• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.2
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• pp.152-161
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• 2024

This paper investigates the manufacturing and fundamental quality characteristics of potassium magnesia phosphate-based non-cement high-volume fly ash repair mortar. To derive the optimal mix for non-cement mortar, the manufacturing characteristics were evaluated based on the magnesia ratio, and the mortar manufacturing characteristics were assessed with the fly ash mixture. Additionally, the non-cement magnesia repair mortar was produced considering the effects of fly ash mixture and basalt fiber. The evaluation results determined the optimal mix of non-cement magnesia repair mortar, and the feasibility was examined through workability and fundamental quality assessments. The optimal magnesia ratio was found to be P:M 1:0.5, with W/B at 30 %. It was also confirmed that mixing FA and basalt fiber improves fiber dispersion and workability. Even with over 50 % FA mixture, the target strength was achieved within six hours, with a flow increase of up to 18 % and a flexural strength decrease of about 1-2 MPa.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.2
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• pp.59-64
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• 2013

The present study is to evaluate physical and mechanical properties of porous concrete having non cement that mainly causes carbon emission. This study aims to explore eco-friendly concrete technology capable of reducing the amount of carbon emission due to the use of normal cement by substituting it with non cement porous concrete to which alkali-activator and blast-furnace slag powder are impregnated. As experimental variables, 5 %, 6 %, 7 %, 8 %, 9 % and 10 % of alkali-activator were substituted as binders and applied. Testing evaluated in this study were pH value, void ratio, compressive strength and residual compressive strength shown after being immersed in $H_2SO_4$ solution and $Na_2SO_4$ solution. The test results were compared with those tested with the use of porous concrete to which 400 $kg/m^3$ of unit cement amount was applied as binder. In consequence, it was concluded that; as for pH value, it was decreased than was the case in which cement was used, but increased with the more the use of alkali activator; as for void ratio and compressive strength, the mix proportion in which 9 % and 10 % of alkali activator were applied in terms of substitution ratio showed the result similar to the mixture in which 400 $kg/m^3$ of unit cement ratio was applied; and, as for residual compressive strength in the case of being immersed in $H_2SO_4$ solution and $Na_2SO_4$ solution, the compressive strength was increased, thus leading to improved chemical resistance.

• Journal of the Korea Concrete Institute
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• v.27 no.3
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• pp.245-252
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• 2015

As people have more interest in environment-friendly structures recently, many researchers are actively researching non-sintered cement in Korea and other countries. Non-sintered cement shows various characteristics of its reaction products and hardeners, depending on the kind of alkali activators. Thus, this study manufactures ground granulated blast furnace slag based non-sintered cement binder by using circulating fluidized bed combustion ash, which is a kind of industrial byproduct, as a stimulant, and investigated its hardening characteristics and hydration, depending on the rate of circulating fluidized bed combustion ash. Besides, this study investigated its insulation property according to the weight lightening of non-sintered cement. As a result, ettringite and C-S-H were mainly formed in the hydration, and it was possible to manufacture a non-sintered cement hardener over 50 MPa. Lastly, it was possible to manufacture a non-sintered cement hardener in a thermal conductivity level of $0.127W/m{\cdot}K$ when the compressive strength was 10 MPa for weight lightening.

• Journal of the Korea Institute of Building Construction
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• v.21 no.2
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• pp.97-104
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• 2021

This study aims to develop non-sintered cement that can replace the Portland cement by utilizing industrial by-products. As a suggestion, the physical properties of non-sintered cement mortar depending on the curing method were investigated with ground granulated blast furnace slag, class C fly ash, and class F fly ash. As a result of the study, it was found that the strength performance and absorption rate were improved through the heat treatment process after steam curing. It was confirmed through crystal phase analysis that the hydration was accelerated after heat treatment, and the bonding material formed a dense internal structure.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.309-310
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• 2023

Slag and ash generally have a higher powder degree than portland cement, so workability may deteriorate under the same unit quantity condition, and strength and durability decrease when the unit quantity is increased. At this time, if an aggregate having a low water absorption and an appropriate particle size is used to recover the loss of strength, it can contribute to reducing the unit quantity of the binder. Therefore, for the purpose of improving the workability and strength of non-sintered cement mortar using slag and ash, ferro nikel slag whose particle size was adjusted was used as an aggregate and its applicability was identified. In this experimental condition, it was confirmed that non-sintered cement mortar tends to improve workability and secure strength when ferro nikel slag having various particle size distributions is used as an aggregate. This can be analyzed as the effect of ferro nikel slag material properties including glassy properties and mixing conditions with a wide particle size distribution.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.569-572
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• 2008

This study carried out to evaluate the quality deviation according to Premixed and Non-Premixed cement for normal and high strength concrete using blast furnace slag and fly ash. The results of experiment are founded that concrete using premixed cement have more performance than non-premixed cement at a point of view for the quality deviations both strength and Chloride ion diffusion. Therefore, it is desirable that premixed cement should be used to decrease strength deviation in high strength concrete and durability deviation in normal strength concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.11a
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• pp.101-104
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• 2005

The world's cement demand is anticipated to increase about 2.558$\%$ every year until the first half of the 21st century. To be closed the increase of cenment damand and simultaneously comply with the Kyoto Protocal, cement that gives less carbon dioxide(Co2) discharge should be urgently developed. If cement can be manufactured with industrial byproducts such as granulated blast furnace slag(GBFS), phosphogypsum(PG), and waste lime(WL) instead of clinker as its counterproposal, there would be many advantages including maximum use of these industrial byproducts for high value-added resources, conservation of natural resources and energy by omitting the use of clinker, minimized environmental pollution problems caused by Co2 discharge and reduction of the cost. So this study aims to solve the problems by manufacturing non-sintered cement.

• Computers and Concrete
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• v.20 no.2
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• pp.145-154
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• 2017

In geological engineering, grouting with Portland cement is a common technique for ground improvement, during which micro-fine cement is applied as a slurry, such that it intrudes into soil voids and decreases soil porosity. To determine the utility and behavior of cements with different Blaine values (index of cement particle fineness) for stabilization of fine sand, non-destructive and destructive tests were employed, such as laser-ray determination of grain size distribution, and sedimentation, permeability, and compressive strength tests. The results of the experimental study demonstrated a suitable mix design for the upper and lower regions of the cement-grading curve that are important for grouting and stabilization. Increasing the fineness of the cement decreased the permeability and increased the compressive strength of grouted sand samples considerably after two weeks. Moreover, relative to finer (higher Blaine value) or coarser (lower Blaine value) cements, cement with a Blaine value of $5,100cm^2/g$ was optimal for void reduction in a grouted soil mass. Overall, study results indicate that cement with an optimum Blaine value can be used to satisfy the designed geotechnical criteria.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.34-35
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• 2021

In this study, we compared and analyzed hydration heat of the Concrete(NC) and non-fired Hwangto Concrete(HT). The Concrete(NC) was based on the mix that showed 30, 45 MPa on compressive strength on 28th and Only cement was used to make it. and We substituted 30% of weight of unit cement to non-fired Hwangto to create non-fired Hwangto Concrete(HT).

• Cement Symposium
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• s.34
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• pp.144-149
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• 2007