• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.235-239
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• 1994

Polymer mortars are mainly used as protective coatings in concrete, reinforced concrete, and more rarely, steel, while polymer concretes represent a new type of structural material capable of withstanding highly corrosive environments. The mechanical properties, chemical stability, and some other useful properties are the reasons research, design, and production organizations. However polymer mortars and polymer concretes have been introduced only recently, and many of their properties are still imperfectly known. And, the main technique in producing polymer concrete is to minimize void volume in the aggregate mass so as to reduce the quantity of the relatively impressive polymer necessary for binding the aggregate. In this study, compressive strength and flexural strength of unsaturated polyester resin concrete are related to quantity of resin and solid volume of aggregate. It was founded that the more solid volume of aggregate increase, the less using quantity of resin decrease with out reducing mechnical properties. When solid volume ratio of aggregate is 70.6%, using quantity of resin is minimized to 10wt.%.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04a
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• pp.57-62
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• 1998

As the waste concrete is increased by demolition according to the plan of city-reconstruction and preperation of city-environment etc, the production of waste concrete in the country is being very increased every years. Because the use of recycled aggregate is low, the cases of unlawful reclamation and disuse are increased. These occur the social and economic problems. This experimental study is to investigate the fluidity, compressive strength and durability of flowing recycled aggregate concrete using the river sand and recycled coarse aggregate according to the replacement rate of fly-ash and to present the fundamental data for the using of flowing recycled aggregate concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.13-18
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• 2003

The concrete structure can be easily damaged due to alkali-aggregate reaction. The alkali-aggregate reaction is a reaction between the alkalies(K or Na) in cement and an unstable mineral of the aggregates. There are several test methods to identify alkali reactivity of aggregates. In general, crushed stones are tested by petrographic examination, chemical method and 모르타르 바 method. This study tested alkali-aggregate reactivity of crushed stones that has different rock types such as granitic, volcanic, metamorphic and sedimentary rocks. Samples are collected from 12 local aggregate production companies. Alkali-reactivity of various rock types was evaluated by using ASTM C 227 and C 1260, and compared the test results of two test methods.

• Construction Engineering and Management
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• v.4 no.1 s.13
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• pp.48-54
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• 2003

An automated system for scanning and characterizing unbound aggregates, called the 'Laser-based Aggregate Scanning System'(LASS), has been developed at the University of Texas at Austin. The system uses a laser profiler to acquire and analyze true three-dimensional data on aggregate particles to measure various morphological properties. Tests have demonstrated that the system can rapidly and accurately measure grain size distribution and dimensional ratios, and can objectively quantify particle shape, angularity, and texture in a size invariant manner. In its present state of development, the LASS machine is a first-generation, laboratory testing device. With additional development, this technology is expected to provide high-quality, detailed information for laboratory and on-line quality control during aggregate production.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.901-904
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• 2006

The government makes efforts to expand the recycling activities of construction waste soil and to increase the usage of recycled aggregate. Accordingly, it has defined the compulsory usage and quality standard by usage of recycled aggregate. To satisfy these efforts requires both technology to produce recycled aggregate which meets the required quality and companies with the technology. Therefore, it requires to review a current status of facilities at the companies which deal with construction wastes. The companies dealing with construction wastes gradually produce the high quality of recycled aggregate. In particular, companies which has over 3-stage processing system for waste concrete continue to increase and means to remove foreign substances are gradually improved.

• International Journal of Highway Engineering
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• v.16 no.5
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• pp.39-47
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• 2014

PURPOSES : This study aimed to analyze economic effect of recycled aggregate production on job-site airport pavement. METHODS : The validation of site recycling for waste concrete as economic efficiency is analyzed through the case study of site recycling at an O airport pavement construction. The break-even point for the cost of site recycling was estimated according to two different waste concrete processing methods such as job-site recycling and processing on commission (or plant). RESULTS : Job-site recycling cost decreases as the use rate of job-site recycled concrete aggregate increases, or the amount of concrete waste increases, but transporting distance decreases. It was shown in an O airport case that as the use rate of job-site recycled concrete aggregate exceeds 61.4 %, the job-site recycling cost is cheaper than the processing cost on commission. CONCLUSIONS : The results of this study can utilize basic data of feasibility for site recycling of waste concrete on airport pavement construction.

• Economic and Environmental Geology
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• v.57 no.2
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• pp.161-175
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• 2024

Aggregate typically refers to sand and gravel formed by the transportation of rocks in rivers or artificially crushed, constituting a core resource in the construction industry. Gyeongsangbuk-do, the largest administrative area in South Korea, produces various sources of gravel, including forest, land (excluding other sources), river, and crushed stone. As of 2022, it has extracted approximately 6.96 million cubic meters of aggregate, with permitted production totaling around 4.07 million cubic meters and reported production of about 2.88 million cubic meters. The aggregate demand in Gyeongsangbuk-do is estimated to be 12.39 million cubic meters according to the estimation method in Ready-Mix Concrete. From the supply perspective, about 120 extraction sites are operational, with most municipalities maintaining an appropriate balance between aggregate demand and supply. However, in some areas, there is inbound and outbound transportation of aggregate to neighboring regions. Regions with significant inbound and outbound aggregate transportation in Gyeongsangbuk-do are areas connected to Daegu Metropolitan City and Pohang City along the Gyeongbu rail line, showing a high correlation with population distribution. Gyeongsangbuk-do faces challenges such as population decline, aging rural areas, and insufficient balanced regional development. Analysis using GIS reveals these trends in gravel demand and supply. Currently in this study, Gyeongsangbuk-do meets its demand for aggregate through the supply of various aggregate sources, maintaining stable aggregate procurement. River and terrestrial aggregates may be sustained as short-term supply strategies due to the difficulty of longterm development. Considering the reliance on raw material supply for selective crushing, it suggests the need for raw material management to maintain stability. Gyeongsangbuk-do highlights quarries in the forest as an important resource for sustainable aggregate supply, advocating for the development of large-scale aggregate quarries as a long-term alternative. These research findings are expected to provide valuable insights for formulating strategies for sustainable management and stable utilization of aggregate resources.

• KIEAE Journal
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• v.14 no.1
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• pp.131-138
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• 2014

The recent interests in securing alternative resource have increased due to environmental issues and exhaustion of natural resources. The government notices production of recycled aggregate using waste concrete as the substitute of the natural aggregate. However, It's important to reduce environmental burden being inevitably made in the process producing recycled aggregate. In this study, the scenarios of transportation distance were set in the transportation phase of production of recycled aggregate. In addition, The possibility of emissions and reduction of carbon dioxide were studied depending on the scenarios. For this study, data about a amount of waste concrete, transportation distance, kind of vehicle, the number of required vehicle, fuel efficiency of vehicle and etc were gathered from 15 companies of intermediate treatment and 60 constructions sites located in Daegu city and Kyungpook area. Based on those data, fuel consumptions and $CO_2$ emissions according to the transportation scheme of waste concrete were calculated. As a result of the study, the emission of carbon dioxide was possible to be reduced by 27.8~75.4% depending on the scenarios of transportation distance.

• Resources Recycling
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• v.16 no.5
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• pp.25-30
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• 2007

In Korea, reutilization of construction waste is gaining attention as construction waste generated increases continuously. Currently, the concrete waste is simply crushed and used as a low value application such as paving, back filling, etc. To meet the demand of aggregate for construction and the resource efficiently, production of high quality recycled aggregate is necessary. Therefore, in this study, a better process for production of high quality recycled aggregate was developed using combination of heat pretreatment and autogenous milling. Test results showed that the recycled aggregate has a density of $2.5\;g/cm^3$ and a water absorption ratio of 3.0%, which meet the specification of the first class of KS F 2573. Currently, a pilot scale autogenous mill is being constructed and tests will be further conducted to develop a commerce-scale process.

• Journal of Korean Society of Rural Planning
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• v.11 no.4 s.29
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• pp.93-98
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• 2005

A aggregate size distribution of soils is an important in successful crop production in reclaimed tidelands. The aggregate size distribution for this study were determined of 0.1mm, 0.25mm, 0.5mm, 1.0mm, and 2.0mm by wet sieving method. Agricultural activity, period of reclamation showed significant effects on aggregate size distribution in reclaimed tidelands. Aggregate MWD was greater in SS and KH(above 1.0m) than in YSG, GHD, SMG, and DH(below 0.5mm) reclaimed tidelands and tidelands. The percentage of aggregates less than < 2mm for SMG, GHD, and SM reclaimed tidelands and tidelands were ranged 8.9%, 36.7%, and 38.0%, respectively. The percentage of > 0.1mm aggregates for SMG, GHD, and SM reclaimed tidelands were ranged 9.0%, 26.0%, and 48.9%, respectively. Results indicated that aggregate size distribution of reclaimed tidelands and tidelands under various agricultural systems vary with reclamation period and soil type.