• 한국건축시공학회지
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• 제12권5호
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• pp.468-477
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• 2012

This study aimed to mix and test mortar incorporating activated Hwangtoh to improve the Hwangtoh brick bond strength of brick structures. To do this, the bond strength correlation of mortar was analyzed by means of materials and experiment factors and levels, and the optimum conditions were suggested after analyzing the physical properties of brick and the mix ratio of mortar and additive. Furthermore, the compressive strength and bond strength were found to be in inverse proportion, and in terms of the materials and mixing level, W/C ratio, substitution ratio of activated Hwangtoh, and fine aggregate grading were shown to have a considerable influence on the strength. In conclusion, the optimum mixing conditions to improve the bond strength are found to set W/C ratio at 65% and replacmenet ratio of activated Hwangtoh at 10%.

• 한국건설순환자원학회논문집
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• 제5권4호
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• pp.366-374
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• 2017

본 연구는 점토와 골재로 구성된 벽돌을 경화하는데 있어 효소 첨가제의 효과를 재료시험과 이미지 프로세싱을 통해 분석하였다. 벽돌의 강도와 밀도 시험에 사용한 벽돌 샘플의 점토/골재 중량비는 70/30, 60/40, 50/50, 40/60, 30/70이였으며, 최대 압축강도와 휨강도는 각각 5MPa와 1.25MPa으로 중량비 60/40에서 발현되었다. 또한 최대 건조단위 중량은 $2.073g/cm^3$으로 중량비 50/50에서 발현되었다. 시험 결과 전반적으로 벽돌의 강도는 효소를 첨가함으로 약 27% 향상되었다. 강도 향상을 위해서는 점토/골재 중량비 60/40, 밀도 향상을 위해서는 점토/골재 중량비 50/50에 효소를 첨가하여 벽돌을 경화하는 것이 효과적인 것으로 확인되었다. 효소 첨가 시 점토-골재 벽돌의 결합구조가 더 치밀해짐을 SEM-EDX 분석과 Matlab을 이용한 이미지 프로세싱을 통해 확인하였으며, 이를 통해 효소가 점토와 골재 간 결합구조를 형성하여 벽돌의 강도와 밀도를 향상시키는 효과가 있는 것으로 판단된다.

• Earthquakes and Structures
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• 제5권4호
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• pp.477-497
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• 2013

This paper reports extensive experimental study done to compare workability and bond strength of five different types of polymer-based bonding agents for reinforcing bars in pinning retrofit. In pinning retrofit, steel pins of 6 to 10 mm diameters are inserted into holes drilled diagonally from mortar joints. This technique is superior to other techniques especially in retrofitting historic masonry constructions because it does not change the appearance of constructions. With an ordinary cement paste as bonding agent, it is very difficult to insert reinforcing bars at larger open times due to poor workability and very thin clearance available. Here, open time represents the time interval between the injection of bonding agent and the insertion of reinforcing bars. Use of polymer-cement paste (PCP), as bonding agent, is proposed in this study, with investigation on workability and bond strengths of various PCPs in brick masonry, at open times up to 10 minutes, which is unavoidable in practice. Corresponding nonlinear finite element models are developed to simulate the experimental observations. From the experimental and analytical study, the Styrene-Butadiene Rubber polymer-cement paste (SBR-PCP) with prior pretreatments of drilled holes showed strong bond with minimum strength variation at larger open times.