This study evaluated the rheological behavior and compressive strength of two cementitious base mortar mixtures with different unit binder contents, water-to-binder ratios, and superplasticizer dosages according to the foam content. Two base mortar mixtures, designated as C500 and C600, with different unit binder contents, water-to-binder ratios, and superplasticizer dosages were prepared. The preformed foams were incorporated at 20%, 40%, and 60% of the base mortar volume. The air content, rheological properties, and compressive strength at 7 and 28d were measured and compared. The air content increased with the foam content. Mixtures containing up to 40% foam exhibited air contents close to the target foam volume immediately after mixing. At a foam content of 60%, the measured air content was lower than the target foam volume, indicating that part of the incorporated foam was not retained during mixing and testing. The flow resistance and compressive strength decreased with increasing foam content. At 28 d, the compressive strengths of the C600-F60 and C500-F60 mixtures were 5.6 MPa and 6.4 MPa, respectively. The 40% foam mixtures exhibited relatively high air retention immediately after mixing and reduced rheological parameters; however, their 28-d compressive strengths exceeded the 8.3 MPa limit specified for controlled low-strength materials (CLSM). The 60% foam mixture satisfied the CLSM strength criterion and could be applicable as a low-strength filling material for sewer pipeline voids. As this study compared two base mortar mixtures with different unit binder contents, water-to-binder ratios, and superplasticizer dosages, the observed differences should not be interpreted as an independent effect of the unit binder content.

ABSTRACT
1. 서론
2. 이론적 배경
    2.1. 저강도 유동성 충전재의 특성
    2.2. 기포 혼입 시멘트계충전재의 특성
    2.3. 자연섬유 혼입 시멘트계 재료의 특성
    2.4. 시멘트계 충전재의 레올로지 특성
3. 실험계획 및 방법
    3.1. 실험계획
    3.2. 사용 재료
    3.3. 배합설계
    3.4. 실험방법
4. 실험 결과
    4.1. 공기량
    4.2. 압축강도
    4.3. 레올로지
5. 결론
REFERENCES

• 전성일(한국건설기술연구원 도로교통연구본부 연구위원) | Jeon Sung-il
• 한상종(한국건설기술연구원 환경연구본부 수석연구원) | Han Sang-Jong
• 노재면(한국건설기술연구원 도로교통연구본부 연구원) | Roh Jae Myun
• 한승연(한국건설기술연구원 도로교통연구본부 수석연구원) | Han Seungyeon Corresponding author