Recently, high-performance and high-fluidity concrete have been studied and developed because high-rised build is constructed. high-performance and self-consolidating concrete is demanded high strength as low w/cm and fluidity as adding superplasticizer. However, these superplasticizer are changed early-age property such as bleeding, segregation and late setting time etc. This study persents the setting time of fluidity mortars evaluated using the measurement of eletrical resistivity. 7th Samples prepared mortars which were adding polycarboxylate type superplasticizer(Ester) or poly naphthalene sulfonate(PNS) and measured the electrical resisitivity during 24 h. As a results, mortars which added superplasticizers were late rising time which is setting time in measurement of electrical resistivity. However, degree of hardening of PNS mortar were higher than Ester mortar.

프리캐스트 바닥판 공법은 바닥판간 이음부가 존재하며, 이음부의 연결성능에 따라 전체 교량 구조물의 성능이 좌우되므로 이음부 의 연결성능 확보가 중요한 요소이다. 본 연구에서는 고강도 강섬유보강콘크리트(High Strength Fiber Reinforced Concrete, HSFRC)가 적용된 비대칭 요철형 이음단면을 갖는 연결형식을 제안하였으며, 이음부의 단면형태, 철근 겹침이음길이 및 겹침이음 형식에 따른 구조실험을 수행 하여 제안된 연결형식의 휨 성능을 평가하였다. 실험결과, 이음부 상세에 관계없이 이음철근은 항복변형률 수준의 인장변형을 나타내었으며, 제안된 연결형식은 충분한 휨 저항성능을 확보하는 것으로 나타났다. 이러한 실험결과는, 현행 도로교설계기준의 최소 겹침이음길이에 대한 규정은 이음부 채움재로 HSFRC를 적용한 프리캐스트 바닥판 이음부에서는 보수적인 규정임을 알 수 있다. 따라서 이음부 채움재로 HSFRC 를 사용함에 의해 철근 겹침이음 상세의 단순화 및 이음부 폭의 감소가 가능하며, 제안된 연결형식은 프리캐스트 바닥판 이음부에 효과적으로 적용 가능할 것으로 판단된다.

Various non-destructive test have been developed to predict the setting time of concrete. Through the electrical resistivity method(Wenner’s four electrode method), the effect of chemical admixture(AE admixture and superplasticizer) added for setting time of concrete mixtures is confirmed. As a result, it is observed that AE admixture dose not affect to change of concrete microstructure but delaying on setting time, and superplasticizer is affected not delaying on setting time, but changing in concrete’s microstructure

Various non-destructive test have been developed to predict the setting time of concrete. Through the electrical resistivity method(Wenner’s four electrode method), the effect of chemical admixture(AE admixture and superplasticizer) added for setting time of concrete mixtures is confirmed. As a result, it is observed that AE admixture dose not affect to change of concrete microstructure but delaying on setting time, and superplasticizer is affected not delaying on setting time, but changing in concrete’s microstructure