• Journal of the Korea Institute of Building Construction
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• v.20 no.5
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• pp.391-397
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• 2020

This study is to compare and analyze the strength, drying shrinkage and carbonation properties of lightweight aggregate mortar using recycling water as prewetting water and mixing water. The flow, compressive strength, split tensile strength, drying shrinkage and carbonation depth of lightweight aggregate mortar with recycling water were measured. As test results, the mortar flow was similar in all mixes regardless of the recycling water content. The compresseive strength of the RW5 mix with 5% recycling water as prewetting water and mixing water was the highest value, about 53.9 MPa after 28 days. In addition, the tensile strength of lightweight mortar was about 3.4 to 3.8 MPa, indicating 7 to 9% of the compressive strength value regardless of recycling water content. In the case of drying shrinkage, the RW2.5 mix using 2.5% recycling water showed the lowest shrinkage rate as about 0.107% at 56 days. The drying shrinkage of the plain mix without recycling water was relatively higher than the RW2.5 and RW5 mix. The RW5 mix showed lowest carbonation depth compared to other mixes. In this study, the RW5 lightweight aggregate mortar with 5% recycling water exhibits excellent compressive strength and carbonation resistance. Therefore, it is considered that if the recycling water, a by-product of the concrete industry, is properly used as prewetting water and mixing water of lightweight mortar and concrete, it will be possible to increase the recycling rate of the by-product and contribute to improve the property of lightweitht aggregate mortar and concrete.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.508-513
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• 2001

Recently, ground granulated blast-furnace slag (GGBFS) has been increasingly used as additive for concrete. Many researchers reported that concrete using GGBFS had a better resistance under severe environments, such as marine or sulfate-rich soils, than Portland type cement concrete. The aim, therefore, of this study is to evaluate on the effectiveness of concrete using GGBFS when the concrete exposes to sulfate-rich environment. The detailed items for experiments show 2 series consisted of sulfate immersion test with mortar and sulfate diffusion test with concrete. The sulfate immersion test was performed for 400 days and contained reduction of compressive strength, length change and XRD analysis. For sulfate diffusion test, sulfate ions diffusivity was calculated on tile consideration of electrochemical theory by the diffusion cell test. As the results of this study, it was found that the concrete using GGBFS as additive was superior to portland type cement concrete. Consequently, the use of concrete with GGBFS for recycling may expect the durable and economical benefits.

• Advances in concrete construction
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• v.13 no.2
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• pp.133-152
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• 2022

Ecological issues such as natural resource reduction and enormous waste disposals are increasingly leading in developing civilization toward sustainable construction. The two primary environmental issues are the depletion of natural resources and the disposal of trash in open landfills. Waste steel fiber (WSF) was investigated for usage as a cement-based concrete (CBC) constituent in this research. Recycling waste fibers both makes cement composites more long and cost-effective, also aids in pollution reduction. The objective of this study is to analyze the impacts of waste fiber on the fresh and mechanical features of concrete using recycled additives. A comparative research on the durability and mechanical qualities of fiber-reinforced concrete (FRC) constructed with natural aggregates was conducted for this aim. The obstacles to successful WSF recycling methods application in the building industry have been investigated, resulting that CBCs with these fibers make an economic and long lasting choice to deal with waste materials. The workability of fiber enhanced concrete was found to be comparable to that of normal concrete. Fibers have a considerable impact on the splitting tensile strength, flexural and compressive strength of recycled concrete. Fiber may enhance the water permeability. When the WSF content is 0.6 kg/m3, the water absorption is nearly half. Fibers would have no effect on its permeability.

• Resources Recycling
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• v.10 no.1
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• pp.16-24
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• 2001

In this study, various mechanical properties of concretes employing waste concrete as aggregate were examined. These concretes were obtained by mixing seven types of aggregate for different ratios. So, the experimental variables are the kinds of aggregates (some different aggregate compositions) and W/C ratio (0.40, 0.45, 0.50). From experimental results, the reliable regression analysis equations between compressive strength and various experimental data for recycled aggregate concrete are presented. Consequently, this study was accomplished to investigate basic engineering properties of recycled aggregate concrete using waste concrete.

• Journal of the Korea Concrete Institute
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• v.18 no.1 s.91
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• pp.117-124
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• 2006

The effects of binder content and recycling mixed waste plastics(PA) content on the workability, work life and hardening shrinkage of fresh polymer concrete using mixed waste plastics are examined. As a result, the workability of the polymer concretes using mixed waste plastics tend to improve with increasing binder content, PA content and filler content. The work life of the polymer concretes using mixed waste plastics is shortened with an increase in the initiator content and curing temperature. The length change of the polymer concretes using mixed waste plastics tend to increased with Increasing binder content and PA content. The result of the present research is expected to make a contribution to the recycling of final mixed waste plastics and the continuing efforts for the development of use of the recycled products are thought to expand the horizon for the recycling of the final mixed waste plastics.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.04a
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• pp.191-196
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• 1994

This study is designed for analyzing the mechanical properties of cement mortar with kind of water, sludge content for the water, mixing proportion and open time of recycling water. And this study is aimed for presenting the reference data in practical use. For the results of this study, the flow properties of fresh mortar and the strength of compresive of hardened mortar is increased until the sludge content 4.5~6.0, but is decreased after the sludge content of that.

• Journal of Environmental Science International
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• v.8 no.2
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• pp.227-231
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• 1999

This study was conducted to investigate the removal characteristics of $PO_4^{3-}-P$ contained in livestock wastewater using waste concrete. With small particle size, increased dosage and temperature of water, $PO_4^{3-}-P$ was well removed by waste concrete.$PO_4^{3-}-P$ was removed by adsorption reaction in low pH of the primary phase, but the crystallization reaction predominated for increasing pH with passed time. As a result of adapting the adsorption isotherm equation, $PO_4^{3-}-P$ removal was more affected by the crystallization reaction than the adsorption reaction. In the SEM micrograph, there was no evident change on the waste concreter surface. Particle size was plate-phase before reaction but appeared a dense form to progress in the crystallization reaction.

• Resources Recycling
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• v.5 no.2
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• pp.52-56
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• 1996

Fix crushing characteristics of construction concrete wastes wcrc rnvcstigatcd in order to scparate the natural aggregatcs. A roll crushcr and a hammcr crusher wcrc used to granulate pre-crushed concrete\ulcorner below 30 rnm The crushers pruducc finer sizes far ccmcnt concrete than for asphalt concrele, and the hammer crushing resulls in separating the aggregales from thc olhers better than thc roll crushing. The narural aggregatcs of orcr 70-90% by volume were obtained from the concretes by using a riffled shaking table.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.459-462
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• 2007

Recently, it has been important issue to recycle the rapid increase of construction waste. The site-recycling of construction waste has been one of alternatives to recycle construction waste. The economic superiority of site-recycling was shown in previous studies, but it is hardly studied in the Quantification of social costs from site-recycling. This study identified the generation of the carbon dioxide from the site-recycling and Quantified the social costs of it. Also, this study performed the comparison and analysis of the social costs of the carbon dioxide in accordance with the aggregate production from the site-recycling, processing on commission, and a stony mountain. The results of this study indicated that the site-recycling was the most effective in the social costs.

• Resources Recycling
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• v.21 no.2
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• pp.47-52
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• 2012

According to the diversification of types of concrete structures, the quality of the concrete which is demanded also, is becoming high performance essentially. The high performance of the concrete leads using of admixtures, generally, in order to produce high strength, concrete has been used to silica fume. Silica fume is excellent mechanical properties, but unlikely to be economic. So, recently as a replacement for silica fume, metakaolin is a lot of research underway. In this study, it is used the metakaolin substitute for silica fume. For in order to prevent loss of liquidity when occurs using the admixtures, we used the silica dioxide. Therefore, concrete with the admixtures and silicon dioxide were examined the mechanical properties.