• Journal of the Korea Institute of Building Construction
• /
• v.15 no.3
• /
• pp.257-263
• /
• 2015

In this study, the quality of blast furnace slag and the engineering properties of recycled aggregate based mortar with variable replacement of blast furnace slag have been focused. Blast furnace slag(BS) manufactured in various areas in Korea were prepared for this study. For the investigation results, 4 types(among the all of 9 types) of the experimental results were identified as below the standard level when using blast furnace slag chosen from different factories. Especially the particle size of the blast furnace slag was considered as the largest problem. When using BS in the recycled aggregates based mortar, the increase amount of blast furnace slag, increased the fluidity but delayed the setting time and decreased strength at early age. Based on the relationship of the amount of BS and the engineering properties of mortar, this study found that the amount of $SO_3$ and L.O.I affect the setting time, 3 days strength and 91 days strength to the certain standard level.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.4 no.1
• /
• pp.76-81
• /
• 2016

Recycled aggregate is a valuable resource in Korea in lack of natural aggregate. Government recognizes the importance and suggests various policies enhancing its use for higher value-added application. Most of recycled aggregate produced currently in Korea, however, is applied for low value-added uses such as embankment, reclamation, etc. Its higher valued application such as for structural concrete is very limited. Although domestic manufacturing technology of recycled aggregate is at the world level, recycled aggregate is not applied for structural concrete. Primary reasons for the limited use of the recycled aggregate include bonded mortar and cracks occurred during crushing and hence it is very difficult to predict and control the quality of recycled aggregate concrete. This research intended to grasp combined characteristics of recycled aggregate, high early strength cement, maximum temperature and time duration of steam curing and then, analyze the effects of factors. Also, it suggested the method to improve field applicability of recycled aggregate concrete.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.1A
• /
• pp.213-218
• /
• 2006

As a manufacturing process of recycled aggregate improves the quality of recycled aggregate shall be sufficient enough to be used for structural concrete. This study characterized compressive strength and elastic modulus of concrete that used recycled coarse and fine aggregate. Before the strength tests, the fundamental characteristics of recycled aggregate were preliminarily analyzed and the recycled aggregate satisfied the class 1 requirements in KS F 2573. As the replacement ratio increased, the compressive strength and elastic modulus of recycled aggregate concrete decreased. When the coarse and fine aggregates were completely replaced with the recycled, the compressive strength and elastic modulus were decreased by 13% and 31%, respectively. Based on the test results, this study suggests equations for predicting the compressive strength and elastic modulus of the recycled aggregate concrete with respect to the replacement ratio. The values from the equations were in good agreement with the test data from this study and others.

• 한국도로학회:학술대회논문집
• /
• 2003.10a
• /
• pp.225-228
• /
• 2003

• Magazine of RCR
• /
• v.15 no.1
• /
• pp.8-15
• /
• 2020

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.2 no.1
• /
• pp.103-112
• /
• 2006

Along with recent improvement of recycling technique, the quality of the recycled concrete aggregate have become very competitive to the natural concrete aggregate. Therefore, a practical use of the recycled concrete aggregate may be possible for structural members. Majority studies about the recycled concrete aggregate was emphasized a limitation of fundamental study concerned with a strength characteristics and durability of the recycled aggregate concrete, there is use for the structural members. Therefore, for the extension of application of recycled concrete aggregate, this investigation verifies the strength characteristics recycled concrete aggregate of the spun-concrete products with various coarse and fine recycled aggregate replacement ratio(coarse recycled aggregate: 0%, 20%, 40%, 60%, 100%; fine recycled aggregate: 0%, 30%, 60%, 100%) and with addition of cellulose fibers(0%, 0.01%, 0.03%, 0.05%, 0.08%). From the test results, The strength of spun concrete used with recycled aggregate [NR specimen], was measured as 72MPa, was found to be very approximately to the strength of spun concrete used with the natural aggregate(NN specimen), was measured as 74MPa, when only fine aggregate was replaced with the recycled. Therefore, the fine recycled concrete aggregate can be successfully used in the spun high strength concrete product. The compressive strength of all specimens used the specialty cellulose fiber were measured as about 70M Pa, however, the increasement of the specialty cellulose fiber content is showed to decrease compressive strength of spun concrete. Therefore, it is anticipated that the specialty cellulose fiber can be applied to the various spun concrete products.

• Journal of the Korea Concrete Institute
• /
• v.21 no.3
• /
• pp.367-375
• /
• 2009

Recently, more focus is shift to imbalances in aggregate market supply and demand and an exhaustion of natural resources. In this situation, Electric arc furnace oxidizing slag (EAF slag) has high application possibility as aggregate for concrete due to similar property with general aggregate. However, it is inherent the problem which causes pop-out by free-CaO contained in slag In this study, we've got the plan to assure the chemical stability of EAF slag, and then experimentally tested the mechanical performance and durability for the fine aggregate used EAF slag. On this test result, we suggest the application plan. At the result of this study, it shows that EAF slag would reduce the surface defect such as pop-out due to natural aging for the fixed hour and adjustment the grain size of EAF slag. And mechanical performance and durability according to the replacement rate of concrete service, were revealed more than equal or equal compare to general aggregate. Hereafter, quality control must precede not to impede the beauty of concrete surface as assure the safety for aging and processing. And, to establish the environmental resource recycling system for by-products of steel, it should be made development of various application and guideline of quality control for the EAF slag aggregate. Moreover, it must be constantly studied all kind of engineering performance and durability for related to this study.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.9 no.1
• /
• pp.109-116
• /
• 2021

In order to replace mineral aggregate used as road pavement materials with steel slag aggregate, this present study evaluated mechanical properties of SMA Concrete mixtures using steel slag aggregate as oxidized slag from electric furnace in iron works. The variables of this experiment are the aggregate type of mineral and steel slag and the sieve sized of 10mm and 13mm. The physical properties inclu ding the specific gravity and absorption rate etc. of the slag aggregate mixtu res satisfied the KS standard as asphalt mixtu re. As a resu lt of evalu ating the mechanical properties of the asphalt mixtures, the optimum asphalt content of the slag aggregate mixtures were lower than that of the mineral aggregate mixtures, but other quality standards were all satisfied. In the deformation strength evaluation, the slag aggregate mixtures were measu red slightly higher than that of the mineral aggregate mixtu res, and the dynamic stability test satisfied the 2,000pass/mm standard value in all specimens. And, the moduli of resilient of the slag aggregate mixtures showed an improved value compared with the mineral aggregate mixtures. Therefore, as the resilient rate of the slag aggregate mixtures improved, it is speculated that there will be an effect of improving public performance according to the repeated traffic load of the vehicle.

• Journal of the Korea Institute of Building Construction
• /
• v.15 no.6
• /
• pp.545-551
• /
• 2015

The aim of this research is suggesting application method of the wasted rock obtained from the limestone quarry of raw material for cement as a coarse aggregate for high strength concrete after crushing and sieving processes. The wasted rock has been normally wasted because of its low quality as a material for cement production. In this research, the concrete using this wasted limestone coarse aggregate was evaluated the constructability based on the performances of workability, air content, and compressive strength. From the experiment, a favorable performance was achieved with a limestone coarse aggregate for high strength concrete comparing to the high strength concrete using granite coarse aggregate.

• Journal of the Korea Concrete Institute
• /
• v.25 no.3
• /
• pp.331-338
• /
• 2013

Under the paradigm of sustainable green growth at the national level, various researches and applications for energy saving in the construction field has been attempted. As a part of energy saving efforts, lightweight concrete was investigated for thermal insulation concrete with phase change material (PCM) which has high heat storage capacity. As a part of energy saving efforts, thermal insulation concrete was investigated and evaluated with lightweight aggregate impregnated by PCM which has high heat storage capacity. As a result, it is found that concrete with lightweight aggregate impregnated by PCM is effective to prevent its quality deterioration by reducing water absorption rate of lightweight aggregate. In addition, it has shown that concretes using lightweight aggregate and impregnated lightweight aggregate improve heat insulation property 33% and 40~43% compared with using normal aggregate, respectively. It is that the lightweight aggregate concrete with impregnated lightweight aggregate has 12~14% lower thermal conductivity than unimpregnated.