미립 잔골재 혼입이 콘크리트의 배합 및 건조수축 균열 특성에 미치는 영향

Abstract

In the middle east and the north africa, very fine sand such as dune sand (or desert sand) is used in concrete production as concrete fine aggregate. The particle size and grading of dune sand are very small and the properties of concrete could be greatly affected when very fine sand is used as concrete fine aggregate. In this study, the effects of very fine sand on the properties of concrete mixture and drying shrinkage cracking were investigated. Under condition of same amount of superplasticizer of plain mixture, to meet the target slump range, water content increased as the replacement of very fine sand increased. Compressive strength of concrete used very fine sand were 7.6~15.3% higher than that of plain concrete. Also, tensile strength were increased 24.0~28.4% when very fine sand used in concrete. Time-to-cracking were 16.8~25.7% shortened and stress rate was increased maximum 32.7% when very fine sand was used in concrete. It indicated that the risk of drying shrinkage cracking of concrete used very fine sand was higher than plain concrete. However, the higher use of very fine sand did not lead the higher risk of drying shrinkage cracking.