• Magazine of the Korea Concrete Institute
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• v.10 no.5
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• pp.217-225
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• 1998

분쇄한 FRP(Fiver-Reinforced Plastics) 폐기물을 사용한 폴리머 모르타르의 물성에 고나하여 조사하였다. 분쇄한 FRP 폐기물을 시멘트 모르타르의 세골재로 재활용하기 위하여 세골재에 대하여 0~50wt% 치환.사용하였고, FRP 폐기물의 사용으로 나타나는 강도 저하현상을 보완하기 위하여 3종류 폴리머 혼화제의 첨가량을 변화시켜 각종 공시체를 제작하였다. 폴리머 혼화제로서는 styrene-bytadiene rubber(SBR) 라텍스, polyacrylic ester(PAE) 에멀젼 및 ethylene-vinyl acetate(EVA)에멀젼을 사용하였다. 분쇄한 FRP 폐기물을 사용한 시멘트 모르타르에 폴리머 혼화제를 첨가하여 만든 폴리머 시멘트 모르타르는 폴리머 혼화제를 첨가하지 않은 모르타르보다 압축 및 휨강도가 크게 증가하였다. 폴리머 시멘트비 10wt%에서 세골재 대용으로 분쇄한 FRP 폐기물의 적정 치환량은 20wt%로 나타났다. 8$0^{\circ}C$에서 가열양생하여 제조한 폴리머 시멘트 모르타르는 폴리머 시멘트비 10wt%이하에서 표준양생한 모르타르보다 강도가 저하되었다. 폴리머 시멘트 포르타르의 흡수율은 폴리머 시멘트비가 증가함에 따라 크게 감소하였다.

• Journal of the Society of Disaster Information
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• v.11 no.3
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• pp.329-336
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• 2015

When diatomite powder was used as an admixture in mortar, its effects on the mortar strength was examined by experimental tests. For the tests, 4 kinds of commercially available diatomite powder were purchased ; one non-calcined product, one calcined product, and flux-calcined product two. The compressive and flexural strength of the mortar according to the increase of added amount of calcined diatomite powder increased at all test ages(7, 28, and 56 days). However, the use of non-calcined diatomite powder worsened the fluidity of mortar severely and that caused much more required water content. And flux-calcined product did not show useful effect on the mortar strength.

• Journal of the Korea Institute of Building Construction
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• v.23 no.4
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• pp.359-367
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• 2023

This experimental study investigates the replacement of conventional Portland cement and sand with non-sintered cement and ferro-nickel slag to formulate eco-friendly cement mortar. The examination aimed to understand the strength properties of non-sintered cement mortar using ferro-nickel slag as fine aggregate by classifying mortar production types, fine aggregates, and curing methodologies. From flexural and compressive strength tests, it was observed that non-sintered cement mortars, incorporating ferro-nickel slag as fine aggregate, exhibited superior strength when compared to both plain mortar and steam-cured non-sintered mortar. This increased strength is attributed to the influence of the particle size, density, and absorption capabilities of the ferro-nickel slag. Furthermore, X-ray Diffraction(XRD) analyses of the mortars verified the presence of MgO, a component of ferro-nickel slag, in the form of a composite oxide. This finding substantiates the consistent strength manifestation of non-sintered cement mortars utilizing ferro-nickel slag as a fine aggregate.

• Journal of the Korea Concrete Institute
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• v.19 no.4
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• pp.457-465
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• 2007

In this paper, polymer-modified repair materials using polymer dispersions with six repair methods are prepared with various polymer-cement ratios, and tested for compressive and flexural strengths through each curing condition such as dry cure, water cure, and freezing and thawing cyclic action. And, the adhesive interface between the polymer-modified mortar and mortar substrate is observed by a scanning electron microscope. From the test results, the compressive and flexural strengths of cement mortar repaired by polymer-modified mortar are improved with a rise in the polymer-cement ratio regardless of the type of polymer and curing conditions. Such an improvement in the strengths of polymer-modified repair materials to ordinary cement mortar is explained by the high adhesion of polymer-modified mortar. Strength reduction of polymer-modified repair materials after freezing and thawing cyclic actions is recognized, but it is lower than that of unmodified mortar. Especially, cement mortar repaired by polymer-modified mortar with a St/BA emulsion has good strength properties compared with those of SBR latex and PA emulsion. Accordingly, it is judged that polymer-modified mortars with a St/BA emulsion are possible to use as repair materials to ordinary cement mortar and concrete.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.1
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• pp.96-100
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• 2009

The properties of recycled fine aggregates which had different source concrete were examined by mortar test. With higher strength of source concrete, specific gravity of recycled fine aggregate was higher and absorption of recycled fine aggregate was lower due to reduction of the volume of adhered cement paste. The compressive strength and flexible strength of mortar with recycled fine aggregate were affected by the interface boundary of new mortar and the strength of adhered mortar. Strength development of mortar with recycled fine aggregate reduced because recycled fine aggregate become a porous material with the smaller strength of source concrete. The drying shrinkage of mortar was about$800{\sim}2000{\mu}m/m$. It was about 1.5 times than that of mortar with natural fine aggregate. Relative dynamic modulus of elasticity was a similar level with that of mortar with natural fine aggregate.

• Journal of the Korea Institute of Building Construction
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• v.21 no.6
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• pp.529-538
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• 2021

In this study, the compressive strength and water contact angle were measured before and after surface abrasion of mortar specimens prepared by mixing two types of water repellents and two types of sands. In addition, the hydration products and chemical bonding of cement mortar by repellent were examined using X-ray diffraction(XRD), thermogravimetry-differential thermal analysis(TG-DTA), and Fourier-transform infrared spectroscopy(FT-IR) to evaluate the performance of these cement mortar mixtures as repair materials. We found that the compressive strength of the cement mortar with water repellent added was decreased compared to that of the plain cement mortar, and that of the oligomeric system was higher than that of the monomeric system. We further found that the contact angle of mortar with water repellent added was increased compared to that of the plain cement mortar, and that of the oligomeric system was increased compared to that of the monomer.

• Resources Recycling
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• v.26 no.6
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• pp.20-28
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• 2017

The direct tensile strength of the mortar specimen containing pitch-based carbon fiber was ranged between 1/27~1/22 as compared to the average compressive strength of mortar. It was found that the direct tensile strength of the mortar containing the same amount of PAN-based carbon fiber was around 1/15. While the case of the control specimen without the carbon fiber was around 1/29. One the other hands, the flexural tensile strength of the mortar containing pitch-based carbon fibers was about 1/12 as compared to the average compressive strength. In case of the mortar specimen with PAN-based carbon fiber and control mortar were 1/10 and 1/13.5, respectively. The tensile performance of the mortar with pitch-based carbon fiber was found to be intermediate between control mortar and the reinforced mortar incorporated with the PAN-based carbon fiber.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.943-948
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• 2013

In this study, the characteristics of polymer-modified mortar which include UM resin, eco-friendly resin, was studied for improving the durability of concrete. UM and cement mortar were mixed with a certain percentage. Eco-friendly UM resin polymer-modified mortar was evaluated by compressive strength, splitting tensile strength, flexural strength, water absorption and chemical resistance experiments. The characteristics of eco-friendly UM resin polymer-modified mortar were evaluated by experiments. Performance of compressive strength and splitting tensile strength were decreasing. On the other hand, performance of flexural strength, water absorption and chemical resistance were increasing. Eco-friendly UM resin polymer-modified mortar reinforced concrete durability performance is excellent.

• Journal of the Korea Institute of Building Construction
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• v.11 no.2
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• pp.181-188
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• 2011

Spalling must be considered when designing high-strength concrete to cope with fire. This study investigates the temperature rise of steel bar in high-strength concrete coated with fireproof mortar using gypsum exposed to fire. It was found that fireproof mortar using gypsum is more effective in constraining the temperature rise of steel bar in the high strength concrete than fireproof mortar using cement, and that the thinner the cover depth of the fireproof mortar, the more significant the influence of the gypsum. In addition, while there was no difference between ${\alpha}$-hemihydrate mortar and ${\beta}$-hemihydrate mortar on the temperature rise of steel bar, the compressive strength of ${\alpha}$-hemihydrate mortar is higher than that of ${\beta}$-hemihydrate mortar.

• Journal of the Korea Concrete Institute
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• v.13 no.6
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• pp.561-567
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• 2001

It is reported that a lot of sludge powder is produced during the process of manufacturing crushed fine aggregate in mines. However, there is a limitation on the its use that most of them are disposed and wasted, which cause environmental pollution. Therefore, in this paper, tests are carried out in order to recycle sludge powder as filler for cement mortar products. Kinds of aggregates and mix proportion of mortar are varied under various contents of sludge powder. According to test results, it is found that cement mortar products using sludge powder as substitution of fine aggregate about 10% have better qualities than those without sludge powder.