• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.3
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• pp.298-305
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• 2024

This paper is a basic study to improve floor impact noise of reinforced concrete slabs. Considering the case where thickness differences occur due to construction, changes in sound insulation characteristics were analyzed when the cross section of a reinforced concrete slab was restored with mortar. The houses subject to analysis were divided into two types, 84 type and 59 type, with different floor plans. When pre-mortaring was done with heavy mortar to restore the cross section on the reinforced concrete slab, the case was when pre-mortaring was done with the reinforced concrete slab alone and with general mortar. Compared with, the difference between vibration acceleration level and sound pressure was measured. As a result of measuring the vibration acceleration level of the slab after pouring the mortar, the CS mortar was 66.4 dB and the ES mortar was 66.1 dB at 84 type 63 Hz, which was more than 2 dB lower than that of regular mortar. In addition, compared to the reinforced concrete slab alone, CS mortar was reduced by 5.5 dB and ES mortar was reduced by 4.6 dB, showing relatively excellent values. As for the floor impact sound pressure, the 84B type was similar at 63 Hz for CS mortar and general mortar at 67.3 dB, and the reduction compared to the reinforced concrete slab alone was 3.6 dB for CS mortar, 2.7 dB for ES mortar, and 2.7 dB for general mortar was reduced by 1.4 dB. By pouring mortar to compensate for the thickness of the reinforced concrete slab, the vibration acceleration level and floor impact noise were reduced, and when a heavy mortar using copper smelting slag fine aggregate was used, relatively excellent performance was found.

• Journal of the Korea Institute of Building Construction
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• v.13 no.3
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• pp.235-241
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• 2013

In this study, a mortar was produced using re-dispersible polymer powders that addresses the defects of aqueous polymer and improves the durability of cement mortar. Also, an attempt was made to examine the properties of polymer modified mortars using re-dispersible polymer powders by strength and durability tests between ordinary Portland cement mortars and polymer modified mortars mixed with aqueous dispersion. The test showed that strength and durability are improved considerably compared with ordinary Portland cement mortar, and the performance of aqueous polymer cement mortar was considerably improved. Accordingly, it is expected that high-quality prepackaged polymer modified mortars can be produced using re-dispersible polymer powders.

• 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 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 Institute of Building Construction
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• v.22 no.6
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• pp.597-606
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• 2022

This paper examined the effect of water repellent type and addition among various factors on the deicing performance of cement mortar surface according to incorporation. As a result, the compressive strength of the water repellentcement mortar compared to the cement mortar, and the compressive strength of the oligomer-based water repellent mortar was higher than that of the monomer-based water repellent. The contact angle of the water-repellent mortar was increased compared to the additive mortar, and the oligomer water-repellent agent compared to the monomer-based water-repellent. As a result of measuring the ice formation time of cement mortar due to the mixing of the water repellent, the ice formation was delayed until 25 minutes for mortar to which the water repellent was added. the measurement of the ice attachment load mortar without water repellent with water repellentwhen the water repellent was added to mortar, deicing performance was increased.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.1
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• pp.85-94
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• 2007

The EVA polymer is used as a modifier in the repair mortar, which contains various admixtures and mineral admixtures. It has been reported that the effect of polymer in cement mortar by the cement-polymer ratio only, but effect of admixtures over the polymer mortar was unknown. In this study, the fresh and mechanical properties of polymer cement mortar influenced by the range of admixtures(CSA expansive addictive, CSA accelerator, gypsum, silica fume) ratio were investigated.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.6
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• pp.80-87
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• 2015

In this study, several properties of mortars made with calcium aluminate cement (CAC) such as hydrated products, strength characteristics, absorption, surface electric resistivity and chloride ions penetration resistance were experimentally investigated. The properties of CAC mortars were compared to those of ordinary portland cement (OPC) mortars. From the test results, it was found that the main hydrated products for CAC mortars were of $C_2AH_8$ and $CAH_{10}$, while CH, ettringite and calcite for OPC mortars. The surface electric resistivity and chloride ions penetration resistance of CAC mortars were significantly beneficial compared to those of OPC mortars. However, it should be noted that the absorption properties of CAC mortars were negatively examined. Thus, it needs to have more study for the improvement of surface absorption of CAC matrices. In addition, the combined mixture of CAC and OPC were ineffective to improve some performances of mortars.

• 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 institute for structural maintenance and inspection
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• v.24 no.1
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• pp.67-73
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• 2020

In this study, the self-healing performance of mortar beams containing self-healing materials was evaluated through experiments. Normal mortar beams and self-healing mortar beams were used In the experiments. The self-healing performance was evaluated by comparing the mortar compressive strength, member strength, and self-healing effects of cracks. The experimental results showed that the compressive strength of mortar containing self-healing material was smaller than that of normal mortar, but the ratio of 118 days compressive strength to 28 days compressive strength was the same. The member strength tended to increase with increasing curing period. In normal mortar specimens, the member strength did not recover even if the curing period increased, but the strength of the self-healing mortar specimens tended to recover as reaction products were produced. The crack width tended to decrease after the healing periods in both specimens, but the reaction product was observed only in the self-healing mortar specimens.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.5 s.57
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• pp.133-141
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• 2009

50 year-old masonry buildings which had been constructed using lime mortar have caused lots of problems because of using different material, cement mortar, when they repair them. Also, there is little information on structural capacities and details of masonry buildings built using lime mortar. In addition, it is difficult to evaluate the structural capacities of the buildings which were often constructed by untrained labors. To preserve the original masonry construction, the study on their construction materials and methodologies has to be carried out. This paper provides basic information for establishing standard details of masonry works using lime mortar in order to overcome these problems when cultural properties are repaired or retrofitted. To do this, compression tests of lime mortar were preformed with the parameters of mixing ratios, mixing material, curing time and curing conditions etc. Based on the test results, the differences between lime mortar and cement mortar were specified and the structural characteristics of lime mortar were also presented in this paper.