This study was performed to analyze the flexural performance of large diameter PHC Pile reinforced with transveres and longitudinal rebar and in-filled concrete. From the flexural test result, it was found that the initial cracking strength and maximum flexural strength of composite PHC pile were approximately 400% and 345% higher than that of the conventional PHC pile.

The purpose of this study is inspection of concrete using impact resonance method and UPV(Ultrasonic Pulse Velocity) method. The frequency polygon of non-destructive testing result shows that non-destructive testing is closely related to compressive strength of concrete.

PSC continuous girders have been used to improve the stability of simply supported girders. The loss of prestress is one of important factors for rational design and construction of the PSC girders. Measurements of prestress loss were conducted with the several test variables that reflect the conditions of continuous joint. Results show that the prestress loss is closely related to a eccentricity.

This paper presents an experimental investigation in order to evaluate fresh and hardened properties of LP (Limestone Powder) blended cement concrete. The cement contents of the mixtures are replaced by LP in the range of 10%, 15%, 25%, and 35%, while a control mixture is prepared with only OPC (Ordinary Portland Cement). The fresh concrete properties like slump and air content are similar to those of control mixture up to 35% of replacement ratio of LP, however a delay in setting time is evaluated. The hardened properties including compressive strength, flexural strength, and rapid freezing and thawing resistance shows similar results of control mixture up to 15% of replacement. Relatively lower strength development is evaluated over 25% replacement of LP. For accelerated carbonation test, resistance to carbonation rapidly decreases with increasing LP replacement ratio due to the limited amount of Ca(OH)2. From the study, LP replacement under 15% can be adopted considering reduction of strength and resistance to carbonation.

The amount of by-product from sulphur increases in domestic industrial facilities. However, the amount of its consumption is limited so that the amount of unused sulphur continues to increase. Therefore, in this study, the use sulfur polymer as the concrete surface protecting material was conducted. The compressive strength showed that as the substitution ratio of filler increased up to 40%, the compressive strength also increased. A high compressive strength was shown at the curing temperature of 40℃ (SS, FA) and 60℃ (OPC) according to the type of filler. The difference of compressive strength between air dry curing and water curing was insignificant so that there was no significant influence of moisture during curing process. The evaluation result of bond strength showed that the highest bond strength was shown at the air-dry condition of 40℃ regardless of type of filler. Bonding didn't occur properly during water curing in comparison to air dry curing. Also, in case of the specimen cured at 60℃, discoloration and hair cracks appeared due to the influence of temperature, and the highest bond strength was shown at the substitution ratio of 20% (SS, FA) and 30% (OPC) according to the type of filler. The releasing test result of harmful substance showed that no harmful substance was released, so there is no harmfulness in the surface protecting material using sulfur polymer. As a conclusion drawn in this study, it is most appropriate to substitute silica by approximately 20%, mix and cure at the air-dry condition of 40℃ in order to use sulfur polymer as the surface protecting material.

In recent years, a rapid growth in the population and urbanization led to an increasing industrial growth. The inadequate treated-wasted water from industry and various non-point sources causes significant negative effects on the stream water. For past few decades, extensive researches have been performed on water purification process. The purpose of this study is to investigate mechanical performance and water purification properties of porous concrete by using effective microorganisms through the site assessment test. The mechanical performance evaluation results showed that the increase void ration caused an decrease in the strength. The optimal mix rate was found to be 15% void rate From the site assessment, it was evaluated that the porous concrete improved the quality of the water and the purification ratios are 34.1 for SS, 14.6% for BOD, 34.9% for COD, 11.4% for T-N, and 12.6% for T-P. The porous concrete and the related purification technique can reduce the non-point pollution sources flowing into the river.

최근 도심지의 노후 된 포장 재정비 및 지하매설물 굴착 복구로 인한 폐아스콘 발생량이 지속적으로 증가하고 있으며, 이러한 건설폐기물 처리의 심각성이 대두됨에 따라 자원순환을 위한 정부의 패러다임 전환 정책이 강화되고 이에 따른 산업인프라 구축이 활발히 진행되고 있다. 한편 폐아스콘 순환골재를 활용한 투수성 재생 아스콘 제조를 통해 탄소배출량 저감, 지하수자원 보존 및 집중호우로 인한 도심지 침수 방지에 효과적일 것으로 예상된다. 따라서 본 연구에서는 투수성 재생아스팔트 혼합물의 제조 및 역학적 특성 규명에 앞서 폐아스콘순환골재의 물리적 특성을 분석하였다. 본 연구에서 사용되는 폐아스콘 순환골재는 G사에서 처리 및 생산된 골재로서 순환골재의 입도 크기별로 25~13mm, 13~8mm 및 8mm 이하의 것으로 분류하여 사용하였다. 25mm이하 폐아스콘 순환골재의 물리적 성질을 KS F 2503 ｢굵은골재의 밀도 및 흡수율 시험｣에 준하여 분석한 결과 밀도 및 흡수율이 각각 2.62 g/cm3, 1.45%로 나타났다. 폐아스콘 순환골재의 품질은 KS F 2572 ｢아스팔트 콘크리트용 순환골재｣에 준하여 실험하였으며, 구재아스팔트 함량 4.43%, 구재아스팔트 침입도(25℃, 1/10mm) 21, 씻기 시험에서 손실되는 양 1.0%, 유기이물질 0.07%, 무기이물질 0.11% 함유하는 것으로 나타나 아스팔트 콘크리트용 순환골재 품질규격에 적합한 것으로 확인되었다. 또한 폐아스콘 순환골재의 체가름시험 결과 골재입도는 25~13mm에서 25mm 100%, 20mm 85%, 13mm 72.5%, 10mm 54.6%, 5.0mm 39.6%, 2.5mm 27.3%, 0.6mm 15.9%, 0.3mm 11.5%, 0.15mm 7.3%, 0.08mm 2.8%, 골재입도 13~8mm에서 25~13mm 100%, 10mm 81.4%, 5.0mm 30.9%, 2.5mm 23.7%, 0.6mm 15.3%, 0.3mm 11.7%, 0.15mm 7.8%, 0.08mm 3.4%, 골재입도 8mm이하에서 25~10mm 100%, 5.0mm 93%, 2.5mm 74.5%, 0.6mm 41.9%, 0.3mm 29.6%, 0.15mm 19.1%, 0.08mm 6.9%의 체통과율이 확인되었으며, 향후 투수성 재생아스콘의 골재로 사용하기 위하여 입도별에 따른 투수성능 및 혼합물의 역학적 특성을 평가하여야 할 것으로 판단된다.

콘크리트 구조물의 내구성능을 감소시키는 열화에는 여러 가지 요인이 있으나, 가장 빈번하게 발생하는 요인 중 하나가 탄산화이다. 이러한 탄산화를 방지하기 위해 표면보호재를 활용하기도 한다. 한편 유황의 부산량은 정유산업 등의 국내 산업발달과 더불어 증가하고 있으며, 내화학성이 뛰어나 콘크리트의 표면보호재로 적합하다 판단된다. 따라서 본 연구에서는 산업부산물인 유황을 개질화하여 제작된 유황폴리머를 사용하여 콘크리트 표면보호재로 활용하기 위한 연구의 일환으로 탄산화저항성 평가를 수행하였다. 본 연구에서는 국내 S정유사에서 부산된 유황폴리머(sulfur polymer, SP)와 채움재로는 FA(fly ash)와 규사(silica sand)를 사용하였다. 배합은 유황폴리머만을 사용한 배합을 Plain으로 하여, 채움재를 유황폴리머 중량의 20% 치환하였다. 채움재의 종류에 따라 FA를 사용한 FA, 규사를 사용한 SS, 규사와 FA를 10%씩 치환한 FS로 총 4가지 배합에 대하여 실험을 수행하였다. 배합한 표면보호재를 120℃에서 용융하여 100 × 100 × 100 mm의 콘크리트 공시체의 한 면에 도포하여 7일간 양생하였다. 그 후 측면과 밑면을 에폭시 수지로 밀봉하여 온도 20 ± 2℃, 상대습도 65 ± 10%, CO2 농도 5.0%로 설정된 탄산화 시험기에서 28일간 촉진탄산화를 진행하였다. 촉진탄산화 수행결과, 표면보호재를 도포하지 않은 공시체의 탄산화 깊이는 12.16 mm로 측정되었으며, Plain 배합에서는 1.31 mm로 약 90%의 중성화 깊이 감소를 나타내었다. 하지만 FA 배합에서는 3.36 mm로 채움재가 오히려 탄산화 저항성을 감소시키는 것으로 나타났다. SS 배합과 FS 배합에서는 각각 0.73 mm, 0.96 mm로 측정되어 탄산화 저항성을 증가시키며, KS 기준인 1.0 mm 이하를 만족시키는 것으로 나타났다. 이러한 결과로부터 유황폴리머를 활용한 표면보호재의 탄산화저항성은 규사를 채움재로 사용하는 것이 가장 효과적이며, 규사와 FA를 같이 사용한 배합도 우수하다 판단된다.

Assessment of surface cracks is important to ensuring the health of concrete structures. Traditional visual inspection processes are time-consuming and their performance depends heavily on the inspector’s skill and experience. In this paper, digital image processing techniques are employed to monitor the surface cracks in concrete. The automated processing method is proposed for further implementation to an flight drone.

The purpose of this study is to use organisms or micro-organism functions for eco-friendly water-purification according to concentration in porous concrete using EM, utilizing bioremediation.

In this study, the applicability evaluation of basalt fiber surface treatment with fluorination. Test results showed that significantly reduce the tensile strength through the basalt fiber surface treatment with fluorination.

Semi-rigid pavement is one of excellent paving methods adopting merits of asphalt-concrete and concrete paving. However, conventional paving methods were mainly used on the new constructed roads. Therefore, in this research we have examined the possibility of using the semi-rigid pavement on occupied roads. Also, confirmed the early-open possibility of pavement by applying the rapid hardening binding material to semi-rigid pavement.

To evaluate the prestressing loss of tendon caused by deflection angle, test is conducted with the variables of a deflection angle and a diameter of deviator head. Results show that the prestressing loss increases when the delfection angle increases but the diameter of deviator head gives no significant influence on the prestressing loss.

In this paper, ultrasonic velocity(UV) test through OPC and Slag concrete is conducted considering porosity under compressive and tensile loading conditions. The test results show that up to 50% of compressive loading condition, UV a little increases and remarkably drops at peak load, however it fluctuates under the tensile loading condition because of the number of increase micro cracks in concrete specimens.

In this paper, it is evaluated for sound and cold joint concrete under compressive load. To evaluate the permeability of the concrete, to prepare a cold joint specimens. And the water permeability evaluated by comparison of the sound and the cold joint concrete. it selected control, 30%, and 60% of the breaking strength. Results of evaluating the permeability of the cold joint concrete under compressive load, and tended to reduce at 30% of load, to increase at 60% of load.

In this study, it was evaluated the permeability of cold joint concrete, to evaluated the permeability considering slag concrete and OPC. In addition, the water permeability was evaluated by comparing the sound and cold joint concrete. As a result, OPC-Joint(3.76×10-10m/s), Slag-Joint(3.36×10-10m/s), OPC(2.65×10-10m/s), Slag(2.36×10-10m/s) was evaluated in this order. The OPC-joint is the most highly evaluated. This is estimated to be because the density of the pore structure.

There are comprehensive efforts to reduce CO2 gases and CO2 reduction can be expected using a limestone powder as a admixture in concrete. In this study, Drying shringkage of concrete using a large amount of limestone powder was evaluated.

Recently, there is comprehensive efforts to reduce greenhouse emissions in a global community. CO2 reduction can be expected using a limestone powder as a admixture in concrete. In this study, Rapid Freezing and Thawing test of concrete using a large amount of limestone powder was evaluated.

The purpose of this study is to more accurately predict the compressive strength of concrete according to mixing proportion using UPV(Ultrasonic Pulse Velocity) method. The equation to predict the compressive strength of concrete is proposed based on the results of UPV method.

The purpose of this study is to establish a mathematical equation to evaluate the compressive strength of concrete from the measured impact resonance test values(Ed). The correlation was made between the measured and evaluated compressive strength values and the correlation was quite strong.