PURPOSES : This study investigated an appropriate saw-cut time frame for jointed concrete pavements. Rectangular slabs (400–500 × 500 × 150 mm) were prepared for saw-cutting tests, and experimental specimens were made using different mixes (type I cement, slag, Fly ash, high early strength cement, etc.) and temperature curing conditions (10, 20, and 25 ℃ as well as variable field conditions). METHODS : A prototype saw-cut device was manufactured to avoid unwarranted joint cutting using uncontrolled saw-cut equipment. The setting times were determined using Proctor penetration resistance (PR) and Ultrasonic pulse velocity (UPV) tests. The setting times were converted to setting maturities. To link the setting time of the concrete with the initiation time for saw cutting, successive parallel cuts were performed on the rectangular slabs for all mixes. A series of saw-cutting attempts were made between the final setting time and the time when the raveling index (denoted by R) exceeded a value of 2. Reconstructed images of the saw-cut segments were then analyzed using ImageJ, which is a commonly used, open-source software tool. RESULTS : Considering the PR and UPV settings, the final setting of the PR test was adopted as the basis for the correlation curve. The saw-cutting maturity at R = 2 was correlated with the setting maturity of each mix and curing condition. CONCLUSIONS : The relationship between the saw-cutting maturity and setting maturity was represented by a lower limit line, based on the test results of this study. The coefficient of determination (R2) for the test was 0.74, indicating that the proposed PR test at the final setting and image-based techniques provided an optimal method by which to determine the saw-cut initiation time. Another upper limit line can be introduced by using the HYPERPAV software tool for any concrete mix under diverse curing conditions..

ABSTRACT
1. 서론
2. 응결 성숙도와 이미지 프로세싱을 이용한 줄눈절삭 시기 산정 개념
    2.1. 성숙도
    2.2. 초기 줄눈절삭 시기 판정을 위한 응결시간 측정
    2.3. 2-D 이미지 프로세싱을 통한 Raveling 지수 산정
3. 배합설계 및 시편 준비
    3.1. 콘크리트 배합설계
    3.2. 시편의 준비
4. 실험 결과 및 분석
    4.1. 응결시험 결과
    4.2. 줄눈 절삭실험 결과
    4.3. 이미지 프로세싱에 의한 줄눈 라벨링 분석
    4.4. 응결성숙도와 절삭성숙도의 관계
5. 결론
REFERENCES

• 오인석((주)일상컨설턴트 대표) | Oh Insuk
• 양성철(홍익대학교 건축공학과 교수) | Yang Sungchul Corresponding author
• 안태봉(우송대학교 철도건설시스템학과 교수) | Ahn Taebong