• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.397-398
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• 2009

Recently, the research about alkaline activity concrete is being progressed actively. In this paper, the effect of many kinds of alkaline activation to fly ash based cement zero mortar is examined.

• Journal of the Korea Concrete Institute
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• v.27 no.3
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• pp.311-317
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• 2015

Cement zero concrete produced by alkali-activators and industrial by-products such as slag instead of cement, enables to solve the environmental pollution problems provoked by the exhaustion of natural resources and energy as well as the discharge of carbon dioxide. However, researches on the cement zero concrete are still limited to material studies and thus, study on the structural behavior of relevant members is essential to use the cement zero concrete as structural materials. This paper aims to evaluate experimentally and analytically the flexural behavior of RC beams using 50 MPa alkali activated slag concrete. To achieve such a goal, flexural tests on three types of RC beam specimens were conducted. A nonlinear analysis model is proposed using the modulus of elasticity and stress-strain relationship of alkali activated slag concrete. The analysis results obtained by the proposed model agree well with the experimental results, which could verify the validity of the proposed model.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.1
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• pp.58-63
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• 2015

Several researches on cement zero concrete using alkali-activators have been conducted to investigate its fundamental material properties such as slump, strength and durability, however, research on the structural behavior of relevant members involving the elastic modulus, stress-strain relationship is essential for the application of this cement zero concrete to structural members. In this paper the shear behavior of reinforced concrete beams using 50 MPa-alkali activated slag concrete was experimentally evaluated. To achieve such a goal, six reinforced concrete beam specimens were fabricated and their shear behaviors were observed. The maximum difference between test results and analysis results in crack shear stress for beam specimens without stirrups is 31%, while that for beam specimens with stirrup is 15%. Furthermore, it is also found that the shear strength of alkali activated slag concrete is by 22~57% greater than the nominal shear strength calculated by design code, implying that shear design equations would provide conservative results on the safety side.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.665-668
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• 2008

Portland cement production-1.5billion tonnes yearly worldwide-contributes substantially to global atmospheric pollution($\sim$7% of total of CO$_2$ emissions). Attempts to increase the utilization of fly ash, a by-products from thermal power plant to partially replace the cement in concrete are gathering momentum. But most of fly ash is currently dumped in landfills, thus creating a threat to the environment. Therefore, In this study, influence of curing temperature(30, 60, 90$^{\circ}$C) on the strength of properties fly ash based cement ZERO mortar was investigate, measured a weight change and pH change according to each care of curing temperature. The test results that a curing at 90$^{\circ}$C is appropriate in case of the high strength concrete is required in the early-age of the curing and 60$^{\circ}$C is efficient for the case of requiring high strength at age 28 days. Furthermore pH variation and value of compressive strength are judged to correlate but change of weight is not the case.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.649-652
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• 2008

Glass is often recycled. In order to recycle, glass is crushed and ground. During this process, glass powder is generated. Most of this scrap glass powder is disposed in landfills. The glass powder, consisting of 73% SiO$_2$ and 16% Al$_2$O$_3$, is richer in components necessary for polymerization than fly ash. In this study, the fluidity and compressive strength of cement zero mortar were investigated, where cement zero mortar was prepared by mixing 5$\sim$15% of glass powder with 100% fly ash mortar. Result of flow test concluded that workability was not affected by adding the powder. After aging for 28 days, the compressive strength increased by approximately 6% with 5% addition of scrap glass powder. With 10% addition, the strength remained the same. In case of 15% addition, the compressive strength decreased by approximately 6%. To summarize the results, 5$\sim$10% addition of scrap glass powder is considered to be most appropriate.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.287-288
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• 2012

In this study, Analyzed the effect of the change in RFA and RCA substitution rate on the concrete containing BS bonding materials but no cement. The findings are as follows. First, the fresh concrete has less slump value and air contents as more RFA and RCA is used. In case of hardened concrete, as more RFA and RCA are used, the higher the compressive strength of concrete becomes. Especially, the compressive strength of concrete which used recycled aggregates only is found to be 2.2 times as high as that of concrete using natural fine and coarse aggregates only. But if the concrete is to be used as the structural concrete having the compressive strength of 13.8 MPa, the alkaline materials and some cement are required to be added.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.10a
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• pp.152-153
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• 2016

In this research, we evaluate the performance for preventing frost damage at early age of mortar using variable cement and self-heating binder. Purpose of final research is preventing freezing and thawing by making the compressive strength 5MPa in 3days below zero temperature without heat curing. We compare the compressive strength of mortar and concrete using variable cements and self-heating binder in low temperature.

• Advances in concrete construction
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• v.8 no.2
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• pp.127-137
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• 2019

Roller Compacted Concrete (RCC) is a zero slump concrete consisting of a mixture of cementitious materials, sand, dense graded aggregates and water. In this study, an attempt has been made to investigate the effect of aggregate type on strength and abrasion resistance of RCC made by using granulated blast furnace slag (GGBS) as partial replacement of cement. Mix proportions of RCC were finalized based upon the optimum water content achieved in compaction test. Two different series of RCC mixes were prepared with two different aggregates: crushed gravel and limestone aggregates. In both series, cement was partially replaced with GGBS at a replacement level of 20%, 40% and 60%. Strength Properties and abrasion resistance of the resultant mixes was investigated. Abrasion resistance becomes an essential parameter for understanding the acceptability of RCC for rigid pavements. Experimental results show that limestone aggregates, with optimum percentage of GGBS, perform better in compressive strength and abrasion resistance as compared to the use of crushed gravel aggregates. Observed results are further supported by stoichiometric analysis of the mixes by using basic stoichiometric equations for hydration of major cement compounds.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.4_2
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• pp.549-563
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• 2022

Continuous global warming is causing ecosystem destruction and direct damage to human life. The main cause of global warming is greenhouse gases, which account for more than 90 % of carbon dioxide. The leaders of each country signed the Paris Agreement at the United Nations Convention on Climate Change (UNFCCC) to reduce greenhouse gas emissions. Currently, the total amount of CO₂ emitted from South Korea is 664.7 million tons as of 2018, ranking eighth in the world. 37 % of South Korea's total CO₂ emissions come from the construction & building field, especially the cement production, which is a construction material. Carbon reduction technologies can be largely divided into four types: carbon reduction (CC), carbon reduction and storage technology (CCS), carbon reduction and utilization technology (CCU), and carbon reduction, storage and utilization technology (CCUS). Overseas, CCUS technology is mainly applied to reduce and store CO₂ emitted from construction and construction field. A technology for permanently storing CO₂ through mineralization by capturing CO₂ and utilizing CO₂ into a cement production process was developed, and this technology is applied to the entire cement industry. However, the development of CCUS technology applicable to the cement industry is still insignificant in South Korea. In this study, carbon dioxide reduction technology and methods for reducing carbon dioxide emitted during the cement manufacturing process, which is the main component of concrete mainly used in civil engineering construction, were investigated. Overseas, it has reached the commercialization stage beyond the demonstration stage as a way to reduce carbon dioxide by vomiting carbonation reactions. Accordingly, if carbon dioxide reduction plan technology generated during cement manufacturing is developed based on domestic technology differentiated from foreign technology, it is expected to contribute one more step to the carbon neutrality policy.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.203-204
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• 2016

In this research, it used cement power and reduction slag, which generates high hydration heat in hydration reation without heat cure below -5℃ degree. Purpose of final research is preventing freezing and thawing by making the compressive strength 5MPa in 3days below zero temperature due to own heat of concrete. and it is the result of physical characteristic and thermal property evaluation of reduction slag. Because reduction sag generates high hydration heat, compressive strength development is excellent. By generating highly Hydration heat by C₁₂A₇ and C₃A in reduction slag, compressive strength is developed in low temperature. In case of displacing only reduction slag without SO₃, it is indicated that quick-setting occurs by shortage of SO₃. For preventing quick-setting, gypsum is used essentially. According to this research result, in case of using reduction slag and gypsum as a ternary system, Compressive strength developed 5MPa in 3days below zero temperature. It is identified to prevent early frost damage of concrete below zero temperature.