Material Properties of Repair Mortar Considering Accelerator Type and Curing Conditions

급결제 종류 및 양생조건을 고려한 보수용 모르타르의 재료특성

Abstract

In general, repair mortar is used to rehabilitate underground communities, but difficulties are encountered in the execution of long-term construction due to spatial co-operatives. In this study, the engineering properties of repair mortar according to the curing condition and accelerator type were reviewed. The results showed that the aluminate, alkali-free and calcium-aluminate precipitates in the water curing conditions showed higher compressive strength at the beginning of age than mortar specimens under air curing conditions, and increased. Especially in CA and AF test specimen with cement mineral quick setting, a large amount of ettringite products were observed compared with AL, thus reducing the pore volume and increasing the strength of the compound by micro-filling effect were found.

최근 구조물 보수보강 사례가 증가되고 있으나 보수용 모르타르의 속경성 부족에 의해 긴급공사의 어려움이 발생되고 있어 모르타르의 급결성을 증대시키고자 AL, AF, CA 급결제와 양생조건을 달리한 강도특성을 검토하였다. 그 결과 경화성상에 있어 CA 시험체가 가장 우수하였으며, 양생조건의 경우 재령 초기에서는 수중양생에서 압축강도가 다소 높아지는 경향을 보였으나 28일에서는 큰 차이가 없었다. 특히, CA 시험체에서 Ettringite생성물이 다량으로 관찰되고 있어, 광물계 급결제의 공극충진 효과에 의한 공극량 감소로 압축강도가 증가하는 것으로 판단된다.

Figure 1. Setting time of mortar

Figure 2. Compressive strength for mortar

Figure 3. 1-day strength increase ratio

Figure 4. 3-day strength increase ratio

Figure 5. Compressive strength for mortar

Figure 6. Adhesive strength for mortar

Figure 7. SEM image at 3 days (Air Curing, ×5000)

Figure 8. SEM image at 3 days (Water Curing, ×5000)

Figure 9. The effect of air curing on MIP results

Figure 10. The effect of water curing on MIP results

Table 1. Physical & chemical properties of URHC

Table 2. The main components of accelerators

Table 3. Experimental program

Table 4. Mix proportion of mortar