• International Journal of Highway Engineering
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• v.7 no.3 s.25
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• pp.71-78
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• 2005

This study focuses on finding out engineering characteristics of asphalt concrete mixtures using mineral fillers with recycled waste lime, which is a by-product in the Soda Ash(Na2CO3) production course. The materials tested in this study were made with 25%, 50%, 75% and 100% of mixing ratio based on the conventional mineral filler ratio to analyze the recycle possibility of the waste lime. The asphalt concrete mixtures with recycled waste lime and hydrated lime, and conventional asphalt concrete mixtures were evaluated through their fundamental engineering properties such as Marshall stability, indirect tensile strength, resilient modulus, permanent deformation characteristics, moisture susceptibility and fatigue resistance. The results indicate that the application of recycled waste lime as mineral filler improves the permanent deformation characteristics, stiffness and fatigue endurance of asphalt concrete mixtures at the wide range of temperatures. It is also found that the mixtures with recycled waste lime show higher resistance against stripping than conventional asphalt concrete mixtures. It is concluded from various test results that the waste lime can be used as mineral fillers and especially can greatly improve resistance to permanent deformation of asphalt concrete mixtures at high temperatures.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.1
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• pp.27-32
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• 2014

This study analyzed the fundamental characteristics of concrete according to a ternary system mixing in order to reduce hydration heat of mass concrete and to improve early age strength. The results are as follows. The fluidity of unconsolidated concrete satisfied the target scope regardless of the binder conditions. When the replacement ratio between FA and BS increased, the slump of low heat-A mix and low heat-B mix increased, and air content was not affected by the change of binders. As for setting time, low heat cement mix had the fastest regardless of W/B, and high early strength low heat mix achieved 6 hours' reduction compared with low heat-B mix at initial set, and 12 hours' reduction at the final set respectively. As for the simple hydration heat, the low mix peak temperature was the highest and low heat-B mix had the lowest temperature. And high early strength low heat mix was similar with that of low heat-B. The compressive strength of hardened concrete had similar strength scope in all mixes except for low heat-B mix at early ages, and had unexceptionally similar one without huge differences at long-term ages.

• Journal of the Korea Concrete Institute
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• v.13 no.2
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• pp.114-122
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• 2001

The purpose of this study was to manufacture sintered lightweight aggregate using paper sludge ash and to evaluate the qualities of the aggregate according to various mix proportions, conditions of pelletization and sintering. The paper sludge ash alone, due to its mineral and chemical compositions could not gain suitable expansion and strength. Hence, it was essential to add mineral additives such as clay, fly ash etc. The optimum muting ratio range determined in this study is as follows , paper sludge ash 30∼50 %, clay 30∼50 %, fay ash 0∼40 %, Paper sludge 0∼10% and hematite 2∼3 %(for manufacturing lightweight aggregate both for non-structural and structural concrete). It was possible to manufacture various lightweight aggregate whose dry specific gravity ranged about from 0.6 to 1.4 by using this optimum mixing ratio. From the test results of the qualities of aggregate, it showed that the 10% granules crushing value test and water absorption percentage ranged about 5∼10 ton and 10∼20%. Thus, it was favorably comparable to those of the imported aggregate. The manufactured lightweight aggregate could be used for structural concrete and non-structural concrete.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.117-124
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• 2010

The aggregate, which does not satisfy the standard of KS F 2573, was selected for this investigation. The 28day compressive strength of recycled aggregate concrete without pozzolan material was 21.7MPa, which was less than the strength of concrete made with crushed stone. However, the compressive strength at 28 days was improved by mixing early rapid hardening cement to the cement at the weight ratio of 2.5%. Furthermore, the compressive strength at 91 days and 180 days increased significantly by adding fly ash, slag powder, and diatom powder. The tensile strength of recycled aggregate concrete with pozzolan material also increased about 40% compared to the general concrete. Futhermore, the shrinkage and creep of recycled aggregate concrete with fly ash and slag powder was a little decreased that of recycled aggregate concrete with fly ash and diatom powder. Relationship between compressive strength and creep coefficient was shown to the linear relation like as ${\sigma}_c=-30CF+404$.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.445-451
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• 2019

In this study, we evaluated the durability of concrete produced with recycled polymer that could replace synthetic polymer, which is the main raw material of bridge deck concrete pavement. As a result of the slump and air content test, the requirements of the Korea Highway Corporation Standard were satisfied with all mixing conditions. The slump was lowered when incorporating the recycled bio-polymer, compared to other mix proportions concrete. In contrast, the compressive strength was increased by 6.3~24.4% when the recycled bio-polymer was mixed, compared to the concrete produced with synthetic polymer. It should be noted that the compressive strength was lowered when synthetic polymer was added to concrete mixture. Durability test results showed the best durability when incorporating synthetic polymer. The durability of concrete also increased as the amount of recycled bio-polymer increased, however, the impact was slightly smaller than that of synthetic polymer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.265-271
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• 2019

The aim of this paper was to improve the shortcomings of Pitcher Concrete, a conventional ethylene-based polymer used in combination with the other components, and present basic data for use as improved road pavement material by applying an acrylic polymer. Existing ethylene polymer-based pitcher concrete materials were selected. Acrylic polymer was then added and the resulting mixture was evaluated. The compressive strength of the existing ethylene-based polymer pitcher concrete combination was low due to the large air gap, and a compressive strength of 24MPa was observed on the 28th day of road use, as defined by KS for an acrylic polymer-based pitcher concrete combination. Regarding the bending strength, the combined strength of the acrylic polymer-based pitcher concrete was excellent, and the factor of the pitcher was measured above the reference, 0.1(mm/s), in all variables. All parameters measured were less than 1%. The acrylic polymer mixing characteristics were able to maintain the dynamic modulus of elasticity for more than 120 cycles, but not more than 80 cycles for the other combinations. Therefore, the addition of more acrylic polymer than conventional ethylene polymer base is effective in improving the durability.

• Structural Engineering and Mechanics
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• v.84 no.3
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• pp.393-411
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• 2022

A high-performance reactive powder concrete (RPC) has been readied alongside river sand, with 1.25 mm particle size when under the condition of 80C steam curing. As a heat and sound insulation, expanded perlite aggregate (EPA) provides economic advantages in building. Concrete containing EPA is examined in terms of cement types (CEM II 32.5R and CEM I 42.5R), doses (0, 2%, 4% and 6%) as well as replacement rates in this research study. The compressive and density of concrete were used in the testing. At the end of the 28-day period, destructive and nondestructive tests were performed on cube specimens of 150 mm150 mm150 mm. The concrete density is not decreased with the addition of more perlite (from 45 to 60 percent), since the enlarged perlite has a very low barrier to crushing. To get a homogenous and fluid concrete mix, longer mixing times for all the mix components are necessary due to the higher amount of perlite. As a result, it is not suggested to use greater volumes of this aggregate in RPC. In the presence of de-icing salt, the lightweight RPC exhibits excellent freeze-thaw resistance (mass is less than 0.2 kg/m²). The addition of perlite strengthens the aggregate-matrix contact, but there is no apparent ITZ. An increased compressive strength was seen in concretes containing expanded perlite powder and steel fibers with good performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4237-4244
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• 2015

This study examined the efflorescence characteristics of a concrete sidewalk block manufactured using recycled stone powder sludge and photocatalytic generated by surface polishing during the sidewalk block manufacturing process. The study evaluated the characteristics of the sidewalk block in terms of its quality, based on the amount of stone powder sludge used, efflorescence, and further based on the mixing ratio and number of applications of the photocatalytic. The experimental results indicated that heavy metals such as lead, hexavalent chrome, cadmium, and mercury were not present in the concrete sidewalk block, thereby confirming the effectiveness of the recycled stone powder sludge. The optimum mixing ratio of used in the concrete sidewalk block (for satisfying KS standard values such as water absorption ratio and flexural strength) was found to be 20%. The concrete sidewalk block incorporating the stone powder sludge and photocatalytic exhibited a water absorption ratio of 5.4% and flexural strength of 5.2 MPa, thereby satisfying the quality standards. Additionally, when the photocatalytic was used, efflorescence did not occur even at the low temperature of $-5^{\circ}C$, and the by the sidewalk block was found to be 70% under normal conditions and 68% when subjected to an accelerated weathering test.

• Resources Recycling
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• v.31 no.5
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• pp.42-51
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• 2022

Aggregate resources in Korea are expected to run out owing to an increase in development demand and construction investment. Recycled concrete aggregates (RCA), extracted from waste concrete, have a lower quality than natural aggregates. However, RCA can produce concrete similar in quality to the normal concrete by aggregate pretreatment, use of admixtures, and quality control. RCA are most suitable for use in precast concrete products such as sidewalk blocks and revetment blocks. Herein, the feasibility of producing revetment blocks using recycled aggregate concrete (RAC), similar in quality to normal concrete, was analyzed. The amount of RCA was varied, and moderate high early strength cement and steam curing were used to produce the concrete test blocks. In the block test, the load resistance characteristics of the blocks were evaluated to determine optimal RAC and glass fiber reinforced polymer (GFRP) rebar compositions. Thus, the variable that reduced the cement content was determined at the same level as that of natural aggregate concrete by the control of steam curing. In the concrete block test, although this depends on the reinforcement ratio, the RAC block exhibited the same or better performance than a normal concrete block. Therefore, the low quality of RCA in RAC is no longer a problem when concrete mixing and curing are controlled and appropriate reinforcement is used.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.113-119
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• 2019

Concrete structures built on reclaimed land are combined with chemical erosion such as chlorine and sulfate ions from seawater. Chloride attack deteriorates the performance of the structure by corroding reinforcing bars. In addition, the waste water treatment structure has a problem that the concrete is deteriorated by the sulfate generated inside. Therefore, in this study, the characteristics and chemical resistance of low heat cement concrete used in wastewater treatment structures constructed on reclaimed land were evaluated. As a result of the experiment, the target slump and air content were satisfied under all the mixing conditions. The slump of low heat cement (LHC) concrete was higher than that of ordinary portland cement (OPC) concrete, while the air content of LHC concrete was smaller than that of OPC concrete with the same mix proportion. As a result of compressive strength test, OPC concrete showed higher strength at younger age compared to 28 days. In contrast, LHC concrete exhibited higher strength than OPC concrete at the age of 56 days. As a result of chlorine ion penetration tests, LHC-B concrete showed chlorine ion penetration resistance performance of the "very low" level at the age of 56 days. As a result of chemical resistance evaluation, when the LHC concrete is applied without epoxy treatment, chemical resistance is improved by about 18% compared to OPC concrete. In testing chemical resistance, the epoxy coated concrete exhibited less than 5% strength reduction when compared to sound concrete.