• Computers and Concrete
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• 제32권6호
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• pp.595-606
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• 2023

Dune sand (DS) has been widely used as a partial replacement for regular sand in concrete construction. Therefore, investigating its mechanical properties is critical for the analysis and design of structural elements using DS as a construction material. This paper presents a comprehensive investigation of the mechanical properties of DS concrete, considering different replacement ratios and strength grades. Regression analysis is utilized to develop strength prediction models for different mechanical properties of DS concrete. The proposed models exhibit high calculation accuracy, with R² values of 0.996, 0.991, 0.982, and 0.989 for cube compressive strength, axial compressive strength, splitting tensile strength, and elastic modulus, respectively, and an error within ±20%. Furthermore, a stress-strain relationship specific to DS concrete is established, showing good agreement with experimental results. Additionally, nonlinear finite element analysis is performed on concrete-filled steel tube columns incorporating DS concrete, utilizing the established stress-strain relationship. The analytical and experimental results exhibit good agreement, confirming the validity of the proposed stress-strain relationship for DS concrete. Therefore, the findings presented in this paper provide valuable references for the design and analysis of structures utilizing DS concrete as a construction material.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.419-422
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• 2005

This paper is examined the properties of Haeju sea sand for concrete. As result, the water absorbtion ratio and the contents of shell and microfines of Haeju sea sand was high. We would expected to utilize the results of this study as a basic data for quality control of Ready Mixed Concrete.

• 산업기술연구
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• 제17권
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• pp.227-232
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• 1997

This study was conducted to evaluate durability of concrete which are increasingly demanded recently. Concrete durability properties incorporating waste foundry sand was performed with the variable of W/C ratio, Sand/Waste foundry sand ratio and Air entrainment-Non air entrainment. Cylinder specimens were made and subjected to freezing and thawing cycle at $-18^{\circ}C$ and $4^{\circ}C$. Dynamic modulus of elasticity were evaluated as F/T cycle increase. The results show that decreasing W/C ratio and AE concrete makes improved resistance of freezing and thawing improved. Especially, resistance of freezing and thawing is improved by Fine aggregate/Waste foundry sand ratio which is 50%, 25%, 0% in a row.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.389-392
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• 2006

In this study, I examined hardening and non-hardening of the DFRCC (Ductile Fiber Reinforced Cementitious Composites) according to sand-aggregate ratio and the diameter of PVA fiber to develope PVA fiber reinforced concrete with the feature of DFRCC. As a result of this study, the fresh properties of DFRC is similar regardless of sand-aggregate ratio. The bending stress of DFRC also increased as the sand-aggregate ratio increased. And the bending stress-displacement was the most stable when the PVA $100{\mu}m$ was used regardless of sand-aggregate ratio.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.271-275
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• 1998

Recently, in the trend of using aggregate, it is common that coarse aggregate is replaced with crushed stone and fine aggregate is replaced with sea sand as a replacing aggregate. In this study, to judge the adaptability of using antiwashout underwater concrete, we used mixed sand (river sand : sea sand= 5 : 5) and changed W/C. After carrying out the research on the strength development of the compressive strength of specimen, tensile strength, fluxural strength which is produced and cured in the air and salt water, we founded that when W/C was low and the amount of AWA and SP were increased, the state of strength development was excellent.

• 콘크리트학회지
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• 제5권3호
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• pp.107-115
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• 1993

최근 건설공사의 급증으로 인한 하천골재의 고갈로 콘크리트용 대체골재로서 해사\ulcorner선사 등이 대구되고 있다. 그러나 해사는 세척하지 않고 그대로 콘크리트에 사용할 경우 콘크리트중의 철근부식 촉진에 따른 콘크리트의 균열발생 등 조기 노후화현상으로 내구성에 많은 문제점을 내포하고 있고, 산사는 국내 연구실적이 전혀 없는 상태에서 지역적으로 무분별하게 사용되고 있어 이들에 관한 제반 공학적 특성 및 활영방안 연구가 시급한 실정이다. 따라서 본 연구는 산사\ulcorner해사를 사용한 콘크리트의 압축강도 특성 및 해사의 염분함량과 콘크리트의 물-시멘트비에 따른 철근부식량과의 관계를 구명하였다.

• 콘크리트학회논문집
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• 제11권5호
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• pp.51-60
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• 1999

When placed under water, concrete is diluted with separating cementitious material and as a result the quality of concrete becomes poor. So as to solve the problem, underwater concrete is increasingly used for the construction and repair of the concrete structure under water. In this paper, 4 kinds of antiwashout admixtures and varying sand percentages were chosen to measure the suspended solids, pH, air contents, setting time and compressive strength of underwater concrete, and they meet "Standard for antiwashout admixture used for concrete". When sand percentage is 43%, the fluidity and filling of underwater concrete are superior to the others.he others.

• International Journal of Concrete Structures and Materials
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• 제3권1호
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• pp.11-14
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• 2009

This paper is interested in the incorporation of crushed sand and desert sand in the composition the self compacting concretes (SCC). Desert dune sand, which has a fine extra granulometry, and the crushed sand, which contains an important content of fines, can constitute interesting components for SCC. Part II consists in studying the behaviour of SCC containing various sands with different origins. These sands, with different sizes, consist of several combinations of rolled sand (RS), crushed sand (CS) and desert sand (DS). The study examines the influence of the granular combination of sands on the characteristics in the fresh and the hardened state of SCC. The results of the experimental tests showed an improvement of the workability of the fresh SCC by combining sands of varied granulometry. The addition of the DS to CS or to RS allowed the increase of the mixture viscosity but decreased the mechanical strengths. Furthermore, the CS-RS combinations increased the compressive and the tensile strengths of the studied SCC. The optimized formulations of sands gave the highest performances of the SCC.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 추계 학술논문 발표대회
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• pp.23-26
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• 2007

In this study, recently it is urgently required that demolition waste concrete has to be recycled on the construction because urban development is accelerated and redevelopment project is rapidly expanded, production quantity of construction and demolition waste concrete is being increased. On the other hand, it has to be solved urgently the unbalance of demand and supply about the fine aggregate because the sea sand is restricted by exhaustion of river sand and intensification of environment influence evaluation. Therefore, the purpose of the study was to show the performance of the apparatus developed by the study and to propose the direction of the optimum operating conditions by having an experimental and positive evaluation about quality of recycled sand produced to develop a separating and selecting device of impurities for recycling of construction wastes which can have a bigger improvement of economical efficiency, productivity, environmental property and quality through a basic property of matter of recycled sand by each operating condition of sand flux in comparison with the existing production system of recycled sand.

• Advances in concrete construction
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• 제11권1호
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• pp.19-32
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• 2021

In the present experimental study, the high performance hybrid fiber reinforced concrete (HPHFRC) is prepared using the Modified Andreasen and Andersen (A&A) particle packing model. Total of 16 trial mixes of HPHFRC with Indian standard sand (SS) and natural river sand (NS) are prepared to achieve the selection criteria (flow percent>150 and compressive strength>80 MPa). Based on the flow percent and compressive strength criteria, the selected mixes evaluated to study the effect of usage of natural river sand (NS) and the expensive Indian standard sand (SS) on the mechanical, durability, and microstructure property of designed HPHFRC. It has been found that the Modified A&A model is reliable to design the mix for HPHFRC with excellent mechanical, durability, and microstructure properties. In addition to that, a moderate difference in the mechanical and durability properties of NS contained HPHFRC and SS contained HPHFRC is found. Based on the obtained results of NS contained HPHFRC, it can be concluded that the use of natural river sand (NS) can be successfully adopted for the production of HPHFRC, resulted in a reduction of the production cost without compromising the excellent performance of HPHFRC.