to present the basic data of the heat of hydration characteristics of the CNT-reinforced cement composite by the simple adiabatic temperature rise test. The results indicated that adding CNT reduced the heat of hydration of cement composites.

This study was intended to estimate the effect of adding CNTs into cement paste on the rheological properties. it was found that higher content of CNTs increase yield stress but there was no noticeable correlation between CNTs dosage and plastic viscosity.

In this study, high performance fiber composites has developed using GGBS and Flyash with PVA fiber. Thus, four mixtures was determined accoding to the ratio of binder. A series of experiments, including slump flow, compressive strength, uniaxial tensile strength tests were carried out to characterize the mechanical properties of the fiber composites. The result of tests, slump flow showed an average 428mm and tensile strain 2% of behavior strain hardening of due to the occurrence multiple micro crack.

In this study, impact of high-velocity projectile by mixing steel fiber, polyamide, nylon, polyethylene fiber which have different shape and properties respectively. Scabbing is restrained because of micro-crack caused by the shock wave offset effect and energy dispersive of synthetic fibers are mixed populations.

The effect of steel fiber types on the self-sensing capacity of strain-hardening fiber-reinforced cementitious composites (SH-SFRCs) was investigated. Three types of fiber, including twisted, smooth and hooked fibers, were used with a volume content of 1.5% in a mortar matrix. Although all the SH-SFRCs exhibited self damage-sensing capacity, the gauge factor, representing for damage-sensing ability, was different according to the types of fiber as follows: twisted (138.09) > smooth (99.85) > hooked (88.50). The SH-SFRC with twisted fiber produced the highest gauge factor which is very favorable for development of self damage-sensor.

In this study, AC/DC responses of CNT-filled cement composites are measured and compared. Based on the results, it is found that AC measurement method is more reliable to measure the electrical resistance of CNT-filled cement composites.

In this study, an equivalent circuit model of CNT-filled cement composites is proposed. Both the polarization effect of electrode/composite interface and the complex resistance effect due to dielectric property of CNT cement composite are considered in the proposed model. Effective of the proposed model will be experimentally validated.

In this study, high-ductile and low-fiber composites have been mixed using Alkali-activated cement-free binders combined with PVA fibers of the volume fraction of 1.0～1.5%. From the direct tensile test of the composites, the low-fiber cement-free composites could exhibit high-ductile tensile behaviors about 4.0～7.0% tensile strains after cracks.

This study was intended to estimate the axial deformation of joint between pavement modules in the rapid-constructible modular pavement system, and to investigate the applicability of two-phase composites for a joint material, which was composed of cement paste, epoxy, or polyurethane as a matrix and sand as particles.