• Structural Engineering and Mechanics
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• 제67권6호
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• pp.579-585
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• 2018

Masonry walls are of a complex (anisotropic) structure in terms of their mechanical properties. The mechanical properties of the walls are affected by the properties of the materials used in wall construction, joint thickness and the type of masonry bond. The carried-out studies, particularly in the seismic zones, have revealed that the most of the conventional masonry walls were constructed without considering any engineering approach. Along with that, large-scale damages were detected on such structural elements after major earthquake(s), and such damages were commonly occurred at the brick-joint interfaces. The aim of this study was to investigate the effect of joint thickness and also type of mortar on the mechanical behavior of the masonry walls. For this aim, the brick masonry walls were constructed through examination of both the literature and the conventional masonry walls. In the construction process, a single-type of brick was combined with two different types of mortar: cement mortar and hydraulic lime mortar. Three different joint thicknesses were used for each mortar type; thus, a total of six masonry walls were constructed in the laboratory. The mechanical properties of brick and mortars, and also of the constructed walls were determined. As a conclusion, it can be stated that the failure mechanism of the brick masonry walls differed due to the mechanical properties of the mortars. The use of bed joint thickness not less than 20 mm is recommended in construction of conventional masonry walls in order to maintain the act of brick in conjunction with mortar under load.

• 공업화학
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• 제10권3호
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• pp.486-490
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• 1999

타일을 부착시키는 tile 전용 cement mortar가 갖추어야 하는 물성인 우수한 보수성, 작업성, open time, 처짐저항성과 타임접착강도 등을 향상시키기 위해 본 연구에서는 mortar에 첨가하는 혼화제들의 홉합비율을 달리하였을 때 나타나는 특성을 비교 분석하였다. Mortar의 보수성 효과를 주는 hydroxypropylmethylcellulose에 소량의 합성 starch을 첨가해 줌으로써 mortar는 보수성을 유지하면서 겉마름이 적게되었고, open time이 길어져 작업성이 향상되었다. 타일의 접착강도를 높이기 위해 polyacrylamide와 ethylenevinyl acetate을 첨가하여 mortar 자체 및 타일의 처짐을 줄였고, 바탕면과 타일과의 mortar 접착력을 증대시켰다. 이와 함께 melment의 첨가로 mortar에 유동성을 주어 작업성을 향상시켰다. 이들 첨가제의 필요량은 cement량에 대해 hydroxypropyl methylcellulose는 0.80~1.20%, starch 0.10~0.15%, polyacrylamide 0.001~0.015%, ethylenevinyl acetate 0.05~0.10% 및 melment 0.003~0.005%의 혼합비율일 때 tile cement mortar의 물성이 향상됨을 알 수 있었다.

• Computers and Concrete
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• 제21권6호
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• pp.705-715
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• 2018

This paper presents an experimentally investigation pertinent to the mechanical properties of rubberized mortar (RM) with styrene-butadiene rubber (SBR). The SBR were used with constant water-to-cement ratio of 0.485 and two different volume proportion of SBR particles were utilized as aggregates. One types of SBR particles with fineness modulus of 4.951 were utilized 0%, 10%, and 20% of aggregate volume. Effectiveness of SBR replacement ratio, curing and aging effect on the compressive strength, flexural strengths as well as load-displacement. Compressive and flexural strength of concrete were investigated at the end of 28-days and 56-days age. Obtained results demonstrated that utilization of SBR reduced the flexural strength of SBR mortar at the earlier curing age while SBR increased. Moreover, mechanical properties of mortar mentioned above were significantly affected by the water cure timing with an increasing proportion of the replacement level of SBR.

• International Journal of Concrete Structures and Materials
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• 제5권1호
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• pp.3-10
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• 2011

Theoretical models for prediction of the mechanical properties of cement mortar are developed based on the morphology and interactions of cement hydration products, capillary pores and microcracks. The models account for intermolecular interactions involving the nano-scale calcium silicate hydrate (C-S-H) constituents of hydration products, and consider the effects of capillary pores as well as the microcracks within the hydrated cement paste and at the interfacial transition zone (ITZ). Cement mortar was modeled as a three-phase material composed of hydrated cement paste, fine aggregates and ITZ. The Hashin's bound model was used to predict the elastic modulus of mortar as a three-phase composite. Theoretical evaluation of fracture toughness indicated that the frictional pullout of fine aggregates makes major contribution to the fracture energy of cement mortar. Linear fracture mechanics principles were used to model the tensile strength of mortar. The predictions of theoretical models compared reasonably with empirical values.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.193-196
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• 2003

In this paper, the experimental investigation for the setting properties of cement paste, the consistency and strength properties of mortar with steel furnace slag dust was performed and compared with those of cement paste and mortar with ground granulated blast furnace slag. When steel furnace slag dust was replaced with normal portland cement, setting time and flow value indicated to good results like as mortar with ground granulated blast furnace slag. However, mortar with steel furnace slag dust expressed to appreciably strength devaluation according to containing ratio, and did not indicate the pozzolanic reaction like as ground granulated blast furnace slag.

• 한국건축시공학회지
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• 제15권5호
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• pp.451-456
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• 2015

본 연구는 시멘트계 바탕 바름재에 사용되는 바닷모래를 대체하기 위한 재료로서 현무암 가공과정에서 발생되는 현무암 석분슬러지를 재활용하기 위해 현무암 석분슬러지를 사용한 경화모르타르의 특성(연도변화, 응결경화, 흡수계수, 건조수축, 그리고 부착강도 실험)을 평가하였다. 현무암 석분슬러지를 사용한 경화모르타르는 콘크리트 바탕 바름재에 사용되는 기존의 보통모르타르의 특성과 유사하거나 좀 더 향상된 성능을 보였다. 그러나, 현무암 석분슬러지를 사용한 경화모르타르는 보통 모르타르보다 재령 8~9일 이후 건조수축이 증가되었고 부착강도는 감소되었다. 그러나 현무암 석분슬러지를 사용한 경우, KS F 4716 '시멘트계 바탕 바름재'에서 요구하는 최소 품질 규준은 만족하였다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.291-296
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• 2007

We measured potential waveform of load, displacement, micro electric signal generated by rock and mortar fracture using PXI A/D Converter. The rock type used for measurement was used granite, limestone and sandstone, and mortar specimen. we made measuring equipment of physical properties to confirm basic information of physical properties, measured physical properties of rock engineering, electric resistivity and seismic velocity. Potential waveform system was built using PXI A/D Converter and measured potential waveform of load, displacement, micro-electric signal generated using this during uniaxial compressive test by the specimen finished such test of physical properties. Using the saturated rock and mortar specimen, micro electric signal increased, and It didn't increase a signal in dried rock and mortar specimen according as load and strain rate increases. But signal also increased in saturated or dried specimen in case of sandstone. It was possible to check the close correlation relationship the signal and fracture behavior by a compressive load as the signal of fracture position was increased bigger than the other position. It was also possible to check the correlation relationship between physical properties and micro geo-electric signal.

• Structural Engineering and Mechanics
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• 제63권3호
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• pp.317-327
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• 2017

The addition of different types of polymers such as SBR, VAE, Acrylic, etc. in concrete and mortar leads to an increase in compressive, tensile and bond strength and decrease in permeability of polymer modified mortar (PMM) and concrete (PMC). The improvement in properties such as bond strength and impermeability makes PMM/PMC suitable for use as repair/retrofitting and water proofing material. In the present study effect of addition of fluoropolymer on the strength and permeability properties of mortar has been studied. In the cement mortar different percentages viz. 10, 20 and 30 percent of fluoropolymer by weight of cement was added. It has been observed that on addition of fluoropolymer in mortar the workability of mortar increases. In the present study all specimens were cast keeping the workability constant, i.e., flow value $105{\pm}5mm$, by changing the amount of water content in the mortar suitably. The specimens were cured for two different curing conditions. Firstly, these were cured wet for one day and then cured dry for 27 days. Secondly, specimens were cured wet for 7 days and then cured dry for 21 days. It has been observed that compressive strength and split tensile strength of specimens cured wet for 7 days and then cured dry for 21 days is 7-13 percent and 12-15 percent, respectively, higher than specimens cured one day dry and 27 days wet. The sorptivity of fluoropolymer modified mortar decreases by 88.56% and 91% for curing condtion one and two, respectively. However, It has been observed that on addition of 10 percent fluoropolymer both compressive and tensile strength decreases, but with the increase in percentage addition from 10 to 20 and 30 percent both the strengths starts increasing and becomes equal to that of the control specimen at 30 percent for both the curing conditions. It is further observed that percentage decrease in strength for second curing condition is relatively less as compared to the first curing condition. However, for both the curing conditions chloride ion permeability of polymer modified mortar becomes very low.

• 콘크리트학회논문집
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• 제28권4호
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• pp.387-394
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• 2016

본 연구에서는 바잘트 섬유보강 콘크리트의 개발을 위한 일환의 기초적 연구로서, 바잘트 섬유 혼합에 따른 기초 품질 특성을 모르타르 수준에서 평가하였다. 실험에 사용된 모르타르 배합은 시멘트만을 사용한 배합과 플라이애시를 50% 혼합한 하이볼륨 플라이애시 배합을 사용하였으며, 비교하여 평가하였다. 실험결과, 플라이애시를 50% 혼합한 하이볼륨 플라이애시 모르타르는 시멘트만 사용한 모르타르보다 섬유 분산성을 향상시키는 효과가 있는 것으로 나타났으며, 섬유 뭉침현상이 상당히 감소되는 것으로 나타났다. 또한 플라이 애시를 50% 이상 다량 사용할 경우, 압축강도는 약 30%의 감소하는 것으로 나타났으며, 바잘트 섬유의 섬유 길이 및 혼합량은 역학적 특성보다 유동 특성에 더 큰 영향을 미치는 것으로 나타났다.

• 한국안전학회지
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• 제31권5호
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• pp.109-116
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• 2016

This study presents the results of experiments to investigate the effect of polymer type and curing temperature on the mechanical properties of polymer mortar. Setting time of two types of polymers, hardening-delayed polymer(HDP) and rapid hardening polymer(RHP), was tested to check the working time. Additionally, flexural strength, compressive strength, and splitting tensile strength was investigated for mortars using these polymers. From these results, it was confirmed that, irrespective to curing temperature, RHP mortar at the curing age of 24h develops the similar mechanical properties to maximum properties and HDP mortar is more sensitive to the curing temperature. In addition, it should be noted that RHP mortar and HDP mortar are suitable in winter and summer, respectively.