콘크리트 도로포장의 손상은 차량의 이동에 의한 진동, 겨울철 제설제 사용, 동결융해 작용 등이 주요 손상원인으로 나타나고 있다. 이러한 손상을 해결하기 위하여 열화 원인에 능동적으로 대응하는 보수재료 및 방법이 적용되어야 하나, 일반적으로 단면복구, 부분보 수를 반복적으로 사용함으로써, 지속적인 열화 현상의 발생으로 도로포장의 기능을 상실하게 된다. 또한, 기존에 사용되고 있는 보수 재료 중 무기계 보수재료는 폴리머 모르타르, 에폭시수지 모르타르 등이 있다. 이러한 재료는 높은 압축강도를 가지고 있으나, 취성 및 부착력이 약한 단점을 나타내고 있다. 따라서 본 연구에서는 보통포틀랜드시멘트(Ordinary Portland Cement), 칼슘알루미네이트계 재 료인 칼슘설포알루미네이트(Calcium Sulfo Aluminate) 및 비정질 알루미네이트(Amorphous Calcium Aluminate)를 사용한 보수 모르타르의 압축강도 및 내동해성을 평가하였다. 보수 모르타르의 압축강도를 분석한 결과, 비정질 알루미네이트를 사용한 보수모르타르의 압축강 도가 보통포틀랜드시멘트 및 칼슘설포알루미네이트를 사용한 보수 모르타르보다 우수하게 나타나는 것을 확인하였다. 한편, 보수 모르 타르의 내동해성 평가는 ASTM C 666 A법에 준하여 실험을 진행하였다. 그 결과, 칼슘설포알루미네이트 및 비정질 알루미네이트를 적용한 보수 모르타르의 상대동탄성계수가 300사이클에서 약 90%이상으로 나타나 보통포틀랜드시멘트를 사용한 보수 모르타르보다 우수한 내동해성을 나타내었다. 따라서, 칼슘설포알루미네이트 및 비정질 알루미네이트를 적용한 보수 모르타르는 우수한 압축강도 및 내동해성을 나타냄으로써 도로포장의 보수재료로 사용이 가능할 것으로 판단된다.

PURPOSES : This study describes the experimental findings on the mechanical properties of calcium aluminate cement (CAC)-based repair mortars with or without natural cellulose fiber (NCF). Additionally, the effect of adding NCF to the reduction of fugitive dust in the CAC powder was examined. METHODS : To produce mortar, four different levels of NCF (0.0.5, 1.0, and 2.0% by binder weight) were adopted, and the water-binder ratio was fixed at 0.485. The flow, strength characteristics, absorption, and surface electrical resistivity of the mortars were measured at predetermined periods. Additionally, SEM observations were performed to examine the microstructural changes and hydrates formed on the 28 day-mortar samples. RESULTS : The addition of NCF led to a decrease in fugitive dust. Regarding the mechanical properties of the mortars, that with 0.5% NCF exhibited a better performance in terms of strength development and surface electric resistivity compared to those of other mortars. However, the addition of NCF was less effective in the enhancement of the absorption of mortars. Further, we discovered that the microstructures of the mortars with additional NCF were comparatively dense compared to those without NCF. CONCLUSIONS : The appropriate addition of NCF can enhance the performance of CAC-based repair materials. However, further studies on the durability of CAC with the addition of NCF are needed to determine the optimal mixture.

PURPOSES : Experimental findings pertaining to the mechanical properties of calcium aluminate cement (CAC)-based repair mortars incorporated with anhydrite gypsum (AG) are described herein. METHODS : To prepare the mortars, three different levels of AG were adopted and the ratio of water–cementitious materials was fixed at 0.50. For comparison, mortar composed of ordinary Portland cement was prepared. The fluidity, setting time, compressive and bond strengths, absorption and surface electric resistivity of the mortars were measured at predetermined periods. RESULTS : The incorporation of AG increases the fluidity but decreases the setting time of the CAC-based repair material system. However, the AG in the CAC mixes does not effectively enhance the compressive strength of the mortars owing to the decreased formation of CA hydrates, such as CAH10 and C2AH8. Meanwhile, the mortar with 10% AG shows excellence absorption. CONCLUSIONS : The mechanical properties of CAC based-mortars rely significantly on the amount of AG incorporated. However, further studies regarding the microstructure and durability of CAC-AG repair mortars must be conducted to obtain the optimal mixture.