In this study, the cement composites incorporating Carbon Nanotube(CNT), Carbon Black(CB), and Carbon Fiber(CF) of 0.5, 1.0, and 1.5% of binder weight were evaluated to provide conductivity. In order to achieve this, compressive strength and electrical resistance were measured. As a result, the conductivity of cement composites incorporating CNTs was more sensitive than that of cement composites containing CB and CF.

The study was conducted to evaluate the penetration performance of Surface Protection Material(SPM) according to the particle size distribution of fine aggregate. The fine three types of aggregates were used, and the amounts of SPM were applied 0.13, 0.25, 0.36, and 0.51 kg/㎡. Test results indicated that the penetration depth of SPM were improved with increasing the amounts of application of SPM. And The penetration depth of SPM were improved with increasing the percentage of passing weight of size of sieve between 0 and 1.25mm.

This study investigates the effects of compressive strengths on mechanical properties of concrete with compressive strengths of 40 and 80 MPa. In this study, The steel fiber an aspect ratio of 64 and a tensile strength of 1,600 MPa used. As the result, There are no significant effect of fiber tensile strength on mechanical properties of normal strength SFRC. For high strength SFRC, Specimen with high strength fiber have superior performance then that with normal strength fiber.

This paper evaluates analytically the flexural behavior of steel fiber reinforced concrete (SFRC) notched beams according to the tensile strength of steel fiber. For this purpose, compressive strength and bending tests of SFRC applying steel fibers with tensil strength of 1,200 and 1,600 MPa was conducted. Strain hardening behavior was observed when using high tensile strength steel fiber. Compression and tensile models were established through test results. For the tensile model, hordijk model and trilinear model were analyzed and compared. The results of analysis showed good agreement when using trilinear model.

This paper describes the effect of steel fiber volume fraction and aspect ratio on mechanical properties of SFRC with compressive strength of 40 MPa. In this study, The fiber volume fractions consist of 0.25%, 0.50% and 0.75% and aspect ratios are 64 and 80 used. The prisms with 150×150×550 mm were made and tested in accordance with EN-14651. Test results show that the superior flexural performance was observed in SFRC with higher fiber volume fraction and aspect ratio.

This study was evaluated the chloride penetration resistance performance of Surface Protection Material(SPM). SPM was applied 0.25 and 0.51 kg/㎡ to the surface of the mortar and immersed aging of the chloride solution 7, 14, and 28 days. As a results, In the case of SPM was applied, chloride did not penetrate until the 28th day.

In this study, the rate of change of electrical resistance with respect to the strength and load of cement composites was investigated by incorporating Carbon Nanotube(CNT) at 0.25, 0.5, 0.75, 1.0% of the binder weight. Compressive strength test It was shown that the load of 30% was repeatedly applied to impart conductivity through the rate of change of electrical resistance. The incorporation rate of CNT greatly affected the compressive strength and the rate of change of electrical resistance.

This study was evaluated the penetration performance according to SPM type. The types of SPM are liquid and cream type. And the amounts of SPM were applied 0.13, 0.25, 0.36, and 0.51 kg/㎡. The specimen size was 100×30mm as KS F 4930. Test results indicated that the penetration depth of SPM were improved with increasing the amounts of application of liquid and cream SPM. In the case of applied cream SPM of 0.13, 0.25 and 0.36 kg/㎡ the standard deviation of penetration depth was less the liquid type SPM was applied.

This paper evaluates the seismic performance of reinforced concrete(RC) frame strengthed with expansive mortar and steel frame. For this purpose, cyclic loading test was conducted, load-displacement relationship and energy dissipation capacity were evaluated. As a results, RC frame retrofitted with steel frame was increased maximum strength and energy dissipation capacity than conventional RC frame.

This paper was conducted to investigate analytically the non-ductile reinforced concrete frame and steel frame. The results of cyclic loading test and analysis was compared. The maximum strength and strength reduction point of test result were similar to analysis result.

In this paper, the effect of steel fiber-reinforced cement composite (SFRCC) on damage resistance of steel tube member. Test results show that the cumulative energy dissipation of SFRCC specimen was about 14% higher than that of Con specimen.

The coupling beam is recognized that critical structural elements, those whose yield strength is likely to be exceeded in the event of a severe earthquake, should be designed and detailed to exhibit large ductilities and stable hysteretic loop. As a result, the alternation reinforcement details of reinforced concrete coupling beam was investigated.

일반적으로, 원전구조물은 다량의 철근이 사용되어 시공과정에서 여러 잠재적 문제점이 발생한다. 특히, 구조부재의 연결부위는 수많은 갈고리철근, 매입철물과 주변 철근 등에 의해 심각한 과밀현상이 발생하므로 여타 다른 부위보다 콘크리트 타설에 더 큰 어려움이 야기 된다. 원전구조물에 사용되는 일반강도(ASTM A615 Gr.60)의 대구경(43 mm & 57 mm) 표준갈고리 철근을 대신하여 고강도(ASTM A615 Gr.80)의 대구경(43 mm & 57 mm) 확대머리 철근을 사용할 수 있도록 관련 기술기준을 개정하여 철근 과밀배근 문제를 해결하는 데 본 연구의 목적이 있다. 확대머리 철근을 원전구조물에 효과적으로 사용하기 위해서는 기존의 정착성능을 그대로 유지하거나 그 이상으로 증가시키면서 사용 제한요건을 완화는 방안을 찾아야 하므로 철근직경, 철근 항복강도, 측면피복 두께와 같이 확대머리 철근의 사용을 제한하는 변수 영향을 검토할 수 있는 실험결과를 분석하여 정착성능을 평가하였다.

This paper describes the flexural characteristic of high strength steel fiber reinforced concrete (SFRC) prisms with different fiber tensile strength. All mixtures have specified compressive strength of 80 MPa and fiber volume fraction of 0.5% and 1.0%. In accordance with EN-14651, SFRC prisms were made and tested under bending loading. Test results indicated that steel fiber has no significant effects on compressive behavior of SFRC. However, flexural behavior of high strength SFRC was improved considerably with increase of fiber tensile strength.

The study was conducted to evaluate the latent heat properties of cement mortar with different contents of phase change material (PCM). The paraffin PCM with melting point of 44℃ used in this study. PCM was added in the mixture with contents ranged from 0 to 30%. Test results indicated that the heat storage performances of cement mortar were improved with increasing the content of PCM.

본 연구에서는 프라이머 도포 여·부 및 압축강도수준 그리고 바닥 마감재 시공재령에 따른 주차장용 바닥 마감재 부착성능을 평가 하였다. 또한 현행 KS 기준에서는 바닥 마감재 부착성능을 모르타르 공시체를 활용하여 평가하도록 제안하고 있지만, 실제 현장에서 바닥 마 감재는 콘크리트 상부면에 시공되기 때문에 바탕면 변화에 따른 부착성능을 추가변수로 계획하여 평가를 진행하였다. 모르타르는 현행기준에 서 제안하고 있는 배합표에 준하여 제작하였으며, 콘크리트 설계기준강도는 18, 30, 50 MPa로 계획하였다. 프라이머는 모르타르 및 콘크리트 재령 28일 변수에 따라 바닥 마감재와 함께 도포되었으며, KS 기준에 준하여 바닥 마감재 재령 일에 따라 부착성능을 평가하였다. 변수에 따른 부착성능 평가결과 바닥 마감재 재령이 경과함에 따라 바닥 마감재 부착성능은 향상되는 것으로 나타났으며, 압축강도가 높아짐에 따라 바닥 마감재 부착성능 또한 향상되는 것으로 나타났다. 이는 파괴양상을 고려하였을 때 콘크리트 쪼갬 인장강도의 영향을 받은 것으로 판단된다. 프 라이머 도포에 따른 부착성능은 유사한 것으로 나타났으며, 프라이머의 사용은 부착강도에 문제없이 콘크리트 표면의 내구성을 향상시킬 수 있을 것으로 판단된다. 또한 콘크리트 및 모르타르 바탕면의 부착강도 특성을 비교한 결과 바닥재의 부착강도는 구성재료 보다 압축강도에 큰 영향을 받는 것으로 나타났다. 따라서 현행 KS 기준의 모르타르 바탕면 실험체의 부착강도를 근거로 실제현장의 부착강도를 예측할 수 있을 것으로 판단된다.

This paper investigates the effect of amount of Paraffin-encapsulated phase change material (PCM) on the thermal energy storage of cement mortar for developing energy saving concrete. The PCM with melting point of 44℃ was used in this study. The added amounts of PCM in the cement mortar were 0, 10, 20 and 30% of cement weight. The results indicated that the heat storage properties of cement mortar was improved with increasing contents of PCM.

This paper provides the flexural test results of steel fiber reinforced concrete (SFRC) prisms with different aspect ratios of steel fibers (60 and 67). All mixtures have specific compressive strength of 40 MPa and steel fiber volume fraction of 0.75%. According to ASTM C 1609 and EN-14651, SFRC prisms with 150×150×550 mm were made and tested under bending loading. Test results indicated that the aspect ratio of hooked-end steel fibers has insignificant effect on the first-cracking strength and flexural behavior of SFRC prisms.

This paper presents the flexural test results of steel fiber reinforced concrete (SFRC) prisms with different lengths of steel fibers. The specified compressive strength of SFRC is 40 MPa. Two types of steel fiber used in this study have lengths (0.5 and 0.9mm). Test results indicated that steel fibers with longer length is more effective to improve the flexural performance of concrete prisms than steel fibers with shorter length.

This paper describes the electrical characteristics of carbon fiber reinforced cement composite under compressive loading. The test results indicated that the electrical resistance changes of cement composite in compression were improved with increasing carbon fiber volume fractions.