• Journal of the Korean Ceramic Society
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• v.43 no.12 s.295
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• pp.846-851
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• 2006

This paper discuss the adsorption and fluidity properties of recycled cement powder with different hydration hysteresis and particle size. Reactivity of hydrated fine powder was negligible low. Therefore, the adsorption and fluidity properties with super-plasticizer for hydrated recycled cement powder was very important for using additive material. Adsorption amount of super-plasticizer was increased by the finer hydrated recycled cement powder addition. And the fluidity of hydrated recycled cement powder was very poor than un-hydrated cement powder. To Improve the fluidity of hydrated recycled cement powder, PC super-plasticizer is the more effective than NS super-plasticizer.

• Environmental Engineering Research
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• v.21 no.4
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• pp.341-349
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• 2016

To improve the utilization rate of construction waste as mine backfilling materials, this paper investigated the feasibility of using recycled powder as mine paste backfilling cementitious material, and studied the pozzolanic activity of recycled construction waste powder. In this study, alkali-calcium-sulfur served as the activation principle and an orthogonal test plan was performed to analyze the impact of the early strength agent, quick lime, and gypsum on the pozzolanic activity of the recycled powder. Our results indicated that in descending order, early strength agent > quick lime > gypsum affected the strength of the backfilling paste with recycled powder as a cementitious material during early phases. The strength during late phases was affected by, in descending order, quick lime > gypsum > early strength agent. Using setting time and early compressive strength as an analysis index as well as an extreme difference analysis, it was found that the optimal ratio of recycled powder cementitious material for mine paste backfilling was recycled powder:quick lime:gypsum:early strength agent at 78%:10%:8%:4%. X-ray diffraction analysis and scanning electron microscope were used to show that the hydration products of recycled powder cementitious material at the initial stages were mainly CH and ettringite. As hydration time increased, more and more recycled powder was activated. It mainly became calcium silicate hydrate, calcium aluminate hydrate, etc. In summary, recycled powder exhibited potential pozzolanic activities. When activated, it could replace cementitious materials to be used in mine backfill.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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• pp.19-22
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• 2006

The quantity of Recycled concrete powder is increased, because it hal been ever so often crushing for production of a good quality recycled aggregates This Study is on the Development of Concrete-Product by Using Recycled Concrete Powder and alto for know performance of concrete-producted having low water contents and it is to know for all of performance of concrete-producted having low water contents The conclusions of this study are following. The use of replacement cement is not effective, because it has strengh of less than 10MPa But It is possible to develop high strength concrete-producted having 39MPa above compressive strength by using recycled concrete powder. Because strength enhancement effects by recycled concrete powder are responsible to optimum grading. The conclusions of this study are following. The use of replacement cement is not effective, because it has strengh of less than 10MPa. It is possible to develop high strength concrete-producted having 39MPa above compressive strength by using recycled concrete powder. Because strength enhancement effects by recycled concrete powder are responsible to optimum grading.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.635-640
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• 2001

Recently, it has been processed to study about recycled aggregate but a study about using of recycled powder is producted when manufacturing recycled aggregate has not been acted. So in this study on the fundamental properties and application as cementious admixture by heating temperature for mortar properties of recycled powder and sand is obtained like following results. It is judged that application of recycled powder of heat treatment on $600^{\circ}C$ and cement replacement ratio below 10% is available.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.172-179
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• 1996

Recently, the broken concrete lumps resulting from the demolition of concrete structures are creshed for reuse as aggregates(i.e. recycled fine and gravel). And also, in the processing of crusing, the recycled powder of an equivalent of between 20% to 30% by wt.% of the broken concrete lumps is generated. The extensive research of recycled concrete aggregates has been carried out in various parts of the world. But less reseatch on the reuse of recycled concrete powder has been carried out. It is the purpose of this report that the study on the quality evaluation of recycled aggregates for recycled concrete. In specially, this report deals with the properties such as flow, compressive strength, bending strength, drying shrinkage and wight loss rate of mortars replaced standard fine aggregate with recycled powders at the rate of 3, 7, 15, 20 and 30 wt.%. Since the characteristics of recycled mortars with the recycled powders were comparable to those of the normal mortar without the recycled powders as described above, its concretes could be found extensive application in such field as concrete products.

• Journal of the Korean Society of Safety
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• v.25 no.2
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• pp.41-46
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• 2010

This is to show some basic data for introducing both circulated aggregate and recycled powder producing waste concrete. Standard-mixing design for 24MPa has been basically used and added and replaced normal aggregate with recycled powder made of waste concrete. In addition, polycarboxylate high-range water reducing agent has been used because recycled powder is missing adhesive strength and it is not compare with cement's adhesive strength. Compressive strength with powder mixture of 2%, 4%, 6%, 8%, and 10% has been decreased down to 80% of normal concrete material strength without recycled powder mixture. This result has same decreasing proportion to tensile strength of the material. Resistant capacity change of beam varying with recycled powder mixture has been decreased down to 60% of normal concrete bean capacity, while there are 80% decrease of material strength. But strength and capacity change has same consistent decrease ratio. It is found that recycled powder with approximately 15% unit concrete volume can be replaced with cement in reasonable admixture mixing condition.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.47-48
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• 2014

This study is to hydration property of low carbon type recycled cement from waste cementitious powder and cement raw materials. Waste cementitious powder possible to low carbon type recycled cement in small part of additive materials. Also, low carbon type recycled cement using waste cementitious powder is suitable for low heat type cement.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.4
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• pp.289-295
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• 2008

The disposal of constructive waste is emerging as a national and social issue and the recycled powder generated by the production of reproductive aggregate is all being abolished or buried Analysis on the harmful effect of recycled powder indicated that because it contained massive cytotoxicity, it could derive secondary pollution to soil and subterranean water. This study set on an idea that one way to recycle recycled powder was to use it as a compound of concrete. In order to study that prospect, recycled powder, instead of cement, was mixed and a comparative analysis was conducted on the mechanical properties and workability. From experimental results, it was judged that application of recycled powder of cement replacement ratio below 20% was available with chemical admixtures. Also application of recycled powder was available to high strength concrete.

• Journal of the Korea Institute of Building Construction
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• v.17 no.6
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• pp.527-534
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• 2017

Accordingly, this study, in order to use powder of recycled aggregate from production of recycled aggregate as an activator of ground granulated blast furnace slag, the influence of added recycled aggregate powder on physical properties of concrete induced ground granulated blast furnace slag were analyzed by hydration stages. The results of the study are summarized as follows: Except for samples eluted powder of recycled aggregate 1%, all the samples were high alkali suspensions with higher than pH 12.0. In particular, when eluted time was 5 hours, the sample eluted powder of recycled aggregate 3% showed about 15 mg/l of calcium hydroxide that was not different from the amount of calcium hydroxide in the mixing water eluted powder of recycled aggregate 5%. Hence, from this results, it can be considered that optimal eluted powder of recycled aggregate was 3% in this study. When using mixing water eluted with powder of recycled aggregate, compared to use of ordinary mixing water, it showed greater compressive strength in the entire ages, and in the sample replaced with ground granulated blast furnace slag by 50%, its compressive strength was greater than that of the OPC. As use of mixing water eluted with powder of recycled aggregate in concrete used with large amount of ground granulated blast furnace slag was more effective for improving compressive strength than ordinary mixing water, it is verified that powder of recycled aggregate had an effect of activator.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.521-524
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• 2006

This study is about the production and properties of waste concrete powder that recycling aggregate is crushed to the waste concrete. We researched the generation and the disposal of recycled concrete powder. It is chemica] and physical features that is compared and analysis according to its production system and repeated crushing of time. Recycled concrete powder is more generated wet process than drying process. In addition, the more it is repeated crushing of time, the more recycled concrete powder is generated. Recycled concrete powder is discovered that wet process is larger of the specific area, lower density and particle size.