도로 노반의 동공 채움보수 및 지반 보강 방법으로 시멘트 혼합물을 사용한 그라우팅 보수공법이 널리 사용되고 있 다. 그러나 그라우팅의 재료로 사용되는 보통 포틀랜드 시멘트는 생산 과정에서 다량의 이산화탄소가 발생하여 환경오염 의 주요 원인으로 간주된다. 따라서 시멘트의 대체 재료로서 각종 산업부산물의 활용 가능성에 대한 연구가 활발하게 이 루어지고 있다. 본 연구에서는 도로 하부 동공 보수 및 보강용 그라우팅 재료로써, 제지 공정에서 발생하는 슬러지를 소 각하여 얻은 제지애쉬(Paper Ash)의 활용 가능성을 유변학적 관점에서 평가하였다. 제지애쉬는 보통 포틀랜드 시멘트와 화학적 조성이 비슷한 것으로 알려져 있다. 제지애쉬-시멘트 혼합물을 물-바인더 비율(W/B) 및 시멘트 치환율에 따라 유변학적 특성을 실험적으로 평가하였다. 실험 결과 제지애쉬의 특성상 100% 제지애쉬 혼합물은 유동성이 매우 낮은 결 과를 나타냈으며, 시멘트 치환율 20%까지 유의미한 유동 특선 개선 효과는 보이지 않았다. 그러나 시멘트 치환율이 20~30% 구간에서 유동성이 급격하게 개선되는 현상을 확인하였고, 30% 이상부터 추가적인 유동성 개선 효과는 미미하 였다. 또한 W/B가 높을수록 유동성은 개선되나 시멘트 치환율이 증가함에 따라 블리딩 발생량이 증가함을 확인할 수 있 었다.

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.

PURPOSES : The objective of this study is to evaluate the mechanical properties of ternary blended cement concrete incorporated with pulverized reject ash (PRA) or pulverized fuel ash (PFA) based on a comparison with those of ordinary Portland cement (OPC) concrete. METHODS : To produce the concretes, the level of OPC replacement is set at 60%, which comprises 30%~45% ground granulate blast furnace slag and 15%~25% of fly ash (FA). The FA can be categorized into PFA, 4PRA (fineness 3,930 cm2/g3), and 8PRA (fineness 7,840 cm2/g3). The compressive strength, surface electric resistivity, initial absorption coefficient, and chloride ion penetrability of OPC and the ternary blended cement concrete are measured at predetermined periods after water curing. RESULTS : It is discovered that the mechanical properties of concrete with 8PRA are better than those of OPC concrete. The performance of 4PRA concrete is worse than that of 8PRA concrete, indicating that the fineness of the PRA can affect the mechanical properties of the ternary blended cement concrete. CONCLUSIONS : The use of PRA is feasible for the production of ternary blended cement concrete, provided that the appropriate mix design and grinding technology are used.

본 연구에서는 폴리머 시멘트 모르타르의 인장성능을 개선하기 위하여 PVA 섬유를 적용하고자 하였다. PVA 섬유 혼입량에 따른 재료특성을 검토하여, 섬유보강 폴리머 시멘트 모르타르의 제조 가이드라인을 제공하고자 하였다. 폴리머 시멘트 모르타르의 제조를 위하여 친수성의 합성수지(SR)를 사용하였다. 실험에 사용된 변수로 (W+SR)/C비를 고정하여, 사용물에 대한 합성수지의 치환율을 일정하게 증가시켜 사용하였다. PVA 섬유의 혼입량은 각각의 실험체에 0%,1%,2%를 혼입하여 실험을 수행하였다. 재료특성 실험으로는 압축강도시험, 쪼갬 인장강도시험, 휨 강도 시험을 수행하였다. 폴리머 시멘트 모르타르에 PVA 섬유를 혼입하면 쪼갬 인장강도 및 휨 강도가 증가하는 것을 확인 하였다. 따라서, 본 연구결과는 합성수지 혼입 폴리머 시멘트 모르타르의 인장성능 개선을 위한 PVA섬유 혼입시 제조 가이드라인으로 활용이 가능할 것으로 판단된다.

PURPOSES : In this study, wasted vinyl aggregate, which possesses better thermal properties than natural aggregate, was used in cement concrete mixture to develop more economical concrete with thermal insulation and freeze prevention effects. METHODS : Slump and air content of the fresh concrete, which substituted its 0%, 5%, and 10% of coarse aggregate with wasted vinyl aggregate, were measured. Compressive strength, Poisson’s ratio, elastic modulus, and splitting tensile strength of hardened concrete were measured by laboratory tests. Thermal properties of concrete such as coefficient of thermal expansion, thermal conductivity, and specific heat were also measured according to replacement ratio of wasted vinyl aggregate. Finally, the thermal insulation and freeze prevention effectiveness of the concrete mixed with wasted vinyl aggregate was confirmed through finite element analysis of road pavement crossing above concrete box culvert made from wasted vinyl aggregate. RESULTS: Even though the physical properties of wasted-vinyl-aggregate concrete such as compressive strength, Poisson°Øs ratio, elastic modulus, and splitting tensile strength were inferior to those of ordinary concrete, they met requirements for structural concrete. The thermal properties of concrete were improved by wasted vinyl aggregate because it decreased thermal conductivity and increased specific heat of the concrete. According to the result of finite element analysis, temperature variation in pavement subgrade was mitigated by box culvert made from wasted-vinyl-aggregate concrete. CONCLUSIONS: Through the laboratory test and finite element analysis of this study, it was concluded that the concrete structures made from wasted vinyl aggregate showed thermal insulation and freeze prevention effects.

CSA, a cement mineral compound that is mainly composed of 3CaO·3Al2O3·CaSO4, generates ettringite as a hydration product after a reaction with glass (lime), gypsum and water to speed up the hardening process and enhance the strength and degree of expansion. When used as a cement admixture, there is increased production of ettringite, which can improve the initial strength in the first three days and ameliorate the reduction in the initial strength caused by the use of fly ash in particular. In this study, a hydrate analysis was performed using XRD and SEM after substitution with fly ash (30%) and CSA (8%) with the goal of observing the effect of CSA on the initial strength of a cement mixture containing fly ash. The results of the analysis showed that an addition of CSA promoted the production of ettringite and improved the initial strength, resulting in the generation of hydrates, which can effectively enhance the long-term strength of these materials.

본 연구에서는 페로니켈슬래그 시멘트를 활용한 FNS 혼합시멘트의 저발열 대류계수에 관한 실험 및 고찰 결과를 소개하 고자 한다. 일반적으로 혼합시멘트의 수화열 해석시에 열전도율, 비열등에 의한 열확산율의 개념은 현행 콘크리트 시방서에 서 열확산율 혹은 열전달률의 식으로 표기되어져 있고, 이와 연관된 외기 대류의 계수는 콘크리트 구조체를 둘러싼 외기환 경의 거푸집, 버블시트, 공기중 조건등에 대한 단순 실험상수가 연구논문 사례등을 기초로 하여 제시되는 수준이다. 본 연구 에서는 열확산율과 대류계수로의 연관성을 심층 고찰하면서 실험을 기반으로한 해석적 검증 연구를 수행하였다.

본 연구에서는 시멘트 복합재료와 직접 혼합 가능한 자기치유 마이크로 캡슐을 제조하였으며, 자기치유 마이크로 캡슐이 혼합된 시멘트 복합재료의 품질 및 균열 치유 성능 특성을 평가하였다. 종래의 경우 자기치유 캡슐 제조와 균열 치유 특성 평가에만 치중되어 평가되어 왔다. 따라서 자기치유 마이크로 캡슐은 시멘트 복합재료와 혼합시 시멘트 복합재료의 품질에 미치는 영향이 있기 때문에 이에 대한 검토를 수행하였다. 자기치유 마이크로 캡슐을 혼합한 시멘트 복합재료의 테이블 플로우 및 공기량 평가 결과 혼합율에 관계없이 테이블 플로우 및 공기량은 큰 영향이 없는 것으로 나타났다. 압축강도 및 쪼갬인장강도는 캡슐 혼합율이 증가할수록 강도가 감소하는 경향이 나타났다. Water Flow에 따른 균열 치유 특성 평가 결과 초기 투수량이 감소하는 결과가 나타났으며, 시간 경과에 따라 반응 생성물 발생하여 균열이 치유되는 것을 확인 할 수 있었다.

Vegetation has a great importance in erosion control and slope stabilization, protecting and restraining the surface soil and increasing the strength and competence of the soil mass. However, normal green soil have poor adhesion to slopes. In order to enhance the adhesion, therefore, the vegetation effect of green slope soil mixed with cement materials was investigated in this study.

This paper was evaluated the mechanical propeties that compressive strength, splitting tensile strength and elastic modulous of self-healing solid type capsules mixed cement composites.

This study is a basic review of the use of CGS generated in IGCC as a fine aggregate for concrete, and a basic feature of cement mortar was considered. The analysis shows that CGS and CS mix ratio is best when the CGS is mixed at about 0~50 % On the basis of workability and strength improvement effects. This is expected to contribute to the strength, workability, and quality improvement of concrete given the optimal mixing of CGS.

In this study, the fiber blending ratio and strain rate effect on the tensile behavior of hybrid fiber reinforced cement composite was evaluated. Hooked steel fiber and polyvinyl alcohol fiber were used for reinforcing fiber. The fiber blending ratio of HSF+PVA were 1.5+0.5, 1.0+1.0 and 0.5+1.5vol.%. As a results, the tensile strength, strain capacity and fracture toughness of the hooked steel fiber reinforced cement composites were improved by the increase of the bond strength of the fiber and the matrix according to increase of strain rate. However, the tensile stress sharply decreased after the peak stress because of the decrease in the number of straightened pull-out fibers by micro cracks in the matrix around hooked steel fiber. On the other hand, PVA fiber showed cut-off fracture at strain rate 10-6/s with multiple cracks. However, at the strain rate 101/s, the multiple cracks and strain capacity were decreased because of the pull-out fracture of PVA fiber. The HSF1.5PVA0.5 shown the highest tensile strength because the PVA fiber suppressed the micro cracks in the matrix around the hooked steel fiber and improved the pull-out resistance of hooked steel fiber. Thus, DIF of strain capacity and fracture toughness of HSF1.5PVA were greatly improved. In addition, the synergistic response of fracture toughness was positive because the tensile stress was slowly decreased after the peak stress by improvement of the pull-out resistance of hooked steel fiber at strain rate 101/s

This study was aimed to investigate the effect of blending cement with crushed aggregate powder on the setting time. crushed aggregate powder was incorporated with the ratio of 0~30 wt.% of cement. The experimental results presented that there was little influence on the intial setting time, whereas the final setting time decreased by blending with higher amount of crushed aggregate powder.

본 연구에서는 해수 침지 온도에 따른 비소성 시멘트 경화체의 물리적 및 역학적 특성에 대해 비교 분석하였다. 비소성 시멘트는 플 라이애시와 고로슬래그미분말을 6:4, 7:3 및 8:2의 중량비로 혼합하여 수산화나트륨과 액상규산나트륨으로 알칼리 활성화 하여 제작되었다. 알칼리 활성화를 위한 활성화제는 플라이애시와 고로슬래그미분말을 혼합한 중량의 5%로 하였으며, 화학첨가제로 탄산칼슘이 사용되었다. 본 연구에서는 알칼리 활성화된 시험체들을 3가지 다른 온도(5°C, 15°C 및 25°C)의 해수에 각각 침지 시킨 후, 침지 재령 3일 및 28일에 대해 경 화체의 압축 강도, 밀도 및 흡수율을 측정하였으며, 해수 침지 재령 28일에 대해서는 XRD 및 SEM 시험 분석을 실시하였다. 또한, 해수 침지 재 령 28일에 대하여 시험체들 내의 수용성 염화물(자유염화물) 및 산-가용성 염화물(총염화물) 함유량을 측정하여 분석하였다. 본 연구에서 해수 온도별로 침지시킨 플라이애시-고로슬래그미분말 혼합 알칼리 활성화 경화체는 플라이애시 혼합률이 증가함에 따라 밀도 감소, 흡수율 증가 및 강도가 감소하는 경향을 나타냈다. 또한 플라이애시 혼합률이 증가할수록 시험체 내의 수용성 염화물 및 산-가용성 염화물의 양이 증가하는 것으로 나타났다. 본 연구에서 제작된 플라이애시-고로슬래그미분말 혼합 알칼리 활성화 경화체는 노출된 해수 온도 영향으로 인한 강도 차이 는 없는 것으로 판단되며, 플라이애시와 고로슬래그미분말의 혼합중량비에 따라 강도 특성이 달라지는 것으로 나타났다.

The objective of this study is the development of an artificial soil composition for vegetation in rock slope condition. In this study, the suitability of artificial soils added the cement-based materials is considered. The results show that the pH value of artificial soil added the micro cement was kept in the range of 7.86 to 8.00.

Even though high performance concrete was developed according to becoming bigger and higher of reinforced concrete building, the rheological evaluation is not enough to use as input data to accomplish the numerical analysis of construction design. Consistency curves were measured by the viscometer as hydration reaction time passed. There are a sudden change of viscosity and yield stress around initial setting in case of low W/B. The increase of workability by the change of free water in cement paste was offset by the coating effect of impermeable layer in case of W/B 40%.