Journal of the Korean Geotechnical Society (한국지반공학회논문집)

Korean Geotechnical Society (한국지반공학회)
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Effect of Immersion and High Temperature on Shear Strength of Cemented Sand

수침 및 고온이 고결모래의 전단강도에 미치는 영향

  • 문홍득 (경상국립대학교 건설환경공과대학 건설시스템공학과) ;
  • 황금비 (경북대학교 공과대학 건설환경에너지공학부) ;
  • 김태헌 (경북대학교 공과대학 건설환경에너지공학부) ;
  • 박성식 (경북대학교 공과대학 토목공학과)
  • Received : 2023.05.26
  • Accepted : 2023.06.25
  • Published : 2023.07.31
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Abstract

This study investigates the impact of water immersion and high temperature on the shear strength of cemented sand through direct shear tests. Standard Jumunjin sand was used and cemented with binders, such as ultra-rapid hardening cement and an epoxy aqueous solution. The binder was mixed at concentrations of 4%, 8%, or 12%. Subsequently, cylindrical cemented specimens with a diameter of 64 mm and height of 25 mm were produced using compaction. The curing period was three days, and the specimens were cured under dry air, immersion, and heating conditions. The heating condition involved subjecting the immersed specimens to a microwave oven three times for three minutes to achieve an internal temperature of approximately 90℃. Regardless of the binder type, the cohesion of the cemented sand increased with higher binder content, whereas the internal friction angle exhibited a slight increase or decrease. Compared with ultra-rapid hardening cemented sand, epoxy-cemented sand displayed an average cohesion that was five times higher and an internal friction angle that was 10° higher. Overall, irrespective of binder type, the shear strength decreased during water immersion and increased during heating. Notably, the epoxy-cemented sand exhibited a three-fold increase in cohesion and a more than 20° increase in the internal friction angle during heating.

본 논문에서는 직접전단시험을 이용하여 수침이나 고온이 고결모래의 전단강도에 미치는 영향에 대해 연구하였다. 고결제로 초속경 시멘트와 에폭시 수용액을 사용하여 표준사인 주문진표준사를 고결시켰다. 고결제는 4, 8, 또는 12%로 혼합한 다음 다짐방식으로 직경 64mm, 높이 25mm의 원주형 고결 공시체를 제작하였다. 양생일은 모두 3일로 동일하며, 양생조건은 대기중 양생, 수침 및 가열 조건이다. 여기서 가열 조건은 수침한 공시체를 전자레인지로 3분씩 3회 반복하여 공시체 내부에 90℃ 정도의 고온을 발생시켰다. 고결제의 종류에 관계없이 고결제 함유량이 증가할수록 고결모래의 점착력은 증가하였으나, 내부마찰각은 약간 증가하거나 오히려 감소하였다. 초속경 시멘트 고결모래에 비해 에폭시 고결모래가 평균적으로 점착력은 5배, 마찰각은 10° 정도 높게 나타나 더 높은 강도를 보였다. 전반적으로 고결제의 종류에 관계없이 수침 시 전단강도는 감소하고 가열 시 전단강도는 증가하였다. 특히, 에폭시 고결모래의 경우 가열 시 점착력은 평균 3배, 내부마찰각은 20° 이상 증가하였다.

Keywords

Acknowledgement

본 연구는 정부(교육부)의 재원으로 한국연구재단의 지원을 받아 수행된 기초연구사업입니다(NRF-2021R1I1A3059731).

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