• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.05a
• /
• pp.327-328
• /
• 2021

In the manufacturing process of ready-mixed concrete, quantity management directly affects the workability and strength of concrete. Therefore, water quantity is the most important management factor for water quality control of ready-mixed concrete. It can be said that the number of unit water in the mix design, the water quantity due to the surface water contained in the aggregate used, and the water quantity taking into account the concentration of sludge contained in the recycling water when using the recycling water are factors that affect the quantity management of ready-mixed concrete. In this study, as a stable quality control method of ready-mixed concrete, a quantity management method by aggregate surface water and a sludge concentration management method according to the use of recycling water were proposed. Thus, we tried to suggest an efficient quantity management method for stabilizing the quality of ready-mixed concrete.

• Journal of the Korean Society of Safety
• /
• v.29 no.4
• /
• pp.123-131
• /
• 2014

Whole amount of waste water, approximately 921.6 liter, for cleaning a ready mixed concrete truck should be used to produce concrete as a mixing water or cleaning water. Recycling water for concrete mixing contains solids, which cause decrease in slump, air and compressive strengths, so it may influence on poor concrete quality. Therefore, it has been maintained to use recycling water with less than 3 percent of solids. Since no evaluation system has been constructed to directly reflect on variability of recycling water from ready mixed concrete plants, it is necessary to develop "Automatic recycling solid measuring system" for quality controls in real time. In this research, sensors measuring waste water concentration in ultrasonic and inductance methods were developed, and automatic system using the sensors were established. The accuracy of measurement sensors developed for recycling water based on various conditions of concentration was proved, and application limits were evaluated. Also, concentration of recycling water using sensors developed from ready mixed concrete plant was measured, and curing method verified the accuracy of the sensors. Moreover, measurement sensors for recycling water in various locations were installed to evaluate the effects on measuring method and spots. The automatic measuring system for recycling water concentration, which is developed in the research, will contribute to improve concrete quality safety through reliable solids maintenance.

• Journal of the Korean Applied Science and Technology
• /
• v.30 no.4
• /
• pp.770-778
• /
• 2013

In this study, a liquid carbonation method was applied for producing precipitate calcium carbonate by liquid-liquid reaction. We recycled the recycling water of ready-mixed concrete, one of construction waste for use source of carbonate ion. A supernatant separated from the recycling water of ready-mixed concrete, as a result of ICP analysis of a cation, $Ca^{2+}$ was contained up to 1100 ppm. We used MEA as a $CO_2$ absorbent for the liquid carbonation. A precipitate $CaCO_3$ was produced at more than MEA 20 wt%. The precipitate $CaCO_3$ as a final product was separated and dried. The result of XRD was confirmed the generation of $CaCO_3$ to calcite structure.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.9 no.1
• /
• pp.92-99
• /
• 2021

CaO-based by-products composed of CaO, SO3, Al2O3, etc. are generally used as raw materials for CaO compounds. When applied to the recovered water of ready-mixed concrete, the hydration reaction of the powder material is accelerated and concrete performance can be improved. In this study, activated sludge was prepared to apply to the recovered water of ready-mixed concrete by mixing CaO-based hot-rolled slag(C12A7) in the recycling water of ready-m ixed concrete. Cem ent paste setting time and mortar compressive strength performance tests confirmed the effect on the hydration reaction. Therefore, the possibility of concrete application using activated sludge was confirmed.

• Journal of the Korean Applied Science and Technology
• /
• v.33 no.2
• /
• pp.239-246
• /
• 2016

In this study, recycling sludge water of Ready-mixed concrete, and was carried out to optimize the system for recycling of the $CO_2$. The most important process in the liquid phase using a carbonation reaction can be recovered ready-mixed concrete is a process for the $Ca^{2+}$ release. $Ca^{2+}$ concentration of the experiment relative to the pH being lowered by the acidic substance during elution was performed. $CO_2$ was trapped in the MEA solution using a generator flue gas. In ready-mixed concrete can be synthesized $CaCO_3$ up to 11kg/1ton. The resulting $CaCO_3$ analysis results show that it is possible to use paper industry.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.4 no.4
• /
• pp.477-482
• /
• 2016

This study investigates the expressions characteristics of compression strength depending on the condition of fresh concrete and cured concrete by producing Non-cement mortar and concrete only with solidified sludge in the dehydrated cake form, recycled concrete and premixed materials(BS, FA) in order to actively use remicon recycling water as resources, rather than as construction waste material. After treating wastewater of pH 12.5 or more with alkali activator and after promoting BS hydration reaction, the amount of BS inflow was found to be increased and compression strength was increased accordingly: these results coincide with the analysis results of TG-DTA and SEM.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.8 no.4
• /
• pp.395-403
• /
• 2020

CaO-based by-product, which consist of CaO, SO3, Al2O3 and so on, has being used to raw materials of CaO compound. When It was applied to recycling water of remicon, concrete performance can be enhanced because hydration reaction of powder material is accelerated. In this study, activated-sludge, which was putted desulfurization gypsum of CaO-based in recycling water, was manufactured to verify effect of them, and then they was investigated by characteristics of redy-mixde concrete. As a result of concrete tests, it was confirmed that there is no problem of strength or drying shrinkage while ensuring workability. Therefore, the possibility of specific application using activated sludge was confirmed.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1994.10a
• /
• pp.105-110
• /
• 1994

This study is applying to the concrete with the variation of the variation of the sludge contents, to analyze the properties of the fresh concrete and the mechanical properties of hardened concrete give the reference data of actual ready mixed concrete. To the result of this study in the condition of W/C 60%. As a result of this experiment and considering the drying shrinkage, it is thought that in using sludge, the less amount of sludge than 4% can produce of good quality concrete.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2019.11a
• /
• pp.153-154
• /
• 2019

In this study, the fluidity and compressive strength of lightweight mortar using recycling water for pre-wetting of artificial lightweight aggregate were compared and analyzed to maximize the utilization of the recycling water, which is a by-product of the Ready-Mixed Concrete industry. For this purpose, the pre-wetting water was replaced with recycling water at the ratio of 0, 2.5, 5, 7.5 and 10%.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.777-780
• /
• 2008

There were some attempt to reuse water with sludge combinative water for ready mixed concrete. But recycling water consist of cement, aggregate and chemical admixture. So it caused deterioration of concrete. The object of this study was to search for recycling method of the recycling water sludge as mineral admixture. This experiment dealed with the effect of $2.5{\sim}12.5$% range of the recycling sludge which can be used for admixture binder(BFS, FA, BFS+FA) on properties of activated recycling water sludge for admixture of concrete. As a result, Although the slump levels reduced and air contents increased as sludge replacement levels increased, it didn't change highly. The compression strength of concrete slightly increased with an increasing amount of recycling water sludge replacement.