폴리카본산계 고성능 감수제와 증점제 조합에 따른 보통강도 고유동 콘크리트의 유동 및 강도특성에 관한 실험적 연구

Abstract

기존의 고유동 콘크리트는 소요의 유동성과 점성 확보를 위해 대부분 단위시멘트량이 높은 고강도 콘크리트 영역으로써, 현재 사용되고 있는 대부분의 콘크리트 구조물이 보통강도 영역임을 감안한다면 현실적인 사용범위확대 및 실용성에 한계가 있었다. 따라서 본 연구에서는 보통강도 영역에서 고유동 콘크리트의 현실적인 적용기준을 마련하고자, PC계 특수 고성능감수제와 2종의 증점제를 조합하여 보통강도 고유동 콘크리트의 유동성, 간극통과성, 자기충전성 및 강도특성을 분석함으로써 보통강도 고유동 콘크리트의 실용화를 위한 기초자료를 제시하고자 한다. High fluidity concrete has a high level of fluidity with the segregation resistance and the self-compacting property without the extra work for compaction. Therefore this concrete represents high quality concrete with excellent workability and enables the easy production of heavily reinforced concrete structures of complex geometry. Despite its obvious advantages, the high cost of high fluidity concrete prevents its wider use. Also the application of typical high fluidity concrete is limited in the normal strength range (18~35 MPa) because of the uneconomical strength development due to large amount of binder. It is required to design the formulation of an economical binders, proper materials and mixtures for normal strength and high fluidity in order to expand the usability of such high fluidity concrete for general application. But if the usage of binders is low in concrete, it is reduced the fluidity and segregation resistance due to the decrease in self-compacting reduction by lack of viscosity. The aim of the study is to evaluate the fluidity and strength of high fluidity concrete for normal strength range using the combination of polycarboxylate viscosity modifying admixture (P-VMA) and methyl cellulose viscosity modifying admixture (C-VMA). To improve the fluidity of concrete, this paper investigated the effects of VMA on the slump flow, passing ability, self-compacting and segregation resistance. In addition, the effect of VMA on compressive strength was investigated. The dosage of P-VMA and C-VMA in the mixtures was 0.2%, 0.4%, 0.6% and 0.1%, 0.2%, 0.3% by weight of the total biders, respectively. As a result of this study it has been found that addition of VMA to concrete improves its fluidity and segregation resistance by increasing the viscosity of concrete, but the compressive strength decreased with increase of VMA.