• Journal of the Korea Institute of Building Construction
• /
• v.12 no.1
• /
• pp.73-86
• /
• 2012

In this research, the possible applicability of mixture blended with natural, crushed, and recycled fine aggregate are discussed. The fresh and hardened properties of mortar using blended fine aggregates are monitored depending on various blending ratio of fine aggregates. Newly developed ternary diagram was also utilized for better interpretation of the data. It was found that air content increased and unit weight decreased as recycled fine aggregate content increased. With moisture type processing of recycled fine aggregate, the mortar flow was not negatively affected by increase in the recycled fine aggregate content. The ternary diagram is found to be an effective graphical presentation tool that can be used for the quality evaluation of mortar using blended fine aggregate.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.11a
• /
• pp.116-119
• /
• 2003

The Natural aggregate will be faced with serious shortage problem within 10 years due to the great amount of consumption in domestic. In order to reserve our natural resources, the construction waste has to be reused as an alternative material. Especially, It is more imminent to find alternative material in case of fine aggregate. This paper presents and experimental results on the fundamental property of concrete using recycled fine aggregate. As a result, it was found that the property of concrete using recycled fine aggregate substituted for 25% of a natural sand was similar in that of crushed fine aggregate.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2005.11a
• /
• pp.29-32
• /
• 2005

Recently, for the problem solution of demand and supply imbalance of fine aggregate due to the shortage of natural fine aggregate and the environment regulation on sea sand extraction in the construction field, the studies for the application of recycled fine aggregate using waste concrete are being progressed versatilely. The purpose of this study is to investigate quality of recycled fine aggregate manufactured by drying manufacturing system which is the manufacture method of high duality recycled fine aggregate, and to analyze on thehardened and durability properties of recycled concrete using it. Therefore it is to present the fundamental data for application and utilization of recycled concrete. The results of this study are as follows; Quality of recycled fine aggregate by drying manufacturing system is improved, and compressive strength, carbonation depth and chloride ion penetration depth of recycled concrete using high quality recycled fine aggregate are similar to those of normal concrete using natural and crashed sand. But, resistance to $H_{2}SO_{4}$ show decreased somewhat.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2006.05a
• /
• pp.85-88
• /
• 2006

This study investigated influence of fine aggregate types on fundamental properties of cement mortar. Test showed that concrete using lime stone crushed fine aggregate(L) exhibited the most favorable fluidity due to grain shape and particle distribution, and next was blending aggregate miting L and G, blending aggregate mixing L and N, granite crushed fine aggregate(G), natural fine aggregate(N) in an order. Concrete using N had the highest air content and L was the smallest value because of the effective filling performance by continuos particle distribution. Compressive, tensile and flexural strength of all concrete using L had the highest value due to the smallest value of air content. It is also found that concrete using L resulted in decrease of drying shrinkage length change ratio.

• Computers and Concrete
• /
• v.24 no.1
• /
• pp.19-35
• /
• 2019

In this paper, the effect of the type and amount of fibers on the physicomechanical properties of concrete containing fine recycled refractory brick (RRB) and natural aggregate subjected to elevated temperatures was investigated. For this purpose, forta-ferro (FF), polypropylene (PP), and polyvinyl alcohol (PVA) fibers with the volume fractions of 0, 0.25, and 0.5%, as well as steel fibers with the volume fractions of 0, 0.75, and 1.5% were used in the concrete containing RRB fine aggregate replacing natural sand by 0 and 100%. In total, 162 concrete specimens from 18 different mix designs were prepared and tested in the temperature groups of 23, 400, and $800^{\circ}C$. After experiencing heat, the concrete properties including the compressive strength, ultrasonic pulse velocity (UPV), weight loss, and surface appearance were evaluated and compared with the corresponding results of the reference (unheated) specimens. The results show that using RRB fine aggregate replacing natural fine aggregate by 100% led to an increase in the concrete compressive strength in almost all the mixes, and only in the PVA-containing mixes a decrease in strength was observed. Furthermore, UPV values at $800^{\circ}C$ for all the concrete mixes containing RRB fine aggregate were above those of the natural aggregate concrete specimens. Finally, regarding the compressive strength and UPV results, steel fibers demonstrated a better performance relative to other fiber types.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.05b
• /
• pp.101-104
• /
• 2005

It analyzed the supply status of fine aggregate and find the point of issue related alternative fine aggregate through researches and interviews. The conclusions of the study are as follows. 1. Ready mixed concrete manufacture used crushed fine aggregate (15.5$\%$) and recycled fine aggregate (1.5$\%$) for alternatives aggregate than 1.3$\%$ in 1991. It is not allowed to use a recycled fine aggregate in ready mixed concrete, but they used it. 2. All alternative aggregate are satisfied the Korean Standard, But they showed low properties of mortar compared to when it replaced with natural fine aggregate. So, it is needed to make another special Korean Standard to use alternative aggregate in normal concrete by mixing method to recover the workability and compressive strength.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.05a
• /
• pp.495-500
• /
• 2001

In this study, it was analized and examined fundamental properties of Electric Pole Recycled Aggregate(EPRA) and hardened properties & chemical resistance with H$_2$SO$_4$by replacement ratios of EPRA, and the results are as follows 1) In the case of electric pole recycled coarse aggregate, All fundamental properties are better than that of normal recycled aggregate and both water absorption and amount of crushed loss are with level of natural aggregate 2) As the replacement ratio of electric pole recycled fine aggregate is increased strength development is decreased. but in the case of coarse aggregate, that of it is with level of natural aggregate 3) As the replacement ratio of electric pole recycled fine aggregate is increased chemical resistance is decreased. but in the case of coarse aggregate, that of it is with level of natural aggregate

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05b
• /
• pp.101-104
• /
• 2006

This study aims to obtain technical data for improvement of utilization of Blast Furnace Slag(BFS), recycled aggregate in the future by complementing fundamental problems of BFS such as manifestation of initial strength and excessive alkali quantity as well as weakness of recycled fine aggregate through manufacturing of recycled fine aggregate mortar using BFS. Since hydroxide ion concentration of calcium hydroxide(Ca(OH)2) ion erupted from recycled fine aggregate newly produced is over 12. In recycled fine aggregate mortar transposing and using BFS powder, calcium hydroxide(Ca(OH)2) erupted from recycled fine aggregate played a role of stimulus from the day 3 and manifestation of compressive strength was slowly increased with mortar using natural fine aggregate and showed considerable increase from the day 7.

• Journal of the Korean Society of Safety
• /
• v.16 no.1
• /
• pp.65-72
• /
• 2001

Portland cement concrete is made with coarse aggregate, fine aggregate, portland cement, water and, in some cases, selected chemical admixture such as air-entraining agents, water reducer, superplasticizer, and so on, and mineral admixture such as fly ash, silica fume, slags, etc. Typically, in the concrete, the coarse aggregate and fine aggregate will occupy approximately 80 percent of the total volume of the finished mixture. Therefore, the coarse and fine aggregates affect to the properties of the portland cement concrete. As the deposits of natural sands have slowly been depleted, it has become necessary and economical to produce crushed sand(manufactured fine aggregate). It is reported that crushed sand differs from natural sands in gradation, particle shape and texture, and that the content of micro fines in the crushed sand affect to the quality of the portland cement concrete. Therefore, the purpose of this paper is to investigate the characteristics of fresh and hardened concrete with higher micro fines. This study provides a firm data to apply crushed sand with higher micro fines.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.4 no.1
• /
• pp.96-100
• /
• 2009

The properties of recycled fine aggregates which had different source concrete were examined by mortar test. With higher strength of source concrete, specific gravity of recycled fine aggregate was higher and absorption of recycled fine aggregate was lower due to reduction of the volume of adhered cement paste. The compressive strength and flexible strength of mortar with recycled fine aggregate were affected by the interface boundary of new mortar and the strength of adhered mortar. Strength development of mortar with recycled fine aggregate reduced because recycled fine aggregate become a porous material with the smaller strength of source concrete. The drying shrinkage of mortar was about$800{\sim}2000{\mu}m/m$. It was about 1.5 times than that of mortar with natural fine aggregate. Relative dynamic modulus of elasticity was a similar level with that of mortar with natural fine aggregate.