• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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• pp.81-84
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• 2006

This study is intended for how to utilize the recycled fine aggregate which is produced by concrete wastes. It analyzes the quality of the fine aggregate which is reproduced through the acid treatment process, and comprehends the characteristics of mortar using the recycled fine aggregate to review whether it can be put to practical use for concrete. The conclusion of the study are as follows 1. The recycled fine aggregate through the acid treat shows the low rate of absorption and high density. 2. Compared to the mortar made from acid liquid precipitated recycled fine aggregate, using nature water precipitated one reduces the flow. 3. The compressive strength of mortar using recycled fine aggregate tends to be reduced according to the kind of precipitated water. Based on the above results, the recycled fine aggregate through the acid treatment process satisfies the quality standards of the first-grade recycled fine aggregate of KS F 2573 (recycled fine aggregate for concrete) but it is concluded that the recycled fine aggregate through the acid treatment process can not used as fine aggregate used concrete because it has destructive characteristics when the mortar is produced

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.63-64
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• 2023

In order to reduce the high absorption ratio of spent coffee grounds, this study examined the compressive strength and absorption ratio of mortar replacing coated spent coffee grounds according to the type of water repellent. In order to examine this, as the water repellent used, a silane-based water repellent (fluorine-based water repellent) and an acrylic-based water repellent, which are film-type water repellents, and a silane/siloxane-based water repellent, which are penetration-type water repellents, were used. The spent coffee grounds were coated with each of three water repellents, and mortar was prepared by mixing cement and fine aggregate. As a result of the experiment, the compressive strength and absorption ratio of the mortar replaced with coated spent coffee grounds coated with the film-type water repellent were superior to the penetration-type water repellent. Therefore, in order to reduce the high absorption ratio of spent coffee grounds, a suitable water repellent is a film-type water repellent. Among them, it is judged that the acrylic type has excellent water repellency and is suitable.

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

• Computers and Concrete
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• v.19 no.1
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• pp.69-78
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• 2017

This study aimed at exploring the effect of presoaking degree of lightweight aggregate (LWA) on the fresh and hardened properties of concrete. Two series (i.e., Series A and Series B) of concrete mixes that were made of LWA with different moisture states were prepared. The presoaking degree of LWA was divided into three types: oven dry state, 1 hour prewetted and 24 hours prewetted. For the Series A, the water content of the lightweight aggregate concrete (LWAC) mixes was adjusted in accordance with the moisture condition of the LWA. Whereas the amount of water added in the Series B mixes was deliberately not adjusted for the moisture condition of the LWA. Slump test, mechanical tests, interfacial transition zone microscopical tests and thermal conductivity test were carried out on the specimens of different concretes and compared with control normal-weight aggregate concretes. The test results showed that the effect of mixing water absorption by LWA with different moisture states was reflected in the fresh concrete as the loss of mixture workability, while in the hardened concrete as the increase of its strength. With the use of oven-dried LWA, the effect of reduction of water-cement ratio was more significant, and thus the microstructure of the ITZ was more compact.

• Advances in concrete construction
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• v.2 no.2
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• pp.77-89
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• 2014

The properties of fresh and hardened concrete made using three types of artificial cold bonded aggregates are determined. The properties, namely, slump, water absorption, compressive strength and splitting tensile strength of concrete containing artificial aggregate are reported. The variables considered are aggregate type and water-to-cement ratio. Three types of cold bonded aggregates are prepared using fly ash and quarry dust. The water-to-cement ratio of 0.35, 0.45, 0.55 and 0.65 is used. The test result indicates that artificial aggregates can be recommended for making the concrete up to a strength grade of 38 MPa. The use of quarry dust in the production of artificial aggregate mitigates environmental concerns on disposal problems of the dust. Hence, the alternate material proposed in this study is a green technology in concrete production.

• Advances in concrete construction
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• v.6 no.6
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• pp.611-629
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• 2018

The objective of present study is to investigate the effect of granulated blast furnace slag (GBS) as partial substitution of natural sand on behaviour of cement mortar. For this, the methods of factorial design with water cement (w/c) ratio and incorporation percentages of GBS as replacement of natural fine aggregate i.e., GBS(%) as factors are followed. The levels of factor w/c ratio are fixed at 0.4, 0.45, and 0.5 and the levels of factor GBS(%) are kept fixed as 0%, 20%, 40%, 60%, 80% and 100%. The compressive strength (CS) of mortar after 3, 7, 14, 28, 56 and 90 days, and water absorption (WA) are chosen as responses of the study. Analysis of variance (ANOVA) of experimental results has been carried out and those are illustrated by ANOVA tables, main effect and interaction plots. The results of study depict that the selected factors have substantial influence on the strength and WA of mortar. However, the interaction of factors has no substantial impact on CS and WA of mixes.

• Advances in concrete construction
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• v.5 no.5
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• pp.437-450
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• 2017

The present work investigates about the development of a novel construction material by utilizing Granulated Blast Furnace Slag (GBS), an industrial waste product, as substitution of natural fine aggregates. For this, experimental work has been carried out to determine the influence of GBS on the properties of concrete such as compressive strength (CS), modulus of elasticity, ultrasonic pulse velocity (UPV), chloride penetration, water absorption (WA) volume of voids (VV) and density. Concrete mixes of water/cement (w/c) ratios 0.45 and 0.5, and incorporating 20%, 40% and 60% of GBS as partial replacement of natural fine aggregate (sand) are designed for this study. The results of the experimental investigation depict that CS of concrete mixes increases with the increasing percentages of GBS. Moreover, the decrease in chloride penetration, WA and VV, and improvement in the modulus of elasticity, UPV, density of concrete is reported with the increasing percentage of GBS in concrete.

• Advances in concrete construction
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• v.16 no.1
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• pp.59-68
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• 2023

In the pumping process, concrete moves along the pipe and experiences both pressure and shear. This changes the workability and flow characteristics of the concrete. However, the effect of pressure and shear on the change in properties of concrete during the pumping process has not yet been accurately identified. This study analyzed the effects of pressure and shear on the properties of concrete during pumping. For quantitative tests, lab-scale test equipment capable of simulating the pressure and shear applied to concrete during pumping was used. For one coarse aggregate type, two paste types, three mortar types, and five concrete types, the effects of pressure, shear, and shear under pressure conditions were examined by varying the maximum pressure (0 to 200 bar) and the rotational speed of the vane for shear (0 to 180 rpm). Under the maximum pressure condition of 200 bar, the water absorption of coarse aggregate increased by 0.62% and that of fine aggregate also increased. When the concrete was under pressure, significant changes (a reduction in a slump and an increase in viscosity and yield stress) compared with the effect of the elapsed time occurred owing to an increase in the water absorption of the aggregates. When both pressure and shear were applied to concrete, both the slump and viscosity decreased. As the rotational speed of the vane increased, changes in properties became significant. Shearing in the absence of pressure maintained the properties of concrete. However, shearing under pressure conditions caused a reduction in slump and viscosity.

• Journal of Power System Engineering
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• v.17 no.2
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• pp.108-113
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• 2013

In this study, lightweight aggregate was made from basalt stone powder sludge. Clay and glass powder were respectively added from 0 to 20 wt% and from 0 to 100 wt%. The glass powder helped to form glassy phase which trapped generating gas in the materials. $CaCO_3$ helping bloating process was added from 0 to 10 wt%. It was possible to produce lightweight aggregate at range from $1150^{\circ}C$ to $1200^{\circ}C$. The specimen was heated in furnace at 1100, 1150 and $1200^{\circ}C$ for 15 min, respectively, to sinter aggregates. Chemical composition of materials were determined, and characteristics were analyzed, including specific gravity, water absorption. Lightweight aggregate which was heated at $1200^{\circ}C$ had specific gravity of $0.53g/cm^3$, water absorption of 3.08%, and this value satisfied KS L 8551 standard.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.151-152
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• 2019

This study is aimed at comparing the effect of cement mortar made of sulfuric acid treated ISO standard sand with that of cement mortar made of normal ISO standard sand. In the water absorption test, water absorption of standard sand increases with the increase of immersion time in sulfuric acid solution. The results show that at the water cement ratio of 0.5, the longer the standard sand is immersed in sulfuric acid, the greater the compressive strength of the cement mortar sample.