• Journal of the Korea Institute of Building Construction
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• v.19 no.3
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• pp.219-228
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• 2019

The aim of the research is to provide a fundamental data of low viscosity typed superplasticizer (SP) on cement-based materials incorporating various supplementary cementitious materials (SCMs). As a relatively new product, low-viscosity typed SP has introduced for high performance concrete with high viscosity due to its high solid volume fraction with various SCMs. However, there are not enough research or reports on the performance of the low viscosity typed SP with cement-based materials incorporting SCMs. hence, in this research, for cement paste and mortar, fluidity and rheological properties were evaluated when the mixtures contained various SCMs such as fly ash, blast furnace slag, and silica fume. From the experiment conducted, it was checked that the low viscosity typed superplasticizer decreased the plastic viscosity of the mixture as well as the yield stress. From the results of this research, it is expected to contribute on introduction of new type SP for high performance concrete or high-viscous cementitious materials.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.601-604
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• 2008

This study as using admixture (G), high early strength agent, calcium hydroxide {a(OH)2} and fine particle cement, etc which have been newly developed for the purpose of quality improvements like the improvement of early strength of concrete that the FA was substituted by 20%, etc, reviewed the possibility of the utilization in the great quantity and the results are summarized as the followings. Slump loss by the kind of mixing material of high early strength agent and Ca(OH)$_2$ showed the smaller width of decrease than that of plain to appear the improved results and fine particle cement and G admixture showed the large slump loss. Air contents were appeared to satisfy the target air contents at all mixing materials. Regarding the compressive strength of the concrete by the kind of mixing material, G admixture was appeared to be highest all on aging 3 days, 7days and 28days at the initial strength. And fine particle cement and high early strength agent showed higher strength increase rate on aging 3days than plain but showed that the increase of strength becomes gradually dulled as aging is increased. And Ca(OH)$_2$ had almost no effect.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.1
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• pp.90-99
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• 2015

This study examined dynamic and characteristics and chloride penetration of concrete mixed with large amount of FA and BFS, which are considered for positive application to construction fields with purpose of long-tern durability of concrete structures. As a result of strength test on FA and BFS, FA concrete showed higher increase of strength compared to OPC, when FA4000 and FA5000 were mixed 30%, respectively. For BFS concrete, those mixed with 30% and 50% of BFS8000, respectively, showed higher or equivalent strength compare to OPC. As a result of test of chloride penetration on FA and BFS, diffusion coefficients of concrete mixed with 30% FA4000 and FA5000, respectively, showed to restrain average 6.5% of diffusion coefficient compared to OPC. And in case of BFS concrete, those mixed with BFS6000 and BFS8000, restrained diffusion of chloride ions 253% and 336%, respectively, compared to OPC. Therefore, Mixing 50% of BFS was most efficient in order to maximize restraint of chloride penetration according to metathesis of large amount. For relation between compression strength and diffusion coefficient of FA and BFS concrete, as strength increased, diffusion coefficient decreased. In this study, when mixing FA and BFS to concrete for long-run durability and restraint against chloride penetration, for FA, mixing it to concrete with less or equivalent 30% of replacement rate was most efficient. And for BFS, as fineness was higher and mixing it to concrete with less or equivalent 50% of replacement rate, there were results of higher strength compared to OPC and more efficient restraint of chloride ions.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.4
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• pp.435-442
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• 2022

In this study, the density of KS L 5110 was compared with that of gas pycnometer and electronic densimeter for efficient density management of cement, blast furnace slag powder and fly ash. Correlation and usability according to the test method were reviewed, and based on the results of the experiment, the availability of alternative test methods was analyzed. As a result of the density test according to test methods, the density of cement, blast furnace slag powder and fly ash tended to decrease in the order of gas pycnometer, KS L 5110 and electronic densimeter. Because the volume range of the sample to be evaluated is different depending on test methods. The coefficient of determination R² was in the range of 0.71 to 0.93, and the correlation according to test methods showed a relatively good correlation. If correction is applied through correlation, it is analyzed that alternative test methods can be used. As a result of the usability review considering the test procedure, measurement time and coefficient of variation, the gas pycnometer had the simplest test procedure and good reliability. In addition, it is expected that the reproducibility between the testers is relatively high because the skill is not greatly required.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.1-7
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• 2018

This study examined the effect of binder-to-soil ratio(B/S) and water-to-binder ratio(W/B) on the flow and compressive strength development of soil concrete using high-volume supplementary cementitious materials. As a partial replacement of ordinary portland cement, 10% by-pass dust, 40% ground granulated blast-furnace slag, and 25% circulating fluidized bed combustion fly ash were determined in the preliminary tests. Using the low-cement binder incorporated with clay soil or sandy soil, a total of 18 soil concrete mixtures was prepared. The flow of the soil concrete tended to increase with the increase in W/B and B/S, regardless of the type of soils. The compressive strength was commonly higher in sandy soil concrete than in clay soil concrete with the same mixture condition. Considering the high-workability and compressive strength development, it could be recommended for low-cement soil concrete to be mixed under the following condition: B/S of 0.35 and W/B of 175%.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.204-211
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• 2020

Poly-Lactic Acid(PLA) fiber is an eco-friendly material and is biodegradable, so it can be utilized for manufacturing porous construction materia ls with interna l pore connection. In this study, domestic PLA fiber products(0.5mm india meter, 1.0mm in length, 10mm in length) were tested for melting at high temperatures and high alkality, and they were incorporated with FA-based geopolymer. Compressive strength was obtained through high temperature curing and alkali activator, however the complete melting of the PLA fiber was not ensured. The previous study handling PLA fiber with 0.003mm in diameter was completely dissolved, but 0.5mm and 1.0mm in diameter showed 42.5% and 33.3% of dissolution ratio, respectively. In addition, the increasing fiber volume led floating fibers during curing, which had a negative effect on its workability and solubility. Although the properties of PLA fiber may vary depending on the raw materials and production conditions, PLA fiber with 0.1mm or less diameter is recommended for porous construction material.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.4
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• pp.75-82
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• 2015

In this study, experimental research was carried out to evaluate steel reinforced ECC (Engineered Cementitious Composites) column, which exhibits excellent crack control property and highly ductile behavior. Ordinary portland cement and high volume fly ash were used as binding materials in the mixture proportions for the purpose of achieving a high level of multiple cracking property with the tightly controlled crack width. To compare with the cyclic behavior of steel reinforced ECC column specimen, a conventional reinforced concrete column was prepared and tested under reversed cyclic loading condition. Based on the cyclic load test, ECC column exhibited higher cyclic behavior, compared to the conventional RC column, in terms of load carrying capacity and energy dissipation capacity.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.104-111
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• 2020

The purpose of this study is to investigate the flexural behavior and plastic hinge of reinforced concrete-ECC composite beams. Ordinary portland cement was used as a binder, and high volume fly ash was also used to improve the properties of ECC. An ECC designed in this study showed high tensile strain capacity of 3.0%. Three types of beams were manufactured according to the replacement length of concrete with ECC. From the bending tests, it was found that load-bearing capacity as well as ductility of beam increased with an increase in the replacement length of concrete with ECC. Curvature ductility and plastic hinge length of beam were also increased.

• Advances in concrete construction
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• v.6 no.6
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• pp.561-583
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• 2018

A variety of polycarboxylate ether (PCE)-based superplasticizers are commercially available. Their influence on the rheological retention and slump loss in respect of concrete differ considerably. Fluidity and slump loss are the cardinal features responsible for the quality of concrete. These are related to the dispersion of cement particles and the hydration process which are greatly influenced by type of polycarboxylate ether (PCE)-based superplasticizers. On the backdrop of relatively less studies in the context of rheological retention of high strength self-consolidating concrete (HS-SCC), the experimental investigations were carried out aiming at quantifying the effect of the six different PCE polymers (PCE 1-6) on the rheological retention of HS-SCC mixes containing two types of Ordinary Portland Cements (OPC) and unwashed crushed sand as the fine aggregate. The tests that were carried out included $T_{500}$, V-Funnel, yield stress and viscosity retention tests. The supplementary cementitious materials such as fly ash (FA) and micro-silica (MS) were also used in ternary blend keeping the mix paste volume and flow of concrete constant. Low water to binder ratio was used. The results reveal that not only the PCEs of different polymer groups behave differently, but even the PCEs of same polymer groups also behave differently. The study also indicates that the HS-SCC mixes containing PCE 6 and PCE 5 performed better as compared to the mixes containing PCE 1, PCE 2, PCE 3 and PCE 4 in respect of all the rheological tests. The PCE 6 is a new class of chemical admixtures known as Polyaryl Ether (PAE) developed by BASF to provide better rheological properties in even in HS-SCC mixes at low water to binder mix. In the present study, the PCE 6, is found to help not only in reduction in the plastic viscosity and yield stress, but also provide good rheological retention over the period of 180 minutes. Further, the early compressive strength properties (one day compressive strength) highly depend on the type of PCE polymer. The side chain length of PCE polymer and the fineness of the cement considerably affect the early strength gain.

• Advances in concrete construction
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• v.16 no.6
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• pp.303-316
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• 2023

Using industrial wastes and construction and demolition (C&D) wastes is potentially advantageous for concrete production in terms of sustainability improvement. In this paper, a sustainable Self-Compacting Concrete (SCC) made with industrial wastes and C&D wastes was proposed by considerably replacing natural counterparts with recycled coarse aggregates (RCAs) and supplementary cementitious materials (SCMs) (i.e., Fly ash (FA), ground granulated blast furnace slag (GGBS) and silica fume (SF)). A total of 12 SCC mixes with various RCAs and different combination SCMs were prepared, which comprise binary, ternary and quaternary mixes. The mechanical properties in terms of compressive strength and static elasticity modulus of recycled aggregates (RA-SCC) mixes were determined and analyzed. Microstructural study was implemented to analyze the reason of improvement on mechanical properties. By means of life cycle assessment (LCA) method, the environmental impacts of RA-SCC with various RCAs and SCMs were quantified, analyzed and compared in the system boundary of "cradle-to-gate". In addition, the comparison of LCA results with respect to mechanical properties was conducted. The results demonstrate that the addition of proposed combination SCMs leads to significant improvement in mechanical properties of quaternary RA-SCC mixes with FA, GGBS and SF. Furthermore, quaternary RA-SCC mixes emit lowest environmental burdens without compromising mechanical properties. Thus, using the combination of FA, GGBS and SF as cement substitution to manufacture RA-SCC significantly improves the sustainability of SCC by minimizing the depletion of cement and non-renewable natural resources.