非破壞檢査法에 따른 콘크리트 部材의 初期材齡狀態에 關한 實驗的硏究 = An Experimental Study on Early Age Condition of Concrete Members with Nondestructive Tests Technique

국문 초록 (Abstract)

비파괴검사법은 기존 건축구조물의 노후화와 자연재해로 인한 구조물의 손상정도를 평가할 수 있는 정밀진단이나 유지관리를 위한 정기점검에 대한 관심사가 증가하고 있는 추세에 중요하며 질적 향상이 불가피하고 특히 초기재령에 따른 콘크리트 부재의 상태평가는 더욱 중요하다. 건축구조물의 신속 정확한 진단을 수행하기 위해서는 응력파 기반 비파괴검사기
법의 장점을 이용한 복합 비파괴검사 기술의 개발이 절실하다. 2016년 9월에 발생한 이스라엘 텔아비브의 한 건설 현장에서 신축 중인 주차장 건물의 붕괴로 인한 인명피해는 콘크리트 구조물의 초기재령 압축강도에 대한 평가의 중요성을 반증해 준다. 이 현장은 붕괴되기 2개월 전 7월에도콘크리트 보가 붕괴되는 사고가 있었으나 초기 재령 상태에서의 콘크리트
압축강도 등 상태평가가 정확하게 이루어지 않아 사고를 미연에 방지하지 못한 것은 교훈으로 남는다.
콘크리트 구조물의 상태를 평가할 때, 시공 후 유지관리 시의 진단뿐만 아니라 시공 중의 품질관리를 위한 다양한 기법을 통한 압축강도 추정이 필요하다. 여기에서 대상 건축물에 손상이나 파괴를 주지 않고 건축물의
상태를 파악하기에 적합한 비파괴검사법을 이용한 진단기법이 주요 관심 사이며, 그 적용성 평가 관련한 많은 연구가 진행되고 있다. 본 연구의 목표는 콘크리트 부재의 초기재령 상태를 파악하기 위한 방법으로 비파괴검사법 중 하나인 초음파속도법과 충격반향기법을 적용하여 콘크리트의 압축강도와 콘크리트 기둥부재의 두께를 추정하고자 한다. 콘크리트 부재 실험체는 설계강도 24, 30, 40 MPa을 대상으로 재령 16, 20, 24, 48, 72, 120시간을 기준으로 6개의 재령에 따른 변수를 설정하여 90개의 모의부재를 제작하여 초기재령의 콘크리트 압축강도 추정과 콘크리트 기둥부재 두께 추정에 관한 실험을 실시하였다. 이로부터 도출된 초음파속도와 압축강도의 상관 관계식은 신축공사 현장에서 콘크리트 구조물의 초기재령 압축강도 추정을 할 수 있으며, 아울러 충격반향기법을 이용하여 콘크리트 기둥부재의 품질관리가 가능함을 확인하였다. 이상의 결과로부터 비파괴검사법은 콘크리트 구조물의 품질관리 기법으로서 그 효용성을 확인하였다.

목차 (Table of Contents)

• 표 목 차 ………………………………………………………………ⅲ
• 그 림 목 차 ………………………………………………………………ⅳ
• 사 진 목 차 ………………………………………………………………ⅴ
• 국 문 요 약 ………………………………………………………………ⅵ
• Ⅰ. 서 론 ·····································································································1
• 1. 연구의 배경 및 목적 ····················································································· 1
• 2. 연구방법 ··········································································································· 2
• Ⅱ. 이론적 고찰 ···························································································3
• 1. 기존문헌 고찰 ·································································································3
• 2. 초음파속도법 ···································································································3
• 5. 충격반향기법 ···································································································7
• Ⅲ. 실험 개요 ·····························································································10
• 1. 실험 계획 ·······································································································10
• 2. 실험 방법 ·······································································································12
• Ⅳ. 실험결과 비교 분석 ···········································································14
• 1. 콘크리트 압축강도 추정 ············································································· 14
• 2. 콘크리트 두께 추정 ····················································································· 35
• Ⅴ. 결 론 ·····································································································38
• 참고문헌 ······································································································39
• ABSTRACT ································································································42
• 감사의 글 ····································································································43