Journal of the Korean Geosynthetics Society (한국지반신소재학회논문집)

Korean Geosynthetics Society (한국지반신소재학회)
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Experimental Study on Evaluating Early-age Strength and Stiffness Characteristics of Controlled Low Strength Material

유동성 채움재의 조기 강도 및 강성 특성 평가를 위한 실험적 연구

  • Son, Dong Geon (School of Agricultural Civil & Bio-Industrial Engineering, Kyungpook National Univ.) ;
  • Jeong, In Up (School of Agricultural Civil & Bio-Industrial Engineering, Kyungpook National Univ.) ;
  • Kim, Dong-Ju (School of Civil, Environmental and Architectural Engineering, Korea Univ.) ;
  • Byun, Yong-Hoon (School of Agricultural Civil & Bio-Industrial Engineering, Kyungpook National Univ.)
  • Received : 2021.11.23
  • Accepted : 2021.12.21
  • Published : 2021.12.31
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Abstract

There are few attempts to estimate the strength and stiffness of controlled low strength material (CLSM) using existing field-testing methods. The objective of this study is to evaluate the resilient modulus of CLSM by using the Light Weight Deflectometer (LWD) and investigate the relationships between the resilient modulus from LWD and the unconfined compressive strength (UCS) and secant modulus of elasticity from unconfined compressive test. Five CLSMs with different mix designs are used to evaluate the flowability and the stiffening of the CLSM in the flow and Vicat needle tests, respectively. To evaluate the early strength and stiffness characteristics, unconfined compressive tests are performed using the CLSM specimens cured for 1 and 7 days. LWD tests are carried out to estimate the resilient modulus of the CLSM specimens. The experimental results show that for the curing time of 1 day, the UCS and secant modulus of elasticity generally increase with the fast setting mortar content (FC). The CLSM specimen with the highest FC shows the significant increase in the UCS and secant modulus of elasticity along the curing time. Overall, the resilient modulus for the curing time of 1 day increases with the FC, while that for the curing time of 7days decreases with an increase in the FC. From the results, the linear relationships between the resilient modulus and UCS and secant modulus of elasticity are established.

기존 현장시험법을 이용한 유동성 채움재의 강도 및 강성 특성을 추정하는 연구는 미미한 실정이다. 본 연구에서는 LWD를 이용하여 CLSM에 대한 강성 특성을 평가하였으며, 일축압축강도시험에서 도출되는 일축압축강도와 할선탄성계수에 대한 상관성을 분석하였다. 5종류의 배합비로 조성된 CLSM시료의 유동성 및 경화특성을 평가하기 위해 플로우시험, 응결시간시험을 수행하였다. 조기 강도 및 강성 특성을 평가하기 위하여, 양생 1일 및 7일이 경과된 시료를 이용하여 일축압축강도시험을 수행하였다. CLSM시료의 회복탄성계수를 추정하기 위하여 LWD 시험도 수행되었다. 실험결과, 양생 1일된 시료에서는 초속경 모르타르의 비율이 증가될수록 일축압축강도와 할선탄성계수가 동시에 증가하였으며, 초속경 모르타르의 비율이 가장 큰 시료에서 양생 7일 후 급격한 일축압축강도와 할선탄성계수의 증가를 보여주었다. LWD 시험결과, 양생 1일된 시료에서는 초속경 모르타르의 비율이 증가할수록 회복탄성계수가 증가되었으나, 양생 7일이 경과되면 초속경 모르타르의 비율이 증가할수록 회복탄성계수가 감소되는 경향이 나타났다. 상관성 분석결과, 일축일축압축강도와 할선탄성계수가 증가할수록 회복탄성계수도 증가되는 선형관계를 보여주었다.

Keywords

Acknowledgement

This work is supported by the Korea Agency for Infrastructure Technology Advancement(KAIA) grant funded by the Ministry of Land, Infrastructure and Transport (Grant 21CTAP-C164273-01).

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